Nature of intrinsic and impure luminescence of MAlP2O7 crystals

The results of the photoluminescence (PL) investigation of pure and chromium-doped MAIP 2 O 7 (M = Na, K, Cs) compounds are presented. The spectra of the intrinsic luminescence of MAlP 2 O 7 crystals consist of a separated UV band at a peak position near 330 nm and a complex wide band which covers the region of visible light up to 750 nm at excitation by VUV synchrotron radiation. The "red" band in 600-1000 nm diapason appears in the PL spectra of crystals doped with chromium ions. The effect of the temperature on the structure, the peak positions and intensities of the luminescence bands was studied. An assumption about the nature of the intrinsic PL was made. The "red" luminescence was considered as a result of the 4 T 2 → 4 A 2 radiation transitions in the impurity cr3 + ions located in the intermediate crystal field.