Glass-forming region, structure and some properties of potassium manganese phosphate glasses

The glass-forming region in the K2O–MnO–P2O5 ternary system was determined and the amorphous nature of the synthesized material was confirmed by X-ray diffraction. Glasses with composition (50-x)K2O-xMnO-50P2O5 (0 ≤ x ≤ 40 mol%) have been studied. Their physical, thermal and spectroscopic properties such as density, molar volume, glass transition temperature infrared and Raman spectroscopies have been investigated to understand the structural role of MnO in studied samples. The density and glass transition temperature increase with the substitution of MnO for K2O. Fourier-Transform Infrared and Raman spectroscopies reveal the depolymerization of the phosphate chains and formation of P–O–Mn bonds by the incorporation of MnO. The formation of P–O–Mn bonds, which replace P–O−···K+ bonds is in accordance with the variation of glass transition temperature (Tg), molar volume (Vm) and density (ρ). The former bonds are the origin of the partial glass-forming ability of Mn2+. A structural model is proposed to explain the experimental results.