Mn4+ MULTISITES AND Mn4+ → Tm3+ ENERGY TRANSFERS IN Gd3Ga5O12 GARNET A. BRENIER, C. PEDRINI, C. MADEJ, G. BOULON et A. SUCHOCKI J. Phys. IV France, 01 C7 (1991) C7-285-C7-288 DOI: 10.1051/jp4:1991777