Ashutosh Tiwari
Abstract
We are pleased to publish the 4 volume, 1st issue, 2013 of the Advanced Materials Letters with ICNANO 2011 special issue, Part 2. This special issue is focused on the ‘Nano- composites and films: Processing, properties, and applications’. The journal continuously intends to provide an international ...
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We are pleased to publish the 4 volume, 1st issue, 2013 of the Advanced Materials Letters with ICNANO 2011 special issue, Part 2. This special issue is focused on the ‘Nano- composites and films: Processing, properties, and applications’. The journal continuously intends to provide an international publication platform for the broad spectrum of issues regarding theoretical and experimental advancements in materials science and engineering including molecular device materials, biomimetic materials, hybrid-type composite materials, functionalized polymers, supramolecular systems, information- and energy-transfer materials, bio- based and biodegradable and/or environmental friendly materials for food, adhesives, drug delivery, tissue engineering, gene delivery, biosensor, structural etc. at macro and nano levels from last 3 years.
Saksham Srivastava
Abstract
This is a scientific review defining the technical feasibility of surface oxidized carbon nanotubes (CNTs) for sorption of divalent metal ions (Cd 2+ , Cu 2+ , Ni 2+ , Pb 2+ , Zn 2+ ) from aqueous solution. By conducting the detailed literature review it was found that the adsorption capacities of CNTs ...
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This is a scientific review defining the technical feasibility of surface oxidized carbon nanotubes (CNTs) for sorption of divalent metal ions (Cd 2+ , Cu 2+ , Ni 2+ , Pb 2+ , Zn 2+ ) from aqueous solution. By conducting the detailed literature review it was found that the adsorption capacities of CNTs remarkably increased after conducting their surface oxidization with NaOCl, HNO3 and KMnO4 solutions. Unlike many microporous adsorbents, CNTs possess ï
Ratheesh R. Thankalekshmi; Samwad Dixit; A. C. Rastogi
Abstract
The nanostructured ZnO thin films are used in solar cells as heterojunction window layer as well as to enhance the junction area. Nanostructures also offer advantage of light scattering property to transmit more light into the absorber layer of solar cells. The optical and light scattering property of ...
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The nanostructured ZnO thin films are used in solar cells as heterojunction window layer as well as to enhance the junction area. Nanostructures also offer advantage of light scattering property to transmit more light into the absorber layer of solar cells. The optical and light scattering property of the nanostructured ZnO thin films doped with Al and Cu have been studied. The homogeneously doped ZnO nanostructured films were synthesized by a flux sublimation technique at ~ 300°C temperature. The structural studies show hexagonal nanocrystal growth in Al doped ZnO film and nanowire structure in Cu doped ZnO film. These doped ZnO films consistently showed two direct band gaps. The low energy band gap of Al and Cu- doped ZnO films originates from the macroscopic structural feature in the film, and the higher energy band gap due to the quantum confinement of nanostructure clusters in the film. Increased transmission in the lower wavelength region is caused by the forward light scattering by the nanostructure. Simulation of the optical absorption spectra of the Al and Cu- doped ZnO films using the modified Mie scattering theory shows consistent match with the experimental absorption spectra. The results show that increased forward scattering of light could be harvested by increasing the nanoparticle density which will enhance the photocurrent generation from the thin film solar cells by using doped ZnO nanostructured film as a window layer or as a transparent conducting electrode.
Sanjay Thorat; Alberto Diaspro; Marco Salerino
Abstract
A photo-polymerizable resin based on bisphenol-A-glycidyldimethacrylate monomer was loaded at both 10 and 50% by weight with particles of alumina of size scales in the 10 micrometers and submicrometer order, termed micro-alumina and nano-alumina, respectively. After curing, the viscoelastic properties ...
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A photo-polymerizable resin based on bisphenol-A-glycidyldimethacrylate monomer was loaded at both 10 and 50% by weight with particles of alumina of size scales in the 10 micrometers and submicrometer order, termed micro-alumina and nano-alumina, respectively. After curing, the viscoelastic properties of these materials were characterized by multifrequency dynamic mechanical analysis at 0.1, 1 and 10 Hz, carried out in bending mode under strain control across the range of temperatures of 2 to 62°C, normally occurring in the mouth. The storage moduli close to body temperature (37°C) and mastication frequency (1 Hz) was evaluated as the main result of the analysis, along with its change on frequency. The stiffest composite was the 50%wt loaded nano-alumina, which reached a modulus of ~6.8 GPa, comparable to those of commercial restorative composites, even in the absence of bonding agent coating of the fillers. The storage moduli at the same frequency but room temperature (25°C) were compared with the elastic modulus resulting from atomic force microscopy nanoindentation. These measurements confirmed the same ranking of materials as the dynamic flexural analysis, while providing elastic modulus values ~50% higher on average. From the dynamic analysis no thermal transition was observed in the considered temperature range, and a stiffening effect appeared at higher frequencies for all the composites.
Sashi Kiran C.; K. K. Nanda
Abstract
Thermal grease is generally used as a thermal interface material for improved conduction between a heat source and heat sink. Here, we report the enhancement of thermal conductivity of commercially available off-the-shelf thermal grease (thermal compound LS6006) used in cooling of electronic devices, ...
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Thermal grease is generally used as a thermal interface material for improved conduction between a heat source and heat sink. Here, we report the enhancement of thermal conductivity of commercially available off-the-shelf thermal grease (thermal compound LS6006) used in cooling of electronic devices, by the addition of multiwalled carbon nanotubes (MWCNTs). The thermal conductivity of the MWCNT mats and MWCNT modified thermal grease was measured relative to the thermal conductivity of the grease, which was taken as the benchmark. The thermal conductivity improves and the optimum thermal management is observed for aligned MWCNT arrays glued through the thermal grease.
Samar Layek; Soumen Kumar Bag;H.C. Verma
Abstract
Multiferroic nano-composite (1-x) BiFeO3–x Li0.5Fe2.5O4 (x=0.25 and 0.5) have been successfully synthesized by mixing the two phases, prepared independently by two different methods followed by annealing at 600 0C. Existence of the two phases in the composite is confirmed by x-ray diffraction pattern. ...
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Multiferroic nano-composite (1-x) BiFeO3–x Li0.5Fe2.5O4 (x=0.25 and 0.5) have been successfully synthesized by mixing the two phases, prepared independently by two different methods followed by annealing at 600 0C. Existence of the two phases in the composite is confirmed by x-ray diffraction pattern. Average particle size is calculated to be about 45 nm for both of these phases. The saturation magnetization, remnant magnetization and coercive field increases linearly with increasing ferromagnetic phase (Li0.5Fe2.5O4) as investigated by VSM measurement. Local magnetic behaviors have been investigated by 57Fe Mössbauer spectroscopic studies. Large dielectric constant of the order of 10 3 -10 4 has been observed in these composites.
Sheilza Aggarwal; Maneesha Garg;Akhilesh Swarup
Abstract
One of the most important requirement of nanotechnology is precision control and manipulation of devices and materials at nanoscale i.e. nanopositioning. Nanopositioners are precision mechatronic system designed to move objects over a small range with a resolution down to a fraction of an atomic diameter. ...
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One of the most important requirement of nanotechnology is precision control and manipulation of devices and materials at nanoscale i.e. nanopositioning. Nanopositioners are precision mechatronic system designed to move objects over a small range with a resolution down to a fraction of an atomic diameter. In particular, desired specifications of any nanopositioners are fast response with no or very little overshoot, large travel range with very high resolution, extremely high precision and high bandwidth. This paper presents design and identification of nanopositioning device consisting of flexure stage, piezoelectric actuator and Linear Variable Differential Transformer (LVDT) as a sensor. Open loop behavior of the nanopositioning device on the basis of time and frequency responses is studied. To improve the system characteristics feedback controllers are used. Step response and frequency response under variety of conditions are obtained to verify the effectiveness of the proposed controllers. In this paper PI and PI2 controllers are designed and system performances are investigated for different values of feedback gain. Unfortunately nanopositioners operating in closed loop achieve high bandwidth at the cost of increased sensitivity to the measurement noise and hence reduced resolution. In this paper H infinity controller is analyzed and performance of the device is studied. Then a comparative study of traditional PI and PI2 controller with H infinity controller on the basis of time and frequency response is given to show which controller is better. Simulation results for the performance analysis are carried out in MATLAB.
S. B. Kondawar; S. W. Anwane; D. V. Nandanwar; S. R. Dhakate
Abstract
Conducting polymer nanocomposites (PANI-CNT and POAS-CNT) have been synthesized by polymerization of aniline (ANI)/ o-anisidine (OAS) in the presence of functionalized multiwall carbon nanotubes (MWCNTs). These nanocomposites have been characterized by UV-VIS, FTIR and SEM to study the effect of incorporation ...
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Conducting polymer nanocomposites (PANI-CNT and POAS-CNT) have been synthesized by polymerization of aniline (ANI)/ o-anisidine (OAS) in the presence of functionalized multiwall carbon nanotubes (MWCNTs). These nanocomposites have been characterized by UV-VIS, FTIR and SEM to study the effect of incorporation of MWCNTs on the morphology, structure and crystalline of the conducting polyaniline and its substitute derivate poly(o-anisidine). UV-VIS spectra shows that polaron-π* and π-π* transition bands of the PANI/POAS chain shifted to longer wavelengths, indicating the interaction between quinoid rings and MWCNTs. FTIR spectra shows that the interaction between the MWCNTs and PANI/POAS may result in ‘charge transfer’, whereby the sp2 carbons of the MWCNTs compete with dopant ions [Cl – ] and perturb the H-bond, resulting an increase in the N-H stretching intensity. Electron microscopy reveals that the interaction between the quinoid ring of PANI/POAS and the MWCNTs causes PANI and POAS polymer chains to be adsorbed at the surface of MWCNTs, thus forming a tubular core surrounding the MWCNTs. The nanocomposites showed high electrical conductivity compared to pure PANI/POAS. Further, PANI-CNT showed high electrical conductivity compared to that of POAS-CNT.
Amit Dubey; Divya Sachdev;Neel Mani Srivasatava
Abstract
In order to develop the mild acidic nanocatalyst, ordered mesoporous silica, SBA -15 was functionalized with chloroacetic acid (SBA/CA) via post synthetic grafting technique for useful acidic conversions such as Knoveneganel condensation, Biginelli synthesis and Mannich reaction. The nanocomposites were ...
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In order to develop the mild acidic nanocatalyst, ordered mesoporous silica, SBA -15 was functionalized with chloroacetic acid (SBA/CA) via post synthetic grafting technique for useful acidic conversions such as Knoveneganel condensation, Biginelli synthesis and Mannich reaction. The nanocomposites were characterized by Powder X-ray Diffraction method, N2 adsorption-desorption isotherm, 13C CP-MAS NMR, FT-IR, TPD and EDXRF. Very high activity and selectivity was observed for all the conversions under milder reaction conditions. Finally, the mechanism of the reaction is proposed and discussed.
Megha P. Mahabole; Ravindra U. Mene;Rajendra S. Khairnar
Abstract
This present paper deals with the investigation on effective utilization of cobalt doped hydroxyapatite (Co-HAp) thick films for improvement in gas sensing and dielectric properties. Chemical precipitation route is used for synthesis of nanocrystalline hydroxyapatite (HAp) bioceramic and ion exchange ...
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This present paper deals with the investigation on effective utilization of cobalt doped hydroxyapatite (Co-HAp) thick films for improvement in gas sensing and dielectric properties. Chemical precipitation route is used for synthesis of nanocrystalline hydroxyapatite (HAp) bioceramic and ion exchange process is carried out for the partial substitution of cobalt ions in HAp matrix. Hydroxyapatite thick films, prepared using screen printing technique, are used as samples for gas sensing and dielectric measurements. The structural identification of HAp thick films is carried out using X-ray diffraction and the presence of functional groups in pure and doped HAp is confirmed by means FTIR spectroscopy. The surface morphology of these films is visualized by means of SEM and AFM analysis. Detailed study on CO2 gas sensing performance of pure and Co-HAp thick films is carried out wherein operating temperature, response/recovery times and gas uptake capacity are determined. It is remarkable to note that Co-HAp film with 0.01M cobalt concentration shows maximum sensitivity to CO2 gas at relatively lower operating temperature of 135 o C in comparison with pure HAp as well as other concentrations of cobalt doped HAp films. The frequency dependent variation of dielectric constant (K) and dielectric loss (tan δ) of HAp thick films are also studied in the range of 10 Hz-1MHz at room temperature. The result shows that increase of cobalt concentration in HAp matrix leads to increase in dielectric constant. The study reveals clear influence of cobalt substitution on dielectric properties and gas sensing properties HAp matrix.
Sunil Rohilla; Atul Kumar;Bhajan Lal; P. Aghamkar; Shyam Sunder
Abstract
Nano-dimensional powder of iron cobalt cyanide hydrate in silica matrix (member of Prussian-blue family) was obtained using ferric chloride, cobalt chloride, potassium cyanide and silica in their dilute solution through coprecipitation method. The crystal structures and surface morphology of nanoparticles ...
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Nano-dimensional powder of iron cobalt cyanide hydrate in silica matrix (member of Prussian-blue family) was obtained using ferric chloride, cobalt chloride, potassium cyanide and silica in their dilute solution through coprecipitation method. The crystal structures and surface morphology of nanoparticles were characterized by the powder X-Ray diffraction (XRD) and transmission electron microscopy (TEM). The formation of compound Fe4 [Co(CN)6]3.16H2O was revealed by Fourier transform infrared (FTIR) spectroscopy. The magnetic properties of prepared samples were measured at room temperature using a Vibrating sample magnetometer (VSM). Effect of the thermal annealing on the phase decomposition and phase evolution of prepared samples for different temperature and time duration has been discussed. The results showed that the structure, phase and shape of the nanocrystallite are strongly influenced by the sintering temperature and time period. Results also showed that direct phase transition from Fe4 [Co (CN)6]3.16H2O to CoFe2O4 occurred at temperature 3000C (2h). The shape of embedded CoFe2O4 (a final product) in silica matrix is almost spherical and its average size ranges 15-25 nm.
A.D. Garje; S.N. Sadakale
Abstract
Synthesized nanophase SnO2 powder is used to fabricate thick film resistors using screen printing technology. The surfaces of the thick film resistors were modified by dip coating in platinum chloride (PtCl2) solution of optimized 1.5 M for different time periods of 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 minutes. ...
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Synthesized nanophase SnO2 powder is used to fabricate thick film resistors using screen printing technology. The surfaces of the thick film resistors were modified by dip coating in platinum chloride (PtCl2) solution of optimized 1.5 M for different time periods of 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 minutes. Sintering of the films is carried out at different temperatures of 550, 600, 650, 700, 750 and 800°C. The films were tested for 400 ppm of LPG. Thick films which were dip coated for 5 minutes and sintered at 750 o C show the highest sensitivity towards LPG which is ten times higher than undoped SnO2 sensors. The characterization of the sensors was done using XRD, EDX and SEM. The sensors were found to be extremely stable and repeatable with a response and recovery time of 10 and 22 s with a minimum detection limit of 5 ppm of LPG.
Laxmi J. Tomar; B.S. Chakrabarty
Abstract
A series of TiO2-ZrO2 mixed oxide samples with various ZrO2-TiO2 content (10, 30, 40, 60, 70 and 90 mol %) were prepared by hydrothermal method. These nanocomposites were characterized by XRD, SEM, UV-vis spectroscopy and Photoluminescence spectroscopy. XRD data identified Anatase and Rutile phases in ...
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A series of TiO2-ZrO2 mixed oxide samples with various ZrO2-TiO2 content (10, 30, 40, 60, 70 and 90 mol %) were prepared by hydrothermal method. These nanocomposites were characterized by XRD, SEM, UV-vis spectroscopy and Photoluminescence spectroscopy. XRD data identified Anatase and Rutile phases in the TiO2 rich samples while Tetragonal and Monoclinic phases in ZrO2 rich samples. The average crystallite size of the samples was between 9 to 26 nm. As per Uv-Vis spectra, the band gaps of TiO2-ZrO2 composites vary from 1.34 eV to 2.48 eV. The absorption spectra show a shift of the absorption edge of TiO2-ZrO2 towards longer wavelength region. The decreased band gap is attributed to the surface trap states. The PL spectrum shows very strong blue-green PL band under excitation at 300 nm. The occurrence of emission peaks in the visible region is attributed to the presence of defect levels below the conduction band.
Dinesh C. Sharma; Y. K. Vijay;Y. K. Sharma; Subodh Srivastava
Abstract
The chromium doped zinc telluride (ZnTe:Cr) as well as ZnTe thin films and their sandwich structures were prepared onto glass substrate by thermal evaporation method under the vacuum of 10-5 Torr. We have studied the structural, optical and electrical properties of thermally evaporated Cr-doped ZnTe ...
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The chromium doped zinc telluride (ZnTe:Cr) as well as ZnTe thin films and their sandwich structures were prepared onto glass substrate by thermal evaporation method under the vacuum of 10-5 Torr. We have studied the structural, optical and electrical properties of thermally evaporated Cr-doped ZnTe thin films as a function of Cr concentration. XRD measurements show that Cr-doped ZnTe films possess the mix phase of cubical and hexagonal structure of ZnTe thin film. The optical energy band gap (Eg) calculated from the optical absorption spectra which was observed around 2.57 eV for undoped ZnTe, and reduced to 1.47 eV for the Cr-doped thin films. The result of I-V characteristics is also presented in this paper.
N.N. Ahlawat; P. Agamkar; N. Ahlawat; A. Agarwal
Abstract
The study of ternary alkali bismuth borate glasses doped with various 3d transition metals (TM) has been carried out to give more information on the oxidation states of 3d transition metal ions doped in a host of ternary alkali bismuth borate glasses. The compositional variation in density and molar ...
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The study of ternary alkali bismuth borate glasses doped with various 3d transition metals (TM) has been carried out to give more information on the oxidation states of 3d transition metal ions doped in a host of ternary alkali bismuth borate glasses. The compositional variation in density and molar volume has been investigated in terms of the structural modification that takes place in the glass matrix on introducing various 3d TM in these glasses. Analysis of FTIR spectra shows the peak positions (cm -1 ) at around 700 cm -1 corresponds to B-O-B bending while the broad peak at 900-1150 cm -1 result due to combined contributions of stretching vibrations of B-O bonds in BO3 units from pyro-orthoborate groups and stretching vibrations of B-O bonds in tetrahedral BO4 units in tri-borate, tetraborate and penta-borate groups. Another broad peak around 1300-1500 cm -1 attributes to vibrations attached to large segments of borate network.
Pawan Kumar; Nitin Rawat;Rajesh Kumar; Subhash Chander Katyal; Sunil Kumar Khah
Abstract
Thin magnetic films have been formed on the surface of Fe 2+ , Fe 3+ and PVA solution applying NH3 vapors. The growth of films has been inferred via island growth mechanism. The film grown for shorter exposure time of NH3 is composed of islands in nanometer range, whereas the film grown for high exposure ...
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Thin magnetic films have been formed on the surface of Fe 2+ , Fe 3+ and PVA solution applying NH3 vapors. The growth of films has been inferred via island growth mechanism. The film grown for shorter exposure time of NH3 is composed of islands in nanometer range, whereas the film grown for high exposure time of NH3 consists islands in micrometer range. For lower NH3 exposure, discrete islands are formed in polyvinyl alcohol (PVA) matrix which coalesces in bigger islands when exposed for larger time to NH3 vapor. Similarly, depending upon the NH3 exposure, nanoparticles inside films vary from 5 to 30 nm. The magnetization measurement shows that the films have thickness dependent saturation magnetization. For the thick film the saturation magnetic field is around 1400 Oe whereas for thin film it is 1000 Oe.
Saruchi Surbhi; Praveen Aghamkar; Sushil Kumar
Abstract
Nanomaterials and nanostructures have received steadily growing interests as a result of their peculiar and fascinating properties and applications. Neodymia-silica nanocomposites were prepared by sol-gel route followed by calcination. The samples were prepared with different concentration of dopant ...
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Nanomaterials and nanostructures have received steadily growing interests as a result of their peculiar and fascinating properties and applications. Neodymia-silica nanocomposites were prepared by sol-gel route followed by calcination. The samples were prepared with different concentration of dopant (Nd2O3) and calcined in a programmable furnace at 1000 °C for 5 h. The structural evolution of samples was investigated by employing techniques such as XRD, FTIR and TEM. X-ray diffraction patterns showed that the samples were nanocrystalline and the size of crystallites has been determined using Debye-Scherrer relation. The FTIR spectra confirmed the presence of functional groups of prepared material. The particle size of samples was also estimated through TEM analysis. It has been observed that crystallinity as well as particle size of the samples increases with increase in dopant concentration.
Ranjana Singh; S. G. Kulkarni; N. H. Naik
Abstract
A number of nanocomposites have been synthesized biomimetically by embedding various transition metal salts in polyvinyl alcohol (PVA) as the preorganised matrix. The metal salts were reduced to metallic form using aqueous sodium borohydride solution. In the present paper, very comprehensive studies ...
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A number of nanocomposites have been synthesized biomimetically by embedding various transition metal salts in polyvinyl alcohol (PVA) as the preorganised matrix. The metal salts were reduced to metallic form using aqueous sodium borohydride solution. In the present paper, very comprehensive studies on thermal decomposition behavior of these composites have been carried out using thermogravimetric and differential scanning calorimetric studies. The transition metal salts/ metals based composites exhibit increased thermal stability as indicated by shift in the decomposition temperature of pure PVA. The DSC data show increase in glass transition temperature of all composites, except the one containing iron, in comparison with neat PVA.The improvement in the thermal stability is explained in terms of decrease in the segmental mobility of polymer chains due to entrapment of metal salt / metal forming a complex with the hydroxyl group of the polymer chains and thus decreasing heat transfer process for decomposition of polymer composites.
Y.B. Wankhede; S.B. Kondawar; S.R. Thakare; P.S. More
Abstract
Conducting polyaniline/silver nanoparticles (PANI-Ag) nanocomposite was synthesized by in-situ polymerization of aniline in the presence of silver nitrate as precursor. Nanocomposite was characterized by UV-VIS, PL, XRD, FTIR, SEM and TGA to study the effect of silver nanoparticles embedded into PANI ...
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Conducting polyaniline/silver nanoparticles (PANI-Ag) nanocomposite was synthesized by in-situ polymerization of aniline in the presence of silver nitrate as precursor. Nanocomposite was characterized by UV-VIS, PL, XRD, FTIR, SEM and TGA to study the effect of silver nanoparticles embedded into PANI on the morphology, structure, crystalline and thermal stability of the conducting polyaniline. The optical studies show that the absorption edge of PANI-Ag nanocomposite exhibits the significant blue shift. The photoluminescence studies show that the emission peak shifted towards the blue when compared to that of bulk PANI-Ag. The broadening sharp peaks in the XRD pattern indicate that the synthesized PANI-Ag nanocomposite is nanocrystalline. FTIR reveals the presence of silver metal ions uniformly embedded into PANI. SEM reveals the rod structure surface morphology of PANI-Ag nanocomposite. Thermogravimetric analysis suggests the presence of silver and also an oligomeric component in the nanocomposite. The combination of PANI as a semiconducting polymer with silver as a noble metal may produce hybrid material that behaves as semiconductor at low temperature and as metal at high temperature.
S.R. Mane; P.S. Patil;P. N. Bhosale; R. M. Mane
Abstract
Thallium (I) doped tungsten heteropolyoxometalate (HPOM) combinatorial thin films have been deposited on glass substrate using simple chemical bath deposition technique. The deposited films were annealed at 100 o C, 150 o C, 200 o C and 250 o C. These annealed thin films were characterized by using SEM, ...
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Thallium (I) doped tungsten heteropolyoxometalate (HPOM) combinatorial thin films have been deposited on glass substrate using simple chemical bath deposition technique. The deposited films were annealed at 100 o C, 150 o C, 200 o C and 250 o C. These annealed thin films were characterized by using SEM, EDAX, AFM, FT-IR, XRD and TGA-DTA techniques for their structural properties. SEM and EDAX results shows that, tungsten HPOM material is polycrystalline in nature and Tl (I) is intercalated in phosphotungustate anion. AFM studies on the films annealed at different temperatures reveal that the surface roughness increases with the increase in annealing temperature, suggesting an increase of crystallization with temperature. FT-IR study confirms the well formation of heteropolyoxometalate material under investigation. Various structural parameters such as lattice constants, crystallite size and grain size have been calculated and they are found temperature dependent. The lattice constant, crystallite size and grain size of tungsten HPOM material increases with increase in temperature. XRD pattern of annealed thin films shows better crystanality of tungsten HPOM material having simple cubic spinel structure. The TGA-DTA study revealed that, Tl3 (PW12 O40) material is thermally stable up to 265.12 o C.
P. Raju;S. R. Murthy
Abstract
The nanocomposites of x TiO2+(1-x)CoF2O4 (≤x≤1) powders were synthesized using microwave-hydrothermal method at a low temperature of 165°C/45min. The synthesized powder was characterized by using XRD, TEM, FTIR and DSC. The particle size was obtained from TEM study varies from 18nm to 34nm ...
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The nanocomposites of x TiO2+(1-x)CoF2O4 (≤x≤1) powders were synthesized using microwave-hydrothermal method at a low temperature of 165°C/45min. The synthesized powder was characterized by using XRD, TEM, FTIR and DSC. The particle size was obtained from TEM study varies from 18nm to 34nm for all the nanopwders. DSC curve of composites shows no anatase to rutile phase transformation. As synthesized powder was densified using a microwave sintering method at 500°C/30min. In the XRD patterns of sintered composite samples, no peaks other than TiO2 and CoFe2O4 were observed. The grain sizes of the composites have been estimated from SEM pictures and they are in between 54 to 78nm. The dielectric properties were measured in the frequency range of 100 Hz to 1 MHz. The frequency variation of dielectric properties is understood with the help of Maxwell–Wagner type of interfacial polarization, which is in agreement with Koop’sphenomenological theory. The thermal variation of dielectric constant and loss studies were also undertaken at a constant frequency of 1kHz. Magnetic properties were also measured on all the composite samples at room temperature. The saturation magnetization (Ms) of the samples decreases with an increase of TiO2 content in CoFe2O4.