\textit{In Situ} Investigation of a Pre-ordered Boundary Layer during LiB $_{3}$O$_{5}$ crystal Growth from MoO$_{3}$ Fluxes: Molecular Understanding of Crystallization

Confocued Raman spectroscopy has been used to \textit{in situ} investigate the crystal-solution interfaces around an as-growing LiB$_{3}$O$_{5}$~crystal from MoO$_{3}$ fluxes. The spectroscopic data reveals the LiB$_{3}$O$_{5}$~crystal growth occurs in a pre-ordered boundary layer, wherein the formation and desolvation of well-ordered lattice-like growth units through a cation-transfer reaction between the solvent and solute. The obtained structural information proves the packing configuration of the solution near the crystal-solution interface is reduced with respect to the bulk one, moreover, suggests a growth mechanism of iB$_{3}$O$_{5}$~crystal from MoO$_{3}$ fluxes at the molecular level As it displays a key role for the crystal growth, the pre-ordered boundary layer can provide new insights into the nature of various growth phenomena such as face-induced well-ordered cluster formation, grown defect formation, solute-solvent interaction and so on.