Zenodo (CERN European Organization for Nuclear Research), 2001
Homopolymerization of acrylonitrile, initiated by p-nitrophcnacyldimethyl sulfonium ylide has bee... more Homopolymerization of acrylonitrile, initiated by p-nitrophcnacyldimethyl sulfonium ylide has been studied at 40o under inert atmosphere using dilatometric technique. The radical polymerization of acrylonitrile follows non-ideal kinetics, since the monomer and initiator exponent values are found to be 1.1 and 0.39, respectively. The polymcl"ization is retrarded hy hydroquinone. The overall activation energy is calculated to be 44 kJ mol-1 • Kinetic data indicate that the polymerization involves free radical mechanism.
La doped lead titanate ceramic compositions Pb1−x La x TiO3 (PLT) for x = 0.0, 0.05, 0.1, 0.2 and... more La doped lead titanate ceramic compositions Pb1−x La x TiO3 (PLT) for x = 0.0, 0.05, 0.1, 0.2 and 0.3 were synthesized by an acrylic acid modified sol-gel route. The microstructure, surface morphology, and optical properties of the resulting compositions were studied by using TGA, X-ray diffraction, Raman Spectroscopy, and UV–Vis spectroscopy. It was found that the acrylic acid acts as a strong gelling agent and the organic residue gets removed completely below 450 °C. Very smooth ceramic powders characterized by single perovskite phase were obtained. A reduction in the tetragonality ratio from 1.0698 to 1.0033 was observed with increasing La content from x = 0.0 to x = 0.3. The effect of reduced tetragonality was corroborated by the peak shift of soft modes in Raman spectra and approximately 2 cm−1 downshift of E(TO1) mode was observed for each atomic weight percent La addition in lead titanate. The average grain size was found decreasing marginally with the increasing La content i...
Abstract In the present work, La-doped lead titanate ceramics (Pb1− x La x TiO3) (x = 0, 0.05, 0.... more Abstract In the present work, La-doped lead titanate ceramics (Pb1− x La x TiO3) (x = 0, 0.05, 0.10, 0.20 and 0.30 mol%) were synthesized using a modified sol–gel route. The crystallization process in resulting ceramics and the effect of La doping on their microstructure have shown that single crystalline phases were obtained above 490 °C. A systematic decrease in lattice tetragonality with La incorporation, as evaluated using tolerance factor was confirmed by X-ray diffractometer and energy dispersive analysis of X-ray measurements. Average crystallite size variation was correlated with the sintering and the La content.
International journal of engineering research and technology, 2018
We have synthesized TiC powders using sol-gel process at temperatures 1100 0 C and above, which r... more We have synthesized TiC powders using sol-gel process at temperatures 1100 0 C and above, which resulted in cubic TiC phases with 4.330Å lattice parameter. Fine nano powders were obtained at 1100°C. The effect of annealing conditions in the temperature range 1100 1500°C resulted in grain broadening with increasing temperature. The repetitive cyclic voltammetry of TiC revealed good electrode like electrochemical properties. Temperature dependent electrical conduction exhibited insulating behaviour up to 600 o C while semiconducting behaviour was observed at high temperatures.
BaTi1-xFexO3 compositions for x = 0.0 - 0.5 were successfully synthesized using solgel method and... more BaTi1-xFexO3 compositions for x = 0.0 - 0.5 were successfully synthesized using solgel method and the structural, dielectric, ferroelectric, and ferromagnetic properties of these compositions were studied. X-Ray diffraction patterns revealed a tetragonal phase in x=0.0 composition which changed to the hexagonal phase in x = 0.4 and 0.5 compositions. The co-existence of tetragonal and hexagonal phases was observed in iron doped samples up to x= 0.3. The difference in ionic radii of Ti and Fe ions was responsible for changing c/a ratio. Average grain size was found gradually increasing with Fe content in these compositions and was also observed in SEM micrographs. The dielectric constant and tangent loss were found decreasing with Fe concentration. The values of remnant and saturation polarizations decreased whereas that of saturation magnetization increased with an increasing content of Fe in barium titanate.
ADVANCED MATERIALS AND RADIATION PHYSICS (AMRP-2020): 5th National e-Conference on Advanced Materials and Radiation Physics, 2021
In this work, BaTi1-xFexO3 ceramics for x=0 to 0.5 were prepared using solid-state reaction techn... more In this work, BaTi1-xFexO3 ceramics for x=0 to 0.5 were prepared using solid-state reaction technique and the structural, dielectric, ferroelectric, and ferromagnetic properties of resulting BaTi1-xFexO3 (0.0 ≤ x ≤ 0.5) compositions have been studied. Structural investigations using X-ray diffraction reveal that the Fe doping leads to the development of hexagonal phase as well as an increase in the average grain size. The coexistence of tetragonal and hexagonal phases strongly depends upon the Fe concentration. The lattice strain was found to decrease from 4.37 x 10−3 lin−2nm for x=0.0 to 2.31 x 10−3 lin−2nm for x=0.5 as the dislocation density decreases from 12.73 x 10−4 to 4.85 x 10−4 dislocations nm−2 with increasing Fe content from x=0.0 to 0.5. A reduction in the dielectric constant (from 1534 to 305) and Remnant polarization (from 1.105 μC/cm2 to 0.015 μC/cm2) was observed with increasing x from 0 to 0.5. All Fe doped samples exhibit ferromagnetic ordering with increasing saturation magnetization (Ms) 0.084 emu/g at x=0.1 to 0.511 emu/g for x=0.5 samples. The increase in Ms was found in corroboration with the hexagonal volume fraction in the samples.
3RD INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC-2019), 2020
Tetragonal lead titanate ceramics in nano particles forms were fabricated via sol-gel method. The... more Tetragonal lead titanate ceramics in nano particles forms were fabricated via sol-gel method. The gelation was achieved via mixing a solution of lead acetate, titanium isopropoxide in a solvent system of ethanol and acetylacetone. The gel was heated in a normal air oven at 120 0 C for 5 hours to get ceramic powder which was calcined at 600 0 C for two hours and cintered upto 1100 0 C. The calcined powder was characterized by X-ray diffraction XRD and SEM analysis. It has been observed that the particle size increases with temperature with a decrease in grain boundary area.
BaZr_xTi-1-xO3 (BZT) ceramics are of great interest because of a different character of dielectri... more BaZr_xTi-1-xO3 (BZT) ceramics are of great interest because of a different character of dielectric response. In this work, combined micro-Raman scattering and dielectric studies were carried out to investigate the phase transition behavior of BZT ceramics and crystals prepared using a conventional powder processing and laser heated pedestal growth techniques, respectively. The single-phase perovskite structure of the ceramics was identified
Light scattering investigations are carried out on BaBi4Ti4O15 (BBiT) which is a member of the Bi... more Light scattering investigations are carried out on BaBi4Ti4O15 (BBiT) which is a member of the Bi-layer structure ferroelectric oxide with n = 4. The BBiT thin films, thickness ∼ 300 nm, were grown on epitaxial conducting LaNiO3 electrodes on epitaxial buffer layers on (100) silicon by pulsed laser deposition. Micro-Raman measurements performed on these films reveal a sharp low-frequency mode at 51 cm−1 along with broad highfrequeficy modes corresponding to other lattice vibrations including TiO6 octahedra. No temperature dependence of the low frequency mode is seen while a weak dependence of the broad high frequency vibrations are observed in the mixed oriented regions. Raman polarization carried out at room temperature indicates that the prominent modes have Alg and Eg symmetries in the BaBi4Ti4O15 thin films.
The dielectric behavior of sol-gel derived Ba 0.80 Sr 0.20 (Zr x Ti 1−x)O 3 (0.0 ≤ x ≤ 0.50) thin... more The dielectric behavior of sol-gel derived Ba 0.80 Sr 0.20 (Zr x Ti 1−x)O 3 (0.0 ≤ x ≤ 0.50) thin films is studied. A relaxor behavior is observed for x ≥ 0.35. The degree of relaxation increases with Zr content. The frequency dependence of the polar regions follows Vogel-Fulcher relation with a characteristic cooperative freezing at freezing temperature (T f). Below T f , a long range polarization ordering is likely to take place. The plausible mechanism of the relaxor behavior of BSZT thin films with Zr contents ≥0.35 has been proposed based on the measured temperature as well as frequency dependent dielectric data. The solid solution system is visualized as a mixture of Ti + 4 rich polar regions and Zr + 4 rich regions; with the increase in Zr content the volume fraction of the polar regions is progressively reduced. At and above 35.0 at.% Zr substitution the polar regions exhibit typical relaxor behavior.
Micro-Raman study in the temperature range of 70-575 K was performed to investigate the overlap o... more Micro-Raman study in the temperature range of 70-575 K was performed to investigate the overlap of the basic phase transitions in barium titanate ceramics and single crystals of low Zr concentration. The possibilities of stress and grain size effects that are crucial for the ...
The polycrystalline samples of 0.8BiSmxFe[Formula: see text]O3–0.2PbTiO3 ([Formula: see text] and... more The polycrystalline samples of 0.8BiSmxFe[Formula: see text]O3–0.2PbTiO3 ([Formula: see text] and 0.20) were prepared by using the conventional solid-state reaction technique and sintered at high temperature (850[Formula: see text]C). X-ray diffraction (XRD) confirms the distorted rhombohedral crystal structure for all the composites at room temperature. The surface morphology was checked by field-emission scanning electron microscope (FESEM) technique and homogeneous mixing of the components was confirmed by energy-dispersive analysis of X-ray (EDAX). The detailed study of dielectric properties of the composites reveals an increasing nature of dielectric constant ([Formula: see text]) and loss tangent (tan[Formula: see text]) with the increase of temperature due to thermal activation. The Arrhenius plots of temperature dependence of AC conductivity yield the activation energy within the material at high-temperature range. The ferroelectric study shows that the remnant polarization ...
In this work, we report on the growth and characterization of polycrystalline BiFeO 3 (BFO) thin ... more In this work, we report on the growth and characterization of polycrystalline BiFeO 3 (BFO) thin films deposited on indium tin oxide (ITO) coated glass substrates via the chemical solution deposition technique. The as-deposited films were crystallized by heat treatment at various temperatures for 1 h in various atmospheres, i.e. oxygen, air and nitrogen. Grazing angle X-ray diffraction (GIXRD) analysis of the heat treated films revealed that both annealing temperatures as well as the atmosphere, had a pronounced effect on the formation of pure perovskite-type BiFeO 3 phase. Ferroelectric measurements showed that the films heat treated in nitrogen showed superior characteristics to those heat treated in air and oxygen with a remanent polarization of 0.52 µC/cm 2 and 1.9 µC/cm 2 for the films annealed at 600 • C and 650 • C respectively at an applied field of 60 kV/cm. BiFeO 3 films annealed in nitrogen also showed maximum dielectric constant (ε r ∼ 300), superior leakage resistance and magnetic properties over other films.
Abstract In this work, structural, dielectric, ferroelectric, and ferromagnetic properties of BaT... more Abstract In this work, structural, dielectric, ferroelectric, and ferromagnetic properties of BaTi1– x Fe x O3 (0 <x < 0.5) ceramics have been investigated. Structural investigations using X-ray diffraction reveal that Fe doping leads to the development of hexagonal phase as well as an increase in average grain size. The coexistence of tetragonal and hexagonal phases strongly depends upon the Fe concentration. The lattice strain and dislocation density are found decreasing with increasing Fe content from x = 0 to 0.5. A reduction in dielectric constant (from 1534 to 305) and Remnant polarization (from 1.105–0.015 μC/cm2) was observed with increasing x from 0 to 0.5. All Fe-doped samples exhibit ferromagnetic ordering with increasing saturation magnetization (Ms) 0.084 emu/g at x = 0.1–0.511 emu/g for x = 0.5 samples.
ABSTRACT Thin films of BaZr0.25Ti0.75O3 in which Ba is partially substituted by Ca are prepared b... more ABSTRACT Thin films of BaZr0.25Ti0.75O3 in which Ba is partially substituted by Ca are prepared by a sol-gel method. Phases and dielectric properties of the films are studied.The crystal structure of BaZr0.25Ti0.75O3 is cubic and does not change with Ca substitution upto x = 0.25 in Ba1-xCaxZr0.25Ti0.75O3. A change from a normal to relaxor behavior is observed for x = 0.20 as indicated by a change in the frequency of dielectric maxima with temperature and other parameters.The dielectric constant and transition temperatures are found to increase with increasing Ca substitution. A tunabilty of 71%, much higher than reported in literature for this material, is observed for x = 0.1 i.e for Ba0.9Ca0.1Zr0.25Ti0.75O3.
In this work, we report on the synthesis and characterization of thin films of (BiFeO3)1−x (PbTiO... more In this work, we report on the synthesis and characterization of thin films of (BiFeO3)1−x (PbTiO3)x (BFPT) solid solutions of compositions around morphotropic phase boundary (MPB) grown on platinized silicon (111) Pt/TiO2/SiO2/Si substrate by sol-gel based spin coating technique. The films were post-annealed at 700 and 750°C for 1 h in air. Morphological analysis of the films was carried out by scanning electron microscopy. Grazing incidence X-ray diffractometry revealed the perovskite structure of the films and peaks suggested the presence of rhombohedral structured pure BFPT phase in polycrystalline form. Scanning electron microscopy suggested that films annealed at 750degC had a denser microstructure as compared to those at 700°C. The room temperature dielectric constant of the films with composition of BF:PT :: 75:25 was measured to be ∼1200 at a frequency of 100 kHz.
Zenodo (CERN European Organization for Nuclear Research), 2001
Homopolymerization of acrylonitrile, initiated by p-nitrophcnacyldimethyl sulfonium ylide has bee... more Homopolymerization of acrylonitrile, initiated by p-nitrophcnacyldimethyl sulfonium ylide has been studied at 40o under inert atmosphere using dilatometric technique. The radical polymerization of acrylonitrile follows non-ideal kinetics, since the monomer and initiator exponent values are found to be 1.1 and 0.39, respectively. The polymcl"ization is retrarded hy hydroquinone. The overall activation energy is calculated to be 44 kJ mol-1 • Kinetic data indicate that the polymerization involves free radical mechanism.
La doped lead titanate ceramic compositions Pb1−x La x TiO3 (PLT) for x = 0.0, 0.05, 0.1, 0.2 and... more La doped lead titanate ceramic compositions Pb1−x La x TiO3 (PLT) for x = 0.0, 0.05, 0.1, 0.2 and 0.3 were synthesized by an acrylic acid modified sol-gel route. The microstructure, surface morphology, and optical properties of the resulting compositions were studied by using TGA, X-ray diffraction, Raman Spectroscopy, and UV–Vis spectroscopy. It was found that the acrylic acid acts as a strong gelling agent and the organic residue gets removed completely below 450 °C. Very smooth ceramic powders characterized by single perovskite phase were obtained. A reduction in the tetragonality ratio from 1.0698 to 1.0033 was observed with increasing La content from x = 0.0 to x = 0.3. The effect of reduced tetragonality was corroborated by the peak shift of soft modes in Raman spectra and approximately 2 cm−1 downshift of E(TO1) mode was observed for each atomic weight percent La addition in lead titanate. The average grain size was found decreasing marginally with the increasing La content i...
Abstract In the present work, La-doped lead titanate ceramics (Pb1− x La x TiO3) (x = 0, 0.05, 0.... more Abstract In the present work, La-doped lead titanate ceramics (Pb1− x La x TiO3) (x = 0, 0.05, 0.10, 0.20 and 0.30 mol%) were synthesized using a modified sol–gel route. The crystallization process in resulting ceramics and the effect of La doping on their microstructure have shown that single crystalline phases were obtained above 490 °C. A systematic decrease in lattice tetragonality with La incorporation, as evaluated using tolerance factor was confirmed by X-ray diffractometer and energy dispersive analysis of X-ray measurements. Average crystallite size variation was correlated with the sintering and the La content.
International journal of engineering research and technology, 2018
We have synthesized TiC powders using sol-gel process at temperatures 1100 0 C and above, which r... more We have synthesized TiC powders using sol-gel process at temperatures 1100 0 C and above, which resulted in cubic TiC phases with 4.330Å lattice parameter. Fine nano powders were obtained at 1100°C. The effect of annealing conditions in the temperature range 1100 1500°C resulted in grain broadening with increasing temperature. The repetitive cyclic voltammetry of TiC revealed good electrode like electrochemical properties. Temperature dependent electrical conduction exhibited insulating behaviour up to 600 o C while semiconducting behaviour was observed at high temperatures.
BaTi1-xFexO3 compositions for x = 0.0 - 0.5 were successfully synthesized using solgel method and... more BaTi1-xFexO3 compositions for x = 0.0 - 0.5 were successfully synthesized using solgel method and the structural, dielectric, ferroelectric, and ferromagnetic properties of these compositions were studied. X-Ray diffraction patterns revealed a tetragonal phase in x=0.0 composition which changed to the hexagonal phase in x = 0.4 and 0.5 compositions. The co-existence of tetragonal and hexagonal phases was observed in iron doped samples up to x= 0.3. The difference in ionic radii of Ti and Fe ions was responsible for changing c/a ratio. Average grain size was found gradually increasing with Fe content in these compositions and was also observed in SEM micrographs. The dielectric constant and tangent loss were found decreasing with Fe concentration. The values of remnant and saturation polarizations decreased whereas that of saturation magnetization increased with an increasing content of Fe in barium titanate.
ADVANCED MATERIALS AND RADIATION PHYSICS (AMRP-2020): 5th National e-Conference on Advanced Materials and Radiation Physics, 2021
In this work, BaTi1-xFexO3 ceramics for x=0 to 0.5 were prepared using solid-state reaction techn... more In this work, BaTi1-xFexO3 ceramics for x=0 to 0.5 were prepared using solid-state reaction technique and the structural, dielectric, ferroelectric, and ferromagnetic properties of resulting BaTi1-xFexO3 (0.0 ≤ x ≤ 0.5) compositions have been studied. Structural investigations using X-ray diffraction reveal that the Fe doping leads to the development of hexagonal phase as well as an increase in the average grain size. The coexistence of tetragonal and hexagonal phases strongly depends upon the Fe concentration. The lattice strain was found to decrease from 4.37 x 10−3 lin−2nm for x=0.0 to 2.31 x 10−3 lin−2nm for x=0.5 as the dislocation density decreases from 12.73 x 10−4 to 4.85 x 10−4 dislocations nm−2 with increasing Fe content from x=0.0 to 0.5. A reduction in the dielectric constant (from 1534 to 305) and Remnant polarization (from 1.105 μC/cm2 to 0.015 μC/cm2) was observed with increasing x from 0 to 0.5. All Fe doped samples exhibit ferromagnetic ordering with increasing saturation magnetization (Ms) 0.084 emu/g at x=0.1 to 0.511 emu/g for x=0.5 samples. The increase in Ms was found in corroboration with the hexagonal volume fraction in the samples.
3RD INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC-2019), 2020
Tetragonal lead titanate ceramics in nano particles forms were fabricated via sol-gel method. The... more Tetragonal lead titanate ceramics in nano particles forms were fabricated via sol-gel method. The gelation was achieved via mixing a solution of lead acetate, titanium isopropoxide in a solvent system of ethanol and acetylacetone. The gel was heated in a normal air oven at 120 0 C for 5 hours to get ceramic powder which was calcined at 600 0 C for two hours and cintered upto 1100 0 C. The calcined powder was characterized by X-ray diffraction XRD and SEM analysis. It has been observed that the particle size increases with temperature with a decrease in grain boundary area.
BaZr_xTi-1-xO3 (BZT) ceramics are of great interest because of a different character of dielectri... more BaZr_xTi-1-xO3 (BZT) ceramics are of great interest because of a different character of dielectric response. In this work, combined micro-Raman scattering and dielectric studies were carried out to investigate the phase transition behavior of BZT ceramics and crystals prepared using a conventional powder processing and laser heated pedestal growth techniques, respectively. The single-phase perovskite structure of the ceramics was identified
Light scattering investigations are carried out on BaBi4Ti4O15 (BBiT) which is a member of the Bi... more Light scattering investigations are carried out on BaBi4Ti4O15 (BBiT) which is a member of the Bi-layer structure ferroelectric oxide with n = 4. The BBiT thin films, thickness ∼ 300 nm, were grown on epitaxial conducting LaNiO3 electrodes on epitaxial buffer layers on (100) silicon by pulsed laser deposition. Micro-Raman measurements performed on these films reveal a sharp low-frequency mode at 51 cm−1 along with broad highfrequeficy modes corresponding to other lattice vibrations including TiO6 octahedra. No temperature dependence of the low frequency mode is seen while a weak dependence of the broad high frequency vibrations are observed in the mixed oriented regions. Raman polarization carried out at room temperature indicates that the prominent modes have Alg and Eg symmetries in the BaBi4Ti4O15 thin films.
The dielectric behavior of sol-gel derived Ba 0.80 Sr 0.20 (Zr x Ti 1−x)O 3 (0.0 ≤ x ≤ 0.50) thin... more The dielectric behavior of sol-gel derived Ba 0.80 Sr 0.20 (Zr x Ti 1−x)O 3 (0.0 ≤ x ≤ 0.50) thin films is studied. A relaxor behavior is observed for x ≥ 0.35. The degree of relaxation increases with Zr content. The frequency dependence of the polar regions follows Vogel-Fulcher relation with a characteristic cooperative freezing at freezing temperature (T f). Below T f , a long range polarization ordering is likely to take place. The plausible mechanism of the relaxor behavior of BSZT thin films with Zr contents ≥0.35 has been proposed based on the measured temperature as well as frequency dependent dielectric data. The solid solution system is visualized as a mixture of Ti + 4 rich polar regions and Zr + 4 rich regions; with the increase in Zr content the volume fraction of the polar regions is progressively reduced. At and above 35.0 at.% Zr substitution the polar regions exhibit typical relaxor behavior.
Micro-Raman study in the temperature range of 70-575 K was performed to investigate the overlap o... more Micro-Raman study in the temperature range of 70-575 K was performed to investigate the overlap of the basic phase transitions in barium titanate ceramics and single crystals of low Zr concentration. The possibilities of stress and grain size effects that are crucial for the ...
The polycrystalline samples of 0.8BiSmxFe[Formula: see text]O3–0.2PbTiO3 ([Formula: see text] and... more The polycrystalline samples of 0.8BiSmxFe[Formula: see text]O3–0.2PbTiO3 ([Formula: see text] and 0.20) were prepared by using the conventional solid-state reaction technique and sintered at high temperature (850[Formula: see text]C). X-ray diffraction (XRD) confirms the distorted rhombohedral crystal structure for all the composites at room temperature. The surface morphology was checked by field-emission scanning electron microscope (FESEM) technique and homogeneous mixing of the components was confirmed by energy-dispersive analysis of X-ray (EDAX). The detailed study of dielectric properties of the composites reveals an increasing nature of dielectric constant ([Formula: see text]) and loss tangent (tan[Formula: see text]) with the increase of temperature due to thermal activation. The Arrhenius plots of temperature dependence of AC conductivity yield the activation energy within the material at high-temperature range. The ferroelectric study shows that the remnant polarization ...
In this work, we report on the growth and characterization of polycrystalline BiFeO 3 (BFO) thin ... more In this work, we report on the growth and characterization of polycrystalline BiFeO 3 (BFO) thin films deposited on indium tin oxide (ITO) coated glass substrates via the chemical solution deposition technique. The as-deposited films were crystallized by heat treatment at various temperatures for 1 h in various atmospheres, i.e. oxygen, air and nitrogen. Grazing angle X-ray diffraction (GIXRD) analysis of the heat treated films revealed that both annealing temperatures as well as the atmosphere, had a pronounced effect on the formation of pure perovskite-type BiFeO 3 phase. Ferroelectric measurements showed that the films heat treated in nitrogen showed superior characteristics to those heat treated in air and oxygen with a remanent polarization of 0.52 µC/cm 2 and 1.9 µC/cm 2 for the films annealed at 600 • C and 650 • C respectively at an applied field of 60 kV/cm. BiFeO 3 films annealed in nitrogen also showed maximum dielectric constant (ε r ∼ 300), superior leakage resistance and magnetic properties over other films.
Abstract In this work, structural, dielectric, ferroelectric, and ferromagnetic properties of BaT... more Abstract In this work, structural, dielectric, ferroelectric, and ferromagnetic properties of BaTi1– x Fe x O3 (0 <x < 0.5) ceramics have been investigated. Structural investigations using X-ray diffraction reveal that Fe doping leads to the development of hexagonal phase as well as an increase in average grain size. The coexistence of tetragonal and hexagonal phases strongly depends upon the Fe concentration. The lattice strain and dislocation density are found decreasing with increasing Fe content from x = 0 to 0.5. A reduction in dielectric constant (from 1534 to 305) and Remnant polarization (from 1.105–0.015 μC/cm2) was observed with increasing x from 0 to 0.5. All Fe-doped samples exhibit ferromagnetic ordering with increasing saturation magnetization (Ms) 0.084 emu/g at x = 0.1–0.511 emu/g for x = 0.5 samples.
ABSTRACT Thin films of BaZr0.25Ti0.75O3 in which Ba is partially substituted by Ca are prepared b... more ABSTRACT Thin films of BaZr0.25Ti0.75O3 in which Ba is partially substituted by Ca are prepared by a sol-gel method. Phases and dielectric properties of the films are studied.The crystal structure of BaZr0.25Ti0.75O3 is cubic and does not change with Ca substitution upto x = 0.25 in Ba1-xCaxZr0.25Ti0.75O3. A change from a normal to relaxor behavior is observed for x = 0.20 as indicated by a change in the frequency of dielectric maxima with temperature and other parameters.The dielectric constant and transition temperatures are found to increase with increasing Ca substitution. A tunabilty of 71%, much higher than reported in literature for this material, is observed for x = 0.1 i.e for Ba0.9Ca0.1Zr0.25Ti0.75O3.
In this work, we report on the synthesis and characterization of thin films of (BiFeO3)1−x (PbTiO... more In this work, we report on the synthesis and characterization of thin films of (BiFeO3)1−x (PbTiO3)x (BFPT) solid solutions of compositions around morphotropic phase boundary (MPB) grown on platinized silicon (111) Pt/TiO2/SiO2/Si substrate by sol-gel based spin coating technique. The films were post-annealed at 700 and 750°C for 1 h in air. Morphological analysis of the films was carried out by scanning electron microscopy. Grazing incidence X-ray diffractometry revealed the perovskite structure of the films and peaks suggested the presence of rhombohedral structured pure BFPT phase in polycrystalline form. Scanning electron microscopy suggested that films annealed at 750degC had a denser microstructure as compared to those at 700°C. The room temperature dielectric constant of the films with composition of BF:PT :: 75:25 was measured to be ∼1200 at a frequency of 100 kHz.
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