Radiative properties of α-ZnAl 2S 4:V spinel type single crystals

Abstract

The absorption and luminescent properties of α-ZnAI 2S 4:V spinel type crystals in the temperature range 10–300 K are investigated. The spectra are assigned to the electronic transitions of trivalent vanadium ions located in octahedral sites. It is shown that at low temperatures the three main components of the revealed IR luminescence spectra are caused by the 1A 1g( 1G)→ 1E g( 1D), 1T 2g( 1D), 3T 2g( 3F)→ 3T 1g( 3F), and 1E g( 1D)→ 3T 1g( 3F) transitions. The observed dependencies of the emission components intensities on temperature are explained assuming that there is a phonon assisted tunnelling between 3T 2g( 3 F) and 1E g( 1D) states. On temperature rise, the 3T 2g( 3F)→ 3T 1g( 3F) vibronic transitions suppress other emission channels, which leads to the enhancement of the integral luminescence intensity and to the broadening of the spectrum centred at λ=1.4 μm.