SITE OCCUPANCIES OF NITRIDE AND OXIDE IONS IN STRONTIUM NIOBIUM OXYNITRIDE PEROVSKITES

2011 ◽  
Vol 25 (31) ◽  
pp. 4167-4170 ◽  
Author(s):  
T. Komiyama ◽  
Y. Masubuchi ◽  
T. Motohashi ◽  
S. Kikkawa
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Space Group ◽  
La Substitution ◽  
Oxide Ions

Crystal structure was refined on Sr - Nb and Sr ( La )- Nb oxynitride perovskites prepared through citrate route by using neutron diffraction. The former had the composition of SrNbO2.11N0.89and crystallized in I4/mcm with a = 0.57099(2) nm , c = 0.81015(5) nm having excess oxide ions in apical 4a site around Nb being compared to the cis- TaO4N2octahedra in SrTaO2N . The latter crystallized in the same space group with Sr0.81La0.19having a = 0.57126(3) nm , c = 0.81055(6) nm . It was assumed that Sr0.81La0.19O1.90N1.10has similar O/N occupancy in both apical 4a and equatorial 8h sites. The La substitution made the O/N occupancies equilibrated around Nb . The niobium valency was slightly less than five in these oxynitride perovskites.

NEUTRON DIFFRACTION STUDY ON (Bi−Pb)2Sr2Ca2Cu3O10

1990 ◽  
Vol 04 (12) ◽  
pp. 791-794 ◽  
Author(s):  
YANG JI-LIAN ◽  
YE CHUN-TANG ◽  
ZHANG BAI-SHENG ◽  
LI JI-ZHOU ◽  
KANG JIAN ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Diffraction Study ◽  
Single Phase ◽  
Polycrystalline Sample ◽  
Neutron Diffraction Study ◽  
Structure Study ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray

The polycrystalline sample of (Bi–Pb)2Sr2Ca2Cu3O10 with Tc=107 K was prepared. The X-ray diffraction proved that the sample is single phase. The crystal structure study on the sample has been carried out by neutron diffraction. The result shows that its structure is tetragonal body-centre structure with space group of I4/mmm, containing a few oxygen atoms at 4e site in Bi–Pb layers.

The structure of perdeuteronaphthalene C10D8 at 12 K by neutron diffraction

1983 ◽  
Vol 163 (3-4) ◽  
Author(s):  
I. Natkaniec ◽  
A. V. Belushkin ◽  
W. Dyck ◽  
H. Fuess ◽  
C. M. E. Zeyen
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Diffraction Data ◽  
Molecular And Crystal Structure ◽  
Monoclinic Space Group ◽  
Neutron Diffraction Data ◽  
Space Group

AbstractThe molecular and crystal structure of perdeuteronaphthalene was refined from neutron diffraction data collected at 12 K on an automatic four-circle diffractometer. The monoclinic space group

Low-Temperature Structure and Magnetic Properties of Tetraphenylarsonium Tetrachloronitridotechnetate(VI)

1996 ◽  
Vol 49 (5) ◽  
pp. 633 ◽  
Author(s):  
BN Figgis ◽  
PA Reynolds ◽  
FK Larsen ◽  
GA Williams ◽  
CD Delfs
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Low Temperature ◽  
Neutron Diffraction ◽  
Single Crystals ◽  
Temperature Structure ◽  
X Ray Diffraction ◽  
Magnetic Susceptibilities ◽  
Space Group ◽  
X Ray

The crystal structure of [As(C6H5)4] [TcNCl4] was determined at 120 K by X-ray diffraction and at 28 K by neutron diffraction. The crystals are tetragonal, space group P4/n, with a 1260.4(3) and c 773.2(2) pm at 120 K. The [TcNCl4]-anion possesses exact C4v symmetry, with Tc≡N distances of 160.3(2) and 162.5(4)pm at 120 and 28 K respectively. Magnetic susceptibilities were measured on single crystals from 300 to 4.5 K. The results indicate a well behaved S ½ system following the Curie-Weiss law with θ -0.13 K

Darstellung und Kristallstruktur von Di-gold(III)bis(selenit)oxid, Au2(SeO3)2O / Preparation and Crystal Structure of Di-gold(III) Bis(selenite) Oxide, Au2(SeO3)2O

1983 ◽  
Vol 38 (1) ◽  
pp. 10-11 ◽  
Author(s):  
Peter G. Jones ◽  
George M. Sheldrick ◽  
Einhard Schwarzmann ◽  
Andreas Vielmäder
Keyword(s):  
Crystal Structure ◽  
Heavy Atom ◽  
Polar Space ◽  
Light Atom ◽  
Space Group ◽  
Extended Structure ◽  
Selenic Acid ◽  
Oxide Ions

Abstract Au2(SeO2)2O was prepared from gold and excess selenic acid in a sealed tube at 533 K. The crystal structure [Pba2, a = 659.2(2), b = 1183.7(3), c = 399.8(1) pm, Z = 2,R = 0.087] was determined; gold atoms are bridged by oxide ions (lying on twofold axes) and selenite ions. The extended structure consists of polymeric layers parallel to the xy-plane. The light atom positions are inaccurate because of the presence of a heavy atom in a polar space group.

Order-Disorder Phase Transition in NaBD4

2004 ◽  
Vol 443-444 ◽  
pp. 287-290 ◽  
Author(s):  
P. Fischer ◽  
Andreas Züttel
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Low Temperature ◽  
Neutron Diffraction ◽  
Room Temperature ◽  
Structure Model ◽  
Space Group ◽  
Disorder Phase Transition ◽  
Low Temperature Crystal Structure ◽  
Disorder Type

By means of neutron diffraction the low-temperature crystal structure of NaBD4 has been determined. At 10 K the lattice parameters are a = 4.332(1) Å and c = 5.869(1) Å. Deuterium is found in a tetrahedral arrangement [sites (8g)] around B. The symmetry corresponds to space group P42/nmc. For room temperature the structure model for NaBD4 of Davis and Kennard with disordered deuterium distributed over two sites has been revised to space group Fm-3 m. Thus the 190 K phase transition known from specific heat measurements is of order-disorder type, caused by reorientations of BD4 tetrahedra.

Iodo-oxyapatite, the first example from a new class of modulated apatites

1999 ◽  
Vol 55 (2) ◽  
pp. 165-169 ◽  
Author(s):  
Peter Alberius Henning ◽  
Sven Lidin ◽  
Vačlav Petříček
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Unit Cell ◽  
Apatite Structure ◽  
Flux Method ◽  
Space Group ◽  
X Ray ◽  
New Class ◽  
Oxide Ions

Iodo-oxyapatite [pentadecacalcium iodide oxide nonaphosphate, Ca15(PO4)9IO] was synthesized by a flux method and the structure was solved from single-crystal X-ray data. The crystal structure was refined in the space group P63/m [a = 9.567 (1), c = 20.754 (2) Å and Z = 2] to wR on F of 0.0459. Iodo-oxyapatite has a typical hexagonal apatite structure but the unit cell is tripled along the hexad owing to ordering of the iodide and oxide ions along this direction.

scholarly journals High temperature tetragonal crystal structure of UPt2Si2

2020 ◽  
Vol 235 (6-7) ◽  
pp. 175-181
Author(s):  
Karel Prokeš ◽  
Oscar Fabelo ◽  
Stefan Süllow ◽  
Jooseop Lee ◽  
John A. Mydosh
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Space Group ◽  
Tetragonal Crystal ◽  
Tetragonal Crystal Structure

AbstractHigh temperature crystal structure of UPt2Si2 determined using single-crystal neutron diffraction at 400 K is reported. It is found that the crystal structure remains of the primitive tetragonal CaBe2Ge2 type with the space group P4/nmm. Anisotropic displacement factors of the Pt atoms at the 2a (3/4 1/4 0) and Si atoms at the 2c (1/4 1/4 z) Wyckoff sites are found to be anomalously large.

Crystal structure of Re-substituted lanthanum tungstate La5.4W1−y Re y O12–δ (0 ≤ y ≤ 0.2) studied by neutron diffraction

2016 ◽  
Vol 49 (5) ◽  
pp. 1544-1560 ◽  
Author(s):  
Andrea Fantin ◽  
Tobias Scherb ◽  
Janka Seeger ◽  
Gerhard Schumacher ◽  
Uta Gerhards ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Water Uptake ◽  
Electron Probe ◽  
Lattice Structure ◽  
Scattering Length ◽  
Pechini Method ◽  
Electron Probe Micro Analysis ◽  
Space Group ◽  
Micro Analysis

A precise determination of sample composition and water uptake of La6−x WO12−δ (0.4 ≤ x ≤ 0.8) and Re-substituted La5.4W1−y Re y O12−δ (0 ≤ y ≤ 0.2) lanthanum tungstate is carried out. Sample compositions and water uptake were determined by electron probe micro-analysis and thermogravimetry, respectively. A single-phase region of Re-substituted lanthanum tungstates is reported. The crystal structure of two selected specimens produced by the citrate-complexation route based on the Pechini method, namely La5.4WO12−δ and La5.4W0.8Re0.2O12−δ, was investigated by neutron diffraction in the temperature range 1.5 ≤ T ≤ 1200 K. The structural model for lanthanum tungstates is validated, according to which the Wyckoff site shared by La and W (Fm{\overline 3}m space group, 24d site) is split with half-site occupancies (Fm{\overline 3}m space group, 48h site). Replacement of W by up to 20 mol% Re does not change the lattice structure, and Re atoms substitute for W statistically in both 4a and 48h Wyckoff sites of the Fm{\overline 3}m space group, as shown by combining the average neutron scattering length procedure, thermogravimetry and electron probe micro-analysis. Using the Willis and Pryor approach to anisotropic displacement parameters it is shown that the remaining static disorder in the unit cell found in La5.4WO12−δ and La5.4W0.8Re0.2O12−δ structures is comparable, when the Fm{\overline 3}m space group with split 48h site is employed. Through the estimation of the Debye temperature for both compounds, extracted from the analysis of thermal expansion coefficients and from the Willis and Pryor approach, anion anharmonic vibrations like those in yttria-stabilized zirconia are proven to exist in LaWO for the first time.

Crystal structure of Mo-substituted lanthanum tungstate La5.4W1−y Mo y O12−δ (0 ≤ y ≤ 0.2) studied by X-ray and neutron diffraction

2019 ◽  
Vol 52 (5) ◽  
pp. 1043-1053 ◽  
Author(s):  
Andrea Fantin ◽  
Tobias Scherb ◽  
Janka Seeger ◽  
Gerhard Schumacher ◽  
Uta Gerhards ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Structural Model ◽  
Scattering Length ◽  
Pechini Method ◽  
Oxygen Deficiency ◽  
Space Group ◽  
X Ray ◽  
Bond Lengths ◽  
The Face

A determination of the detailed crystal structure of an Mo-substituted lanthanum tungstate series, La6−x W1−y Mo y O12−δ (0 ≤ y ≤ 0.2, δ is the oxygen deficiency), is presented. Material of composition La5.4W0.8Mo0.2O12−δ (y = 0.2) produced by the citrate-complexation route based on the Pechini method was investigated by high-resolution X-ray diffraction and neutron diffraction in the temperature range 10 ≤ T ≤ 298 K. The results are compared with a non-substituted material La5.4WO12−δ. A structural model established earlier for lanthanum tungstates and Re-substituted lanthanum tungstates is confirmed, according to which the Wyckoff site shared by La and W is split with half site occupancies (Fm\bar 3m space group, 48h site) and also accommodates Mo atoms. Substitution of W by up to 20 mol% Mo does not change the face-centred cubic lattice: Mo atoms substitute W statistically on both 4a and 48h Wyckoff sites of the crystal structure, which is described by the Fm\bar 3m space group. These results were obtained from the combination of the average neutron-scattering length and average X-ray scattering power procedures with electron-probe micro-analysis. The temperature dependence of bond lengths in dry and wet (D2O) conditions shows that vacant oxygen sites are located on the 32f Wyckoff sites also in Mo-substituted lanthanum tungstates, and that the bond lengths between La on 4b and O on 32f increase with increasing pO2 and pD2O, reflecting the filling of oxygen vacancies and the increase in coordination of La on 4b.

The Crystal Structure of Potassium Nickel Arsenate; KNiAsO4

1988 ◽  
Vol 43 (8) ◽  
pp. 1053-1055 ◽  
Author(s):  
A. M. Buckley ◽  
S. T. Bramwell ◽  
P. Day ◽  
W. T. A. Harrison
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Neutron Diffraction ◽  
Unit Cell ◽  
Hexagonal Cell ◽  
Space Group ◽  
Powder Neutron Diffraction

AbstractThe crystal structure of potassium nickel arsenate. KNiAsO4 has been determined by high resolution powder neutron diffraction at 30 K. The unit cell of KNiAsO4 is rhombohedral. space group R3̄, with hexagonal cell constants, a = 4.97208(2) (Å). c = 28.52606(10) (Å). The compound is isomorphous with NaNiAsO4.

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