Synthesis, Structure and Luminescence Property of Two Lanthanum Phosphites Hydrate: La2(H2O)x(HPO3)3 (x=1,2)

Crystal Research Center, Shanghai Institute of Ceramics, CAS* Shanghai Institute of Ceramics, Chinese Academy of Science, China**
â—‹Jing-Tai Zhao* Ding-Bang Xiong** Hao-Hong Chen** Xin-Xin Yang**

Two new lanthanum phosphites hydrate, La2(H2O)(HPO3)3 (a) and La2(H2O)2(HPO3)3 (b) were synthesized by hydrothermal method. Their crystal structures were determined by X-ray single crystal method (a, monoclinic, C2/c (No.15); a=20.820(5)Å, b=6.717(2)Å, c=14.123(3)Å, β=101.261(3) deg., V=1937.0(8)Å3; Z=8; b, triclinic, P-1 (No. 2); a=8.168(3)Å, b=8.439(2)Å, c=9.337(3)Å, α=115.641(3) deg., β=98.655(3) deg, γ=105.124(3) deg., V=533.87(1)Å3, Z=2). Both crystal structures present three-dimensional open framework structures containing channels, and a adopts intersecting type. In the two structures, the face-sharing dimers of LaOn (n=8, 9) were observed. Furthermore, both of the two compounds doped with Ce+3 showed intensive broad emission band around 340nm under UV excitation.
Keywords: Hydrothermal synthesis; Crystal structure; Lanthanum phosphite hydrate; Luminescence property