The Debye-Waller factor approaching the glass-transition temperature in phosphate glasses

The temperature dependence of the mean square displacement, (it 2), calculated by elastic neutron scattering for two phosphate glasses, (AgI)(x)(AgPO3)(1-x) with x = 0.3, 0.55, is analysed. The studied samples are probed in a wide range of temperatures going from a few tens of K up to the glass transition temperature and well into the undercooled liquid state. In the low temperature regime a solid like behaviour appears, showing a linear temperature dependence of the Debye-Waller factor, while around T, the onset of a pronounced increase of < u(2)> is observed. The temperature dependence of the normalized elastic intensity and the drawn out Debye-Waller factor are fitted and analyzed by the theoretical previsions of Mode Coupling Theory finding a good agreement. (c) 2006 Elsevier B.V. All rights reserved.