scholarly journals Structural, Dielectric, Magnetic and Magneto-Dielectric Properties of (1-x)BiFeO3–(x)CaTiO3 Composites

2021 ◽  
Author(s):  
Bushra Khan ◽  
Aditya Kumar ◽  
Preeti Yadav ◽  
Gulab Singh ◽  
Ashok Kumar ◽  
...  
Keyword(s):  
Ac Conductivity ◽  
Sol Gel ◽  
Negative Temperature ◽  
Tangent Loss ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Changes ◽  
Different Temperatures ◽  
Ferromagnetic Ordering ◽  
Jonscher’S Power Law

Abstract (1-x) BiFeO3–(x) CaTiO3 [(1-x) BFO – (x) CTO, (x = 0, 0.1, 0.2 and 0.3)] composites were synthesized using sol-gel chemical rout method. X-ray diffraction investigation shows the crystal structure changes from rhombohedral to monoclinic for 0 ≤ x ≤ 0.2, and it changes to orthorhombic at x ≤ 0.3. The Field Emission Scanning Electron Microscope (FESEM) investigation confirms the the microstructure consists of randomly oriented, homogenous, and non-uniform grains. The dielectric permittivity (ε) and tangent loss (tanδ) decreases with increasing frequency and show dielectric anomalies (as a hump) at different temperatures for different compositions. The incorporation of CTO, decreases three order of leakage current (up to x = 0.2) and significantly improve the magnetization and magneto-dielectric coupling. The frequency-dependent ac conductivity obeys Jonscher’s power law with large ac conductivity dispersion for higher frequencies with increasing CTO concentration. The variations of ac conductivity with the inverse of temperature obey the Arrhenius equation and show negative temperature coefficient of resistance (NTCR) behavior. The ferromagnetic (FM) properties in BFO-CTO increases significantly with an increase of the CTO concentration. The coercive field increases with increasing CTO concentration suggesting a competition between the antiferromagnetic and ferromagnetic ordering. At room temperature, all the samples show strong magneto-dielectric coupling.

scholarly journals Enhanced electrical conductivity in Zr-Doped (La0.7Ba0.3)(Mn0.5Fe0.5)O3 solid solutions

2020 ◽  
Vol 10 (06) ◽  
pp. 2050032
Author(s):  
Yogesh Kumar ◽  
Jaswinder Pal ◽  
Parambir Singh Malhi ◽  
Rakesh Kumar
Keyword(s):  
Electrical Conductivity ◽  
Solid Solutions ◽  
Ac Conductivity ◽  
Small Polaron ◽  
Negative Temperature ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Maximum Value ◽  
Jonscher’S Power Law

The perovskite ([Formula: see text][Formula: see text]([Formula: see text][Formula: see text][Formula: see text]O3, where [Formula: see text] = 0.1, 0.2 and 0.3, ceramics were synthesized by solid-state reaction method. The introductory structural studies were followed through by X-ray diffraction technique and the results have disclosed that all the samples were crystallized into an isolated phase. The Zr substitution in the resulting solid solutions increases the electrical conductivity and the maximum value of ac conductivity has been found to be [Formula: see text]118.8 S [Formula: see text] cm[Formula: see text] for [Formula: see text] = 0.3 at 200[Formula: see text]C (at 1 MHz). The frequency dependence of ac conductivity data follows Jonscher’s power law. The variation of the exponent [Formula: see text] versus temperature follows the nonoverlapping small polaron tunneling (NSPT) model. The dielectric relaxation has been observed to be of non-Debye nature for all measuring temperatures (50–200[Formula: see text]C). The impedance spectroscopy reveals that all the samples exhibit negative temperature coefficient of resistance (NTCR) behavior. The prepared samples (for [Formula: see text] > 1) are supposed to be suitable for cathode materials in SOFCs.

scholarly journals Frequency and Temperature Dependent Dielectric Response of Fe3O4 Nano-crytallites

2014 ◽  
Vol 6 (3) ◽  
pp. 399-406 ◽  
Author(s):  
M. Z. Ansar ◽  
S. Atiq ◽  
K. Alamgir ◽  
S. Nadeem
Keyword(s):  
Magnetite Nanoparticles ◽  
Sol Gel ◽  
Dielectric Behavior ◽  
Tangent Loss ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Dielectric Tangent Loss ◽  
Auto Combustion ◽  
Combustion Technique

Magnetite nanoparticles have been prepared by using sol-gel auto combustion technique. The samples are prepared by using different concentrations of fuel. Structural characterization has been done using X-Ray diffraction technique and it was observed that fuel concentration can affect the structural properties of Magnetite nanoparticles. The dielectric properties for all the samples such as dielectric constant (??), dielectric tangent loss (tan ?) and dielectric loss factor (??) have been studied as a function of frequency and temperature in the range 10 Hz–20 MHz  and it was found that these nanoparticles can be used in microwave devices because of their good dielectric behavior. © 2014 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi: http://dx.doi.org/10.3329/jsr.v6i3.17938 J. Sci. Res. 6 (3), 399-406 (2014)

Study of Pseudoboehmite Synthesis by Sol-Gel Process

2006 ◽  
Vol 45 ◽  
pp. 260-265 ◽  
Author(s):  
Antônio Hortêncio Munhoz Jr. ◽  
Leila Figueiredo de Miranda ◽  
G.N. Uehara
Keyword(s):  
Sol Gel ◽  
Thermo Gravimetric Analysis ◽  
Ammonium Hydroxide ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Sol Gel Process ◽  
Different Temperatures ◽  
Sol Gel Synthesis

A pseudoboehmite was obtained by sol-gel synthesis using aluminum nitrate as precursor. It was used a 2n full factorial design for studying the effect of the temperature of synthesis, the concentration of ammonium hydroxide, and the radiation dose in the product of sol-gel synthesis. The product of the synthesis was analyzed by scanning electron microscopy, x-ray diffraction of the product (after firing the pseudoboehmite at different temperatures), and it was also analyzed the temperature of endothermic and exothermic transformations using the thermo gravimetric analysis (TG) and differential scanning calorimetry (DSC). The X-ray diffraction data show that α-alumina was obtained at 1100o C.

Preparation and Characterization of Doped Nanometer TiO2

2007 ◽  
Vol 26-28 ◽  
pp. 649-652 ◽  
Author(s):  
Lin Yun Song ◽  
Yu Cheng Wu ◽  
Xiang Fen Lu
Keyword(s):  
Degradation Rate ◽  
Sol Gel ◽  
Complexing Agent ◽  
Gel Formation ◽  
X Ray Diffraction ◽  
Nano Tio2 ◽  
Doped Tio2 ◽  
X Ray ◽  
Different Temperatures

With Ti(OBu)4 as precursor, and HAC as complexing agent, pure and Fe-doped TiO2 gelatins were prepared by sol-gel method. During the process of gel formation, metal ions were dispersed into the porous TiO2 matrix. Then, powders of pure nano-TiO2 and Fe-doped nano-TiO2 were prepared by drying, grinding and calcining at different temperatures. The grain size and phase structure of pure and Fe-doped TiO2 after calcined at different temperatures, were studied by X-ray diffraction (XRD) and Beckman Coulter Sorption Analysis. The results showed that, the Fe3+-TiO2 had better photocatalytic activity in degradation rate of methyl orange under sunlight. The degradation rate was up to 93% as the system was placed under sunlight for 5 h. The optimum calcination temperature for the best catalytic activity was determined to be 500°C, and the mechanism was discussed.

A Study on the Preparation of Nano-Crystalline Barium Titanate Powder by a Sol-Gel Method

2007 ◽  
Vol 121-123 ◽  
pp. 53-56 ◽  
Author(s):  
J. Azadmanjiri ◽  
Hojjatollah K. Salehani ◽  
A. Dehghan Hamedan ◽  
M. Sadeghi
Keyword(s):  
Crystallite Size ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Uniform Size ◽  
Impedance Analyzer ◽  
X Ray ◽  
Nano Crystalline ◽  
Sol Gel Process ◽  
Different Temperatures ◽  
Scanning Electron

In this work, high purity BaTiO3 (BT) nano-powders by a sol-gel process was prepared with Ba(NO3)2 and Ti(C4H9O)4 materials in order to acquire uniform size grains. The effects of the crystallinity, microstructure of BT nano-powders calcined at different temperatures and dielectric properties of the ceramics were investigated by XRD, SEM and impedance analyzer, respectively. Scanning electron microscopy and X-ray diffraction investigation revealed cubic plates and crystallite size. The results revealed that crystallite size and calcination temperature of BT and influence on the dielectric constant.

COMPLEX IMPEDANCE SPECTROSCOPY ON ZnO-B2O3 DOPED (Ba, Sr)TiO3 CERAMICS

2010 ◽  
Vol 17 (01) ◽  
pp. 27-32 ◽  
Author(s):  
SANG-HO MOON ◽  
YONG-SU HAM ◽  
JUNG-HYUK KOH
Keyword(s):  
Impedance Spectroscopy ◽  
Complex Impedance ◽  
Negative Temperature ◽  
Nyquist Plot ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Bst Ceramics ◽  
Grain Growth Behavior ◽  
Microscopy Images

BST ceramics with doping of 1, 3, and 5 wt.% ZnBO were prepared by the conventional mixed oxide method and sintered at 1100°. X-ray diffraction analyses were carried out to verify the structural properties. 1, 3, and 5 wt.% ZnBO doped BST ceramics were crystallized with weak tetragonal structure at 1100°C. The grain growth behavior and shapes were investigated by scanning electron microscopy images. The electrical properties of 1, 3, and 5 wt.% ZnBO doped BST ceramics were investigated by impedance spectroscopy at the different temperatures (350, 375, and 400°C). Impedance spectroscopy data presented in Nyquist plot show the existence of both grain and grain boundary effects in all specimens. 1, 3, and 5 wt.% ZnBO doped BST ceramics showed negative temperature coefficient of resistance (NTCR). Also, the capacitances and resistances of grains and grain boundaries for 1, 3, and 5 wt.% doped BST ceramics were simulated through equivalent circuit with the parallelly connected capacitors and resistors. The capacitance and resistance were decreased when temperature and ZnBO dopants were increased.

scholarly journals Effect of Al3+ Substitution On Magnetic and DC Electrical Resistivity Properties of NiZnCu Nanoferrites

2021 ◽  
Author(s):  
N MURALI
Keyword(s):  
Electrical Resistivity ◽  
Negative Temperature Coefficient ◽  
Sol Gel ◽  
Combustion Process ◽  
Negative Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Auto Combustion ◽  
Ft Ir ◽  
Resultant Material

Abstract Al substituted Ni0.4Zn0.35Cu0.25Fe2-xAlxO4 (x = 0.00, 0.05, 0.10, 0.15, 0.20) samples is synthesized using the sol-gel auto-combustion process. X-ray diffraction shows its cubic spinel structure. The lattice constant decreases as the Al3+ content increases. The sizes of the crystallites are also decreasing in the range of 32.15 nm to 22.89 nm. The wavenumbers of tetrahedral and octahedral sites sighted in the FT-IR spectra are similar to that of the precursor. The increment in the Al3+ content increases the DC conductivity. The electrical resistivity decrease with an increase in the temperature, i.e., it has a negative temperature coefficient with resistance similar to semiconductors. VSM results show their isotropic nature forming single domain ferrimagnetic particles. The resultant material is widely significant, as indicated by its result.

scholarly journals Nanosized LaCo0.6Fe0.4O3 perovskites synthesized by citrate sol gel auto combustion method

2014 ◽  
Vol 8 (2) ◽  
pp. 87-92 ◽  
Author(s):  
Unikoth Megha ◽  
Karakat Shijina ◽  
George Varghese
Keyword(s):  
Sol Gel ◽  
Combustion Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dense Microstructure ◽  
Metal Nitrates ◽  
Average Grain Size ◽  
Auto Combustion ◽  
Different Temperatures ◽  
Lcr Meter

LaCo0.6Fe0.4O3 (LCFO) nanopowder was synthesized from constituent metal nitrates, citric acid and ethylene glycol by citrate sol gel autocombustion method and calcined at different temperatures. The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX) and Fourier transform infrared spectra (FTIR), whereas dielectric properties were investigated with LCR-meter. The FTIR spectra, taken for the xerogel and the sample calcined at 1000?C, confirm that the organic groups were removed during calcination and oxide structure was formed. The XRD result shows that LCFO has rhombhohedral crystal structure with R-3C space group and forms single phase after calcination at 600?C. The activation energy of crystallite growth, determined from the Arrhenius plot, was 17?2 kJ/mol. Surface feature studies of the powders were obtained from SEM. At 1000?C, dense microstructure with wellshaped grain boundaries was obtained and the average grain size was around 400 nm. EDAX confirms the elemental composition. Finally, from the dielectric studies, it was found that the dielectric constant (?r) as well as dielectric loss tangent (tan ?) decreases with increase in frequency.

Temperature of Formation Studies for LiMn1.5Ni0.5O4 Using X-Ray Diffraction

2005 ◽  
Vol 480-481 ◽  
pp. 77-80
Author(s):  
A. Mat ◽  
M.Z.A. Yahya ◽  
Mohd Ali Sulaiman ◽  
R. Puteh ◽  
A.K. Arof
Keyword(s):  
Lithium Batteries ◽  
Sol Gel ◽  
Active Material ◽  
Present Form ◽  
X Ray Diffraction ◽  
Active Materials ◽  
X Ray ◽  
Precursor Material ◽  
Different Temperatures ◽  
Solgel Method

The objective of this paper is to show that annealing lithiated transition metal oxide (LTMO) precursors obtained by the sol-gel method at insufficiently high temperatures may not produce the intended pure cathode active materials required in lithium batteries. In this work, LiMn1.5Ni0.5O4 which is a potential cathode active material in the 5 V-class is prepared by the solgel method. The precursor material was obtained when the solid gel was dried and heated at different temperatures in the range between 200 °C and 900 °C for 4 hours. It was observed that on heating the precursor material at least at 500 °C for 4 hours the material produced was LiMn1.5Ni0.5O4 in the present form as proven by the x-ray diffractogram (XRD). On heating at temperatures below this, the formation of LiMn1.5Ni0.5O4 was uncomplete and at temperatures above 500 °C the intensity of the peak at 2q = 18° decreases. The noise level also increased at temperatures above 500 °C.

Structural and Luminescence Properties of Nanocrystalline Eu3+-doped Gd2O3

2008 ◽  
Vol 1074 ◽  
Author(s):  
Segundo Jauregui ◽  
Oscar Perales-Perez ◽  
Omar Vasquez ◽  
W. Jia ◽  
M. S. Tomar ◽  
...  
Keyword(s):  
Annealing Temperature ◽  
Sol Gel ◽  
Luminescence Properties ◽  
Atomic Fraction ◽  
Photoluminescence Intensity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Species Being

ABSTRACTThe present work addresses the synthesis and characterization of red emitting Gd2-xEuxO3 nanocrystalline phosphors by a modified sol-gel based method. The effects of the annealing temperature and atomic fraction of Eu3+ ions, ‘x’, on the structural and luminescence properties of the produced oxides have been systematically investigated. X-ray diffraction analyses revealed that crystalline cubic-Gd2O3 host structure was obtained when the intermediates (x=0.01-0.30) were annealed at different temperatures in air. Photoluminescence spectra of doped Gd2O3 powders showed all transitions of Eu3+ species, being the 5D0→7F2 transition the most intense. On a common sample-weight basis, the highest photoluminescence intensity was obtained at ‘x’ = 0.15. The energy transfer from host to dopant was verified for all evaluated ‘x’ values, which suggest the actual incorporation of Eu species into the Gd-oxide lattice. It was also found that the photoluminescence intensity was strongly dependent on the annealing temperature and dopant concentration.

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