Pressure Raman studies on the quenched high-pressure Phase of KTb(MoO_4)_2 with a KY(WO_4)_2-type structure

摘要

The high pressure-temperature quenched phase of KTb(MoO_4)_2-type structure as synthe- sized and investigated by Raman scattering under pressure up to 26 Gpa. The Raman spectral features were analyzed in terms of the structural units, in particular the MoO_6 polyedra and the Mo-O bond lengths, by relating the structure of the phase with that of the β-KY(WO_4)_2. It is suggested that two types of MoO_6 groups may be present to account for the calculated Mo-O bond lengths. No pressure-induced phase transition is found up to 26 Gpa. The Tb fluorescence is totally absent in the quenched phase and reappears on heating to 500 deg.C, when the conversion of the material to the original orthorhombic phase of KTMO takes place.