INFRARED TO VISIBLE LUMINESCENCE UPCONVERSION BY Yb3+ RE3+ ENERGY TRANSFER IN β' -ALUMINA (RE3+=Er3+, Ho3+, Tm3+)
, and
J. Phys. IV France, 01 C7 (1991) C7-411-C7-414
DOI: 10.1051/jp4:19917105
