FORMATION OF NEODYMIUM-ALUMINUM OXIDE BINARY-SYSTEM PREPARED FROM NITRATES BY COPRECIPITATING WITH AMMONIA

The phase and texture conversions in the Nd2O3-Al2O3 binary system of variable molar composition occurring during the heat treatment at temp eratures up to 1200 degrees C in air were studies by XRD, DTA, and the specific surface area S-BET measurements. the samples were synthetize d by neutralization of solutions of aluminium and neodymium nitrates w ith ammonia. It was shown that above 460 degrees C, samples rich in Nd , produced amorphous, non-porous materials which crystallized at 800-9 00 degrees C to give perovskite NdAlO3, and transition mixed phase Nd- Al-O with structure of hexagonal neodymium oxide (A-Nd2O3) with the la ttice constants (for the Al:Nd=50:50% mol content) a=4.009 Angstrom, c =5.038 Angstrom. This phase is unstable and decomposes at 930 degrees C to give perovskite NdAlO3. The crystallization temperatures for samp les with low nd content are shifted towards higher temperatures.