The Preparation and Structure of Cadmium Rhenium Oxide, Cd2Re2O7

Donohue, P.C.; Longo, J.M.; Rosenstein, R. D.; Katz, Lawrence C

doi:10.1021/ic50030a013

Cited by 63 publications

(51 citation statements)

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“…Sakai et al also reported superconductivity in the same compound independently [6], and Jin et al reported similar results later [7]. The compound has been known to possess the ideal pyrochlore structure at room temperature, and show metallic conductivity down to T = 4 K [8]. In addition to the observation of superconductivity in Cd 2 Re 2 O 7 we found remarkable anomalies at 200 K both in the electrical resistivity and magnetic susceptibility measurements [5].…”

Section: Introductionsupporting

confidence: 72%

“…Purple octahedral crystals of a few mm in length were obtained. From the facts that both CdO (Cd) and ReO 3 (Re 2 O 7 ) are volatile and that crystals adhered to the walls, it is considered that the crystal growth occurred by a vapor transport mechanism, as discussed in a previous study [8]. The Cd/Re molar ratio was 1.00 ± 0.02 as determined by electron-probe microanalyses (EPMA) and was 0.995 as determined by inductively coupled plasma (ICP) spectrometry.…”

Section: Methodsmentioning

confidence: 99%

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Structural phase transition in the superconducting pyrochlore oxide Cd2Re2O7

Hanawa

Yamaura

Muraoka

et al. 2002

Journal of Physics and Chemistry of Solids

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We report a structural phase transition found at T s = 200 K in a pyrochlore oxide Cd 2 Re 2 O 7 which shows superconductivity at T c = 1.0 K. X-ray diffraction experiments indicate that the phase transition is of the second order, from a high-temperature phase with the ideal cubic pyrochlore structure (space group Fd 3 m) to a low-temperature phase with another cubic structure (space group F 4 3m). It is accompanied by a dramatic change in the resistivity and magnetic susceptibility and thus must induce a significant change in the electronic structure of Cd 2 Re 2 O 7 .

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Section: Introductionsupporting

confidence: 72%

Section: Methodsmentioning

confidence: 99%

Structural phase transition in the superconducting pyrochlore oxide Cd2Re2O7

Hanawa

Yamaura

Muraoka

et al. 2002

Journal of Physics and Chemistry of Solids

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“…An alternative recipe was also employed with starting materials CdO (99.9%), Re (99.99%), and ReO 3 (>99%). 9 The final products showed no obvious difference from the first approach. As shown in Fig.…”

Section: Crystal Growthmentioning

confidence: 89%

“…The refined lattice constant was a = 10.2244(6) Å , in fairly good agreement with the previously reported 10.219 Å . 9 The data sets were collected using systematic absences consistent with an F-centered cell (hkl: h + k, h + l, k + l = 2n + l), as the room-temperature structure was known to be pyrochlore. 10 The initial locations of the metal ions were determined by the Patterson heavy-atom method, and the remaining atom positions were revealed by Fourier mapping using the SHELXL97 program.…”

Section: Crystal Structure Inclusions and Stoichiometrymentioning

confidence: 99%

Crystal Growth, Structure, and Stoichiometry of the Superconducting Pyrochlore Cd2Re2O7

Jin

Chakoumakos

et al. 2007

Journal of Elec Materi

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We report single-crystal growth of the superconducting pyrochlore Cd 2 Re 2 O 7 using a vapor transport technique. Several parameters of the growth conditions, including hot-zone temperature and starting stoichiometry, were varied in order to control the formation of ReO 2 inclusions, as confirmed by the electron microscopy, resistivity, and magnetic susceptibility measurements. The Rietveld refinement of x-ray (neutron) powder diffraction was found to be consistent with a cubic structure Fd3m with lattice constant a = 10.2250 (10.2358) Å and reduced coordinate of O1 = 0.3184 (0.3177) at 293 K (250 K). We also studied the oxygen stoichiometry by means of redox reactions, electron microprobe analysis (EMPA), and x-ray/neutron diffractions. Particularly, the neutron powder diffraction on the 114 Cd-enriched specimens yielded an oxygen deficiency d = 0.14 ± 0.03 solely at the O2 site, which was consistent with the EMPA results. The EMPA indicated that the oxygen deficiency is homogeneous in the bulk and in a range of 0.01 ± 0.18-0.23 ± 0.19.

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“…The compound exhibits two more phase transitions at T s1 =200 K and T s2 =120 K, where electrical and magnetic properties change dramatically [7,8,9]. The former is of the second order, while the latter is of the first order.…”

mentioning

confidence: 99%

Low Temperature Symmetry of Pyrochlore Oxide Cd₂Re₂O₇

2002

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We report the X-ray study for the pyrochlore oxide Cd2Re2O7. Two symmetry-lowering structural transitions were observed at Ts1=200 K and Ts2=120 K. The former is of the second order from the ideal cubic pyrochlore structure with space group F d3m to a tetragonally distorted structure with I4m2, while the latter is of the first order likely to another tetragonal space group I4122. We discuss the feature of the lattice deformation.A series of pyrochlore oxides A 2 B 2 O 7 show a variety of interesting conductive and magnetic properties, depending on the substitutions of A and B sites [1]. Geometrical frustration on the pyrochlore lattice leads to an exotic ground state such as spin ice for magnetic insulators [2], while for metallic systems a unique heavy carrier behavior is found in spinel LiV 2 O 4 having a pyrochlore lattice made of V atoms [3]. In the pyrochlore structure, the A site occupied by a rare-earth or a post-transition metal cation forms a distorted (6+2) coordination, while the B site occupied by a transition metal cation forms a distorted octahedron BO 6 with an equal B-O distance. The structure comprises two interpenetrating pyrochlore lattices composed of the A or B sites (see Fig. 1).Recently, Hanawa et al. and the others reported the first superconductor Cd 2 Re 2 O 7 (T c =1 K) in the family of pyrochlore oxides [4,5,6]. The compound exhibits two more phase transitions at T s1 =200 K and T s2 =120 K, where electrical and magnetic properties change dramatically [7,8,9]. The former is of the second order, while the latter is of the first order. These transitions are accompanied by structural transitions. Three phases appearing are named as phase I (T >T s1 ), II (T s1 >T >T s2 ), and III (T

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The Preparation and Structure of Cadmium Rhenium Oxide, Cd₂Re₂O₇

Abstract: A cadmium rhenium oxide has been prepared with the formula Cd2Re20~. Its structure is of the pyrochlore type. For the face-centered cubic unit cell, a = 10.219 A. The room temperature resistivity is about 2 X 10~3 ohm cm.

Cited by 63 publications

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Structural phase transition in the superconducting pyrochlore oxide Cd2Re2O7

Structural phase transition in the superconducting pyrochlore oxide Cd2Re2O7

Crystal Growth, Structure, and Stoichiometry of the Superconducting Pyrochlore Cd2Re2O7

Low Temperature Symmetry of Pyrochlore Oxide Cd₂Re₂O₇

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The Preparation and Structure of Cadmium Rhenium Oxide, Cd2Re2O7

Abstract: A cadmium rhenium oxide has been prepared with the formula Cd2Re20~. Its structure is of the pyrochlore type. For the face-centered cubic unit cell, a = 10.219 A. The room temperature resistivity is about 2 X 10~3 ohm cm.

Cited by 63 publications

References 0 publications

Structural phase transition in the superconducting pyrochlore oxide Cd2Re2O7

Structural phase transition in the superconducting pyrochlore oxide Cd2Re2O7

Crystal Growth, Structure, and Stoichiometry of the Superconducting Pyrochlore Cd2Re2O7

Low Temperature Symmetry of Pyrochlore Oxide Cd2Re2O7

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The Preparation and Structure of Cadmium Rhenium Oxide, Cd₂Re₂O₇

Low Temperature Symmetry of Pyrochlore Oxide Cd₂Re₂O₇