The compositional dependence of ac conductivity(δac),real(δ′)and imaginary(δ′′)parts of complex electric conductivity(δ*)was investigated as a function of temperature(T)and frequency(f) for Mn_(0.7+x)Zn_(0.3)Si...The compositional dependence of ac conductivity(δac),real(δ′)and imaginary(δ′′)parts of complex electric conductivity(δ*)was investigated as a function of temperature(T)and frequency(f) for Mn_(0.7+x)Zn_(0.3)Si_(x)Fe_(2-2x)O_(4),x=0.0,0.1,0.2 and 0.3 spinel ferrite system.The compositional dependence of lattice constant values suggested that the most of the substituted Si4+-ions reside at grain boundaries and only a few Si-ions are inside grains.The variation ofδ_(ac)(x,f,T)is explained on the basis of segregation and diffusion of Si4+ions at grain boundaries and grains,respectively,and the electrode effect.Thermal variation of ac conductivity at fixed frequency suggested two different mechanisms which could be responsible for conduction in the system.It is found that δ*is not the preferred presentation for dielectric data and the scaling process of real part of conductivity by normalized frequency and the scaled frequency were found unsuccessful.The fitting results of ac conductivity data with path percolation approximation were found suitable in low-frequency regime while in high-frequency regime,effective medium approximation(EMA)was found successful.展开更多
基金New Delhi for supporting the work under Major Research Project scheme and Dr.D.S.Kothari Post Doctoral Fellowship,respectively(2015-2018).
文摘The compositional dependence of ac conductivity(δac),real(δ′)and imaginary(δ′′)parts of complex electric conductivity(δ*)was investigated as a function of temperature(T)and frequency(f) for Mn_(0.7+x)Zn_(0.3)Si_(x)Fe_(2-2x)O_(4),x=0.0,0.1,0.2 and 0.3 spinel ferrite system.The compositional dependence of lattice constant values suggested that the most of the substituted Si4+-ions reside at grain boundaries and only a few Si-ions are inside grains.The variation ofδ_(ac)(x,f,T)is explained on the basis of segregation and diffusion of Si4+ions at grain boundaries and grains,respectively,and the electrode effect.Thermal variation of ac conductivity at fixed frequency suggested two different mechanisms which could be responsible for conduction in the system.It is found that δ*is not the preferred presentation for dielectric data and the scaling process of real part of conductivity by normalized frequency and the scaled frequency were found unsuccessful.The fitting results of ac conductivity data with path percolation approximation were found suitable in low-frequency regime while in high-frequency regime,effective medium approximation(EMA)was found successful.
