Hydrothermal phase stability study of Li2B4O7

• Li2B4O7 was grown hydrothermally via spontaneous nucleation in 10−6 M LiOH.
• γ-LiBO2γ-LiBO2 formed from 350 °C to 550 °C and Li3B5O8(OH)2 was observed at 250 °C.
• A solubility study showed γ-LiBO2 to be more thermodynamically stable than Li2B4O7.
• Hydrothermal formation of Li2B4O7 was shown to result from kinetic growth.

Growth of Li2B4O7 by the hydrothermal method was attempted in 10−6 M LiOH, by both spontaneous nucleation and transport growth. Li2B4O7 grew out of the first spontaneous nucleation reaction, while the seed dissolved and γ-LiBO2 formed during the transport growth reactions. A species thermodynamic stability study showed that γ-LiBO2 formed exclusively from 350 °C to 550 °C, and Li3B5O8(OH)2 was observed at 250 °C; Li2B4O7 was not observed. A solubility study on Li2B4O7 did not achieve equilibrium conditions, but did demonstrate that γ-LiBO2 is significantly more thermodynamically stable than Li2B4O7 under the tested conditions. Formation of Li2B4O7 hydrothermally was shown to result from kinetic growth.

Every boron in lithium γ-metaborate is tetrahedrally coordinated with oxygen, and each tetrahedron is linked to four other tetrahedrons, creating a strong B-O lattice surrounding the lithium atoms.Figure optionsDownload as PowerPoint slide