Crystal Structures and Reference Powder Patterns of BaR2ZnO5 (R=La, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, and Tm)
James A. Kaduk, Winnie Wong-Ng, W Greenwood, J Dillingham, B H. Toby
Reference x-ray patterns and the crystal structure of the lanthanide compounds, BaR2ZnO5, in which R=La, Nd, Sm, Eu, Gd, Dy, Ho, Y, and Er, were studied by x-ray Rietveld refinement technique. A structural trend was confirmed for this series of compounds. The compounds with smaller R (Sm, Eu, Gd, Dy, Ho, Y, Er and Tm) are isostructural to the orthorhombic green phase (BaY2CuO5). The lattice parameters for compounds with R= Tm to Sm range from a= 7.01855(9) Angstrom} to 7.20452(14) Angstrom}, b=12.25445 (17) Angstrom}, and c=5.6786(14) Angstrom} to 5.81218(11) Angstrom}, respectively. R is seven-coordinate inside a monocapped trigonal prism. These prisms share edges to form wave-like chains parallel to the long b-axis. The BaR2ZnO5 compounds which contain larger R (La and Nd) crystallize in the tetragonal 14/mcm space group. The lattice prameters are a=6.90982(10) Angstrom}, c=11.5977(2) Angstrom} for BaLa2ZnO5, and a=6.75979(5) Angstrom} and c=11.54560(12) Angstrom} for BaNd2ZnO5. The structure consists of ZnO4 tetrahedra (instead of planar CuO4 groups as found in BaR2CuO5) with 10-coordinate bicapped square prismatic Ba and 8-coordinate bicapped trigonal prismatic R ions between them. The x-ray reference patterns will be included in the Powder Diffraction File (PDF).
, Wong-Ng, W.
, Greenwood, W.
, Dillingham, J.
and Toby, B.
Crystal Structures and Reference Powder Patterns of BaR<sub>2</sub>ZnO<sub>5</sub> (R=La, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, and Tm), Journal of Research (NIST JRES), National Institute of Standards and Technology, Gaithersburg, MD
(Accessed June 9, 2023)