Ferroelectric Relaxor Behavior and Dielectric Relaxation in Strontium Barium Niobate – A Lead-Free Relaxor Ceramic Material

Abstract

Various compositions of single-phase ceramics of Strontium barium niobate, SrxBa1-xNb2O6 (x=0.25, 0.50 abbreviated as SBN25 and SBN50) have been synthesized by standard solid-state reaction route by a precise control of cooling rate and optimizing the sintering temperatures. Material calcined at 1250 o C and sintered at 1300 o C is stabilized in pure phase with a tetragonal structure having density >95%. Lattice parameters for SBN25 (a= 12.467(4) Å, c=3.956(5) Å), and SBN50 (a= 12.435(2) Å, c= 3.945(7) Å). Both compositions show a relaxor type behavior with a diffuse phase transition. Modified Curie-Weiss law is used to fit the dielectric data. The dielectric relaxation obeys the Vogel-Fulcher relationship with a freezing temperature of 277.3K for SBN25 and 278.4K for SBN50. Significant dielectric dispersion is observed in the low frequency regime in both components of dielectric permittivity and a small dielectric relaxation peak is observed. This is associated with the defect related hopping process. The value of tilt parameter (α) in Cole-Cole analysis varies from 0.12 to 0.17 for SBN25 and 0.13 to 0.21 for SBN50 with increasing the temperature from 75 o C to 150 o C, indicates poly-dispersive nature of the dielectric relaxation. This material can be a good candidate for hologram and electro-optic data storage media.

Characterization of pores in polished low temperature co-fired glass-ceramic composites for optimization of their micromachining

“…Ceramic composite materials are steadily conquering new areas of application, as desired functional properties can be specifically adjusted by combining material properties of matrix and filler in a sophisticated way. So is it for example possible to improve properties such as their mechanical strength [1][2][3] or energy density [4] and tune parameters like permittivity [5][6][7] or conductivity [8]. Widely used processes for the synthesis of such composites are spray pyrolysis [8,9] and powder-based sintering [1,6,7,10,11] which entail a porous material structure.…”

“…So is it for example possible to improve properties such as their mechanical strength [1][2][3] or energy density [4] and tune parameters like permittivity [5][6][7] or conductivity [8]. Widely used processes for the synthesis of such composites are spray pyrolysis [8,9] and powder-based sintering [1,6,7,10,11] which entail a porous material structure. Low temperature cofired ceramics (LTCC) are a group of glass-ceramic matrix composites that are densified by viscous flow as the major driving mechanism during the sintering process [12].…”