Volume 3, Issue 6, December 2012

Editorial 'ICNANO 2011' Special Issue Part-1

Masoud A. Mehrgardi

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 441-441
DOI: 10.5185/amlett.2012.12001

We are pleased to publish the 3 volume, 6th issue, 2012 of the Advanced Materials Letters with selected peer-reviewed papers presented in the “International Conference on Nanomaterials and Nanotechnolgy (ICNANO 2011)”, which was held at the conference center, University of Delhi, India during 18-21 December 2011. This conference was organized by the International Association of Advanced Materials (IAAM), University of Delhi and VBRI Press. The purpose of conference was to bring together leaders from industry and academia in research, design, development and application of nanomaterials and nanotechnology. Scientific themes of conference were: Nano-Optoelectronics, Nano-Biomaterials & Biomedical Nanotechnology, Nano-Advanced Materials, Nano-Fabrication, Nano-Characterization, Nano-Green Energy & Environment, and Nano-Computational Simulation & Theory.

Gas Effect On The Surface Photovoltage Of Porphyrin Functionalized ZnO Nanorods

Yuvaraj Sivalingam; Arnaldo D Amico;Corrado Di Natale; Gabriele Magna; Giuseppe Pomarico; Eugenio Martinelli; Roberto Paolesse

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 442-448
DOI: 10.5185/amlett.2012.icnano.144

Recent studies suggest that the gas sensitivity of porphyrin-functionalized ZnO nanorods can be activated under visible light illumination. Then the use of properly coloured light tuned to the absorbance spectra of individual porphyrins could enable a control of sensors sensitivity. The effect of light on the sensitivity to gases is critically governed by the transport phenomena of electronic charge across the interfaces of organic and inorganic structures. Therefore, accurate measurements of energy levels and contact potential differences in porphyrins functionalized ZnO nanorods are important to intepret the sensing properties of such hybrid materials. For the scope, Kelvin probe measurements of porphyrin-ZnO structures were performed exposing the material in dark and visible light and to organic vapours. Results provide an experimental basis to understand the mutual effects of gas adsorption and illumination to the device conductivity.

Calculation Of Lattice Thermal Conductivity Of Suspended GaAs nanobeams: Effect Of Size Dependent Parameters

S. M. Mamand; M. S. Omar; A. J. Muhammed

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 449-458
DOI: 10.5185/amlett.2012.icnano.102

Theoretical calculations of the magnitude and temperature variation of the measured thermal conductivity of undoped and doped GaAs nanobeams will present. The calculations have been performed by employing modified Callaway’s theoretical model. In the model, both longitudinal and transverse modes are explicitly taken into account. Scattering of phonons is assumed to be by nanobeam boundaries, imperfections, dislocations, electrons, and other phonons via both normal and Umklapp processes. A method is used to calculate the Debye temperature and phonon group velocities for undoped and doped nanobeams from their related melting points. Phonon confinement and size effects as well as the role of dislocation in limiting thermal conductivity are investigated. The drop in thermal conductivity of doped nanobeams compared to that of the undoped beams arises from electron-phonon scattering and additional phonon scattering from a large number of point impurities due to the presence of dopant atoms. Effect of Gruneisen parameter, surface roughness, and dislocations are successfully used to correlate the calculated values of lattice thermal conductivity to that of the experimentally measured curves.

Comparative Study Of TiO2 and TiSiO4 nanoparticles Induced Oxidative Stress And Apoptosis Of HEK-293 Cells

Ramovatar Meena; ;Paulraj R.; Ruchita Pal; Surya Narayan Pradhan; and Paulraj R.

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 459-465
DOI: 10.5185/amlett.2012.icnano.157

The aim of this study is to compare the cyto and genotoxic effects of TiO2 and TiSiO4 nanoparticles on human embryonic kidney cells (HEK-293). The cell viability, induction of oxidative stress, and cell apoptosis induction were assessed after 48 h of cell exposure to TiO2 and TiSiO4 nanoparticles separately. Our results showed that nanoparticles induce the generation of reactive oxygen species (ROS) followed by significant depletion of glutathione levels and increased lipid peroxidation. The cells exhibited apoptotic morphology like condensed chromatin and nuclear fragmentation after 48 h of treatment. Both the particles induce oxidative stress and DNA damage in a dose dependent manner. Oxidative stress is the underlying mechanism by which nanoparticle causes DNA damage and apoptosis. This study further indicate that TiO2 nanoparticles has more toxic effects than TiSiO4 nanoparticles on HEK cells, which demonstrate that larger size may be responsible for retardant of cellular uptake. This might be reducing the toxicity of TiSiO4 nanoparticles.

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.

Synthesis Of Mercaptopropionic Acid Stabilized CdS Quantum Dots for Bioimaging In Breast Cancer

P. Kumar; D. Kukkar; A Deep; S.C. Sharma; L.M. Bharadwaj

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 471-475
DOI: 10.5185/amlett.2012.icnano.296

Semiconductor inorganic nanocrystals or quantum dots (QDs) are nowadays extensively used for imaging and analysis of bio-molecules owing to their superior optical properties over conventional organic fluorophores. They have excellent potential for synthesizing molecular probes against various biological markers such as free antigens, cell surface markers/antigens, bacteria, viruses and tissues. Traditional synthesis protocols of the QDs generally lead to the formation of hydrophobic nanocrystals. For biological applications, post-synthesis modifications need to be introduced to render required hydrophilicity. However, such additional steps make the tiny QDs structures bulky, which is unwanted in subsequent in-vivo executions. The present work reports a simple method for the direct synthesis of hydrophilic carboxyl (–COOH) functionalized CdS QDs using mercaptopropionic acid as a sulfur source and stabilizer. This aqueous synthesis route avoids the requirement of extra surface modification steps. The size and surface morphology of the synthesized CdS QDs were studied by electron microscopy. The average diameter of the QDs has been found to be in the range of 2-3.5nm. Spectral studies confirmed the grafting of –COOH terminal on the synthesized nanocrystals. Band gap energy and the theoretical size of the particles were calculated and found in good agreement with the experimental analysis. Due to the size quantization effect, the estimated band gap energy (2.6eV) of the QDs was on a higher side than that reported (2.4eV) for the bulk material. The synthesized nanocrystals can be further conjugated with bio-molecules for high-throughput drug screening, clinical immunological assays and protein-protein interaction studies.

A Study On The Electrospinning Behaviour And Nanofibre Morphology Of Anionically Charged Lignin

Makoto Schreiber; Singaravelu Vivekanandhan; Amar Kumar Mohanty; Manjusri Misra

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 476-480
DOI: 10.5185/amlett.2012.icnano.336

The electrospinnability of anionically charged sodium carbonate lignin using positive-voltage electrospinning was explored. The lignin was mixed with polyethylene oxide (PEO) in order to enhance the electrospinning performance by improving the viscoelastic properties. Lignin fibres containing varying concentrations of lignin were obtained by employing various applied voltages. The effect of increased lignin content on the electrospinning behaviour and the obtained fibre morphologies were observed. The electrospun fibres were characterised using scanning electron microscopy (SEM) to investigate their microstructure. SEM analysis showed the formation of well defined lignin fibres and the results indicate that the morphologies are highly depend on the PEO:lignin composition.

Green Synthesis Of Gold Nanoparticles Using Camellia Sinensis And Kinetics Of The Reaction

Sontara Konwar Boruah; Chitrani Medhi;Okhil Kumar Medhi; Prabin Kumar Boruah; Pradyut Sarma

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 481-486
DOI: 10.5185/amlett.2012.icnano.103

In this paper we report the green synthesis of gold nanoparticles (AuNPs) by using a simple, faster, low cost, eco-friendly technique. The green synthesis of AuNPs was done by using fresh young leaves and leaf buds of tea (Camellia Sinensis). Reduction of HAuCl4 by polyphenols present in young leaves and leaf buds of tea extract at room temperature provides AuNPs (Au 3+ →Au 0 ).The UV-Visible absorption spectrum of AuNPs in tea extract shows two bands at around 534 and 752 nm, which results from transverse and longitudinal surface plasmon resonance (SPR) respectively. In fluorescence spectroscopy study, AuNPs in tea extract shows fluorescence emission at 450 and 705 nm when excited at 350 nm. The kinetics of the reaction rate (Au 3+ →Au 0 ) with respect to time was studied with the help of UV-Visible and fluorescence spectroscopy. The reaction rate evaluated with the help of UV-Visible and fluorescence spectroscopy was found to be almost similar in results. The kinetics of the reaction also suggests that the reaction was fast and completed in 28 minutes. The amount of tea extract determines the core size of the AuNPs. The core size of the AuNPs decreases as the amount of tea extract increases and it causes the blue-shift of SPR band. The physical properties, particle size and morphology of AuNPs were characterized using X-ray diffractometer (XRD), field emission scanning electron microscope (FESEM) and high resolution-transmission electron microscopy (HR-TEM) techniques. The AuNPs size in the range ~2.94-45.58 nm with an average of 13.14 nm.

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 Green Tea Loaded Microemulsion For Vaginal Infections

S. Gupta; R. Gabrani;S. Dang; J.K. Sahni; J. Ali

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 493-497
DOI: 10.5185/amlett.2012.icnano.205

Natural products are important sources for new drug development. Though antibiotic therapies are first line of treatment for vaginal infections but prolonged use results in various side effects, hence there is a need to develop alternative therapies based upon natural products. Green tea powder (GTP) has been reported to exhibit anti-microbial activity and has synergistic effect with some antibiotics. Conversely, the role of GTP against vaginal infections has not been explored extensively. GTP is safe even at high doses but exhibits poor oral bioavailability. Encapsulation of GTP in a microemulsion (ME) vehicle would protect it against degradation. Aim of this study is to formulate GTP loaded MEs for vaginal application and to assess its efficacy against various vaginal pathogens. UV analysis of the GTP was done and solubility studies in various oils, surfactants and co-surfactants were carried out to select various phases of MEs. Titrations were carried out with various oil:Smix ratios and the data obtained was used to plot pseudo-ternary phase diagrams. The emulsion regions which corresponded to particle less, transparent regions and within GRAS limits were subjected to thermodynamic stability studies. Droplet size of thermodynamically stable MEs was found to be in nanometre range. Escherichia coli and Staphylococcus epidermidis were found to be sensitive to GTP and its ME via disc diffusion assay.

Effect Of Barrier Height On Linear And Nonlinear Photoabsorption and Refractive Index Change In Si Quantum Dots

S.P. Purohit; ;K.C. Mathur; and K.C. Mathur

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 498-503
DOI: 10.5185/amlett.2012.icnano.230

The effect of barrier height on the photoabsorption process and refractive index changes are studied for the intraband transitions in spherical single electron Si quantum dots embedded in dielectric matrix. We use the effective mass approximation and consider (i) the finite, and (ii) infinite barrier height at the interface of the dot and matrix material. The results obtained for the dipole allowed S-P transition show that the increase in barrier height leads to blue shift in peak positions of absorption coefficient and refractive index change. We also investigate the effect of intensity and dot radius on the above parameters.

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.

Silver Nano Particles Impregnated Alumina For The Removal Of Strontium(II) From Aqueous Solution

Rajesh Kumar; Thomas N. Abraham;Surendra K. Jain

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 507-510
DOI: 10.5185/amlett.2012.icnano.138

This study was carried out for removal of strontium (II) from aqueous solutions using silver nano particle impregnated alumina. The silver nano particle impregnated alumina was prepared by reduction method and characterized using UV-Vis spectroscopy, X-ray diffraction and scanning electron microscopy (SEM). The aim was to find the capability of the material for the removal of strontium from contaminated water under different conditions such as initial concentration of strontium, contact time and neutral pH. The adsorption isotherms were prepared, correlated to Freundlich and Langmuir models and it was found that the adsorption data could be fitted better by Freundlich model than Langmuir one.

Co And Fe Doped SnO2 nanorods By Ce Co-doping And Their Electrical And Magnetic Properties

Jasneet Kaur; Jaspreet Kaur; R. K. Kotnala; Vinay Gupta; Kuldeep Chand Verma

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 511-514
DOI: 10.5185/amlett.2012.icnano.142

In the present work, the self-assembly of Co 2+ and Fe 3+ doped SnO2 nanoparticles (Co and Fe = 5 mol% each) into nanorods by co-doping of Ce 3+ (4 mol%) ions is studied. The nanorods are prepared by a chemical route using polyvinyl alcohol as surfactant with the composition Sn0.91Co0.05Ce0.04O2 (SCC54) and Sn0.91Fe0.05Ce0.04O2 (SFC54). The X-ray diffraction (XRD), transmission electron microscopy (TEM), magnetic and electrical measurements are used to characterize these nanorods. The XRD pattern show the tetragonal rutile and polycrystalline nature of SnO2 nanorods which is also confirmed by TEM. The TEM images exhibit that the diameter of SCC54 nanorods lie in the range of 15-20 nm, length~100-200 nm whereas for SFC54 specimen, diameter ~5-15 nm and length ~50-100 nm. In our previous work, we fabricated Co and Fe (3 and 5 mol% each) doped SnO2 nanoparticles which exhibited high ferromagnetism. It is observed that on Ce 3+ co-doping, nanoparticles assembled themselves into rod like structures and the values of saturation magnetization and dielectric properties have further enhanced. Thus the nature and the concentration of dopants are found to play crucial role in tuning the morphology, magnetic and electrical properties of nanostructures. The values of saturated magnetization (Ms) are 1.14 and 0.14 emu/g and coercive field are 112 and 42 Oe, in SCC54 and SFC54 specimen, respectively, at room temperature. The variation in dielectric behavior is attributed due to the interface polarization. However, in lower frequency regime, the decreasing trend of dielectric permittivity with increasing frequency is explained by the Maxwell-Wagner theory and Koops’ model, whereas, in higher frequency region, the resonant behavior is observed due to nano size effect.

Growth, Characterization And I-V characteristics Of Tin Oxide Nanowires

Anima Johari; M.C. Bhatnagar;Vikas Rana

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 515-518
DOI: 10.5185/amlett.2012.icnano.251

One-dimensional wire shaped tin oxide (SnO2) nanostructures have been synthesized by thermal evaporation method. The growth of SnO2 nanostructure was carried out on gold catalyst layer coated silicon substrate. X-ray diffraction (XRD) results reveals that synthesized SnO2 nanowires have polycrystalline nature with tetragonal rutile structure. SEM, TEM and EDX observation concludes that the uniform SnO2 nanowires (diameter ~ 40 nm and length ~ 50 μm) grow with vapor-liquid-solid (VLS) mechanism. I-V characteristics of single SnO2 nanowire show semiconducting behaviour. Due to structural and electrical properties of SnO2 nanowire, these nanowires would be a promising candidate for gas sensing applications.

Evidence Based Green Synthesis Of Nanoparticles

Anamika Mubayi; Sanjukta Chatterji; Prashant K. Rai; Geeta Watal

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 519-525
DOI: 10.5185/amlett.2012.icnano.353

Nowadays, nanotechnology has grown to be an important research field in all areas including medicinal chemistry. The size, orientation and physical properties of nanoparticles have reportedly shown to change the performance of any material. For several years, scientists have constantly explored different synthetic methods to synthesize nanoparticles. On the contrary, the green method of synthesis of nanoparticles is easy, efficient, and eco-friendly in comparison to chemical-mediated or microbe-mediated synthesis. The chemical synthesis involves toxic solvents, high pressure, energy and high temperature conversion and microbe involved synthesis is not feasible industrially due to its lab maintenance. Since, green synthesis is the best option to opt for the synthesis of nanoparticles, therefore the nanoparticles were synthesized by using aqueous extract of Moringa oleifera and metal ions (such as silver). Silver was of particular interest due to its distinctive physical and chemical properties. M. oleifera leaf extract was selected as it is of high medicinal value and it does not require any sample preparation and hence is cost-effective. The fixed ratio of plant extract and silver ions were mixed and kept at room temperature for reduction. The color change from yellow to reddish brown confirmed the formation of nanoparticles. Further, the synthesized nanoparticles were characterized by UV, EPMA, XRD and FTIR data. The antimicrobial activity of synthesized nanoparticle has also been examined in gram positive and gram negative bacteria and encouraging results are in hand.

Electron Spin Resonance In Electrodeposited Cobalt Nanowire Arrays

Sachin Pathak;Manish Sharma

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 526-532
DOI: 10.5185/amlett.2012.icnano.259

Arrays of magnetic nanowires electrodeposited into nano-channel templates have attracted a lot of attention and research efforts in recent years. They are a promising system for perpendicular magnetic recording media. A major issue regarding the fabrication of such nanowires is the interplay between the structure and magnetic properties. In this paper template-assisted electrodeposition technique using a three-electrode electrochemical cell is used to produce high density cobalt nanomaterial arrays with cylindrical shapes. The morphology of the samples is investigated by means of Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The length and average diameter of Cobalt nanowire arrays was found 4–15 µm and ~300 nm, respectively. The structural characteristic of the samples is examined using XRD and EDX, which confirm the hexagonal closely packed cobalt array structures. Magnetic property measurements show the influence of morphology on the magnetic properties of the arrays. Magnetic characterizations were carried out by Magneto-optical Kerr Effect (MOKE) and Electron paramagnetic resonance (EPR). The experimental results suggest close agreement with the resonance field seen in micro-magnetic modelling. We have calculated the resonance field for single nanowires with different length and for an array of seven nanowires. It is shown that the resonance field varies with the length, the interaction strength and also the spacing of the nanowires.

Magnetic And Dielectric Properties Of Multiferroic BiFeO3 nanoparticles Synthesized By A Novel Citrate Combustion Method

Samar Layek;H.C. Verma

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 533-538
DOI: 10.5185/amlett.2012.icnano.242

Single phase BiFeO3 nanoparticles have been successfully synthesized for the first time by a novel citrate combustion method without using any solvent. Well mixed metal nitrates along with citric acid which is used as fuel combust to give BiFeO3 nanoparticles after annealing. These particles are single phase in nature and crystallize in the rhombohedral distorted perovskite structure (space group-R3c) which has been confirmed by the Rietveld refinement of the room temperature powder x-ray diffraction data. Nearly spherical particles of average particle size 47 nm have been seen from transmission electron micrograph. Room temperature magnetic hysteresis measurement shows weak ferromagnetism though the magnetization does not saturate upto 1.75 T applied field. The coercive field value is calculated to be 180 Oe which is 3 times higher than that prepared by solvent free combustion method using glycine. 57 Fe Mössbauer spectrum can be fitted with a sextet corresponding to single magnetic state of hyperfine field about 49.5 T corresponding to Fe 3+ state of the iron atom. The dielectric relaxation and ac conductivity as a function of frequency have been discussed. High dielectric permittivity has not been found in these nanoparticles like other reported BiFeO3  ceramics.