A Re-investigation of the Crystal Structure of the Perovskite PbZrO3 by X-ray and Neutron Diffraction

1997 ◽  
Vol 53 (1) ◽  
pp. 135-142 ◽  
Author(s):  
D. L. Corker ◽  
A. M. Glazer ◽  
J. Dec ◽  
K. Roleder ◽  
R. W. Whatmore
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Lead Zirconate ◽  
Conclusive Evidence ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Investigations

The crystal structure of the perovskite lead zirconate PbZrO3 has been redetermined using single-crystal X-ray diffraction (Mo Kα radiation, λ = 0.71069 Å). Single-crystal data at 100 K: space group. Pbam, a = 5.884 (1), b = 11.787 (3), c = 8.231 (2) Å, V = 570.85 Å3 with Z = 8, μ = 612.6 cm−1, D x = 8.06 Mg m−3, F(000) = 1168, final R = 0.033, wR = 0.061 over 555 reflections with I > 2σ(I). An investigation is made into previous contradicting reports of a possible disorder in the O atoms and their origin by examining the crystal pseudo-symmetry. Information distinguishing an ordered and disordered oxygen substructure is shown to reside in weak l odd reflections. Because of their extremely low intensities these reflections have not contributed sufficiently in previous X-ray structure investigations and hence, to date, conclusive evidence differentiating between ordered and disordered models has not been possible. By collecting single-crystal X-ray data at low temperature and by using exceptionally long scans on selected hkl, l odd, reflections, a new accurate structure determination is presented and discussed, showing the true ordered oxygen positions. Because of the large difference in scattering factors between lead and oxygen when using X-rays, a neutron diffraction Rietveld refinement using polycrystalline samples (D1A instrument, ILL, λ = 1.90788 Å) is also reported as further evidence to support the true ordered oxygen structure revealed by the low-temperature X-ray analysis.

The Great Barrier Reef Expedition 1928–29: The crystal structure and occurrence of weddellite, ideally CaC2O4·2.5H2O, from the Low Isles, Queensland

2016 ◽  
Vol 80 (2) ◽  
pp. 399-406 ◽  
Author(s):  
Stuart J. Mills ◽  
Andrew G. Christy
Keyword(s):  
Crystal Structure ◽  
Coral Reef ◽  
Low Temperature ◽  
Great Barrier Reef ◽  
Single Crystal ◽  
Structure Study ◽  
Barrier Reef ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Report

Abstract“Envelope crystals” collected during The Great Barrier Reef Expedition in May 1929 have been studied using low-temperature synchrotron single-crystal X-ray diffraction. The crystals are shown to be weddellite, with the largest content of zeolitic water reported to date. A new H2O site has been located within the crystal structure. Study of the crystals show that the end-member formula for weddellite should be reported as CaC2O4·(2.5 – x)H2O, where 0≤x≤ 0.25, instead of CaC2O4·(2H2O or CaC2O4·(2 + x )H2O. This is also the first report of weddellite occurring in a coral reef.

X-ray and neutron diffraction investigation at 298 K of NH4I · NH3 and ND4I · ND3 containing the cation H3N – H … NH3+ and D3N – D … ND3+

1992 ◽  
Vol 200 (3-4) ◽  
Author(s):  
H. J. Berthold ◽  
E. Vonholdt ◽  
R. Wartchow ◽  
T. Vogt
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Single Crystal Structure ◽  
X Ray ◽  
Single Crystal Structure Analysis

AbstractNHA single crystal structure analysis of NThe deuterated compound NThe structures of the ordered low temperature phases will be reported separately.

Investigation into the Crystal Structure of the Perovskite Lead Hafnate, PbHfO3

1998 ◽  
Vol 54 (1) ◽  
pp. 18-28 ◽  
Author(s):  
D. L. Corker ◽  
A. M. Glazer ◽  
W. Kaminsky ◽  
R. W. Whatmore ◽  
J. Dec ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Room Temperature ◽  
Lead Zirconate ◽  
Crystal Structure Analysis ◽  
Temperature Structure ◽  
X Ray Diffraction ◽  
Neutron Data ◽  
X Ray

The room-temperature crystal structure of the perovskite lead hafnate PbHfO3 is investigated using both low-temperature single crystal X-ray diffraction (Mo Kα radiation, λ = 0.71069 Å) and polycrystalline neutron diffraction (D1A instrument, ILL, λ = 1.90788 Å). Single crystal X-ray data at 100 K: space group Pbam, a = 5.856 (1), b = 11.729 (3), c = 8.212 (2) Å, V = 564.04 Å3 with Z = 8, μ = 97.2 mm−1, F(000) = 1424, final R = 0.038, wR = 0.045 over 439 reflections with F >1.4σ(F). Polycrystalline neutron data at 383 K: a = 5.8582 (3), b = 11.7224 (5), c = 8.2246 (3) Å, V = 564.80 Å3 with χ2 = 1.62. Although lead hafnate has been thought to be isostructural with lead zirconate, no complete structure determination has been reported, as crystal structure analysis in both these materials is not straightforward. One of the main difficulties encountered is the determination of the oxygen positions, as necessary information lies in extremely weak l = 2n + 1 X-ray reflections. To maximize the intensity of these reflections the X-ray data are collected at 100 K with unusually long scans, a procedure which had previously been found successful with lead zirconate. In order to establish that no phase transitions exist between room temperature and 100 K, and hence that the collected X-ray data are relevant to the room-temperature structure, birefringence measurements for both PbZrO3 and PbHfO3 are also reported.

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

scholarly journals Detailed single crystal studies on silicates using neutron diffraction

2014 ◽  
Vol 70 (a1) ◽  
pp. C1110-C1110
Author(s):  
Martin Meven ◽  
G. Gatta
Keyword(s):  
Neutron Diffraction ◽  
Single Crystal ◽  
Room Temperature ◽  
Structural Features ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Order And Disorder ◽  
Structural Details ◽  
Displacement Regime

Up to now minerals of the silicate family are an interesting and versatile topic of research. Different members of the epidote, lithium tourmaline and beryl groups with very different structural features were studied on the single crystal diffractometer HEIDI at the hot source of the Heinz Maier-Leibnitz Zentrum in Garching (MLZ) in the recent past. The combination of neutron and X-ray diffraction in combination with other methods revealed for each of the studied minerals valuable information about their structural details. Epidote, an important mineral for metamorphic or magmatic petrology was studied with neutrons at room temperature and at 1070 K. The results confirm the high structural stability with no dehydration and only slight thermal expansion [1]. A combined study with x-ray and neutron diffraction on the complex boro-cyclo-silicate elbaite give insight to the displacement regime and H and O order and disorder respectively [2]. Combined single crystal diffraction with x-rays at room temperature and with neutrons at 2.3 K on pezzottaite, an obverse/reverse twin of the beryl family reveals a complex displacement regime with possible partial H2O replacement [3].

scholarly journals The incommensurately modulated structures of low-temperature labradorite feldspars: a single-crystal X-ray and neutron diffraction study

2020 ◽  
Vol 76 (1) ◽  
pp. 93-107
Author(s):  
Shiyun Jin ◽  
Huifang Xu ◽  
Xiaoping Wang ◽  
Ryan Jacobs ◽  
Dane Morgan
Keyword(s):  
Low Temperature ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Diffraction Data ◽  
Neutron Diffraction Study ◽  
Neutron Diffraction Data ◽  
X Ray Diffraction ◽  
Subsolidus Phase ◽  
X Ray ◽  
Modulated Structures

Labradorite feldspars of the plagioclase solid solution series have been known for their complicated subsolidus phase relations and enigmatic incommensurately modulated structures. Characterized by the irrationally indexed e-reflections in the diffraction pattern, e-labradorite shows the largest variation in the incommensurate ordering states among the e-plagioclase structures. The strongly ordered low-temperature e-labradorite is one of the last missing pieces of the e-plagioclase puzzle. Nine plutonic and metamorphic labradorite feldspar samples from Canada, Ukraine, Minnesota (USA), Tanzania and Greenland with compositions ranging from An52.5 to An68 were studied with single-crystal X-ray diffraction. Two crystals from Labrador, Canada, and Duluth, MN, USA, with wide enough twin lamellae were analyzed with single-crystal neutron diffraction. The incommensurately modulated structures of e-plagioclase are refined for the first time with neutron diffraction data, which confirmed that the T—O distance modulation in the low-temperature e-plagioclase results from the Al–Si ordering in the framework. Detailed configurations of the M site are also observed in the structures refined from neutron diffraction data, which were not possible to see with X-ray diffraction data. The relation between the q-vectors and the mole% An composition is revealed for the entire compositional range of e-plagioclase, from An25 to An75. The previously proposed two-trend relation depending on the cooling rate and phase transition path is confirmed. A new classification of e-plagioclase (e α, e β and e γ) is proposed based on the q-vector of the structure, which makes it an independent character from the presence/absence of density modulation. New parameters are proposed to quantify the ordering states of these complicated aperiodic structures of e-plagioclases, such as the difference between 〈T1o—O〉 and 〈T1m—O〉 at phase t = 0.2 or the normalized intensity of the (071\bar 1) reflection.

Crystal structure of an inclusion complex between chiral monoaza-15-crown-5 and S(–)-1-phenyl-ethyl ammonium percholorate

2003 ◽  
Vol 218 (5) ◽  
Author(s):  
Süheyla Özbey ◽  
F. B. Kaynak ◽  
M. Toğrul ◽  
N. Demirel ◽  
H. Hoşgören
Keyword(s):  
Crystal Structure ◽  
Inclusion Complex ◽  
Single Crystal ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
New Type

AbstractA new type of inclusion complex, S(–)-1 phenyl ethyl ammonium percholorate complex of R-(–)-2-ethyl - N - benzyl - 4, 7, 10, 13 - tetraoxa -1- azacyclopentadecane, has been prepared and studied by NMR, IR and single crystal X-ray diffraction techniques. The compound crystallizes in space group

scholarly journals An investigation of polyhedral deformation in two mixed-metal diarsenates: SrZnAs2O7and BaCuAs2O7

2015 ◽  
Vol 71 (4) ◽  
pp. 330-337 ◽  
Author(s):  
Sabina Kovač ◽  
Ljiljana Karanović ◽  
Tamara Đorđević
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
General Formula ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
X Ray ◽  
Open Framework ◽  
Geometrical Characteristics ◽  
Barium Copper

Two isostructural diarsenates, SrZnAs2O7(strontium zinc diarsenate), (I), and BaCuAs2O7[barium copper(II) diarsenate], (II), have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction. The three-dimensional open-framework crystal structure consists of corner-sharingM2O5(M2 = Zn or Cu) square pyramids and diarsenate (As2O7) groups. Each As2O7group shares its five corners with five differentM2O5square pyramids. The resulting framework delimits two types of tunnels aligned parallel to the [010] and [100] directions where the large divalent nine-coordinatedM1 (M1 = Sr or Ba) cations are located. The geometrical characteristics of theM1O9,M2O5and As2O7groups of known isostructural diarsenates, adopting the general formulaM1IIM2IIAs2O7(M1II= Sr, Ba, Pb;M2II= Mg, Co, Cu, Zn) and crystallizing in the space groupP21/n, are presented and discussed.

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