B. C. Sutar; Piyush R. Das; R. N. P. Choudhary
Abstract
Lead-free polycrystalline material Sr(Bi0.5V0.5)O3 was prepared using a high- temperature solid state reaction technique (calcinations and sintering temperature =850 and 950 o C, respectively) using high-purity ingredients. The formation of the material in the monoclinic crystal structure was confirmed ...
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Lead-free polycrystalline material Sr(Bi0.5V0.5)O3 was prepared using a high- temperature solid state reaction technique (calcinations and sintering temperature =850 and 950 o C, respectively) using high-purity ingredients. The formation of the material in the monoclinic crystal structure was confirmed by preliminary X-ray structural analysis with room temperature data.The nature of microstructure obtained by scanning electron microscopy (SEM) shows that the compound has well defined grains which are uniformly distributed throughout the surface of the sample. Detailed studies of dielectric and impedance properties of the material carried out in the frequency range of 1 kHz –1MHz at different temperatures (30 0 C to 455 0 C) have provided many interesting properties. Detailed studies of dielectric properties of the compound showed an existence of diffus e phase transition around 258 0 C. The temperature dependence of electrical parameters (impedance, modulus etc.) of the material exhibits a strong correlation of its microstructure with the electrical parameters. The negative temperature coefficient of resistance (NTCR) behavior also was observed in the material. The complex electric modulus analysis indicates the presence of hopping conduction mechanism in the system with non-exponential type of conductivity relaxation. The nature of variation of dc conductivity with temperature confirms the Arrhenius behavior of the material. The ac conductivity spectra show a typical signature of an ionic conducting system, and are found to obey Jonscher’s universal power law.
S. Behera; Piyush R. Das; B. N. Parida; P. Nayak; R. N. P Choudhary
Abstract
The polycrystalline sample of complex tungsten-bronze compound Li2Pb2Sm2W2Ti4Ta4O30 was prepared by a high-temperature solid-state reaction technique. Room temperature X-ray diffraction (XRD) study suggests the formation of a single-phase compound. Microstructure of the pellet sample was studied by scanning ...
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The polycrystalline sample of complex tungsten-bronze compound Li2Pb2Sm2W2Ti4Ta4O30 was prepared by a high-temperature solid-state reaction technique. Room temperature X-ray diffraction (XRD) study suggests the formation of a single-phase compound. Microstructure of the pellet sample was studied by scanning electron microscope. The temperature variation of dielectric constant shows dielectric anomaly in the sample. Study of electrical properties (impedance, conductivity, etc.,) of the material exhibits a strong correlation between its micro-structure (i.e., bulk, grain boundary, etc) and electrical parameters. A typical Arrhenius behavior was observed in the temperature dependence of dc conductivity.
Anita Mekap; Piyush R. Das; R. N. P. Choudhary
Abstract
The polycrystalline sample of ZnSb2O4 was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray diffraction (XRD) studies of powder sample of ZnSb2O4 showed the formation of single-phase compound at room temperature. The surface morphology of the pellet sample of ZnSb2O4 was ...
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The polycrystalline sample of ZnSb2O4 was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray diffraction (XRD) studies of powder sample of ZnSb2O4 showed the formation of single-phase compound at room temperature. The surface morphology of the pellet sample of ZnSb2O4 was recorded at room temperature using a scanning electron microscope (SEM). Detailed studies of dielectric properties (εr, tan δ) and impedance parameters of the material provide an insight into the electrical properties and understanding of types of relaxation process occurred in the material. Temperature variation of dc conductivity shows that this compound exhibits negative temperature coefficient of resistance (NTCR) and frequency dependence of ac conductivity suggests that the material obeys Jonscher’s universal power law.
B. N. Parida; R. Padhee;R. N. P. Choudhary; Piyush R. Das
Abstract
A new ferroelectric oxide (Li2Pb2Gd2W2Ti4Nb4O30) of the tungsten bronze structural family was synthesized using a high temperature solid-state reaction (i.e., mixed-oxide) method at 1100 o C. Room temperature structural analysis (XRD) shows the formation of a new compound in single phase. The ferroelectric ...
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A new ferroelectric oxide (Li2Pb2Gd2W2Ti4Nb4O30) of the tungsten bronze structural family was synthesized using a high temperature solid-state reaction (i.e., mixed-oxide) method at 1100 o C. Room temperature structural analysis (XRD) shows the formation of a new compound in single phase. The ferroelectric phase transition temperature (much above the room temperature) was determined by the dielectric and polarization measurements. Impedance, modulus and electrical conductivity of the material exhibit a strong correlation between its micro-structure and electrical parameters. The existence of non-exponential-type of conductivity relaxation in the compound was confirmed by detailed studies of its transport properties.
Piyush R. Das; B. Pati; B.C. Sutar; R.N.P. Choudhury
Abstract
Complex impedance analysis of new tungsten bronze ferroelectric vanadates, Na2Pb2R2W2Ti4V4O30 (R = Gd, Eu), was carried out on samples prepared relatively at low temperature using a mixed-oxide technique. The formation of the materials under the reported conditions has been confirmed by an X-ray diffraction ...
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Complex impedance analysis of new tungsten bronze ferroelectric vanadates, Na2Pb2R2W2Ti4V4O30 (R = Gd, Eu), was carried out on samples prepared relatively at low temperature using a mixed-oxide technique. The formation of the materials under the reported conditions has been confirmed by an X-ray diffraction technique. A preliminary structural analysis exhibits orthorhombic crystal structure of the materials at room temperature. The electrical properties of the materials have been studied using ac impedance spectroscopy technique. Detailed studies of impedance and related parameters exhibit that the electrical properties of the materials are strongly dependent on temperature, and bear a good correlation with their microstructures. The temperature dependence of electrical relaxation phenomenon in the materials has been observed. The bulk resistance, evaluated from complex impedance spectra, is found to decrease with rise in temperature, exhibiting a typical negative temperature co-efficient of resistance (NTCR) – type behavior similar to that of semiconductors. A small contribution of grain boundary effect was also observed. The complex electric modulus analysis indicates the possibility of hopping conduction mechanism in the system with non-exponential type of conductivity relaxation. The ac conductivity spectra exhibit a typical signature of an ionic conducting system, and are found to obey Jonscher’s universal power law.