Synthesis, crystal structure and optical properties of the new lead fluoride borate—Pb2BO3F

A new compound, Pb2BO3F, has been grown by high temperature solution method from the PbO–PbF2–B2O3 system for the first time. The crystal structure of this compound has been identified by single crystal X-ray diffraction analysis. It crystallizes in the hexagonal system, space group P63/m (No. 176) with unit-cell parameters a=7.2460(3) Å, c=14.5521(17) Å, Z=6, V=661.69(9) Å3. Its structure was solved by the direct methods and refined to R1=0.0163 and wR2=0.0367. The structure of Pb2BO3F consists of the distorted PbO3F2 groups and BO3 triangles, which are all symmetric with each other in the gestalt structure to the extent that the Pb2BO3F compound crystallizes in the symmetric space group. The powder X-ray diffraction pattern of the Pb2BO3F has been measured. The BO3 functional groups presented in the sample were identified by FTIR spectrum. The DTA curve of Pb2BO3F suggests that Pb2BO3F melts congruently at 448 °C.

Graphical AbstractThe Pb atoms are in the five coordination environments bonded to three O atoms and two F atoms to make up the distortional PbO3F2 polyhedra. Every six PbO3F2 polyhedra are connected by one F(1) atom to form the symmetrical structure, and then the distortion of the PbO3F2 polyhedra is offset.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A new compound, Pb2BO3F, has been grown by high temperature solution method from the PbO–PbF2–B2O3 system for the first time. ► It crystallizes in the hexagonal system, space group P63/m (No. 176) with unit-cell parameters a=7.2460(3) Å, c=14.5521(17) Å, Z=6, V=661.69(9) Å3. ► UV–vis-NIR Diffuse-Reflectance spectrum shows that its ultraviolet cutoff edge is about 288 nm. ► DTA curve of Pb2BO3F suggests that Pb2BO3F melts congruently at 448 °C.