The structural relaxation in vanadium phosphate glass studied by DMA

Abstract

The mechanism of structure evolution and microscopic hidden flow in glasses before yield and glass-to-liquid transition(GLT) remains unclear. In this work, the dynamic mechanical relaxation and stress relaxation spectra of vanadium-phosphate binary glass (V2O5-P2O5) when approaching the glass transition temperature T g were investigated by using the dynamic mechanical analysis (DMA). The β and α relaxation behaviors, occurring respectively at T β~ 483 K and T p~543 K and quite similar to those observed in the metal glass systems, were observed, which indicated the occurrence of the slowing-down microscopic localized flow in the investigated vanadium-phosphate glasses. This was further verified by the experimental observation and theoretical prediction of the linear logarithmic relation between the peak height of the β relaxation and the relaxation rate, i.e. ln( Δ ) µ −ln( v ). Furthermore, three stages during the structural evolution of the β and α relaxation in vanadium-phosphate glasses were observed from the temperature dependent curve of the non-exponential factor of β KWW obtained by the Kohlrausch-Williams-Watts (KWW) fitting: (I) β KWW β KWW β KWW>0.5, the region of macroscopic flow.