OPTICAL PROPERTIES OF Cr3+ ION IN LaMgAl11O19 and La1-x Ndx MgAl11O19 B. VIANA, V. PONCON, C. GARAPON, A. M. LEJUS, D. VIVIEN et G. BOULONJ. Phys. Colloques, 48 C7 (1987) C7-505-C7-507DOI: https://doi.org/10.1051/jphyscol:19877120