Processing and ferroelectric behavior of textured KSr2Nb5O15 ceramics

Abstract

< 001 >-textured KSr2Nb5O15 (KSN) ceramics were fabricated in a matrix of SrNb2O6 and KNbO3 powders via reactive templated grain growth (TGG), using < 001 >-oriented acicular KSN particles as the template for grain growth. KSN phase formation started at 1100 degrees C and was complete at 1300 degrees C. Template particles grew at the expense of matrix grains with increasing sintering time and temperature, resulting in improved texture fraction, f. A maximum fraction of 0.98 was obtained in 1.5 wt% Nb2O5 and 10 wt% template containing samples sintered at 1450 degrees C for 6 h. A template content of 10 wt% resulted in a high quality of texture with a narrow distribution of elongated grains in [001]. The highly textured ceramics (f >= 0.9) had a remanent polarization of 0.19 C/m(2) in the polar c direction, [001], as compared to 0.03 C/m(2) in the non-polar a or b direction and 0.04 C/m(2) as for the random sample. The estimated saturation polarization (P-sat) was 0.25 C/m(2) which is comparable to reported KSN single crystal value of 0.25 C/m(2). This indicates that TGG is a viable method to fabricate textured ceramics having ferroelectric properties close to the single crystals.