Preparation and Characterisation of High Density, High Purity Lanthanum Aluminate Bulk Ceramics

摘要

In this work some methods for preparation of lanthanum aluminate bulk ceramics were compared. High purity lanthanum aluminate LaAlO{sub}3 (LAO) ceramic samples of high density (>94%) were prepared via three different routes and the morphology, chemical and electrical properties of the samples were investigated. For high purity samples a sol-gel route A. Douy and P. Odier [1] and a thermal nitrate decomposition route Shaji Kumar et al. [2] were introduced to reduce unintentional doping by the preparation process to a minimum. As a standard route the mixed oxide process was chosen. In sol-gel and nitrate decomposition procedures the formation temperature of LaAlO{sub}3 from its oxides was lowered by using reactive γ-alumina from the pyrolysis of initial aluminium nitrate instead of commonly used α-alumina (corundum) in the mixed oxide process. No commercial γ-alumina of sufficient purity is known. Differences in the electrical behaviour of the samples were measured, indicating some correlations between the samples' different morphology, purity and its' preparation parameters.