Synthesis and: In situ ion irradiation of A-site deficient zirconate perovskite ceramics

Abstract

The influence of A-site vacancies on zirconate perovskite structured ceramics of formula A1-xLa2x/3ZrO3 (A = Ca, Sr, Ba) has been investigated using 400 keV Kr+in situ ion irradiation in a TEM with varied temperature from 100 K to 673 K. The solubility limit of La within the Ba1-xLa2x/3ZrO3 system was 5.33 ml% (x = 0.08) using a solid-state synthesis route, with space group symmetry of Pm3m for x ≤ 0.08. The Ca0.9La0.067ZrO3 and Sr0.9La0.067ZrO3 samples were found to synthesise single-phase with the Pcmn and Pbnm symmetries of their respective end member structures. The addition of 6.67 ml% La (x = 0.1) in CaZrO3 and SrZrO3 was found to decrease the critical temperature of amorphisation, Tc, in comparison with the undoped structures. A similar decrease was found for the 5.33 ml% La doped BaZrO3 structure. Namely, values were observed for doped samples of 404 K, 520 K and 621 K (A = Sr, Ca, Ba respectively), compared to 440 K, 623 K and 675 K for SrZrO3, CaZrO3 and BaZrO3, respectively. This follows similar behaviour to that observed in titanate systems at low dopant levels, and these findings have been discussed in relation to both the presence of cation vacancies in the doped samples and the presence of the La cation. Void formation, growth and induced morphology changes have also been characterised, onset by ion irradiation.