The polymorphs of the Na+ ion conductor Na3PS4 viewed from the perspective of a group-subgroup scheme

2020 ◽  
Vol 235 (1-2) ◽  
pp. 1-6 ◽  
Author(s):  
Stefan Seidel ◽  
Wolfgang G. Zeier ◽  
Rainer Pöttgen
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Solid State ◽  
Crystal Chemical ◽  
Solid State Electrolyte ◽  
Ion Conductor ◽  
Space Group ◽  
Temperature Modification ◽  
Subgroup Scheme ◽  
High Temperature Modification

AbstractThe Na+ solid state electrolyte Na3PS4 is currently being investigated due to its high ionic conductivity and its synthesis-dependent crystal structure. Na3PS4 adopts a tetragonal low-temperature modification with space group P 4̅21c that transforms to a cubic high-temperature modification with space group I 4̅3m (Tl3VS4 type). These two modifications are related by a group-subgroup scheme. The symmetry reduction proceeds via a translationengleiche transition from I 4̅3m to I 4̅2m and subsequently via a klassengleiche transition to P 4̅21c. The tetragonal phase with space group I 4̅2m corresponds to the K2HgSnSe4 type. The group-subgroup scheme of this tetragonal branch of the Bärnighausen tree is discussed along with the crystal chemical consequences and results of diffraction experiments. The structure of K3SbSe4 (space group R 3c) belongs to the rhombohedral branch of the aristotype Tl3VS4.

Crystal Structure of Hf2GaSb3

2012 ◽  
Vol 194 ◽  
pp. 1-4
Author(s):  
Iryna Tokaychuk ◽  
Yaroslav Tokaychuk ◽  
Roman E. Gladyshevskii
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Ternary Compound ◽  
Powder Diffraction ◽  
Structure Type ◽  
Space Group ◽  
X Ray ◽  
Temperature Modification ◽  
Pearson Symbol ◽  
High Temperature Modification

The structure of the new ternary compound Hf2GaSb3 was determined by means of X-ray powder diffraction. It crystallizes with the structure type Zr2CuSb3 which represents a ternary ordered derivative of the UAs2 type (Pearson symbol tP6, space group P-4m2, a = 3.89841(8), c = 8.62650(19) Å). The ternary compound can be regarded as an ordered, Ga-stabilized derivative of the high-temperature modification of the binary antimonide HfSb2 (structure type UAs2).

scholarly journals Synthesis and Raman spectra of K-Ca double carbonates: K2Ca(CO3)2 bütschliite, fairchildite, and K2Ca2(CO3)3 at 1 ATM

2019 ◽  
Vol 64 (9) ◽  
pp. 967-973
Author(s):  
A. V. Arefiev ◽  
I. V. Podborodnikov ◽  
A. F. Shatskiy ◽  
K. D. Litasov
Keyword(s):  
Raman Spectroscopy ◽  
Raman Spectrum ◽  
High Temperature ◽  
Solid State ◽  
Raman Spectra ◽  
Solid State Reaction ◽  
Atmospheric Pressure ◽  
Intense Band ◽  
Temperature Modification ◽  
High Temperature Modification

Here we present results on synthesis of double K-Ca carbonates at atmospheric pressure in closed graphite capsules. The mixtures of K2CO3 and CaCO3 corresponding to stoichiometry of K2Ca(CO3)2 and K2Ca2(CO3)3 were used as starting materials. The low-temperature modification of K2Ca(CO3)2 was synthesized by a solid-state reaction at 500°C during 96 h. The high-temperature modification of K2Ca(CO3)2 as well as the K2Ca2(CO3)3 compound were synthesized both by a solid-state reaction at 600°C during 72 h and during cooling of the melt from 830 to 650°C for 30 min. The obtained carbonates were studied by Raman spectroscopy. The Raman spectrum of bütschliite is characterized by the presence of an intense band at 1093 cm-1 and several bands at 1402, 883, 826, 640, 694, 225, 167 and 68 сm-1. The Raman spectrum of fairchildite has characteristic intense bands at 1077 and 1063 cm-1, and several bands at 1760, 1739, 719, 704, 167, 100 сm-1. In the Raman spectrum of K2Ca2(СO3)3 intense bands at 1078 and 1076 cm-1 and several bands at 1765, 1763, 1487, 1470, 1455, 1435, 1402, 711, 705, 234, 221, 167, 125 and 101 сm-1 were found. The collected Raman spectra can be used to identify carbonate phases entrapped as microinclusions in phenocrysts and xenoliths from kimberlites and other alkaline rocks.

Zur Kenntnis des Argyrodit-Strukturtyps: Die Kristallstruktur von Ag8SiS6 / The Argyrodite Structure Type : The Crystal Structure of Ag8SiS6

1977 ◽  
Vol 32 (4) ◽  
pp. 373-379 ◽  
Author(s):  
Bernt Krebs ◽  
Jürgen Mandt
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Room Temperature ◽  
Structure Type ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Temperature Modification ◽  
Face Centered ◽  
Temperature Factors ◽  
High Temperature Modification

The room temperature modification of Ag8SiS6 is orthorhombic, space group Pna21, with α = 15.024, b = 7.428, c = 10.533 Å, Z = 4. A complete single crystal X-ray structure analysis shows the structure to contain tetrahedral SiS4(4-) units (Si-S 2.094(12) ... 2.130(12) Å) besides isolated sulfide groups coordinated by Ag; the compound may thus be formulated as Ag8(SiS4)(S)2. The coordination of the Ag atoms by sulfur is distorted tetrahedral (Ag-S 2.557...2.757 A), approximately trigonal planar (Ag-S 2.386...2.775 A, with one additional weakly bonded axial S at 2.991 ... 3.330 Å), or linear (Ag-S 2.414... 2.443 Å). Within the (ordered) Ag sublattice the temperature factors are significantly higher than for Si and S, indicating a certain mobility of the Ag atoms. The arrangement of the thiosilicate -sulfide part of the structure is pseudocubic face-centered, showing the close structural relationship to the disordered cubic high temperature modification of Ag8GeTe6.

Sign in / Sign up

Export Citation Format

Share Document