Yttrium oxide upconverting phosphors. Part 2: Temperature dependent upconversion luminescence properties of erbium in yttrium oxide

Emission bands from Er3+ ions on C-2 and S-6 sites of cubic Y2O3 have been observed under 632.8 mn excitation. The well-known green hot band in the re gion of 520-540 nm and a new blue-green hot band in the region of 469-474 n m have been observed from Er3+ on both sites. These hot bands are assigned to the H-2(11/2) --> I-4(15/2) and the F-4(3/2) --> I-4(15/2) transitions, respectively. In addition to observing different thermal behavior for the e missions from Er3+ ions on different lattice sites due to these transitions , different thermal behavior has also been observed for the F-4(5/2) --> I- 4(15/2), F-4(9/2) --> I-4(15/2), S-4(3/2) --> I-4(15/2), and S-4(11/2) --> I-4(15/2) transitions. The (4)G(11/2) --> I-4(15/2), H-2(9/2) --> I-4(15/2) , and I-4(9/2) --> I-4(15/2) transitions gave rise to bands which were too weak for accurate temperature-dependent studies. Emission arising from the F-4(7/2) --> I-4(15/2) transition was observed with 514.5 but not 632.8 nm excitation.