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Kelly ND, Savvin S, Dutton SE. Crystal structure and specific heat of calcium lanthanide oxyborates Ca 4
LnO(BO 3) 3. Z KRIST-CRYST MATER 2022. [DOI: 10.1515/zkri-2022-0029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
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.
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Affiliation(s)
- Nicola D. Kelly
- Cavendish Laboratory , University of Cambridge , J J Thomson Avenue , Cambridge , CB3 0HE , UK
| | - Stanislav Savvin
- Institut Laue-Langevin , 71 Avenue des Martyrs , 38000 Grenoble , France
| | - Siân E. Dutton
- Cavendish Laboratory , University of Cambridge , J J Thomson Avenue , Cambridge , CB3 0HE , UK
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Weigel T, Hanzig J, Mehner E. The crystal structure of single crystalline PrCa4O[BO3]3. Z KRIST-CRYST MATER 2022. [DOI: 10.1515/zkri-2021-2072] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
PrCa4O[BO3]3 was grown as a single crystal by the Czochralski method. The precursor material was synthesized by solid state reaction under O2 atmosphere and sintered after grinding under N2 atmosphere with a content of 20% H2. The Czochralski crystal growth proceeded under N2 atmosphere with an <010> oriented GdCa4O[BO3]3 crystal seed. A PrCa4O[BO3]3 crystal with a cylinder length of 20 mm, a diameter of 15 mm, and weight of 23.1 g was obtained. The crystal structure was solved from single crystal X-ray diffraction data in the monoclinic crystal system with space group C1m1 (No. 8), the lattice parameters a = 8.1293(6) Å, b = 16.062(1) Å, c = 3.6023(2) Å, β = 101.371(2)°, formula units of 2 and final R- and wR2-values below 3.8%. A mixed occupancy between Pr and Ca of 6.0% was found.
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Affiliation(s)
- Tina Weigel
- TU Bergakademie Freiberg, Institut für Experimentelle Physik , Leipziger Str. 23 , 09599 Freiberg , Germany
| | - Juliane Hanzig
- TU Bergakademie Freiberg, Institut für Experimentelle Physik , Leipziger Str. 23 , 09599 Freiberg , Germany
| | - Erik Mehner
- TU Bergakademie Freiberg, Institut für Experimentelle Physik , Leipziger Str. 23 , 09599 Freiberg , Germany
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