Hydrothermal Crystal Growth of Lithium Tetraborate and Lithium Gamma-Metaborate.

摘要

Growth of lithium tetraborate by the hydrothermal method was attempted in 10(caret)-6 M LiOH, both by spontaneous nucleation and transport growth. Tetraborate grew out of the first spontaneous nucleation reaction, while the seed dissolved and lithium gamma-metaborate formed during the transport growth reactions. A species thermodynamic stability study showed gamma-metaborate formed exclusively from 350 deg C to 550 deg C, and Li3B5O8(OH)2 was observed at 250 deg C; tetraborate was not observed. A solubility study on lithium tetraborate did not achieve equilibrium conditions, but did demonstrate that gamma-metaborate is significantly more thermodynamically stable than tetraborate under the tested conditions. Formation of lithium tetraborate hydrothermally was shown to result from kinetic growth.