Peculiarities of LiB3O5 crystallization from melts studied by Raman spectroscopy

Specific features of melting and crystallization scenarios of lithium triborate LiB3O5 (0.25Li2O·0.75B2O3) are studied in situ by Raman spectroscopy. It is shown that the scenario depends on thermal history of the melt. In particular, it is possible to obtain both homogeneous and chemically inhomogeneous states of the melt at a temperature above the melting point. The factors favoring homogeneous melt and crystallization are discussed. It is shown that the Raman line near 135 cm−1 demonstrates clearly the soft-mode behavior, merging with 111 cm−1 Raman line above 400 °C, and indicating a weak phase transition near this temperature.