scholarly journals Mixed-metal phosphates K1.64Na0.36TiFe(PO4)3 and K0.97Na1.03Ti1.26Fe0.74(PO4)3 with a langbeinite framework

2021 ◽  
Vol 77 (12) ◽  
Author(s):  
Igor V. Zatovsky ◽  
Nataliia Yu. Strutynska ◽  
Ivan V. Ogorodnyk ◽  
Vyacheslav N. Baumer ◽  
Nickolai S. Slobodyanik ◽  
...  
Keyword(s):  
High Temperature ◽  
Single Crystals ◽  
Three Dimensional ◽  
The Other ◽  
Site Symmetry ◽  
Mixed Metal ◽  
Metal Phosphates ◽  
Temperature Range ◽  
Molar Ratios ◽  
Sodium Cations

Single crystals of the langbeinite-type phosphates K1.65Na0.35TiFe(PO4)3 and K0.97Na1.03Ti1.26Fe0.74(PO4)3 were grown by crystallization from high-temperature self-fluxes in the system Na2O–K2O–P2O5–TiO2–Fe2O3 using fixed molar ratios of (Na+K):P = 1.0, Ti:P = 0.20 and Na:K = 1.0 or 2.0 over the temperature range 1273–953 K. The three-dimensional framework of the two isotypic phosphates are built up from [(Ti/Fe)2(PO4)3] structure units containing two mixed [(Ti/Fe)O6] octahedra (site symmetry 3) connected via three bridging PO4 tetrahedra. The potassium and sodium cations share two different sites in the structure that are located in the cavities of the framework. One of these sites has nine and the other twelve surrounding O atoms.

scholarly journals Ca5Zr3F22

2012 ◽  
Vol 68 (4) ◽  
pp. i23-i23 ◽  
Author(s):  
Abdelghani Oudahmane ◽  
Malika El-Ghozzi ◽  
Daniel Avignant
Keyword(s):  
Solid State ◽  
Single Crystals ◽  
Solid State Reaction ◽  
Title Compound ◽  
Three Dimensional ◽  
The Other ◽  
Site Symmetry ◽  
Coordination Numbers ◽  
Rotation Axes ◽  
Dimensional Network

Single crystals of Ca5Zr3F22, pentacalcium trizirconium docosafluoride, were obtained unexpectedly by solid-state reaction between CaF2and ZrF4in the presence of AgF. The structure of the title compound is isotypic with that of Sr5Zr3F22and can be described as being composed of layers with composition [Zr3F20]8−made up from two different [ZrF8]4−square antiprisms (one with site symmetry 2) by corner-sharing. The layers extending parallel to the (001) plane are further linked by Ca2+cations, forming a three-dimensional network. Amongst the four crystallographically different Ca2+ions, three are located on twofold rotation axes. The Ca2+ions exhibit coordination numbers ranging from 8 to 12, depending on the cut off, with very distorted fluorine environments. Two of the Ca2+ions occupy interstices between the layers whereas the other two are located in void spaces of the [Zr3F20]8−layer and alternate with the two Zr atoms along [010]. The crystal under investigation was an inversion twin.

Structural-phase transition in (Cu2Te)2−x(ZnTe)x at high temperature

2021 ◽  
pp. 2150113
Author(s):  
H. B. Gasimov ◽  
R. M. Rzayev
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
High Temperature ◽  
Single Crystals ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Range ◽  
Xrd Study ◽  
Xrd Method

Cu2Te single crystal was grown by the Bridgman method. X-ray diffraction (XRD) study of Cu2Te single crystals in the temperature range of 293–893 K was performed and possible phase transitions in the mentioned range of temperature have been investigated. (Cu2Te)[Formula: see text](ZnTe)[Formula: see text] single crystals also were grown with [Formula: see text], 0.05, 0.10 concentrations and structural properties of the obtained single crystals were investigated by the XRD method in the temperature range 293–893 K. Lattice parameters and possible phase transitions in the mention temperature range were determined for (Cu2Te)[Formula: see text](ZnTe)[Formula: see text] single crystals for [Formula: see text], 0.05, 0.10 concentrations.

scholarly journals Crystal structure of langbeinite-related Rb0.743K0.845Co0.293Ti1.707(PO4)3

2015 ◽  
Vol 71 (3) ◽  
pp. 251-253 ◽  
Author(s):  
Nataliia Yu. Strutynska ◽  
Marina A. Bondarenko ◽  
Ivan V. Ogorodnyk ◽  
Vyacheslav N. Baumer ◽  
Nikolay S. Slobodyanik
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Point Group ◽  
Three Dimensional ◽  
Type Structure ◽  
Group Symmetry ◽  
Site Symmetry ◽  
Point Group Symmetry ◽  
Crystallization Method ◽  
Temperature Crystallization

Potassium rubidium cobalt(II)/titanium(IV) tris(orthophosphate), Rb0.743K0.845Co0.293Ti1.707(PO4)3, has been obtained using a high-temperature crystallization method. The obtained compound has a langbeinite-type structure. The three-dimensional framework is built up from mixed-occupied (Co/TiIV)O6octahedra (point group symmetry .3.) and PO4tetrahedra. The K+and Rb+cations are statistically distributed over two distinct sites (both with site symmetry .3.) in the large cavities of the framework. They are surrounded by 12 O atoms.

Plastic Deformations in L10-Ordered Single Crystals with their c/a Ratios Less than Unity

2007 ◽  
Vol 561-565 ◽  
pp. 459-462
Author(s):  
Katsushi Tanaka ◽  
Hiromitsu Ide ◽  
Yoshinori Sumi ◽  
Kyosuke Kishida ◽  
Haruyuki Inui
Keyword(s):  
Shear Stress ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Room Temperature ◽  
The Other ◽  
Compressive Deformation ◽  
Positive Temperature ◽  
Plastic Deformations ◽  
Temperature Range ◽  
Critical Resolved Shear Stress

Compressive deformation of L10-ordered single crystals of FePd whose c/a ratio less than unity have been investigated from room temperature to 823 K. The results show that the critical resolved shear stress (CRSS) for octahedral glide of ordinary dislocations is smaller than that of super-lattice dislocations in all the temperature range investigated, that is the opposite sense to the case of Ti-56 mol% Al. The CRSS for ordinary dislocations virtually independent to the temperature. On the other hand, the CRSS for super dislocations exhibits a weak positive temperature dependence from room temperature up to 573 K and decreases in higher temperatures.

scholarly journals Structural features of the oxidonitridophosphates K3 M III(PO3)3N (M III = Al, Ga)

2021 ◽  
Vol 77 (12) ◽  
Author(s):  
Igor V. Zatovsky ◽  
Ivan V. Ogorodnyk ◽  
Vyacheslav N. Baumer ◽  
Ivan D. Zhilyak ◽  
Ruslana V. Horda ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Three Dimensional ◽  
Metal Cations ◽  
Structural Features ◽  
The Self ◽  
The Other ◽  
Site Symmetry ◽  
Flux Method ◽  
Cubic Crystals

Cubic crystals of tripotassium aluminium (or gallium) nitridotriphosphate, K3 M III(PO3)3N (M III = Al, Ga), were grown by application of the self-flux method. In their isostructural crystal structures, all metal cations and the N atom occupy special positions with site symmetry 3, while the P and O atoms are situated in general positions. The three-dimensional framework of these oxidonitridophosphates is built up from [M IIIO6] octahedra linked together via (PO3)3N groups. The latter are formed from three PO3N tetrahedra sharing a common N atom. The coordination environments of the three potassium cations are represented by two types of polyhedra, viz. KO9 for one and KO9N for the other two cations. An unusual tetradentate type of coordination for the latter potassium cations by the (PO3)3N6– anion is observed. These K3 M III(PO3)3N (M III = Al, Ga) compounds are isostructural with the Na3 M III(PO3)3N (M III = Al, V, Ti) compounds.

scholarly journals Synthesis and crystal structure of NaCuIn(PO4)2

2020 ◽  
Vol 76 (3) ◽  
pp. 366-369
Author(s):  
Elhassan Benhsina ◽  
Jamal Khmiyas ◽  
Said Ouaatta ◽  
Abderrazzak Assani ◽  
Mohamed Saadi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Three Dimensional ◽  
Atmospheric Conditions ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
Sodium Cations ◽  
Oxygen Atoms

Single crystals of sodium copper(II) indium bis[phosphate(V)], NaCuIn(PO4)2, were grown from the melt under atmospheric conditions. The title phosphate crystallizes in the space group P21/n and is isotypic with KCuFe(PO4)2. In the crystal, two [CuO5] trigonal bipyramids share an edge to form a dimer [Cu2O8] that is connected to two PO4 tetrahedra. The obtained [Cu2P2O12] units are interconnected through vertices to form sheets that are sandwiched between undulating layers resulting from the junction of PO4 tetrahedra and [InO6] octahedra. The two types of layers are alternately stacked along [101] and are joined into a three-dimensional framework through vertex- and edge-sharing, leaving channels parallel to the stacking direction. The channels host the sodium cations that are surrounded by four oxygen atoms in form of a distorted disphenoid.

Temperature Fluctuations Inside the CANDU Reactor Moderator Test Facility (MTF)

2012 ◽  
Author(s):  
Araz Sarchami ◽  
Nasser Ashgriz ◽  
Marc Kwee
Keyword(s):  
High Temperature ◽  
Tube Bundle ◽  
Three Dimensional ◽  
Symmetry Plane ◽  
Temperature Fluctuations ◽  
The Other ◽  
Test Facility ◽  
Temperature Distributions ◽  
Frequency Fluctuations ◽  
Temperature Liquid

Three dimensional numerical simulation is conducted on the CANDU Moderator Test Facility (MTF). Heat generation inside the tank is modeled through surface heating. Transient variations of the temperature and velocity distributions inside the tank are determined. The results show that the flow and temperature distributions inside the moderator tank are three dimensional and no symmetry plane can be identified. A high temperature zone, located on the top left corner of the tank, is identified. The inlet jets are found to flow along the walls of the tank and impinge on each other at the top of the tank. This impingement point is located more towards the right side of the tank. The impingement of these two flow result in a secondary downward moving jet, which penetrates into the tube bundle. This secondary jet divides the tank into two sides. One side contains high temperature liquid and the other side contains low temperature liquid. The temperature contours along the length of the tank have a saddle shape, with high temperatures towards the edges of the saddle. This is due to strong wall jet flows in the middle planes pushing the hotter fluid towards the end walls of the tank. Competition between the upward moving buoyancy driven flows and the downward moving momentum driven flows, results in the formation of circulation zones inside the tank. The numerical results for MTF indicate that the moderator tank operates in the buoyancy driven mode. Any small disturbances in the flow or temperature can make the system unstable and asymmetric. Once the system comes out of symmetry, it cannot go back to symmetry. This results in circulating buoyancy driven flow at one side and a momentum driven flow at the other side of tank. Different types temperature fluctuations are noted inside the tank: (i) large amplitude temperature fluctuations are mainly at the boundaries between the hot and cold; (ii) low amplitude temperature fluctuations are mainly in the core of the tank with more uniform temperature distributions; (iii) high frequency fluctuations are in the regions with high velocities; and (iv) low frequency fluctuations are in the regions with lower fluid velocities.

scholarly journals Structure cristalline de type alluaudite K0.4Na3.6Co(MoO4)3

2015 ◽  
Vol 71 (1) ◽  
pp. 4-7 ◽  
Author(s):  
Rawia Nasri ◽  
Noura Fakhar Bourguiba ◽  
Mohamed Faouzi Zid
Keyword(s):  
Solid State ◽  
Three Dimensional ◽  
The Other ◽  
Solid State Reactions ◽  
Site Symmetry ◽  
Potassium Sodium ◽  
Triple Molybdate

A new triple molybdate, potassium sodium cobalt tris(molybdate), K0.4Na3.6Co(MoO4)3, was synthesized using solid-state reactions. The Co2+and one Na+cation are located at the same general site, each with occupancy 0.5. Another site (site symmetry 2) is occupied by Na+and K+cations, with occupancies of 0.597 (7) and 0.402 (6), respectively. The other two Na+cations and one of the two Mo atoms lie on special positions (site symmetries -1, 2 and 2, respectively). The structure is characterized byM2O10(M= Co/Na) dimers, which are linked by MoO4tetrahedra, forming infinite layers. The latter are connected firstly by insertion of one type of MoO4tetrahedra and secondly by sharing corners with the other type of MoO4tetrahedra. This results in an open three-dimensional framework with the cavities occupied by the Na+and K+cations. The structure is isotypic with Na3In2As3O12and Na3In2P3O12. A comparison is made with structures such as K2Co2(MoO4)3andβ-NaFe2(MoO4)3and their differences are discussed.

scholarly journals Crystal structure of alluaudite-type NaMg3(HPO4)2(PO4)

2015 ◽  
Vol 71 (7) ◽  
pp. 813-815 ◽  
Author(s):  
Ahmed Ould Saleck ◽  
Abderrazzak Assani ◽  
Mohamed Saadi ◽  
Cyrille Mercier ◽  
Claudine Follet ◽  
...  
Keyword(s):  
Point Group ◽  
Three Dimensional ◽  
The Other ◽  
Group Symmetry ◽  
Strong Hydrogen Bond ◽  
Site Symmetry ◽  
Point Group Symmetry ◽  
Hydrogen Phosphate ◽  
Hydrothermal Conditions ◽  
Different Types

The title compound, sodium trimagnesium bis(hydrogen phosphate) phosphate, was obtained under hydrothermal conditions. In the crystal, two types of [MgO6] octahedra, one with point group symmetry 2, share edges to build chains extending parallel to [10-1]. These chains are linked together by two kinds of phosphate tetrahedra, HPO4and PO4, the latter with point group symmetry 2. The three-dimensional framework delimits two different types of channels extending along [001]. One channel hosts the Na+cations (site symmetry 2) surrounded by eight O atoms, with Na—O bond lengths varying between 2.2974 (13) and 2.922 (2) Å. The OH group of the HPO4tetrahedron points into the other type of channel and exhibits a strong hydrogen bond to an O atom of the PO4tetrahedron on the opposite side.

High temperature dielectric relaxation anomalies in Ca0.9Nd0.1Ti0.9Al0.1O3−δ single crystals

RSC Advances ◽  
2015 ◽  
Vol 5 (96) ◽  
pp. 78414-78421 ◽  
Author(s):  
G. Murugesan ◽  
R. Nithya ◽  
S. Kalainathan ◽  
Shamima Hussain
Keyword(s):  
High Temperature ◽  
Dielectric Relaxation ◽  
Single Crystals ◽  
Room Temperature ◽  
Dielectric Studies ◽  
Floating Zone ◽  
Temperature Range

We herein report dielectric studies on Ca0.9Nd0.1Ti0.9Al0.1O3−δ single crystals grown by the optical floating zone technique in the temperature range from room temperature to 660 K.

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