scholarly journals Synthesis and Hydrothermal Study of (Na,K)M2(PO4)3 (M = Ti, Zr, Hf) Solid Solutions

2010 ◽  
Vol 12 (3,4) ◽  
pp. 195
Author(s):  
E.A. Asabina ◽  
V.I. Pet'kov ◽  
A.M. Kovalsky ◽  
A.R. Kotelnikov
Keyword(s):  
Solid Solutions ◽  
High Pressures ◽  
Sol Gel ◽  
Distribution Coefficients ◽  
Exchange Reactions ◽  
Sodium Potassium ◽  
Cell Parameters ◽  
Fluid Systems ◽  
Concentration Dependences ◽  
Comparison Of The Results

(Na,K)M2(PO4)3 (M = Ti, Zr, Hf) continuous solid solutions were synthesized by sol-gel and solidstate methods. Cation-exchange reactions in the NaM2(PO4)3–KM2(PO4)3–NaCl–KCl–H2O systems were<br />studied at T = 723 – 973 K and p = 100 – 200 MPa. The concentration dependences of unit cell parameters of the studied phosphates were found. The sodium/potassium distribution coefficients in the phosphate-fluid systems were functions of the solid solution compositions, that is, the systems behave nonideally. The excess volumes and excess Gibbs functions of solid solutions mixing were fitted to thirdorder polynomials and described in terms of the Margules model. From the comparison of the results obtained Ti-, Zr-, and Hf-systems, we made the conclusion that the titanium phosphates show greater<br />nonideality than zirconium and hafnium phosphates and lower thermodynamic stability to decomposition to double phosphates at high pressures and temperatures.

scholarly journals Spray‐dried sol‐gel glass‐ceramic powders based on the tunable thermal expansion of quartz and keatite solid solutions

2021 ◽  
Author(s):  
Alessio Zandona ◽  
Gundula Helsch ◽  
Aurina Martínez Arias ◽  
Alfred P. Weber ◽  
Joachim Deubener
Keyword(s):  
Thermal Expansion ◽  
Solid Solutions ◽  
Glass Ceramic ◽  
Sol Gel ◽  
Ceramic Powders ◽  
Spray Dried

Electrochemical Performance Optimization of Li2NixFe1−xSiO4 Cathode Materials for Lithium-Ion Batteries

2017 ◽  
Vol 14 (2) ◽  
Author(s):  
Atef Y. Shenouda ◽  
M. M. S. Sanad
Keyword(s):  
Performance Optimization ◽  
Electrochemical Impedance ◽  
Coulombic Efficiency ◽  
Sol Gel ◽  
Lithium Ion ◽  
Electrochemical Impedance Spectra ◽  
Cell Parameters ◽  
Sol Gel Process ◽  
Eis Measurements ◽  
And Function

Li2NixFe1−xSiO4 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1) samples were prepared by sol–gel process. The crystal structure of prepared samples of Li2NixFe1−xSiO4 was characterized by XRD. The different crystallographic parameters such as crystallite size and lattice cell parameters have been calculated. Scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) investigations were carried out explaining the morphology and function groups of the synthesized samples. Furthermore, electrochemical impedance spectra (EIS) measurements are applied. The obtained results indicated that the highest conductivity is achieved for Li2Ni0.4Fe0.6SiO4 electrode compound. It was observed that Li/Li2Ni0.4Fe0.6SiO4 battery has initial discharge capacity of 164 mAh g−1 at 0.1 C rate. The cycle life performance of all Li2NixFe1−xSiO4 batteries was ranged between 100 and 156 mAh g−1 with coulombic efficiency range between 70.9% and 93.9%.

Thermodynamical study of (CaGa2S4)x(BaGa2S4)1−x solid solutions

2021 ◽  
pp. 2150469
Author(s):  
T. G. Naghiyev ◽  
R. M. Rzayev
Keyword(s):  
Free Energy ◽  
Solid Solutions ◽  
Calculation Method ◽  
Solid Phase ◽  
Ternary Compounds ◽  
Free Energy Of Formation ◽  
Concentration Dependences ◽  
Solid Phase Reactions ◽  
Two Phases ◽  
Energy Of Formation

The solid solutions of [Formula: see text] were synthesized by solid-phase reactions from powder components of CaS, BaS, and Ga2S3. The temperature-concentration dependences of the Gibbs free energy of formation of [Formula: see text] solid solutions from ternary compounds and phase diagrams of the CaGa2S4–BaGa2S4 were determined by a calculation method. It was revealed that continuous solid solutions are formed in these systems. The spinodal decomposition of [Formula: see text] solid solutions into two phases is predicted at ordinary temperatures.

scholarly journals Structural Transformations in Crystals Induced by Radiation and Pressure. Part 7. Molecular and Crystal Geometries as Factors Deciding about Photochemical Reactivity under Ambient and High Pressures

Crystals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 299 ◽  
Author(s):  
Krzysztof Konieczny ◽  
Arkadiusz Ciesielski ◽  
Julia Bąkowicz ◽  
Tomasz Galica ◽  
Ilona Turowska-Tyrk
Keyword(s):  
High Pressures ◽  
Unit Cell ◽  
Geometrical Parameters ◽  
Isopropyl Group ◽  
Unit Cell Parameters ◽  
Photochemical Reactivity ◽  
Space Group ◽  
Cell Parameters ◽  
Pressure Part ◽  
Asymmetric Unit Cell

We studied the photochemical reactivity of salts of 4-(2,4,6-triisopropylbenzoyl)benzoic acid with propane-1,2-diamine (1), methanamine (2), cyclohexanamine (3), and morpholine (4), for compounds (1), (3), and (4) at 0.1 MPa and for compounds (1) and (2) at 1.3 GPa and 1.0 GPa, respectively. The changes in the values of the unit cell parameters after UV irradiation and the values of the intramolecular geometrical parameters indicated the possibility of the occurrence of the Norrish–Yang reaction in the case of all the compounds. The analysis of the intramolecular geometry and free spaces revealed which o-isopropyl group takes part in the reaction. For (1), the same o-isopropyl group should be reactive at ambient and high pressures. In the case of (2), high pressure caused the phase transition from the space group I2/a with one molecule in the asymmetric unit cell to the space group P1¯ with two asymmetric molecules. The analysis of voids indicated that the Norrish–Yang reaction is less probable for one of the two molecules. For the other molecule, the intramolecular geometrical parameters showed that except for the Norrish–Yang reaction, the concurrent reaction leading to the formation of a five-membered ring can also proceed. In (3), both o-isopropyl groups are able to react; however, the bigger volume of a void near 2-isopropyl may be the factor determining the reactivity. For (4), only one o-isopropyl should be reactive.

scholarly journals Clinopyroxene Solid Solutions in the CaMgSi2O6 – Ca0,5AlSi2O6 Cross-Section at High P-T Parameters

2020 ◽  
Vol 34 ◽  
pp. 37-54
Author(s):  
S. V. Banushkina ◽  
◽  
A. I. Turkin ◽  
A. I. Chepurov ◽  
◽  
...  
Keyword(s):  
Cross Section ◽  
Solid Solutions ◽  
Atmospheric Pressure ◽  
High Pressures ◽  
Experimental Investigations ◽  
Electric Resistance ◽  
Resistance Furnace ◽  
Mineral Association ◽  
Electric Resistance Furnace ◽  
Piston Cylinder

Clinopyroxenes (Cpx) are one of the main rock-forming minerals, but stoichiometry of their compositions was called into question. In particular, an idea of hypothetical calcium molecule Eskola (CaEs, Ca0,5AlSi2O6) existence was expressed. This minal has structure vacancy and silica excess. Numerous experimental investigations in CMAS-system (CaO-MgO-Al2O3-SiO2) have showed that the question of non-stoichiometric Cpx existence remains open. This paper presents the results of an experimental study of the diopside Di (CaMgSi2O6) – calcium molecule Eskola CaEs (Ca0,5AlSi2O6) cross-section in the CMAS-system. The experiments were carried out in the following pressure and temperature range: P=10-4 – 3,0 GPa; T=966 – 15250C. Experiments at atmospheric pressure (10-4 GPa) were performed on a vertical shaft electric resistance furnace; high-pressure ones were performed on a "piston-cylinder" type apparatus. Samples obtained were analyzed using electron microprobe (EMP), scanning electron microscope (SEM) and Raman spectrometer. Depending on the P-T conditions, the samples contain the following phases: anorthite An, garnet Grt, diopside Di, clinopyroxene Cpx, quartz Qtz (tridymite Tr – for experiments at atmospheric pressure), and glass L. The data array on the composition of clinopyroxenes crystallized in this cross-section with diopside in various associations is generalized and supplemented. Clinopyroxenes were found to form quaternary solid solutions of diopside Di (CaMgSi2O6) – enstatite En (Mg2Si2O6) – calcium molecule Tschermak CaTs (CaAl2SiO6) – calcium molecule Eskola CaEs (Ca0,5AlSi2O6). The CaTs and CaEs minals contents are positively correlated with the amount of aluminum in clinopyroxene, and this relationship is particularly pronounced for CaTs. It is confirmed that clinopyroxenes in this cross-section can contain an excess of silica at both atmospheric and high pressures. Apparently, the cation vacancy that exists in pyroxene structure can participate in ordering processes. As a result the pyroxenes of another structure (not diopside – C2/c-symmetry) can be crystallized from total compositions in the Di-CaEs cross-section. Additional research is needed to support this hypothesis. Besides, at present investigation it was not possible to establish an unambiguous relationship between the Cpx composition and P-T-parameters, since it is also associated with both the mixture initial composition and the mineral association. Further experiments are required to justify any geothermobarometric dependence.

scholarly journals FABRICATION AND PROPERTIES OF Co DOPED Bi0.5K0.5TiO3 – BiFeO3 SOLID SOLUTION

2018 ◽  
Vol 56 (1A) ◽  
pp. 197
Author(s):  
Nguyen Hoang Tuan
Keyword(s):  
Solid Solution ◽  
Raman Spectroscopy ◽  
Magnetic Properties ◽  
Crystal Structures ◽  
Solid Solutions ◽  
Sol Gel ◽  
Structure And Properties ◽  
Antiferromagnetic Ordering ◽  
Co Doped ◽  
Good Agreement

In this study, we present some results on the structure and properties of the solid solution of Bi0.5K0.5TiO3– BiFeCoO3 (BKT – BFCO) by Sol-gel method. Crystal structures of BKT – BFCO solid solutions were studies by XRD and Raman spectroscopy. The results were in good agreement with the previous reports of Bi0.5K0.5TiO3– BiFeO3 (BKT – BFO) and Bi0.5K0.5TiO3 – BiCoO3 (BKT – BCO) solid solutions. The magnetic properties were investigated via unsaturated M-H loop, which showed the competition of paramagnetic and antiferromagnetic ordering in BKT – BFCO. However, differing from the BKT – BFO and BKT – BCO solid solutions, the unclear values of saturated magnetism in BKT – BFCO raised the unexplained question, which needed further studies.

scholarly journals Influence of mild Cr3+ doping on the structural, optical, photochromic, and thermochromic reversibility of nano-titania systems

2019 ◽  
Vol 97 (4) ◽  
pp. 347-354 ◽  
Author(s):  
Rizwin Khanam ◽  
Dambarudhar Mohanta
Keyword(s):  
Band Gap ◽  
Anatase Phase ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Incident Radiation ◽  
Optical Absorption Spectroscopy ◽  
Smart Windows ◽  
Cell Parameters ◽  
Doped Titania ◽  
Reversible Thermochromism

We report on the effect of chromium doping on the band gap lowering of nano-titania (TiO2) and subsequent implications as regards coloration characteristics mediated via photochromism and thermochromism processes. As can be found in the X-ray diffractograms, the sol-gel derived, Cr3+-doped nano-TiO2 systems have exhibited an anatase phase with the evidence of peak shifting towards a lower diffraction angle. The average crystallite size decreases, whereas lattice unit cell parameters and, consequently, cell volume, tend to increase with the inclusion of Cr3+ into the titania host. To be specific, 1% Cr-doped titania system showed nearly 5.8% cell expansion as compared to its un-doped counterpart. As revealed from the optical absorption spectroscopy, a narrowing of band gap is observed for the Cr doped nano-titania system: 3.18 eV for the un-doped system, and 2.61 and 2.41 eV for 0.3% and 1% Cr doping cases, respectively, considering direct band-to-band transitions. Moreover, doping led noticeable lowering of the exponent (n value), from its normal value, which suggests inclusion of adequate non-parabolicity feature to the energy band scheme. The photochromic feature, for a given incident radiation, demonstrates a lowered transmission response with increasing Cr content. A reversible thermochromism response has also been demonstrated for doped nano-titania systems subjected to heating with temperature varying between 0–55 °C. The Cr3+ doped nano-titania and similar systems would find scope in smart windows, display components, photocatalysis, etc., when a select coloration is desired.

Physicochemical characterization of Pt and Ir particles deposited on Ce(1-x)Ru(x)O2 solid-solutions for CO oxidation

MRS Advances ◽  
2019 ◽  
Vol 4 (61-62) ◽  
pp. 3433-3440
Author(s):  
E. Gonzalez-A ◽  
R. Rangel ◽  
J. Lara ◽  
J. J. Alvarado ◽  
P. Bartolo
Keyword(s):  
Solid Solutions ◽  
Crystal Size ◽  
Sol Gel ◽  
Physicochemical Characterization ◽  
Metallic State ◽  
Wet Impregnation ◽  
Iridium Nanoparticles ◽  
Gel Technique ◽  
Near Future

AbstractPt/Ce1-xRuxO2 and Ir/Ce1-xRuxO2 catalysts were prepared through the sol-gel technique, under microwave heating. In a first step, the Ce1-xRuxO2 solid solutions were prepared. Subsequently, an incipient wet impregnation process was carried out to homogeneously achieve the dispersion, either of platinum or iridium nanoparticles. The Pt/Ce1-xRuxO2 and Ir/Ce1-xRuxO2 catalysts were characterized by means of SEM, XRD, XPS, TEM, and specific surface area measurements. Crystal size and shifting into the CeO2 structure were detected after ruthenium doping producing the Ce1-xRuxO2 solid-solutions. Trough XPS technique Pt and Ir nanoparticles were found evenly dispersed in a metallic state. Those features allow us to foresee that, in the near future, these materials could be used efficiently as catalysts for oxidation process.

Luminescence Properties of Sol–Gel Derived Ceramic GdNbхTa1 –хO4 and YNbхTa1 –хO4 Solid Solutions

2020 ◽  
Vol 56 (4) ◽  
pp. 437-442
Author(s):  
M. N. Palatnikov ◽  
M. V. Smirnov ◽  
S. M. Masloboeva ◽  
O. B. Shcherbina ◽  
N. V. Sidorov ◽  
...  
Keyword(s):  
Solid Solutions ◽  
Sol Gel ◽  
Luminescence Properties
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