Sanyal, D and Banerjee, D and Bhattacharya, R and Patra, S K and Chaudhuri, S P and Nandi Ganguly, B and De, U (1996) Study of transition metal ion doped mullite by positron annihilation techniques. Journal of Materials Science, 31 (13). pp. 3447-3451. ISSN 0022-2461