Impedance spectroscopy study of Bi 0.5 (Na 0.74 K 0.16 Li 0.10 ) 0.5 TiO 3 -Ba(Zr 0.05 Ti 0.95 )O 3 ceramics prepared via combustion technique

Abstract

Abstract Lead free (1- x )Bi 0.5 (Na 0.74 K 0.16 Li 0.10 ) 0.5 TiO 3 - x Ba(Zr 0.05 Ti 0.95 )O 3 or BNKLT-100 x BZT, 0.025 ≤ x ≤ 0.125, ceramics with single-phase perovskite structure were prepared via a combustion technique. Impedance spectroscopy was conducted over a wide temperature and frequency range in order to investigate the influences of BZT on electrical properties and conduction mechanisms. Analysis using impedance complex plane plots combined with spectroscopic plots of the imaginary component of the impedance and electric modulus revealed an electrically homogeneous microstructure with increasing BZT content. With the increase in BZT content, the resistivity increased from ~10 6 Ω-cm at x = 0.025 to ~10 7 Ω-cm at x = 0.125. The activation energy determined from an Arrhenius-type plot of conductivity was also found to increase from 0.97 eV ( x = 0.025) to 1.62 eV ( x = 0.125), which is close to half of the optical bandgap, suggesting a change in conduction mechanism towards an intrinsic electronic conduction mechanism. IS measurement under different oxygen partial pressure was also performed on selected sample. The possible defect chemistry conditions responsible for the observed electrical properties will also be discussed.