Dielectric relaxation in lead‐free perovskite Ba(Bi_1/2Nb_1/2)O₃

Abstract

A new lead‐free perovskite ceramic Ba(Bi1/2Nb1/2)O3 was prepared by a conventional ceramic technique at 1185 °C in oxygen atmosphere. X‐ray diffraction analysis of the compound indicated the formation of a single‐phase monoclinic structure. Dielectric study revealed a diffuse phase transition at 340 °C. Cole–Cole analyses suggested the dielectric relaxation to be of non‐Debye type. Electric modulus studies supported the hopping type of conduction in Ba(Bi1/2Nb1/2)O3. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Structural and Electrical Properties of Lead‐Free Perovskite Ba(Al1/2Nb1/2)O3

“…The value of τ o and U are estimated using linear least squares fit to the data points shown in inset of Fig. 7 and are respectively, 24.86 ns and 0.24 eV, which are comparable to the reported values for similar systems: Ba(Fe 1/2 Nb 1/2 )O 3 (0.174 eV 10 ), Ba(Fe 1/2 Ta 1/2 )O 3 (0.15 eV 13 ), and Ba(Bi 1/2 Nb 1/2 )O 3 (0.34 eV 17 ).…”

“…It can be seen from the impedance plots that the data are not represented by full semicircle rather they are depressed one, i.e., centers of semicircles lie little below the abscissa Z′‐axis. Here α>0 and it increases with the rise in temperature, suggesting the dielectric relaxation to be of non‐Debye type in BAN, similar to Ba(Fe 1/2 Nb 1/2 )O 3 4 and Ba(Bi 1/2 Nb 1/2 )O 3 17 . This may happen due to the presence of distributed elements in the material–electrode system.…”

“…S ince the discovery of high‐dielectric constant in CaCu 3 Ti 4 O 12 , a number of lead‐free perovskites have been studied 1,2 . These materials include A(Fe 1/2 B 1/2 )O 3 (A≡Ba, Sr, Ca; B≡Nb, Ta, Sb), 3–14 Ba(Al 1/2 Nb 1/2 )O 3 , 15,16 Ba(Bi 1/2 Nb 1/2 )O 3 , 17 etc., and they generally exhibit high dielectric constant (10 3 –10 5 ). These materials can be useful for electronic/microelectronic applications.…”

Structural and electrical properties of lead-free perovskite ceramic: Ba(In1/2Nb1/2)O3

“…centre of semicircle lies below the abscissa Z′-axis. Here α N 0, suggesting the dielectric relaxation to be of non-Debye type in BIN, similar to Ba(Al 1/2 Nb 1/2 )O 3 [9] and Ba(Bi 1/2 Nb 1/2 )O 3 [26]. This may happen due to the presence of distributed elements in the material-electrode system [17].…”

“…The values of Z″ reach a maximum peak (Z″ max ), called relaxation frequency (f m ), which are slightly asymmetric in nature. The asymmetric broadening of peaks in Z″-f plots suggests that there is a spread of relaxation times, thereby indicating the existence of a temperature dependent electrical relaxation in the material [21,26]. The most probable frequency ω m was obtained from the frequency at which Z″ max is observed.…”