Formation Region of K-Al-Priderite (K_xAl_xTi_8-xO₁₆)

Abstract

Pseudobinary phase relations relevant to K-Al-priderite (K_xAl_xTi_8-xO₁₆) have been given with the incongruent melting temperature of priderite and the eutectic melting temperature between priderite and rutile. From the lattice parameter change K-Al-priderite has been proved to occur in the range of 1.47<x<1.80 at 1200°C. With increasing x the a-axis decreases from 10.064 to 10.042Å, while the c-axis expands from 2.937 to 2.939Å. The formation range becomes narrow with increasing temperature and finally converges at x=1.5. The stability of K-Al-priderite with x=1.5 was discussed in connection with the formation of a super structure.