Synchrotron X-ray electron density in the layered LaOCl structure

Oxidation State and Local Structure of Chromium Ions in LaOCl

LaOCl doped with 0–10 mol% Cr was synthesized by thermal decomposition of chlorides. X-ray diffraction (XRD) analysis revealed that incorporation of chromium results in a decrease of the lattice parameter a and a simultaneous increase of the lattice parameter c. The local structure of chromium ions was studied with X-ray photoelectron (XPS), X-ray absorption (XANES), multifrequency electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) spectroscopy techniques. It was determined that synthesis in oxidizing atmosphere promotes the incorporation of chromium ions predominantly in the 5+ oxidation state. Changes of chromium oxidation state and local environment occur after a subsequent treatment in reducing atmosphere. Spin-Hamiltonian (SH) parameters for a Cr⁵⁺ and two types of Cr³⁺ centers in LaOCl were determined from the EPR spectra simulations.

Dehydration synthesis and crystal structure of terbium oxychloride, TbOCl

Terbium oxychloride, TbOCl, was synthesized via the simple heat-treatment of TbCl₃·6H₂O and its structure was determined by refinement against X-ray powder diffraction data. TbOCl crystallizes with the matlockite (PbFCl) structure in the tetra­gonal space group P4/nmm and is composed of alternating (001) layers of (TbO)_n and n Cl⁻.

Terbium oxychloride, TbOCl, was synthesized via the simple heat-treatment of TbCl₃·6H₂O and its structure was determined by refinement against X-ray powder diffraction data. TbOCl crystallizes with the matlockite (PbFCl) structure in the tetra­gonal space group P4/nmm and is composed of alternating (001) layers of (TbO)_n and n Cl⁻. The unit-cell parameters, unit-cell volume, and density were compared to the literature data of other isostructural rare-earth oxychlorides in the same space group and showed good agreement when compared to the calculated trendlines.