Luminescent monitoring of metal dititanium triphosphates as promising materials for radioactive waste confinement

The potential use of luminescent probes for control over the structural state of MTi2(PO4)3 double metal phosphates as host materials for radioactive waste confinement is examined. Luminescence spectra of pure and metal (Al, In, V) and rare-earth (Pr, Sm, Dy) doped MTi2(PO4)3 (M = Li, Na, K) phosphate compounds (in crystalline and related amorphous forms) under X-ray, VUV (synchrotron radiation), UV and visible light excitations are analyzed. Electronic structure and absorption spectra of NaTi2(PO4)3 crystals are calculated by the full-potential LAPW method. The origin of the self and impurity emission bands of MTi2(PO4)3 materials is defined. It was shown that nitrogen laser with 337.1 nm generation wavelength is the most effective excitation source for remote monitoring of incorporation of various types of waste elements into MTi2(PO4)3 hosts and for control over states of these hosts during storage of radioactive waste.