La3 B6 O13 (OH): The First Acentric High-Pressure Borate Displaying Edge-Sharing BO4 Tetrahedra.

ABSTRACT: La3 B6 O13 (OH) was obtained by a high-pressure/high-temperature experiment at 6?GPa and 1673?K. The compound crystallizes in the space group P21 (no. 4) with the lattice parameters a=4.785(2), b=12.880(4), c=7.433(3)?Å, and ?=90.36(10)°, and is built up of corner- as well as edge-sharing BO4 tetrahedra. It represents the first acentric high-pressure borate containing these B2 O6 entities. The compound develops borate layers of "sechser"-rings with the La3+ cations positioned between the layers. Single-crystal and powder X-ray diffraction, vibrational and MAS NMR spectroscopy, second-harmonic generation (SHG) and thermoanalytical measurements, as well as computational methods were used to affirm the proposed structure and the B2 O6 entities.

SUBMITTER: Fuchs B 

PROVIDER: S-EPMC7317773 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature