Crystal structure and specific heat of calcium lanthanide oxyborates Ca4 LnO(BO3)3
Open Access
- 20 July 2022
- journal article
- research article
- Published by Walter de Gruyter GmbH in Zeitschrift für Kristallographie - Crystalline Materials
- Vol. 237 (8-9), 317-327
- https://doi.org/10.1515/zkri-2022-0029
Abstract
Calcium lanthanide oxyborates Ca4 LnO(BO3)3 are of interest for their optical and electromechanical properties. Their crystal structure has been well characterised using powder and single-crystal X-ray diffraction but there remains some disagreement regarding cation ordering in these compounds. In this study, combined X-ray and neutron powder diffraction was employed to study the cation distribution and obtain accurate boron and oxygen atomic coordinates for six Ca4 LnO(BO3)3 compounds (Ln = Pr, Nd, Tb, Ho, Er, Yb) at room temperature and one (Ln = Tb) at 50 and 1.5 K. All compounds adopt the previously reported monoclinic structure with space group Cm. The Ln 3+ ions are disordered over two of the three metal sites, with the extent of disorder increasing across the lanthanide series with decreasing ionic radius. Low-temperature neutron data for Ca4TbO(BO3)3 showed a decrease in paramagnetic scattering on cooling but no obvious magnetic Bragg or diffuse scattering at the lowest temperature of 1.5 K. We report specific heat data at cryogenic temperatures for eight Ca4 LnO(BO3)3 compounds and relate the magnetic properties of these compounds to their structural behaviour.Keywords
Funding Information
- EPSRC
This publication has 36 references indexed in Scilit:
- Magnetic properties of hole-doped SCGO, SrCr8Ga4−xMxO19(M = Zn, Mg, Cu)Journal of Physics: Condensed Matter, 2011
- Investigation of the dielectric and piezoelectric properties of ReCa4O(BO3)3 crystalsJournal of Physics D: Applied Physics, 2011
- Site Specific X-ray Anomalous Dispersion of the Geometrically Frustrated Kagomé Magnet, Herbertsmithite, ZnCu3(OH)6Cl2Journal of the American Chemical Society, 2010
- Synthesis and luminescence of Ca4YO(BO3)3:Eu3+ for fluorescent lamp applicationOptical Materials, 2010
- Strong anisotropic thermal expansion in boratesPhysica Status Solidi (b), 2008
- Titanium-III warwickites: A family of one-dimensional disordered magnetic systemsPhysical Review B, 1994
- Structural investigations of new calcium - rare earth (R) oxyborates with the composition Ca4RO(BO3)3Chemistry of Materials, 1992
- Neutron scattering lengths and cross sectionsNeutron News, 1992
- Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenidesActa Crystallographica Section A, 1976
- A profile refinement method for nuclear and magnetic structuresJournal of Applied Crystallography, 1969