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Raman spectra and luminescence of the minerals with aeschynite and euxenite crystal structure

Metamict minerals aeschynite-(Y) and polycrase-(Y) showed aeschynite and euxenite structure after recrystallization, respectively. Raman spectra of these minerals show luminescence lines strongly interfering with normal vibration modes (Fig. 1), especially in 200-500 cm-1 range (region of Ti/Nb/Ta-O stretching and bending modes). However, their synthetic analogs of REETiTaO6 composition having single REE content and aeschynite or euxenite structure do not show luminescence lines using 488 and 514.5 nm Ar excitation lines up to 900 cm-1 with exception of the Er member [1]. In the case of polycrase-(Y) a separated strong luminescence line is also observed at 684 cm-1. The origin of luminescence in these minerals is discussed in term of the complex REE composition, the crystal field formed in the structure during recrystallization process and its influence on REE in cation sites.

aeschynite; euxenite; Raman spectra; luminescence

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