BaZrO₃ and BaHfO₃: preparation, properties and compatibility with YBa₂Cu₃O_7-x

Abstract

Single-phase BaZrO₃ and BaHfO₃ polycrystalline powders were prepared by solid-state reaction and by spray-drying methods. BaHfO₃ ceramic was fabricated at 1300°C for 24 h after pre-sintering HfO₂ and BaCO₃ powders at 1040°C for 4 h. Homogeneous powders of BaZrO₃ and BaHfO₃ were also prepared by a spray-drying route. The interaction between YBa₂Cu₃O_7-x (YBCO) and BaHfO₃ and BaZrO₃ was investigated in the temperature range 900–1060°C using heat-treatment cycles appropriate to composite reaction processing and melt-texturing. The results indicate that neither compound reacts significantly with YBCO at 950°C, and BaHfO₃ is still unreactive up to 1000°C. Both of them are also very stable during the melting-texture process. BaHfO₃ and BaZrO₃ are thus very promising substrate materials and buffer layers for the deposition of thin and thick films and as container materials for bulk YBCO superconductors; BaHfO₃ seems to be a more stable material than BaZrO₃.