In situ Raman investigation of a LiB sub(3)O sub(5) melt toward understanding the structural memory phenomena

• Published in: CrystEngComm Vol. 17; no. 48; pp. 9357 - 9362
• Main Authors: Feng, Dexuan, Zheng, Guimei, Zhao, Ying, Zhang, Bo, Wan, Songming, You, Jinglin, Hu, Zhanggui
• Format: Journal Article
• Language: English
• Published: 01.12.2015
• Subjects: Crystal structure; Crystals; LBO; Melting; Melts; Rings (mathematics); Transformations; Transforms
• ISSN: 1466-8033
• DOI: 10.1039/c5ce01873k

Lithium triborate (LiB sub(3)O sub(5), LBO) is the most widely used nonlinear optical crystal. During the LBO crystal melting process, several interesting and important phenomena, called as structural memory, have been found. However, the essence of these phenomena remains unclear. In order to explain these phenomena, high-temperature Raman spectroscopy was used to investigate in situ the structures of a LiB sub(3)O sub(5) melt at different temperatures. Two important structural transformations were found during the LBO crystal melting process: (1) when the crystal begins to melt, every two adjacent basic building units (B sub(3)O sub(4)Oe sub(2)) in the crystal structure transforms to a B sub(4)O sub(5)Oe sub(4) group and a B sub(2)O sub(3) molecule. (2) Above 860 degree C, the B sub(4)O sub(5)Oe sub(4) units react with the B sub(2)O sub(3) molecules to form boron-oxygen chains whose minimal repeated unit is the B sub(3)O sub(4)Oe sub(2) six-membered ring. These results prove that LBO is an incongruently melting compound and provide a rationale for understanding the special structural memory phenomena.