Crystallographic studies of BaR2ZnO5 (R=La, Nd, Dy, Ho, Er, and Y)

Wong‐Ng, W.; Toby, B.H.; Greenwood, W. F.

doi:10.1017/s0885715600009994

Cited by 12 publications

(16 citation statements)

References 26 publications

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“…The refined structural parameters show good agreement with the previous structural studies [17,22] and in particular the significant decrease in cell constants and cell volume linked to the replacement of lanthanum by neodymium is clear. The effect of partially replacing the lanthanides by Ca 2+ on the lattice parameters of the samples is shown in Fig.…”

Section: Crystal Structuresupporting

confidence: 86%

“…AC conductivity (10 kHz) measurements were performed with a Solartron 1260 FRA as a function of the oxygen partial pressure between values corresponding to wet hydrogen and wet oxygen, and as a function of the water vapour partial pressure from dry (3 × 10 −5 atm) to wet (0.028 atm) conditions in the temperature range of 400 to 1000°C. Rietveld analysis of the long scan data sets recorded for x = 0, 0.05, 0.1 and 0.15 samples was undertaken using the basic starting model suggested by Michel et al [17] and subsequently confirmed by WongNg et al [22] based on analysis of neutron diffraction data. This has distinct positions for the lanthanide and barium ions within the tetragonal unit cell.…”

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

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Structure and conductivity of acceptor doped La2BaZnO5 and Nd2BaZnO5

2015

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Section: Crystal Structuresupporting

confidence: 86%

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

Structure and conductivity of acceptor doped La2BaZnO5 and Nd2BaZnO5

2015

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“…Successful replacement of Cu by Zn in the lanthanide Ba-R-Cu-O system has been described [5–9]. According to Michel et al [5–8], selected barium lanthanum zinc oxides apparently isostructural to the “green phases”, BaR 2 CuO 5 [2], can be prepared.…”

Section: Introductionmentioning

confidence: 99%

“…According to Michel et al [5–8], selected barium lanthanum zinc oxides apparently isostructural to the “green phases”, BaR 2 CuO 5 [2], can be prepared. The structures of the La, Nd, and Y-compounds have been studied using x-ray powder diffraction [5,6] and neutron powder diffraction methods [9]. It was found that, while the structures of the La and Nd analogs are tetragonal, the Y-compound is orthorhombic.…”

Section: Introductionmentioning

confidence: 99%

Crystal structures and reference powder patterns of BaR2ZnO5 (R = La, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, and Tm)

Kaduk¹,

Wong‐Ng²,

Greenwood³

et al. 1999

J. Res. Natl. Inst. Stand. Technol.

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Reference x-ray powder patterns and the crystal structures of the lanthanide compounds, BaR2ZnO5, in which R = La, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, or Tm, were determined by the x-ray Rietveld refinement technique. A structural trend was confirmed for this series of compounds. The compounds with smaller ionic radii (R = Sm, Eu, Gd, Dy, Ho, Y, Er, or 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) Å to 7.20452(14) Å, b = 12.25445 (17) Å to 12.5882(2) Å, and c = 5.6786(14) Å to 5.81218(11) Å, respectively. R is sevenfold coordinated 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 size R (La and Nd) crystallize in the tetragonal space group I4/mcm. The lattice parameters are a = 6.90982(10) and c = 11.5977(2) Å for BaLa2ZnO5, and a = 6.75979(5) Å and c = 11.54560(12) Å for BaNd2ZnO5. The structure consists of ZnO4 tetrahedra (instead of planar CuO4 groups as found in BaR2CuO5) with 10-fold coordinated bicapped square prismatic Ba and 8-fold coordinated bicapped trigonal prismatic R ions between them. The reference x-ray powder patterns will be submitted to the Powder Diffraction File (PDF).

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“…1 hain of one-cap trigonal prisms (6,5,0) and ( Layer of trigonal dodecahedra (7,5,0) and pentagonal bipyramids ( 3 Framework of one-cap trigonal prisms (7,9,2), (6,5,0), (6,5,0) and (4, 3, (8,7,1), pentagonal bipyramids (7,5,1) and (7,5,0) and octahedra (5, 2, (8,6, 0), (8, 6, 0), (8,5, 0) and (7,5,1) and pentagonal bipyramids (7, 5, 3 Framework of trigonal dodecahedra (8,12,0) and pentagonal bipyramids (7, 9, 3 Framework of pentagonal bipyramids (7, 11, 1), (7, 10, 1) and octahedra (6, 9, atoms, varies from 0.085 to 0.079. With an increase in the C.N., the G 3 value decreases, indicating an increase in the environment uniformity.…”

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confidence: 99%

Coordination Polyhedra LnO n (Ln = Tb, Dy, Ho) in Crystal Structures

2005

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Within the framework of our research into the crystal chemistry of lanthanides, this study is devoted to oxygen compounds of terbium, dysprosium, and holmium. From databases [1,2], 456 compounds were selected complying with the following conditions: (a) Ln atoms (Ln = Tb, Dy, or Ho) form LnO n coordination polyhedra; (b) the crystal structure was determined to R ≤ 0.1 ; and (c) the structures contain no randomly disordered Ln or O atoms. These compounds were found to contain 195, 191, and 184 crystallographically nonequivalent sorts of Tb, Dy, and Ho atoms, respectively. Whereas Dy and Ho are present only as Ln(III), in the case of Tb, 22 sorts of Tb(IV) atoms were also found. The full list of compounds is available from the authors: vologzhanina@fromru.com.The coordinates of hydrogen atoms in 104 compounds, which had not been determined by the authors of structural studies, were calculated at the first investigation stage using the HSite program [3] included in the structure-topological TOPOS package [4]. The coordination numbers (C.N.s) of all atoms were determined by the method of intersecting spheres [5], according to which any two atoms are considered to be chemically bonded if the common face of their Voronoi-Dirichlet polyhedra (VDP) is described by the I 4 , I 3 , or I 2 intersection. Terbium C.N.s were found to be 6-10, or 12, those of dysprosium vary from 6 to 10, and those of holmium are 6 to 9; in all three cases, the most frequently encountered value is 8. Using the TOPOS software [4], characteristics of the lanthanide VDP were calculated for all 456 compounds (Table 1) and statistical analysis of the results was carried out.In the structures of the compounds in question, the VDP of Ln atoms form in total 6490 faces. Of these, the method of intersecting spheres distinguished 4375 valence faces corresponding to Ln-O chemical bonds. In addition, another 25 faces with I 4 or I 2 type intersections correspond to Ln-Q contacts (Q = Li, Ba, Co, Zn, Cu or Mn, Table 2). For the Ln-Q bonds found, the interatomic distances are 0.02-0.49 Å shorter than the sum of the atomic or Slater radii of the atoms (in the case of BaCoHo 2 O 5 {65467} [17], the Ho-Co interatomic distance is equal to the sum of atomic radii but is shorter than the sum of the Slater radii of the elements), while the solid angles ( Ω ) of the faces range from 1.5 to 2.7%. Here and below, Ω are expressed in percent of the full solid angle, equal to 4 π steradian. Taking into account the above-mentioned Ln-Q contacts, island (bi-or trinuclear) and framework fragments consisting only of metal atoms can be distinguished in the structures. Since the presence of the Ln-Q bonds almost does not influence characteristics of the lanthanide VDP, only the C.N.s with respect to oxygen atoms were taken into account in all calculations.The remaining 2090 faces of the Tb, Dy, and Ho VDP belong to I 0 and I 1 type intersections and describe non-valence Ln···Z contacts. The greatest numbers of Ln···Z contacts was found for Z = O, H, Ba, and Cu (568, 323, 312, a...

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Crystallographic studies of BaR₂ZnO₅ (R=La, Nd, Dy, Ho, Er, and Y)

Cited by 12 publications

References 26 publications

Structure and conductivity of acceptor doped La2BaZnO5 and Nd2BaZnO5

Structure and conductivity of acceptor doped La2BaZnO5 and Nd2BaZnO5

Crystal structures and reference powder patterns of BaR2ZnO5 (R = La, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, and Tm)

Coordination Polyhedra LnO n (Ln = Tb, Dy, Ho) in Crystal Structures

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