Europium doped LiNiPO4 and undoped LiNiPO4 were prepared by Pechini method. Compound formation temperature was confirmed from thermogravimetry and differential thermal analysis （TG/DTA）. Powder X-ray diffraction （...Europium doped LiNiPO4 and undoped LiNiPO4 were prepared by Pechini method. Compound formation temperature was confirmed from thermogravimetry and differential thermal analysis （TG/DTA）. Powder X-ray diffraction （XRD） pattern confirmed the formation of pure LiNiPO4 compound with an orthorhombic structure. The conductivity and modulus analyses of the samples were carried out at different temperatures and frequencies using the complex impedance spectroscopy technique. The conductivity parameters such as ion hopping frequency and the charge cartier concentration term were calculated using Almond and West formalisms. An increase of one order of magnitude in the ionic conductivity has been observed for 1.0% Eu-doped LiNiPO4. （mole fraction）. The complex modulus studies suggest the presence of non-Debye type of relaxation in the materials.展开更多
LiCeO2 was prepared by a solid-state reaction method using microwave heat treatment and identified by X-ray diffractometry.LiCeO2 has monoclinic crystal structure whose conductivity and dielectric properties were stud...LiCeO2 was prepared by a solid-state reaction method using microwave heat treatment and identified by X-ray diffractometry.LiCeO2 has monoclinic crystal structure whose conductivity and dielectric properties were studied over a range of frequency(42 Hz to 1 MHz) and temperatures(30-500 °C) using ac technique of complex impedance analyzer HIOKI 3532.Combined impedance and modulus plots were used as tools to analyze the sample behaviour as a function of frequency at different temperatures.The d.c.conductivity...展开更多
Temperature dependent X-ray diffraction(XRD)and dielectric properties of perovskite Ba(Zr_(0.2)Ti_(0.8))O_(3) ceramic prepared using a standard solid-state reaction process is presented.Along with phase transitions at...Temperature dependent X-ray diffraction(XRD)and dielectric properties of perovskite Ba(Zr_(0.2)Ti_(0.8))O_(3) ceramic prepared using a standard solid-state reaction process is presented.Along with phase transitions at low temperature,a new phase transition at high temperature(873℃ at 20 Hz),diffusive in character has been found where the lattice structure changes from monoclinic(space group:P2=m) to hexagonal(space group:P6=mmm).This result places present ceramic in the list of potential candidate for intended high temperature applications.The AC conductivity data followed hopping type charge conduction and supports jump relaxation model.The experimental value of d_(33)=98 pC/N was found.The dependence of polarization and strain on electric field at room temperature suggested that lead-free Ba(Zr_(0.2)Ti_(0.8))O_(3) is a promising material for electrostrictive applications.展开更多
Lead-free Ba(Fe_(1/2)Nb_(1/2))O_(3)/PVDF O_(3) composites were fabricated using melt.mixing technique.X-ray diffraction,scanning electron microscopy,dielectric,impedance,ac conductivity,magnetic force microscopy(MFM)a...Lead-free Ba(Fe_(1/2)Nb_(1/2))O_(3)/PVDF O_(3) composites were fabricated using melt.mixing technique.X-ray diffraction,scanning electron microscopy,dielectric,impedance,ac conductivity,magnetic force microscopy(MFM)and vibrating sample magne-tometer studies were undertaken to characterize the samples.Average crstallite size of the Ba(Fe_(1/2)Nb_(1/2))O_(3) powder,estimated using Williamson-Hall approach,was found to be~42 nm.The fller particles of~0.5-1 pum were found to disperse in the polymer matrix of all the composites.Filler concentration dependent values of real and imaginary parts of complex permittivity showed increasing trend and were seen to follow Bruggeman and Furukawa equations.The data for ac conductivity exhibited negative temperature coeficient of resistance character of the test materials and were found to obey Jonscher's power law.The correlated barier hopping model was found to explain satisfactorily the mechanism of charge transport occurring in the system.MFM confirmed the presence of magnetic phases in the composites.Typical magnetization versus applied field curves indicated the possibility of magnetoelectric coupling in the system.Hence,the present composites have shown themselves as potential multi-functional candidate materials for use in high density data storage applications.展开更多
文摘Europium doped LiNiPO4 and undoped LiNiPO4 were prepared by Pechini method. Compound formation temperature was confirmed from thermogravimetry and differential thermal analysis （TG/DTA）. Powder X-ray diffraction （XRD） pattern confirmed the formation of pure LiNiPO4 compound with an orthorhombic structure. The conductivity and modulus analyses of the samples were carried out at different temperatures and frequencies using the complex impedance spectroscopy technique. The conductivity parameters such as ion hopping frequency and the charge cartier concentration term were calculated using Almond and West formalisms. An increase of one order of magnitude in the ionic conductivity has been observed for 1.0% Eu-doped LiNiPO4. （mole fraction）. The complex modulus studies suggest the presence of non-Debye type of relaxation in the materials.
文摘LiCeO2 was prepared by a solid-state reaction method using microwave heat treatment and identified by X-ray diffractometry.LiCeO2 has monoclinic crystal structure whose conductivity and dielectric properties were studied over a range of frequency(42 Hz to 1 MHz) and temperatures(30-500 °C) using ac technique of complex impedance analyzer HIOKI 3532.Combined impedance and modulus plots were used as tools to analyze the sample behaviour as a function of frequency at different temperatures.The d.c.conductivity...
文摘Temperature dependent X-ray diffraction(XRD)and dielectric properties of perovskite Ba(Zr_(0.2)Ti_(0.8))O_(3) ceramic prepared using a standard solid-state reaction process is presented.Along with phase transitions at low temperature,a new phase transition at high temperature(873℃ at 20 Hz),diffusive in character has been found where the lattice structure changes from monoclinic(space group:P2=m) to hexagonal(space group:P6=mmm).This result places present ceramic in the list of potential candidate for intended high temperature applications.The AC conductivity data followed hopping type charge conduction and supports jump relaxation model.The experimental value of d_(33)=98 pC/N was found.The dependence of polarization and strain on electric field at room temperature suggested that lead-free Ba(Zr_(0.2)Ti_(0.8))O_(3) is a promising material for electrostrictive applications.
文摘Lead-free Ba(Fe_(1/2)Nb_(1/2))O_(3)/PVDF O_(3) composites were fabricated using melt.mixing technique.X-ray diffraction,scanning electron microscopy,dielectric,impedance,ac conductivity,magnetic force microscopy(MFM)and vibrating sample magne-tometer studies were undertaken to characterize the samples.Average crstallite size of the Ba(Fe_(1/2)Nb_(1/2))O_(3) powder,estimated using Williamson-Hall approach,was found to be~42 nm.The fller particles of~0.5-1 pum were found to disperse in the polymer matrix of all the composites.Filler concentration dependent values of real and imaginary parts of complex permittivity showed increasing trend and were seen to follow Bruggeman and Furukawa equations.The data for ac conductivity exhibited negative temperature coeficient of resistance character of the test materials and were found to obey Jonscher's power law.The correlated barier hopping model was found to explain satisfactorily the mechanism of charge transport occurring in the system.MFM confirmed the presence of magnetic phases in the composites.Typical magnetization versus applied field curves indicated the possibility of magnetoelectric coupling in the system.Hence,the present composites have shown themselves as potential multi-functional candidate materials for use in high density data storage applications.
