The influence of temperature on narrow I 1 and I 2 lines in the luminescence spectrum of Ni0.6Zn0.4O

The behavior of the luminescence spectrum of solid solution Ni_0.6Zn_0.4O, in which two intense narrow lines were recently discovered, is investigated as a function of temperature. It is shown that the intensity of one of the lines drops in accordance with the Mott law with increasing temperature in the range between 10 and 50 K. The lines experience broadening, and the ratio of their intensities changes. In addition, the lines shift toward lower energies. This shift and broadening of both lines occur differently, suggesting that they are of different nature.