Formation kinetics of SrBaNbO and LiBO crystals from 0.25SrO-0.75BaO-NbO-LiO-2BO glass.

We have investigated the transition kinetics of SrBaNbO (SBN) and LiBO (LBO) crystals from 0.25SrO-0.75BaO-NbO-LiO-2BO (SBNLBO) glass under isothermal and non-isothermal processes. With increasing temperature, there are two consecutive steps of crystallization of SBN and LBO from the glass. The Johnson-Mehl-Avrami function indicates that the crystallization mechanism of SBN belongs to an increasing nucleation rate with diffusion-controlled growth. The crystallite size of SBN ranges from 40 to 140 nm but it is confined to within 30-45 nm for LBO during the whole crystallization process. The relationship between the nano size and strain of SBN based on the Williamson-Hall method, and the change of activation energies of SBN and LBO crystallization analyzed by using the isoconversional model are discussed. A comparison of phonon modes between as-quenched glass and fully transformed crystals clearly shows that the low dimensional vibration modes in the structurally disordered glass change to highly dimensional network units with the formation of crystals.