Synthesis and structural characterization of orthorhombic Cu3–δ Sb (δ ≈ 0.1) and hexagonal Cu3Sb1–xInx (x ≈ 0.2) phases

2021 ◽  
Vol 236 (3-4) ◽  
pp. 61-70
Author(s):  
Jordan Sinclair ◽  
Sviatoslav Baranets ◽  
Svilen Bobev
Keyword(s):  
Low Temperature ◽  
Orthorhombic Phase ◽  
Structure Type ◽  
Rich Phase ◽  
Space Group ◽  
Type Space ◽  
Binary Phase ◽  
Cubic Form ◽  
Temperature Form ◽  
Ca 50

Abstract Cu3Sb is a known copper-rich phase in the Cu–Sb binary phase diagram. It is reported to be dimorphic, with a low-temperature form adopting the orthorhombic Cu3Ti structure type (space group Pmmn, No. 59). The high-temperature form crystallizes in the cubic space group F m 3 ‾ m $Fm‾{3}m$ (No. 225), and is isostructural with BiF3. Neither polymorph has been carefully characterized to date, with both structures being assigned to the respective structure type, but never refined. With this study, we provide structural evidence, based on single-crystal and powder X-ray diffraction data that the low-temperature orthorhombic phase exists with a significant amount of defects on one of the Cu-sites. As a result, its composition is not Cu3Sb, but rather Cu3–δ Sb (δ = 0.13(1)). The cubic form could not be accessed as a part of this study, but another Cu-rich phase, Cu3Sb≈0.8In≈0.2, was also identified. It adopts the hexagonal Ni3Sn structure type (space group P63/mmc, No. 194) and represents an In-substituted variant of a hitherto unknown structural modification of Cu3Sb. Whether the latter can exist as a binary phase, or what is the minimum amount of In inclusions needed to stabilize it remains to be determined. Measurements of the thermopower of Cu3–δ Sb (δ = 0.13(1)) were conducted in the range of 300–600 K and demonstrated a maximum value of ca. 50 μV/K at 600 K, indicative of a p-type transport mechanism. Electrical resistivity measurements for the same sample confirmed that it exhibits metallic-like behavior, with a room temperature value of 0.43 mΩ cm. Electronic structure calculations show the absence of a band gap. Thermal analysis was utilized to ascertain the congruent melting of both phases.

A tetragonal polymorph of SrMn2P2made under high pressure – theory and experiment in harmony

2017 ◽  
Vol 46 (21) ◽  
pp. 6835-6838 ◽  
Author(s):  
Weiwei Xie ◽  
Michał J. Winiarski ◽  
Tomasz Klimczuk ◽  
R. J. Cava
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Tetragonal Phase ◽  
Ambient Pressure ◽  
Structure Type ◽  
Space Group ◽  
Type Space ◽  
Tetragonal Phase Transition ◽  
Theory And Experiment

A trigonal–tetragonal phase transition in SrMn2P2is proposed and confirmed experimentally under high pressure. At ambient pressure, SrMn2P2crystallizes in the primitive trigonal La2O3structure type (space groupP3̄m1) in blue. Under high pressure, the tetragonal ThCr2Si2structure type (space groupI4/mmm) in red is more stable.

The New Ternary Silicide ErCo3Si2

2014 ◽  
Vol 69 (3) ◽  
pp. 369-372
Author(s):  
Mariya Dzevenko ◽  
Inna Bigun
Keyword(s):  
Structure Type ◽  
Vertex Polyhedron ◽  
Coordination Polyhedra ◽  
Space Group ◽  
Type Space ◽  
Ternary Silicide

The new ternary silicide ErCo3Si2 adopts the ErRh3Si2 structure type (space group Imma, Pearson code oI24, Z = 4, a = 6:950(1), b = 9:020(2), c = 5:230(1) Å, R1 = 0:0565, wR2 = 0:0355, 253 F2 values, 23 variables). It is a deformation derivative of the CeCo3B2 structure type. The coordination of the Er atom shows a normal 20- vertex polyhedron [Er(Si6Co12Er2)]. The two similar coordination polyhedra of Co are a distorted icosahedron [Co(Si4Co4Er4)], and a distorted icosahedron with one capped face [Co(Si4Co5Er4)]. The Si atom is surrounded by the polyhedron [Si(Co6Si2Er3)]

Powder diffraction data of a new compound Al0.35GdGe2

2008 ◽  
Vol 23 (1) ◽  
pp. 60-62 ◽  
Author(s):  
Lingmin Zeng ◽  
Jiejun He ◽  
Pingli Qin ◽  
Xiangzhong Wei
Keyword(s):  
Ternary Compound ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Type ◽  
Powder Diffraction Data ◽  
Space Group ◽  
X Ray ◽  
Type Space

A new ternary compound Al0.35GdGe2 has been synthesized and studied by means of X-ray powder diffraction technique. The ternary compound Al0.35GdGe2 crystallizes in the orthorhombicwith the CeNiSi2 structure type (space group Cmcm, a=4.0874(2) Å, b=16.1499(5) Å,c=3.9372(1) Å, Z=4, and Dcalc=8.007 g/cm3).

Compounds Ln5(Ag, Ga)19 – x (Ln = Gd, Tb) – Defective Partially Ordered Representatives of the Rb5Hg19 Structure Type

2005 ◽  
Vol 60 (9) ◽  
pp. 929-932 ◽  
Author(s):  
Roman V. Gumeniuk ◽  
Lev G. Akselrud ◽  
Yurij B. Kuz’ma
Keyword(s):  
Crystal Structures ◽  
Structure Type ◽  
Space Group ◽  
X Ray ◽  
Type Space ◽  
Partially Ordered ◽  
New Compounds

New compounds Ln5(Ag, Ga)19−x (Ln = Gd, Tb) have been found to crystallise with the Rb5Hg19 structure type (space group I4/m). The crystal structures were refined for Gd5Ag1.8Ga15 and Tb5Ag2Ga15.6 from X-ray powder data: a = 9.4635(1), c = 9.8638(2) Å , RI = 0.093 and a = 9.4313(1), c = 9.8491(2) Å , RI = 0.085, respectively. Some positions in the crystal structures of new the compounds are occupied partially.

Order and disorder in acenaphthylene

1973 ◽  
Vol 334 (1596) ◽  
pp. 19-48 ◽  
Keyword(s):  
Low Temperature ◽  
Room Temperature ◽  
Temperature Structure ◽  
Intermediate Form ◽  
X Ray Diffraction ◽  
Space Group ◽  
Order And Disorder ◽  
Temperature Form ◽  
Diffraction Effects

Acenaphthylene, C 12 H 8 , occurs in space group Pbam (or Pba2) at room temperatures (23 °C) with a = 7.705 (5), b = 7.865 (5), c = 14.071 (5) Å and Z = 4, and is disordered. At about 130 K it undergoes a reversible transition to space group P2 1 nm with a = 7.588 (13), b = 7.549 (10), c = 27.822 (2) Å and Z = 8 (85 K) with an ordered structure. A general study of the system has revealed that the structure of both forms consists of layers of closely packed molecules stacked in the c direction. The room temperature structure has a two-layer repeat and the low temperature form a four-layer repeat. Observation of diffuse X-ray diffraction effects at temperatures close to the transition indicates that an intermediate form having a six-layer repeat is formed. A preliminary structure determination of the low-temperature form reveals that the four layers though having a similar packing scheme differ in the orientation of the constituent molecules relative to c . It is proposed that the almost circular shape of the molecules allows each layer to change its identity under thermal agitation by a rotation of its constituent molecules in their own planes. The transition can be explained in terms of changes of the correlations between neighbouring layers. A simple model based on short-range order parameters is described, which explains the occurrence of the six-layer intermediate and the observed sequence of diffuse diffraction phenomena. The nature of the structure of the disordered room temperature form, which is predicted by this model, is confirmed as far as possible with the data available which are limited because of the dearth of high-angle diffraction maxima.

Crystal data of the low-temperature solid form of 2-methyl-2-nitro-propanol(MNP)

1994 ◽  
Vol 9 (2) ◽  
pp. 84-86 ◽  
Author(s):  
J. Ll. Tamarit ◽  
N. B. Chanh ◽  
P. Négrier ◽  
D. O. López ◽  
M. Barrio ◽  
...  
Keyword(s):  
Low Temperature ◽  
Single Crystal ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Crystal Data ◽  
Powder Diffraction Data ◽  
Space Group ◽  
X Ray ◽  
Type Space ◽  
Solid Form

By means of X-ray single crystal Weissenberg photographs, the crystal of the low-temperature solid form of 2-methyl-2-nitro-propanol, (CH3)2C(NO2)(CH2OH), has been determined and found to be of the monoclinic type, space group P21/c. The cell constants were refined from X-ray powder diffraction data: a=6.195(3) Å, b=19.116(7) Å, c=16.598(7) Å, and β = 90.12(2)° with Z = 12. The indexed pattern at 293 K is given.

The Crystal Structure of Eu11Sb10

1979 ◽  
Vol 34 (9) ◽  
pp. 1213-1217 ◽  
Author(s):  
R. Schmelczer ◽  
D. Schwarzenbach ◽  
F. Hulliger
Keyword(s):  
Crystal Structure ◽  
Structure Type ◽  
Thermal Parameters ◽  
The Other ◽  
Interatomic Distances ◽  
Space Group ◽  
Type Space ◽  
True Structure

Abstract Eu11Sb10 crystallizes in the tetragonal Ho11Ge10 structure type, space group I4/mmm, with a = 12.325(2), c = 18.024(4) Å; Z = 4. Large thermal parameters of certain atoms and unusual interatomic distances might suggest that the true structure is slightly distorted, but attempts to desymmetrize the structure were unsuccessful. Analogous anomalies occur in most of the other representatives of the Ho11Ge10 type. Eu11Sb10 appears to be metallic. It contains divalent Eu and is antiferromagnetic below TN ≈ 5 K. Other new representatives of the Ho11Ge10 structure type are Sr11Sb10, Sr11Bi10 and Ba11Sb10.

scholarly journals Phase equilibria in the Gd–Cr–Ge system at 1070 K

2021 ◽  
Vol 22 (2) ◽  
pp. 248-254
Author(s):  
M. Konyk ◽  
L. Romaka ◽  
Yu. Stadnyk ◽  
V.V. Romaka ◽  
V. Pashkevych
Keyword(s):  
Phase Diagram ◽  
Isothermal Section ◽  
Ternary System ◽  
Electron Microprobe ◽  
Structure Type ◽  
Space Group ◽  
X Ray ◽  
Type Space ◽  
Ternary Compounds ◽  
Pearson Symbol

The isothermal section of the phase diagram of the Gd–Cr–Ge ternary system was constructed at 1070 K over the whole concentration range using X-ray diffractometry, metallography and electron microprobe (EPM) analysis. Three ternary compounds are realized in the Gd–Cr–Ge system at the temperature of annealing: Gd117Cr52Ge112 (Tb117Fe52Ge112 structure type,  space group Fm-3m, Pearson symbol cF1124, a = 2.8971(6) nm), GdCr6Ge6 (SmMn6Sn6 structure type, space group P6/mmm, Pearson symbol hP16, a = 0.51797(2), c = 0.82901(4) nm) and GdCr1-хGe2 (CeNiSi2 structure type, space group Cmcm, Pearson symbol oS16, a = 0.41569(1)-0.41593(8), b = 1.60895(6)-1.60738(3), c = 0.40318(1)-0.40305(8) nm). For the GdCr1-xGe2 compound the homogeneity range was determined (x=0.73 – 0,69).

Low-temperature phase transition and magnetic properties of K3YbSi2O7

2021 ◽  
Vol 77 (4) ◽  
Author(s):  
Predrag Dabić ◽  
Volker Kahlenberg ◽  
Biljana Krüger ◽  
Marko Rodić ◽  
Sabina Kovač ◽  
...  
Keyword(s):  
Phase Transition ◽  
Magnetic Properties ◽  
Phase Transformation ◽  
Low Temperature ◽  
Orthorhombic Phase ◽  
Temperature Phase ◽  
Space Group ◽  
Temperature Phase Transition ◽  
New Type ◽  
Low Temperature Phase

The new ambient-temperature hexagonal (space group P63 /mmc) polymorph of tripotassium ytterbium(III) disilicate (β-K3YbSi2O7) has been synthesized by the high-temperature flux method and subsequently structurally characterized. In the course of the temperature-dependent single-crystal diffraction experiments, a phase transformation of β-K3YbSi2O7 to a novel low-temperature orthorhombic phase (β′-K3YbSi2O7, space group Cmcm) has been observed at about 210 K. β-K3YbSi2O7 is isostructural with K3ErSi2O7, whereas β′-K3YbSi2O7 adopts a new type of structure. Both compounds can be built up from a regular alternation of layers of two types, which are parallel to the (001) plane. In the octahedral layer, YbO6 octahedra are isolated and linked by K1O6+3 polyhedra. The second, slightly thicker sorosilicate layer is formed by a combination of Si2O7 dimers and K2O6+3 polyhedra. The boundary between the layers is a pseudo-kagome oxide sheet based on 3.6.3.6 meshes. The phase transition is due to a tilt of the two SiO4 tetrahedra forming a single dimer which induces a decrease of the Si—O—Si angle between bridging Si—O bonds from 180° (dictated by symmetry in space group P63/mmc) to ≃164°. Magnetic characterization indicates that K3YbSi2O7 remains paramagnetic down to 2 K, showing no apparent influence of the phase transformation on its magnetic properties. Analysis of the magnetization data revealed the positions of the three lowest crystal field levels of the Yb3+ cations, as well as the corresponding projections of their angular momentum on the direction of the magnetic field.

Über eine neue Modifikation von As2O5/On a New Modification of As2O5

1979 ◽  
Vol 34 (1) ◽  
pp. 10-13 ◽  
Author(s):  
Martin Jansen
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
High Temperature ◽  
Low Temperature ◽  
Continuous Phase ◽  
Continuous Phase Transition ◽  
Space Group ◽  
Lattice Constants ◽  
Temperature Form

Abstract High temperature Guinier photographs of As2O5 indicate a continuous phase transition to HT-As2O5, which is accomplished at 305 ± 3 °C. The crystal structure of HT-As2O5 has been derived from the low temperature form; space group and lattice constants are P41212-D44 and a = 857.2 pm, c = 463.6pm (310 °C), respectively. According to symmetry considerations, the phase transition is expected to be of pure ferroelastic-paraelastic type (422F 222).

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