Keywords : nanoparticles


Green Synthesis of ZnO and Ag-ZnO Nanoparticles using Macrotyloma Uniflorum: Evaluation of Antibacterial Activity

Raghavendra K. Sali; Malatesh S. Pujar; Shivaprasadagouda Patil; Ashok H. Sidarai

Advanced Materials Letters, 2021, Volume 12, Issue 7, Pages 1-7
DOI: 10.5185/amlett.2021.071645

In this work, using Macrotyloma Uniflorum leaves an affordable and eco-friendly, ZnO and Ag-ZnO metal oxide nanoparticles were reported. Ensuing ZnO and Ag-ZnO nanoparticles were characterized by UV–visible spectroscopy, FT-IR Spectroscopy, X-ray diffraction, Scanning Electron Microscopy with Energy Dispersive Spectroscopy, Transmission Electron Microscopy, and Dynamic Light Scattering. The green synthesized ZnO and Ag-ZnO nanoparticles comprise an average size of about 120.16 nm and 91.17 nm respectively. The minimum inhibitory concentrations (MIC) of these ZnO and Ag-ZnO nanoparticles and mixtures thereof, Ag-ZnO, were determined on B.subtilis, Streptococci and E.coli cultures. MIC and their antimicrobial activity were studied in vitro; both types of nanoparticles showed high antibacterial activity. Also, it has shown excellent results with MIC value of 62.5 µg/ml for antibacterial activity against ZnO and Ag-ZnO nanoparticles. The Ag-ZnO nanoparticles were shown better antimicrobial effect than the ZnO nanoparticles. So, we can strongly suggest these green synthesized nanoparticles as a potent agent for biological applications.

Influence of Manganese and Copper Doping on Structural and Optical Properties of Chromium Oxide Nanoparticles

Jagriti Behl; Raksha Saini

Advanced Materials Letters, 2021, Volume 12, Issue 3, Pages 1-5
DOI: 10.5185/amlett.2021.031613

Mn and Cu-doped Cr2O3 nanoparticles were prepared by the co-precipitation method followed by calcination at 400 0 C for 3h. These synthesized nanoparticles were characterized by Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy, and UV/Visible spectroscopy. SEM images showed the irregular and nearly spherical structure of the Undoped and doped Cr2O3 nanoparticles respectively. The particle size of obtained nanoparticles exhibits in the range of 30-60 nm.  X-ray diffraction study reveals at temperature 400 0 C, undoped and Cu-doped Cr2O3 nanoparticles exist in the crystalline phase and Mn-doped Cr2O3 nanoparticles exist in the amorphous phase. UV-Visible spectra have been used to determine the band gap of the synthesized nanoparticles. The optical band gap value has been calculated by using Tauc’s method and Kubelka Munk method. Results indicate band gap calculated by Kubelka-Munk method is higher (4.7, 4.5 and 4.32 eV) than Tauc’s method. (4.18, 4.0, 3.96 eV). It is also concluded the decrease in the band gap (in both Tauc’s and Kubelka Munk method) was observed by the addition of dopant.

Understanding of intriguing metal to semiconductor transition in Ni0.5Zn0.5Fe2O4 nanoparticulates

Pooja Y. Raval; Shrey K. Modi; Khayati G. Vyas; Priya L. Mange; Kunal B. Modi

Advanced Materials Letters, 2021, Volume 12, Issue 3, Pages 1-6
DOI: 10.5185/amlett.2021.031614

Temperature-dependent electrical transport characteristics of un-milled and high-energy ball-milled  samples (3 h (70 nm), 6 h (55 nm) and 9 h (45 mm)) of Ni0.5Zn0.5Fe2O4 spinel ferrite were explored. A well-defined metal to semiconductor transition exhibited by all the samples has been construed in view of direct and superexchange cationic interactions and delocalization to localization of charge carriers on increasing temperature. The peak temperature (Tmax) was found to shift towards a higher temperature side on milling principally governs by the lattice vibration scattering and intrinsic excitation. The crystallite size reduction, enhancement in strain and sudden decrease in the formation and octahedral site occupancy of Fe 2+ ions on milling found responsible for the prodigious rise (~ 250 times) in normalized resistivity values for the sample comminuted for 9 h. The spectrum of energies corresponds to charge trapping centers that cause small bump (3 h milled sample) and sharp cusp (9 h milled sample) for T>Tmax. These materials may be found suitable for thermal cutoff switching applications.

Nanotoxicological Assessments to Warranty the use of Functionalized Y2O3 Nanoparticles for Biomedical Applications

D. Chávez-García; K. Juarez-Moreno; R. Reyes; J. Barrera; G. A. Hirata

Advanced Materials Letters, 2020, Volume 11, Issue 12, Pages 1-9
DOI: 10.5185/amlett.2020.121583

This study is a summary of our results on synthesis, functionalization and biomedical application of luminescent lanthanide doped nanoparticles with Y2O3 as host lattice. The nanoparticles (NPs) studied were Y2O3 and Y2O3: Eu 3+ and they are water-monodispersed, synthesized by the sol-gel method and surface modified to be biocompatible with a silica shell. The NPs were conjugated with amine groups and folic acid to detect specific cancer cells. We carried out a complete nanotoxicological evaluation of NPs in HeLa and MCF-7 cancer cells and fibroblast (L929) cell line. Our results corroborate the bio- and hemo-compatibility of NPs. No in vitro inflammatory response mediated by macrophages was elicited and no genotoxic effect was scored by comet assay. Internalization of folic acid-functionalized NPs was detected by flow cytometry comparing the internal cellular complexity and the cytoplasmic localization of NPs was confirmed by confocal microscopy. We provide with more evidences to warranty the biosafety of down conversion nanoparticles based on Y2O3: Eu 3+ and functionalized with folic acid for further biomedical and bio-imaging applications.

Applications of nano-scale Cirrus DopantTM to improve existing coatings

See Leng Tay; Chris Goode; Wei Gao

Advanced Materials Letters, 2019, Volume 10, Issue 6, Pages 421-424
DOI: 10.5185/amlett.2019.2219

The use of ceramic nano-powders to create composite coatings is well known but is neither simple to industrialize nor environmentally friendly. Patented Cirrus Dopant™ technology from Cirrus Materials Science offers the performance advantages of nano-composite coatings without the implementation and process drawbacks. Cirrus Dopant™ technology is applicable to commercial baths for a large variety of electrolytic and electroless deposited coatings including Ni, Ni-P, Ni-B, Co-P, Au, Ag, Sn, and Zn-Ni. Successful application of the technology simply requires optimization of a specialized Dopant™ to the bath. This paper discusses the process and results for nano-doping commercially important coating baths.

Physical and mechanical properties of microwave absorber material containing micro and nano barium ferrite  

Hashem Al-Mattarneh; Mohamed Dahim

Advanced Materials Letters, 2019, Volume 10, Issue 4, Pages 259-262
DOI: 10.5185/amlett.2019.2226

The rapid development of electronic systems and telecommunications has resulted in a growing and intense interest in microwave electromagnetic absorber technology and microwave absorber materials. In this study, thermoplastic natural rubber barium ferrite composite was developed using micro and Nano barium ferrite filler. This paper presented the improvement of the mechanical properties of the thermoplastic natural rubber barium ferrite (TPNR-BF) composite when the size of barium ferrite filler changed from 3 um to 55 nm. TPNR was prepared as hosting material, and the barium ferrite with particle size 3 um was used as filler. Five samples of the composite were prepared with barium ferrite content range from 0% to 20% by an increment of 5%. The same procedure was used to prepare five samples using barium ferrite with a particle size of 55 nm. Physical and Mechanical properties of the composite were determined such as density, SEM, hardness, stiffness, tensile stress, and strain. Also, the magnetic properties and hysteresis diagram and SEM were evaluated for both composites barium ferrite types. The results indicate that all mechanical properties decline with the increasing BF content due to the increasing size of the weak interfacial zone between the polymer and the filler. This trend could be enhanced by replacing the micro barium ferrite with Nanosize barium ferrite. The level of improvement in mechanical properties increases at high filler content.

Effect of the substrate bias in diamond deposition during hot filament chemical vapor deposition: Approach by non-classical crystallization 

Jin-Woo Park; Kwang-Ho Kim; Nong-Moon Hwang

Advanced Materials Letters, 2018, Volume 9, Issue 9, Pages 638-642
DOI: 10.5185/amlett.2018.2082

The effect of the substrate bias on the diamond deposition was studied using a hot filament chemical vapor deposition (HFCVD) reactor. Both growth rate of diamonds and sp < sup > 3 /sp < sup > 2 ratio increased with increasing the substrate bias from – 200 V to + 45 V. At + 60 V where the DC glow discharge occurred, however, the data deviated significantly from the tendency. These results were explained by the new concept of non-classical crystallization, where a building block of diamond growth is a charged nanoparticle rather than an atom. Based on the previously reported experimental confirmation of the gas phase generation of negatively-charged diamond nanoparticles, the bias effect on the diamond deposition behavior could be consistently explained.

Synthesis and modelling of nanoparticles for chemical looping reforming  

Stefan Andersson; Paul Inge Dahl; Stephen A. Shevlin; Ingeborg-Helene Svenum; Yngve Larring; Julian R. Tolchard; Zheng Xiao Guo

Advanced Materials Letters, 2018, Volume 9, Issue 6, Pages 439-443
DOI: 10.5185/amlett.2018.1929

Experimental and complementary modelling studies on the potential use of iron oxide nanoparticles in chemical looping reforming processes have been performed. In order to avoid coarsening of the nanoparticles, and thereby loss of reactivity, at relevant process temperatures (700-900°C), the active metal oxide was embedded in an inert support material of lanthanum silicate. Micro reactor tests indicate that partial combustion occurs in reactions of reduced iron oxide with methane instead of pure reforming. Density Functional Theory and kinetic Monte Carlo calculations have been used to support and complement the experiments. The modelling supports efficient reactivity towards exposure of hydrogen, which is also observed experimentally. Reactivity towards methane is only tested for the fully oxidized state, Fe2O3, and not for the reduced oxide, giving results that are complementary to the experiments. Copyright © 2018 VBRI Press.

Nanoparticles-enabled low temperature growth of carbon nanofibers and their properties for supercapacitors

Rickard Andersson; Amin M. Saleem; Ioanna Savva; Theodora Krasia-Christoforou; Peter Enoksson; Vincent Desmaris

Advanced Materials Letters, 2018, Volume 9, Issue 6, Pages 444-449
DOI: 10.5185/amlett.2018.1948

Carbon nanostructures are of great interest for a variety of applications, but their current processing throughput limits their industrial full scale deployment. This paper presents a cost effective and simple fabrication process, where vertically aligned carbon nanofibers are grown using DC-PECVD at CMOS compatible temperatures from catalytic nanoparticles, spin-coated from stable polymer-nanoparticle colloidal suspensions. Two different catalysts, Co and Cu, are investigated by growing carbon nanofibers at temperatures ranging from 390°C to 550°C, using suspensions with various concentrations of nanoparticles. The length and morphology of the grown nanofibers are examined using SEM and the electrical properties are investigated using electrochemical measurements on samples arranged as supercapacitor devices. Vertically aligned CNFs are successfully grown from both types of catalyst. The Co-derived fibers are long and arranged in a denser carpet-like structure, while the Cu-derived fibers are shorter and in a sparser formation of free-standing individual fibers. All electrochemical measurements show typical supercapacitor behaviour even at high scan rates of 200 mVs -1 , with the fibers grown from Co showing great increase in capacitance over the bare chip reference device, including the samples grown at 390°C. 

Preparation of polymer nano-photocatalysts by using triton X-100 to improve performance of photocatalytic hydrogen generation

Yanyu Zhang; Palas Baran Pati; Haining Tian

Advanced Materials Letters, 2018, Volume 9, Issue 5, Pages 326-330
DOI: 10.5185/amlett.2018.1833

Organic semiconducting polymer nano-particles, as nano-photocatalysts for light driven proton reduction, have been prepared by using Triton X-100 as surfactant. The nano-photocatalysts prepared by Triton X-100 showed well dispersibility in water and no precipitation observed after photocatalysis. The effect of molecular weight and concentration on photocatalysis has been investigated, indicating that the particle size shows significant influence on photocatalytic performance. The sample with 100 µg/ml photocatalysts gave the best hydrogen evolution amount of 0.4 µmol/ml and apparent quantum yield of 1.3% at 450 nm.

Assembly and characterization of ZnO nanoparticles for Grätzel's solar cells  

Glécia V. S. Luz; Wang. S. Hui; Renata C. Roncoleta; Pedro H. O. Nogueira; Lourdes M. Brasil; Pilar Hidalgo

Advanced Materials Letters, 2018, Volume 9, Issue 4, Pages 284-290
DOI: 10.5185/amlett.2018.1599

This research aimed to build hybrid solar cells, based on Grätzel method. We used the Polyethylene Terephthalate (PET) polymer as a substrate containing a layer of Indium Tin Oxide (ITO). Films of ZnO nanoparticles (ZnO NPs) synthesized by Pechini Method, and four different dyes were tested: Congo Red (CR), Bromocresol Green (BG), Acridine Orange (AO) and a Ruthenium Complex (RC). ZnO NPs were analyzed by XRD, which generated peaks corresponding to hexagonal wurtzite crystalline structure. We also conducted analysis by UV–Vis. Spectroscopy and Transmission Electron Microscope (TEM). Rietveld analysis determined the crystal size of 115.23 ± 28.16 nm. The deposition of ZnO and dye thin films were made through spin-coating. The electrical properties of the formed films were characterized with Van der Pawn method. Efficiency in converting light in electricity under an OSRAM 20W light bulb was tested after the devices were built. The smaller sheet resistance results were obtained for material containing: PET/ITO/ZnO/CR and PET/ITO/ZnO/AO. As expected, the best open-circuit voltage (Voc) results reached were 64 and 73 mV to CR and AO, respectively. Therefore, the results demonstrated satisfactory interaction between the ZnO-Dye-Electrolyte layers.

Study of the properties of La-doped ZnS thin Films synthesized by Sol-gel method

Amel Tounsi; Djahida Talantikite-Touati; Hamid Merzouk; Hadjira Haddad; Roumaïssa Khalfi

Advanced Materials Letters, 2018, Volume 9, Issue 3, Pages 216-219
DOI: 10.5185/amlett.2018.1963

The thin layers of undoped ZnS and ZnS doped La with different concentrations (2, 4, 6, 8 and 10%) were deposited on glass substrates using sol-gel and dip-coating methods. The structural characterization of these samples was carried out by the  X-rays diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). UV-visible and Fourier Transform Infrared spectroscopy (FTIR) have been used to study the effect of dopant on the optical properties of ZnS doped La thin films. Atomic force microscopy images of the films have revealed homogeneous and granular structure and the SEM micrographies show deposit films with uniform and porous structure. The optical transmission spectra in the UV - visible range have shown that all the doped films present a good optical transmission in the visible domain.

Optical and structural characteristics of ZnO nanopowders for different preparation methods

Advanced Materials Letters, 2017, Volume 8, Issue 12, Pages 1193-1198
DOI: 10.5185/amlett.2017.1581

Zinc oxide (ZnO) nanoparticles (NPs) were synthesized by different methods known as Pechini and Sol-Gel. It was observed during the experiments significant differences comparing these methods as: particle size, time applied, crystallinity and chemical residues generated by-products. The NPs were analysed by X-ray diffraction (XRD), ultraviolet-visible (UV-Vis.) absorption and Raman spectroscopy techniques. X-Ray Difractograms showed peaks corresponding to hexagonal wurtzite crystalline structure. It was observed that NPs obtained by the Pechini showed better homogeneity and crystallinity; these presented average size of 115 nm. The NPs produced by Sol-Gel method showed crystallites with smaller average size of 8 nm. The band gap energy (Eg) obtained using UV-Vis for ZnO NPs synthesized by Pechini was 3.39 eV. Still, the results for Sol-Gel method with 5 and 10 hours of reactions were 3.53 eV and 3.55 eV respectively. Raman data obtained by Pechini and Sol-Gel Methods showed characteristics peaks. The obtained data confirmed the ZnO phase samples and the proportional relationship to the enlargement with the intensity of peaks E2 High ˜ 438 cm -1 , as evidenced by literature. These results lead to the applicability of both NPs in optoelectronic and fluorescent applications. 

Investigations of nanostructured three-phase-foams and their application in foam concretes – A summary

Christina Kr

Advanced Materials Letters, 2017, Volume 8, Issue 11, Pages 1072-1079
DOI: 10.5185/amlett.2017.1593

Recently, a new approach was developed and published which focuses on the preparation of inorganic foams and their application in foam concrete production. Through the incorporation of nanostructured pozzolans in the foam structure, so-called three-phase-foams show a higher stability than foams only based on surfactants. Due to pozzolanic hardening, shrinkage cracks were healed and reaction products can be observed. By implementation of nanotubes in the foam structure as nanoreinforcement, a further stabilization was reached. After incorporation of wet three-phase-foams in cement paste, foam concretes with improved mechanical properties were achieved. It was also shown that the pore size distribution was similar to the introduced three-phase-foams and also smaller pore sizes can be observed compared to foam concretes based on surfactant foams. Additionally, a specific shell-like pore structure was obtained and a theoretical model developed. This could be confirmed by investigations of the influence of the surfactant used on the formation and carbonation of calcium hydroxide. To further enhance the mechanical properties of foam concretes based on three-phase-foams, an UHPC (Ultra-high Performance Concrete) formulation has been applied. Resultant UHPC foam concretes showed dense packed borders, improved homogeneity related to the pore size distribution and enhanced mechanical properties. Furthermore, the UHPC approach was combined with nanoreinforcement. 

Polypyrrole-Pd nanocomposites modified gold electrode for electrochemical detection of ascorbic acid

Nitin R. Dighore; Suresh T. Gaikwad; Anjali S. Rajbhoj

Advanced Materials Letters, 2017, Volume 8, Issue 7, Pages 762-767
DOI: 10.5185/amlett.2017.6987

The fabrication of an electrochemical sensor based on polypyrrole-Pd nanocomposites modified gold electrode (PPy-Pd-AuE) and its electrodetection of ascorbic acid is described. The PPy-Pd nanocomposites were synthesized by chemical method and characterized by different techniques. The Pd nanoparticles incorporated with PPy were confirmed by x-ray diffraction, scanning electron microscope, elemental dispersive spectroscopy and transmission electron microscopy analysis. The electrochemical behavior of polypyrrole-Pd nanocomposites towards the electro catalytic oxidation of ascorbic acid was investigated by cyclic voltammetry, differential pulse voltammetry and square wave voltammetry. The observed cyclic voltammetry, differential pulse voltammetry and square wave voltammetry response depended linearly on concentration of ascorbic acid in the range of 100-1000 mM with correlation coefficients of R 2 =0.977, R 2 =0.980, R 2 = 0.990 and sensitivity 7.96 mA/mM.cm 2 , 0.70 mA/mM.cm 2 and 2.10 mA/mM.cm 2 respectively. The reproducibility of PPy-Pd-AuE electrode from CV, DPV and SWV were found to be 3.9%, 4.69% and 2.98 % respectively. These results indicate the PPy-Pd-AuE exhibited excellent platform and could be used for electrochemical determination of ascorbic acid. 

The freeze-thaw technique for exfoliation of graphite: A novel approach for bulk production of scroll-free graphene oxide sheets

Vishal S. Makadia; Lalit M. Manocha; Satish Manocha; Hasmukh L. Gajera

Advanced Materials Letters, 2017, Volume 8, Issue 3, Pages 262-264
DOI: 10.5185/amlett.2017.6407

A freeze-thaw technique is put forth as a novel approach to exfoliating graphene oxide sheets (GO-sheets) in aqueous media.  This method does not use shear force or high-temperature treatment at any stage. Avoiding these factors prevents scrolling and promotes defect-free synthesis of the graphitic planes.  The research shows how the freeze-thaw technique successfully exfoliates graphitic planes without producing scrolls or defective graphene oxide planes. Further, when compared to conventional exfoliation methods, it was found that the freeze-thaw technique increased the surface area significantly. 

Utilization Of Low-cost Activated Carbon From Rapid Synthesis Of Microwave Pyrolysis For WC Nanoparticles Preparation

Atikah Ali; Rubia Idris

Advanced Materials Letters, 2017, Volume 8, Issue 1, Pages 70-76
DOI: 10.5185/amlett.2017.6964

In this study, the low-cost activated carbon from pistachio shell waste was sought through experiments using rapid synthesis of microwave-induced pyrolysis. The effect parameters of activating agents and microwave power on the surface area and carbon yield were studied. The results revealed that, well-grown pore structures with the highest surface area (681.2 m 2 g -1 ) and the highest carbon yield (70.3%) were produced using K2CO3 as an activating agent and 600 W power level exposed to 15-minute irradiation. The activated carbon with the highest porosity (AC600) was subsequently utilized in the tungsten carbide (WC) preparation which employed a facile method of mechanical milling. Finally, a high-thermal treatment under inert conditions was performed to completely convert W into WC. The physicochemical properties of the catalyst were evaluated by N2 adsorption-desorption, XRD, FESEM and TEM. It was observed that, the tungsten carbide produced was small and uniform spherical nanoparticles with average diameters of 60 to 100 nm.  High porosity and high surface area of catalyst support were identified as factors leading to a homogeneous distribution of metal catalyst. Therefore, the nanoparticles of WC produced were attributed to activated carbon with high porosity (AC600) due to well distribution of the tungsten crystal phase.

Room Temperature Ferromagnetism In ITO And Ni Doped ITO

Seelam Harinath Babu; Shaik Kaleemulla

Advanced Materials Letters, 2016, Volume 7, Issue 11, Pages 891-896
DOI: 10.5185/amlett.2016.6391

To fabricate spintronics devices with easy of processing we require reliable dilute magnetic semiconductors (DMS) at room temperature. Here we report the development of DMS material based on Indium tin oxide (ITO) with optimal tin concentration ((In0.95Sn0.05)2O3). The ITO and Ni-doped ITO nanoparticles were synthesized in quartz tube under reduced pressure at elevated temperature. The stoichiometric samples were crystallined in cubic bixbyite structure with change in the unit cell volume with Ni doping and shown average particle size of 50 nm in electron micrographs. Estimated energy band gap of Ni-doped ITO is found to be 3.15 eV. The magnetic properties of materials revealed that optimal doping of Sn gives highest magnetization and further increase of doping with Ni 2+ ions in In 3+ sites lead to deterioration of ferromagnetism induced by Sn 4+ . The observed ferromagnetism is attributed to the localized ferromagnetic exchange interactions induced by spin polarized electrons trapped in oxygen vacancies. The deterioration of ferromagnetism is attributed to excess anionic vacancies created by Ni doing and promotion of antiferromagnetic exchange with increase of Ni 2+ ion concentration as evidenced from magnetic hysteresis loop at 100 K.

Electronic Structure Study And Dielectric Properties Of Amorphous ZrO2 And HfO2

Aditya Sharma; Shalendra Kumar;Hyun-Joon Shin; Mayora Varshney; Sejun Kang; Jaeyoon Baik; Tae-Kyun Ha; Keun-Hwa Chae

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 17-22
DOI: 10.5185/amlett.2016.6136

ZrO2 and HfO2 powder samples were prepared by using the chemical precipitation method and subsequent annealing. Crystal structure, local electronic structure and dielectric constant of amorphous and crystalline powders of ZrO2 and HfO2 have been examined using the synchrotron X-ray diffraction, O K-edge X-ray absorption spectroscopy, Zr 3d and Hf 4f core-level X-ray photoelectron spectroscopy and temperature dependent dielectric measurements, respectively. Amorphous ZrO2 and HfO2 powders exhibit a local tetragonal structure, with mixed +3 and +4 valence states of Zr and Hf ions, and demonstrated the high dielectric performance. After the heat treatment, the tetragonal phase transforms into the monoclinic phase with dominant +4 valence state of Zr and Hf ions and the larger sized ZrO2 and HfO2 nanoparticles exhibited low dielectric constant. The manifestation of high dielectric constants in the amorphous ZrO2 and HfO2 samples is because of the hopping of electrons between the Zr +3 -Zr +4 and Hf +3 -Hf +4 networks. 

Formation And Stabilization Of ZnO Nanoparticles Inside MCM-48 Porous Support Via Post-synthetic Organometallic Route

Mahuya Bandyopadhyay; Hermann Gies; Wolfgang Gr

Advanced Materials Letters, 2015, Volume 6, Issue 11, Pages 978-983
DOI: 10.5185/amlett.2015.5963

The interpenetrating 3-dimensional channel system of silica MCM-48 has been selected for the deposition of ZnO nanoparticles. The post-synthetic organometallic route was employed to load the mesoporous silica with ZnO-precursor molecule. Calcination of the composite transformed the organometallic sorbate to the corresponding metal oxide. X-ray powder diffraction, N2-Adsorption and TEM measurement have supported the efficient loading and growth of ZnO particles in the channels of mesoporous silica matrix. EXAFS analysis (ZnK-edges) also complemented the metal uptake. Presence of nano-dispersed and nanosized ZnO particles confined by the mesoporous pore system was established by TEM and EXAFS analysis.

Investigations On Multiferroic, Optical And Photocatalytic Properties Of Lanthanum Doped Bismuth Ferrite Nanoparticles

Manpreet Kaur; K. L. Yadav; Poonam Uniyal

Advanced Materials Letters, 2015, Volume 6, Issue 10, Pages 895-901
DOI: 10.5185/amlett.2015.5861

Single phase Bi1-xLaxFeO3 nanoparticles have been successfully synthesized with varied concentration (0.0 ≤ x ≤ 0.2) for the photocatalytic degradation of an industrial dye. The room temperature X-ray diffraction (XRD) pattern of La 3+ doped BiFeO3 nanoparticles reveals the structural phase transition from rhombohedral (R3c) to orthorhombic (Pnma) at x=0.1, which is further analyzed via Rietveld refinement. The La 3+ doped BiFeO3 nanoparticles have much negative enthalpy of formation (ΔHf) than undoped BiFeO3. The particle size gradually decreases from ~132 to ~68 nm with La 3+ doping. Magnetic and ferroelectric transition temperatures are found to be slightly shifted towards room temperature upto x= 0.1 and then higher temperature side which could be attribute to the particle size effect. All compositions presented weak ferromagnetic ordering, which indicates that the La 3+ substitution in the BiFeO3 matrix released the latent magnetization. The increase in the energy band gap from 2.045 to 2.658 eV with cutoff wavelengths 639.58 and 513.061 nm for x=0.0 and 0.2 respectively, increases the visible light efficiency of photocatalytic activity in La 3+ doped BiFeO3 samples. The photodegradation efficiency of La 3+ doped BiFeO3 for azo-dye RB-5 is observed to be ~27% higher as compared to the undoped BiFeO3 (43% photodegradation efficiency), which makes it suitable for visible-light responsive photocatalysis for photocatalytic applications.

Electrospun Self-assembled ZnO Nanofibers Structures For Photocatalytic Activity In Natural Solar Radiations To Degrade Acid Fuchsin Dye

Ashish Gupta; Deoram V. Nandanwar; Sanjay R. Dhakate

Advanced Materials Letters, 2015, Volume 6, Issue 8, Pages 706-710
DOI: 10.5185/amlett.2015.5834

Zinc oxide (ZnO) nanoparticles, self-assembled in the form of one dimensional ZnO nanofibers were synthesized using electrospinning technique from solution of polyvinyl alcohol (PVA) and zinc acetate followed by calcination at 600°C in oxidizing environment. Scanning Electron Microscope (SEM) analysis demonstrates that morphology of ZnO nanofibers having rough surface and corresponding Energy Dispersive Spectrometry (EDAX) confirmed the Zn: O atomic ratio approximately in 50:50. Transmission electron microscopy (TEM) images clearly demonstrate the rough morphology is due to the self-assembling of ZnO nanoparticles having diameter approximately 50nm. X-ray Diffraction (XRD) reveals the polycrystalline structure and Raman spectra show some shifts in phonon modes. The PL graph show exceptional emission at 342nm due to band-band transition. Under solar radiations as produced ZnO nanofibers degrades the 99% of 25ppm acid fuchsine which proven through UV spectra when compared to blank dye solution. This shows that natural solar radiations are sufficient to excite theses self-assembled high surface area ZnO nanofibers to show its photocatalytic activity.

Erbium Induced Raman Studies And Dielectric Properties Of Er-doped ZnO Nanoparticles

C. Jayachandraiah; G. Krishnaiah

Advanced Materials Letters, 2015, Volume 6, Issue 8, Pages 743-748
DOI: 10.5185/amlett.2015.5801

Pure and erbium (1.30, 1.79, 2.83 and 3.53 at. %) doped ZnO nanoparticles are synthesized by wet chemical co-precipitation method. The synthesized samples are characterized by powder X-ray diffraction (XRD), energy-dispersive analysis of X-rays (EDAX), transmission electron microscopy (TEM), Raman spectroscopy, UV–visible diffusion reflectance spectroscopy (DRS) and LCR Impedance spectroscopy. The XRD measurements confirmed the hexagonal wurtzite structure of all samples and size of the particle is found to be decreased with Er content. TEM images show spherical shape with more agglomeration in Er doped ZnO nanoparticles. Raman spectra confirmed the hexagonal wurtzite structure of pure and Er doped ZnO nanoparticles with E2 (high) mode at 438 cm -1 and presence of other possible defects. UV visible DRS shows decrease in the band gap with increasing Er 3+ in ZnO host. Dielectric constant, dielectric loss factor and ac conductivity properties were decreased with Er dopant in tune with Maxwell -Wagner principle and surface-orientation polarizations.

Photoluminescence And Photoconductivity Of Ni Doped Titania Nanoparticles

Anand Kumar Tripathi; Mohan Chandra Mathpal; Promod Kumar; Vivek Agrahari; Manish Kumar Singh; Sheo Kumar Mishra; M. M. Ahmad; Arvind Agarwal

Advanced Materials Letters, 2015, Volume 6, Issue 3, Pages 201-208
DOI: 10.5185/amlett.2015.5663

The Ni doped titania nanostructures were synthesized by sol-gel method followed by calcination at 400°C for one hour. The optical band gap for these nanostructures indicates the red shift. The doped TiO2 nanostructures are spherical in shape. The pure TiO2 exhibits all the possible emission bands while Ni-doped TiO2 nanoparticles show blue-green emission bands. The results suggest that Ni2+ replace some Ti 4+ in TiO2 lattice with tensile strain while TiO2 remained in the form of anatase phase, reduces its band gap energy. The synthesized TiO2 exhibits enhanced photoconducting properties. The work suggest that the titania based materials can have potential applications in photovoltaics, optoelectronic devices and photoconductors in replacement of expansive materials by controlling the compositions and morphology of the nanostructures.

Effect Of Synthesis Time On Structural, Optical And Electrical Properties Of CuO Nanoparticles Synthesized By reflux Condensation Method

N. Bouazizi; R. Bargougui; A. Oueslati; R. Benslama

Advanced Materials Letters, 2015, Volume 6, Issue 2, Pages 158-164
DOI: 10.5185/amlett.2015.5656

CuO nanopowder oxide was synthesized by reflux condensation method without any surfactants or templates, using copper nitrate in deionized water and aqueous ammonia solution. The structural, optical and electrical properties of the sample were investigated using X-ray diffraction (XRD), FT-IR, UV–visible spectroscopy and impedance spectroscopy measurements. The X-ray diffraction patterns revealed that CuO nanoparticles (NPs) was formed in pure monoclinic phase and good crystalline quality, whose NPs sizes were of the order 25 nm which an average size can be tailored by the synthesis time. FT-IR spectra of CuO NPs used to detect the possible adsorbed species on the CuO materials. In addition, the peaks at 529 and 604 cm-1 correspond to the characteristic stretching vibrations of Cu-O bond in the monoclinic CuO. The optical absorption property has been determined by UV–visible Spectroscopy in the wavelength range of 200–800 nm which indicate the energy gap (Eg). As result, Eg increases with increasing the synthesis time from 2.72 to 1.87 eV. The complex measurement has been investigated at room temperature, and in the frequency range 40 Hz–100 kHz, showing that Nyquist plots (Z' versus Z'') are well fitted to an equivalent circuit model which consists of a parallel combination of a bulk resistance Rb and constant phase elements CPE. On the other hand, the capacitance and the conductance of CuO NPs have a proportional relationship to the charge transfer and the surface electrode-pallet. These properties make these materials very promising electrode.

Green Synthesis Of Gold Nanoparticles From The Leaf Extract Of Nepenthes Khasiana And Antimicrobial Assay

B.S. Bhau; Sneha Ghosh; Sangeeta Puri; B. Borah; D.K. Sarmah; Raju Khan

Advanced Materials Letters, 2015, Volume 6, Issue 1, Pages 55-58
DOI: 10.5185/amlett.2015.5609

Synthesis of nanoparticles from various biological systems has been reported, but among all, biosynthesis of nanoparticles from plants is considered as the most suitable method. The use of plant material not only makes the process eco-friendly but also the abundance makes it more economical. The aim of this study was to investigate the ability of this plant to synthesis gold nanoparticles and study the properties of the nanoparticles thus produced. Antimicrobial activity and medicinal values of Nepenthes khasiana fascinated us to utilize it for biosynthesis of gold nanoparticles. The synthesized gold nanoparticles were characterized by UV-vis spectrophotometry, Scanning Electron Microscopy, X-ray Diffraction, Fourier Transform Infra-red Spectroscopy and Transmission Electron Microscopy. Different time intervals for the reaction with aqueous chloroauric acid solution increase in the absorbance with time and became constant giving a maximum absorbance at 599.78 nm at three hours of incubation. The results from XRD, TEM and SEM supports the biosynthesis of triangular and spherical shaped Gold nanoparticles between 50nm to 80 nm. In this study, the antimicrobial property of the AuNPS was exploited against human pathogenic micro-organisms. The results of TEM, SEM, FT-IR, UV-VIS and XRD confirm that the leaves extract of N. Khasiana can be used to produce Gold nanoparticles with significant amount of antimicrobial activity.​

Electrical And Polarization Behaviour Of Titania Nanoparticles Doped Ferroelectric Liquid Crystal

Swadesh Kumar Gupta; Dharmendra Pratap Singh; Rajiv Manohar*

Advanced Materials Letters, 2015, Volume 6, Issue 1, Pages 68-72
DOI: 10.5185/amlett.2015.5614

The present study focuses on the effect of anatase TiO2 (titania) nanoparticles (NPs) on conductivity and polarization in a ferroelectric liquid crystal (FLC). Different dielectric and electro-optical measurements have been conducted to explore the charge transportation and polarization mechanism in titania NPs doped FLC system. Doping of titania NPs show reduced dc conductivity of doped LC system attributed to the trapping of free charges by titania NPs at its surface. Polarization has been found to increase at low fields indicating reduction of field screening effect in doped FLC system. Optical response of the doped FLC system has been improved due to decreased intervention of ionic charges particularly at small electric fields. The present study will be helpful in minimizing the slow response problems and the grey level shift in liquid crystal devices which arise due to ionic effects.

Effective Antimicrobial Filter From Electrospun Polyacrylonitrile-silver Composite Nanofibers Membrane For Conductive Environments

Anisha Chaudhary; Ashish Gupta; Rakesh B. Mathur; Sanjay R. Dhakate

Advanced Materials Letters, 2014, Volume 5, Issue 10, Pages 562-568
DOI: 10.5185/amlett.2014.572

Electrospun nanofibers based antimicrobial filter were examined for their capability to build conductive environment. An antimicrobial agent, silver nitrate (AgNO3), was added to the nanofibers membrane for its ability to prevent growth of microorganisms over the filter media. In this direction in the present investigation the different fractions of silver nanoparticles were in-situ synthesized in PAN solution and then polyacrylonitrile (PAN)-silver composite nanofibers membrane filter was prepared by electrospinning technique. The resultant solution and PAN-silver composite nanofibers was characterized by UV–visible spectroscopy, scanning electron microscope, atomic force microscope and X-ray diffraction. Antibacterial property of PAN silver composite nanofibers were investigated against gram positive Staphylococcus aureus and gram negative Escherichia coli microorganisms. The formation of clear zone suggests that composite nanofibers containing silver nanoparticles show strong antibacterial activity and it increases with increasing silver content in the composite nanofibers. The PAN-silver composite nanofibers sheet was also examined for filtration of microorganisms and dust particles. It was observed that PAN-silver composite nanofibers filter proven to be an excellent filter for creating microorganism and dust free hygienic environment. Thus electrospun PAN nanofibers filters containing an antibacterial agent can be a promising solution for effective microorganism filtration from indoor air in hospitals or other places which are more prone to bacterial infections.

Synthesis Of Porous Titania And Its Application To Dye-sensitized Solar Cells

Ammar Elsanousi; Kamal Khalifa Taha; Nazar Elamin

Advanced Materials Letters, 2013, Volume 4, Issue 12, Pages 905-909
DOI: 10.5185/amlett.2013.5472

Nanocrystalline porous titania with rutile and anatase bi-phase structure has been fabricated by the sol-gel method without the introduction of any surfactant, using tetrabutile titanate as precursor. The porous material was integrated as an electrode in a dye-sensitized solar cell as an electrode and its photoelectrical parameters were measured. Experimental measurements showed that the cell exhibits higher values of short-circuit current density and overall conversion efficiency compared to P25 (typical commercial titania powder) cells. The overall conversion efficiency of both samples was calculated to be 2.81 and 1.57 for the prepared and commercial (P-25) sample respectively. This drastic increase in the conversion efficiency of the prepared sample was attributed to its high surface area and porous structure, allowing more sensitizer dye to be chemically anchored in the electrode and, as a consequence, improved the light harvesting drastically. These results indicate that it is possible to achieve commendable conversion efficiencies using porous bi-phase titania.

Dielectric Relaxation And Electrical Properties Of ZnO1-xSx nanoparticle dispersed Ferroelectric Mesophase

Dharmendra Pratap Singh; A. C. Pandey;Rajiv Manohar; Swadesh Kumar Gupta

Advanced Materials Letters, 2013, Volume 4, Issue 7, Pages 556-561
DOI: 10.5185/amlett.2012.11463

The ZnO1-xSx, metal oxide nanoparticles (MNPs) have been dispersed in the ferroelectric mesophase (FLC). The electrical properties and dielectric relaxation processes have been studied for the MNPs dispersed FLC system with the variation of frequency and temperature. The dielectric measurements have been carried out in the frequency interval of 1Hz-10MHz to investigate different relaxation processes. Three different relaxation modes have been observed in the case of the pure FLC at frequency 2.5Hz, 20Hz and Goldstone relaxation mode at 200Hz. The addition of MNPs, suppressed the relaxation mode observed at 2.5 Hz for the pure FLC whereas the relaxation mode observed at 20 Hz is shifted to the higher frequency side. The conductivity and the relative permittivity of the pure FLC have also been enhanced by the dispersion of the MNPs. The present investigation establishes the MNPs as an intelligent material to tune the relaxation process and to enhance the conductivity of the materials.

Effect Of Electron Beam Irradiation On Photoluminescence Properties Of Thioglycolic Acid (TGA) Capped CdTe Nanoparticles

Chethan Pai S; L. M. Kukreja;Ganesh Sanjeev; M. P. Joshi; S Raj Mohan; T. S. Dhami; Jayakrishna Khatei; K S Koteshwar Rao

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 454-457
DOI: 10.5185/amlett.2012.ib.113

Irradiation effects of 8 MeV electrons on photoluminescence properties of thioglycolic acid (TGA) capped CdTe quantum Dots (QD) are presented. Steady-state and time-resolved photoluminescence (PL) spectroscopy were used for anlayzing PL properties of both irradiated and unirradiated quantum dots. The Photoluminescence peak, intensity and lifetimes were found to vary with dose. At lower doses (up to 5kGy), they were found increasing and at higher doses (up to 20kGy) it decreased. The PL peak position also shifted toward low energy and broadened with increase of dose. Initial increase in PL intensity (upto 5kGy) is due to passivation of surface defects leading to high radiative recombination. At higher doses the damage of capping layer takes place leading to aggregation effects.

Characterization And Evaluation Of Nano-sized α-Fe2O3 pigments synthesized Using Three Different Carboxylic Acid

M. F. R. Fouda; M. A. Wahba;M. F. El-Shahat; M. B. ElKholy; S. A. Mostafa; A. I. Hussien

Advanced Materials Letters, 2013, Volume 4, Issue 5, Pages 347-353
DOI: 10.5185/amlett.2012.9421

AnchorUniform α-Fe2O3 nanoparticles have been prepared by sol gel method using three different carboxylic acids citric, tartaric and succinic acids as chelating agents. The structure and morphology of α-Fe2O3 samples were characterized using (TGA), (XRD), (TEM), (IR) and diffuse reflectance spectroscopy (DRS) techniques. The TEM images revealed that in all cases, the products consisted of 18–25 nm sized particles close to the average crystallite size calculated from XRD data by the Scherrer’s formula. Among the prepared samples, the sample that has the best thermal stability, the smallest particle size and the reddest color is that prepared in presence of tartaric acid. The prepared samples were evaluated as pigments according to the American Society for Testing and Materials (ASTM) standard methods for evaluation of pigments.

Fabrication of ZnS:Cu/PVA Nanocomposite Electroluminescence Devices for Flat Panel Displays

Sakshi Sahare; S. J. Dhoble; Pranav Singh; Meera Ramrakhiani

Advanced Materials Letters, 2013, Volume 4, Issue 2, Pages 169-173
DOI: 10.5185/amlett.2012.6374

The powder of ZnS nanoparticles were prepared by using chemical deposition technique and characterized by electroluminescence techniques are reported in this paper. The estimated size of ZnS:Cu nanocrystals with change in capping agent concentration and ZnS:Cu/PVA nanocomposites and no effect of doping has been observed on the absorption spectra. Electroluminescence (EL) investigations of nanocrystalline powder as well as nanocomposites, it is seen that Log B vs. 1/V curve is a straight line with negative slope. This indicates that EL is produced by acceleration-collision mechanism. The detail EL characterization and application in display devices of these materials are reported in this paper.

Improvement In Ferromagnetism Of NiFe2O4 nanoparticles With Zn Doping

Sukhdeep Singh; R.K. Kotnala;Kuldeep Chand Verma; Manpreet Singh; N.K. Ralhan

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 504-506
DOI: 10.5185/amlett.2012.icnano.226

Structural, microstructural, infrared analysis and magnetic properties of Ni1-x ZnxFe2O4 (NZ) [x = 0.30 (NZ30), 0.35 (NZ35) and 0.40 (NZ40)] nanoferrites have been thoroughly studied. These NZ nanoferrites were synthesized by chemical combustion route and annealed at 500 o C for 5h. Fourier transform infrared (FTIR) spectra of these samples were used to identify formation of Ni-Zn spinel ferrites. These FTIR results show two characteristic absorption bands corresponding to M-O intrinsic stretching vibrations at the tetrahedral site and octahedral-metal stretching around 570-550 cm -1 and 450-435 cm -1 , respectively. The X-ray diffraction shows the polycrystalline with spinel phase of these ferrites. The value of lattice constant a(Å) = 8.370, 8.371 and 8.380 respectively, for NZ30, NZ35 and NZ40 which are consistent with that reported for pure NiFe2O4. The average particles size is measured using Debye-Scherer’s relation which lies in the range of 25-65 nm. Transmission electron microscopy measured average grain size is 26, 41 and 66 nm, respectively for NZ30, NZ35 and NZ40 samples. The magnetic measurement shows saturation magnetization (Ms) of 67.63, 74.97, 80.63 emu/g, remanent magnetization (Mr) 20.01, 25.30, 25.30 emu/g and coercive field (Hc) 154.12, 154.13, 154.11 O e , respectively for NZ30, NZ35 and NZ40. Highest saturation magnetization with Zn doping has been observed in the case of NZ40.

Low Molecular Weight Palmitoyl Chitosan: Synthesis, characterization And Nanoparticle Preparation

Yogesh M. Choudhari; Sachin V. Detane; Sushant S. Kulthe; Chandrakant C. Godhani; Nazma N. Inamdar; Seema M. Shirolikar; Lalit C. Borde; Vishnukant K. Mourya

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 487-492
DOI: 10.5185/amlett.2012.icnano.203

Low molecular weight chitosan (LMWC) exhibits higher water solubility and produces nanoparticles of fairly low particle size. However, poor drug loading and shorter circulation time in body limits its application in preparation of nanoparticles. Acylation of LMWC ensures extended circulation of nanoparticles in body and hence enhanced bioavailability of the drug. We therefore synthesized the acylated LMWC using palmitoyl chloride and confirmed its synthesis by FTIR and NMR spectroscopy. The nanoparticles of LMWC and low molecular weight palmitoyl chitosan (LMWPC) were prepared by miniemulsion and chemical crosslinking method using glutaraldehyde and 5-fluorouracil (5FU) as a model drug. The nanoparticles were evaluated for particle size, zeta potential, morphology, drug loading and drug release. TEM analysis revealed nanosize and spherical nature of the particles. The palmitoyl chain of LMWPC increased particle size from 83.2±2.5 nm to 93.4±3.2 nm whereas zeta potential of nanoparticles decreased from 12.5±2.2 mV to 4.2±1.1 mV due to diminished amino groups of LMWPC as a result of acylation. The drug loading in nanoparticles was increased from 13.8±0.95% to 30.2±1.9%. LMWC showed 80±2.08% as maximum drug released in 10 h while only 52.3±2.14% was released in 24 h for LMWPC. Hence, LMWPC nanoparticles ensure increased drug loading capacity and sustained drug release profile without significant change in particle size.

Development And Characterization Of Atorvastatin Calcium Loaded chitosan Nanoparticles For Sustain Drug Delivery

Afifa Bathool; Gowda D. Vishakante; Mohammed S. Khan; H.G. Shivakumar

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 466-470
DOI: 10.5185/amlett.2012.icnano.153

The aim of this study is to formulate and characterize atorvastatin loaded chitosan loaded nanoparticles prepared by solvent evaporation method for sustained release. Low oral bioavailability of Atorvastatin calcium (14%) due to an extensive high first-pass effect makes it as prime target for oral sustained drug delivery. Weighed amount of drug and polymer were dissolved in suitable organic solvent DMSO and 2% acetic acid as an organic phase. This solution is added drop wise to aqueous solution of Lutrol F68 and homogenized at 25000rpm followed by magnetic stirring for 4hrs. Nanoparticles were evaluated for its particle size, scanning electron microscopy (SEM), Fourier-Transform infrared spectroscopy (FTIR), percentage yield, drug entrapment and for in vitro release kinetics. Among the four different ratios, 1:4 ratio showed high drug loading and encapsulation efficiency. SEM studies shows that prepared nanoparticles were spherical in shape with a smooth surface. Particle size of prepared nanoparticles was found to be in range between 142 nm to 221 nm. FTIR and DSC shows drug to polymer compatibility ruling out any interactions. In vitro release study showed that the drug release was sustained up to 7 days. Hence, prepared nanoparticles proved to be promising dosage form for sustained drug delivery of atorvastatin reducing dosing frequency, thus increasing the patient compliance.

Induced Size Effects Of Gd3+ ions Doping On Structural And Magnetic Properties Of Ni-Zn Ferrite Nanoparticles

Balwinder Kaur; Avanish Kumar Srivastava;Rajendra Prasad Pant; Manju Arora; Ajay Shankar

Advanced Materials Letters, 2012, Volume 3, Issue 5, Pages 399-405
DOI: 10.5185/amlett.2011.7288

Gd 3+ ions substituted in Ni0.5Zn0.5GdxFe2-xO4 (where x = 0.1, 0.2, 0.3) ferrite nanoparticles in the size range from 15 to 25 nm were prepared by chemical method. The effect of Gd 3+ ions in spinel structure in correlation to structural and magnetic properties have been studied in detail using XRD, HRTEM and EPR techniques. The spin resonance confirms the ferromagnetic behaviour of these nanoparticles and higher order of dipolar-dipolar interaction. On increasing Gd 3+ ions concentrations, the super exchange interaction i.e. increase in movement of electron among Gd 3+ - O - Fe 3+ in the core group and the spin biasing in the glass layer has been interpreted. The decrease in ‘g’ value and increase in relaxation time is well correlated with the change of particle size on different concentrations of Gd 3+ ions in Ni-Zn ferrite.

A Comparative Analysis Of Structural, Optical And Photocatalytic Properties Of ZnO And Ni Doped ZnO Nanospheres Prepared By Sol Gel Method

Shashi Kant;Amit Kumar

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 350-354
DOI: 10.5185/amlett.2012.5344

Zn1-xNixO (x=0, 0.5) nanoparticles were successfully prepared by sol gel method. Structural analysis was performed by XRD confirming phase purity and crystalline wurtzite structure. Surface morphology of nanosystems was performed by Scanning Electron Microscopy (SEM) and High Resolution Transmission Emission Microscopy (TEM) .Due to doping of ZnO nanoparticles the absorption shifted towards the visible region from UV region .The absorption increases on doping in the visible region.The Photocatalytic activity of both the doped and undoped ZnO was analysed via degradation of Methylene Blue. The Methylene Blue decomposition rate of pure ZnO and Nickel doped ZnO nanoparticles were studied under UV –Visible region. In the visible region both pure and doped ZnO decomposed Methylene Blue.This confirms the potential application of ZnO Nanoparticles for removal of harmful dyes from waste water and drinking water.The doping has a pronounced effect on the photocatalytic activity of nanoparticles. The degradation rate of the dye increased in case of Ni doped ZnO nanospheres.

Synthesis Of CdSe Nanoparticles By Solvothermal Route: Structural, Optical And Spectroscopic Properties

Punita Srivastava;Kedar Singh

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 340-344
DOI: 10.5185/amlett.2012.5341

We have developed successfully the synthesis of highly yielded CdSe nanoparticles (NPs) at 60 0C by solvothermal route in which the cadmium and selenium precursors have been dissolved in deionized water, ethylene glycol and hydrazine hydrate. This route is very facile, inexpensive and less hazardous and ensures almost complete yield of the precursors. The powder product was well characterized by powder X- ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), UV-Vis spectroscopy, Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) .It is investigated that as synthesized powder has a hexagonal (Wurtzite) structure of CdSe with diameters of the particles are in the range of 10-15 nm. The formation mechanism is also discussed.

Liquid-Phase Synthesis of Nickel Nanoparticles stabilized by PVP and study of their structural and magnetic properties

Mandeep Singh; Manish Kumar; Frantisek Stipanek; Pavel Ulbrich; Pavel Svoboda; Eva Santava; M.L. Singla

Advanced Materials Letters, 2011, Volume 2, Issue 6, Pages 409-414
DOI: 10.5185/amlett.2011.4257

We have synthesized nickel nanoparticles using nickel chloride as a precursor in ethanol using PVP (Poly Vinyl Pyrrolidone) as a surfactant and hydrazine hydrate as reducing agent at 60 °C in a facile manner. The structural analysis showed that particles are face-centered cubic and monodisperse within the PVP matrix with average size about 3 nm. The magnetic analysis shows the superparamagnetism of the single-domain nickel nanoparticles with the blocking temperature (Tb) exists around 14 K with clear hysteretic effect observation below this blocking temperature.

Biological approach of zinc oxide nanoparticles formation and its characterization

Ravindra P. Singh; Vineet K. Shukla; Raghvendra S. Yadav; Prashant K. Sharma; Prashant K. Singh; Avinash C. Pandey

Advanced Materials Letters, 2011, Volume 2, Issue 4, Pages 313-317
DOI: 10.5185/amlett.indias.204

Herein, we are reporting a novel biological approach for the formation of zinc oxide (ZnO) nanoparticles using Maddar (Calotropis procera) latex at room temperature. X-Ray diffraction (XRD) pattern reveals the formation of ZnO nanoparticles, which shows crystallinity. Transmission electron microscopy (TEM) suggested particles size and shape in the range of 5-40 nm. Scanning electron microscopy (SEM) image reveals that the particles are of spherical and granular nature. UV-Vis absorption shows characteristic absorption peak of ZnO nanoparticles. Photoluminescence (PL) studies were performed to emphasize its emission properties. This simple and cost-effective biological approach for the formation of ZnO NPs has a promising application in biosensing, electronics and photonics.

pH Dependant Fungal Proteins In The ‘green’ Synthesis Of Gold Nanoparticles

Rashmi Sanghi; Preeti Verma

Advanced Materials Letters, 2010, Volume 1, Issue 3, Pages 193-199
DOI: 10.5185/amlett.2010.5124

An efficient, simple and environment friendly biosynthesis of gold nanoparticles (GNPs), mediated by fungal proteins of Coriolus versicolor is reported. By altering the reaction conditions, the intracellular synthesis of GNPs on the fungal mycelium, could be well tailored to produce extracellular GNPs in the aqueous medium. The reaction rate and the morphology of the particles were found to depend on parameters such as pH, incubation temperature and concentration of gold solution. The gold nanoparticles were characterized by UV–Vis, SEM and AFM techniques, demonstrating high stability of gold nanoparticles in aqueous media, via the protein layer. The size of the gold nanoparticles using AFM studies was found to be in the range 5–30 nm. These nanoparticles were found to be highly stable as even after prolonged storage for over 6 months they do not show aggregation. A plausible mechanism explaining the role of different possible proteins under different conditions, in the formation of gold nanoparticles has been investigated using FTIR. This study represents an important advancement in the use of fungal protein for the extracellular synthesis of functional gold nanoparticles by a green and mild technique in one pot.

Synthesis, Characterization And Optical Properties Of Nanosized CdS Hollow Spheres

Radheshyam Rai; Seema Sharma

Advanced Materials Letters, 2010, Volume 1, Issue 3, Pages 269-273
DOI: 10.5185/amlett.2010.7140

In the present paper, we synthesized the CdS hollow spheres by using PMMA sphere templates of 298-301 nm diameters and 20-51 nm of shell thickness. A CdS hollow sphere was characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), optical absorption and photoluminescence technique. CdS products are all cubic face-centered structure with the cell constant a = 5.815 Å. We also explore the morphology, structure and possible synthesis mechanism. A possible template mechanism has been proposed for the production of the hollow CdS nano-particles. The band gap of bulk CdS is about 2.45 eV, showing an absorption onset of bulk at about 513 nm. This shows a blue shift in the absorption spectra due to the quantum size effect, which is quite possible due to the small size of the CdS nano crystals as is evident in XRD pattern. The diameter of the beads is about 265-310 nm. The change in beads size due to the CdS over-layer is not so apparent in structures, due to its small thickness. The average diameter of the sphere is similar to that of the beads. Therefore, the spherical shells were obtained after the removal of PMMA core.

Studies On Characterization Of Corn Cob Based Nanoparticles

Advanced Materials Letters, 2010, Volume 1, Issue 3, Pages 246-253
DOI: 10.5185/amlett.2010.9164

Corn cobs (central part of maize) are either treated as waste or burnt as fuel causing environmental concern. In order to achieve its value addition in new research areas, corn cob can be processed chemically to find ways to generate new end products with added values at very low price. Cellulose-based nanoparticles (CPNs) have an ability to remain intact in stomach environment and small intestine together with the presence of specific enzymes produced by cellulytic bacteria (ruminococus) for colon biodegradability and makes this biopolymer a suitable raw material for the biomedical field, particularly as a colon-specific drug carrier. Cellulose-based nanoparticles (CPNs) were prepared from corn cob raw material by treating it with sodium hydroxide in the range 0-24% of sodium hydroxide concentration, oven dry basis at 165oC for 1.5 h at liquor to solid ratio of 4.5:1. The sample obtained at the optimised condition (18% NaOH concentration, oven dry basis of raw materials) was washed with deionised water, disintegrated and filtered through 80 mesh screens. Powder thus obtained was delignified by acidified sodium chlorite and dried in a vacuum oven to constant weight. Dried powder was further separated by 270 mesh screens. An average particle size approximately equal to 22 nm was obtained by using Transmission Electron Microscopy (TEM). Its crystallinity, functional group and agglomerated particle size was determined by X-ray Diffraction (XRD), Fourier Transform Infrared (FT-IR) and Scanning Electron Microscopy (SEM) techniques respectively.