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
Lead-free x(0.50(Ba_(0.7)Ca_(0.3)TiO_(3)-0.50Ba(Zr_(0.2)Ti_(0.8)O_(3)-(1-x)PVDF ceramic–polymer nanocomposites with x=0.025,0.05,0.10,0.15,0.20,0.25 were prepared using melt-mixing technique.The distribution of nanoc...Lead-free x(0.50(Ba_(0.7)Ca_(0.3)TiO_(3)-0.50Ba(Zr_(0.2)Ti_(0.8)O_(3)-(1-x)PVDF ceramic–polymer nanocomposites with x=0.025,0.05,0.10,0.15,0.20,0.25 were prepared using melt-mixing technique.The distribution of nanoceramic filler particles(0.50(Ba_(0.7)Ca_(0.3)TiO_(3)-0.50Ba(Zr_(0.2)Ti_(0.8)O_(3)in the PVDF matrix were examined using scanning electron microscope.Impedance analysis indicated the negative temperature coefficient of resistance character of all the test specimens.Filler concentrationdependent piezoelectric coefficient(d33Þdata followed exponential growth types of variation.The data for ac conductivity were found to obey Jonscher’s power law.The correlated barrier hopping(CBH)model was found to explain the mechanism of charge transport occurring in the system.The low value of loss tangent(-10^(-2))along with the high value of d_(33) foreshadowing the prospect of present nanocomposite is a better nonlead option for piezo-sensing/detection applications,especially in bio-medical area.展开更多
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.
文摘Lead-free x(0.50(Ba_(0.7)Ca_(0.3)TiO_(3)-0.50Ba(Zr_(0.2)Ti_(0.8)O_(3)-(1-x)PVDF ceramic–polymer nanocomposites with x=0.025,0.05,0.10,0.15,0.20,0.25 were prepared using melt-mixing technique.The distribution of nanoceramic filler particles(0.50(Ba_(0.7)Ca_(0.3)TiO_(3)-0.50Ba(Zr_(0.2)Ti_(0.8)O_(3)in the PVDF matrix were examined using scanning electron microscope.Impedance analysis indicated the negative temperature coefficient of resistance character of all the test specimens.Filler concentrationdependent piezoelectric coefficient(d33Þdata followed exponential growth types of variation.The data for ac conductivity were found to obey Jonscher’s power law.The correlated barrier hopping(CBH)model was found to explain the mechanism of charge transport occurring in the system.The low value of loss tangent(-10^(-2))along with the high value of d_(33) foreshadowing the prospect of present nanocomposite is a better nonlead option for piezo-sensing/detection applications,especially in bio-medical area.
