SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF La4Mn3Ge5.2Si0.8O22, A NEW COMPOUND WITH THE PERRIERITE STRUCTURE

摘要

A new layered germanate La4Mn3Ge5.2Si0.8O22 has been prepared and its structure was determined from single crystal diffraction data. This compound crystallizes in the monoclinic space group P21/c with a=11.956(2) angstroms, b=5.642(1) angstroms, c=14.180(3) angstroms, beta=114 degrees09(3), and Z=2 formula units by cell. The structure has been refined to residuals of R=3.14% for 1380 observations and 152 parameters. La4Mn3Ge5.2Si0.8O22 is isostructural with perrierite Ce4Fe2 Ti3Si4O22, a naturally occurring sorosilicate mineral. The framework consists of rutile-like slabs formed of alternating chains of GeO6 octahedra and Mn3+O6 distorted octahedra, located between layers of mixed Ge1.2Si0.8O7 disilicates groups that separate the isolated Mn2+O6 octahedra. A structural comparison with La4Mn5Si4O22 is discussed. 21 refs.