The phase diagram of the system GeSe2–SnSe
is studied by means of X-ray diffraction, differential thermal analysis and
measurements of the density and the microhardness of the material. There are
no intermediate compounds in it, as well as regions of range of solid solutions
at room temperature on the base of GeSe2 and SnSe.
There are two non-variant equilibria in the system: eutectic (where Te=530±5°C and xe= 40 mol% SnSe) and metaeutectic
and xm=98 mol% SnSe).
Phase diagrams for cuprates of alkaline earth and rare earth elements are presented, covering binary to quintenary oxides and including selected solid solution series with other elements. Elementary crystal chemical data are included for identification of the occurring phases. Chemical stability is discussed with respect to the high-temperature reactions with Lewis acids like CO2, protons, etc. Particularly the occurrence of oxide carbonates is consistently pointed out as one of the possible reasons for contradictory results in phase diagrams which comprise oxides with high basicity.
DTA and TG methods were used to study the melting, polymorphic transformation and thermal decomposition processes of alkali metal and ammonium mixed bifluorides formed by mutual replacement of the cations in the crystal lattice. We studied the structural features and the characteristics in the changes of thermal properties of individual compounds, solid solutions with unlimited solubility and solid solutions with limited solubility.
Authors:Ana Braileanu, Maria Zaharescu, D. Crişan, and E. Segal
The scientific interest for the Bi2O3-PbO system has increased due to the importance of the PbO in the high-Tc superconducting phase formation in the Bi2O3-SrO-CaO-CuO system. Also Bi2O3-PbO system contains compounds with some specific semiconductor and dielectric properties and Bi2O3-based solid solutions are well known as high oxygen ion conductors.
Previously, several low melting defined compounds have been identified in the system: 6Bi2O3·PbO; 3Bi2O3·2PbO; 4Bi2O3·5PbO; 4Bi2O3·6PbO and Bi2O3·3PbO.
This work deals with the phase formation and thermal stability of these compounds. Under non-isothermal conditions, in all mixtures regardless of the Bi2O3/PbO ratio, the compound 6Bi2O3·PbO is preferentially formed, followed by the compound 4Bi2O3·5PbO. The formation of the compound 4Bi2O3·6PbO was not confirmed while the formation of the compound Bi2O3
3PbO occurs through a complex mechanism which includes an intermediate step in which a solid solution with the litharge structure was identified. Under isothermal conditions in the same temperature range the tendency to form the stoichiometric compounds increases. All compounds form, decompose and melt at temperatures between 530–780°C.
Authors:D. Bhosale, N. Choudhari, S. Sawant, V. Patil, P. Kulkarni, and V. Kelkar
Homogeneous solid solution oxalates of Fe2+, Cu2+, Mg2+ and Zn2+ metals were prepared by co-precipitation from respective metal acetate solutions with oxalic acid solution. The thermogravimetric
(TG) analysis of co-precipitated oxalate complexes with general formula MgxCu(0.50-x)Zn0.50Fe2(C2O4)3nH2O (x=0.00, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50) were carried out by manual method in static air atmosphere.
The total mass loss % and stepwise mass loss % values are in good agreement with theoretically calculated mass loss % values.
The thermal decomposition of oxalate complexes occur at relatively lower temperatures (561 to 698 K). The lowering of decomposition
temperatures may be attributed to earlier initiation of Fe2+ oxalate in oxalate complexes.
At temperatures between 598–698 K the thermal decomposition of Cu-Mg-Zn-Fe solid solution oxalate complexes leads to formation
of ferrites of spinel structure. After tampering at 873 and 1273 K, homogeneous ferrites arise, which is revealed from XRD
It has been established by XRD, DTA and TG methods that phases of solid solution type of MoO3 in SbVO5 are formed in the system V2O5-MoO3-a-Sb2O4. The Mo6+ ions are incorporated into the crystal lattice of SbVO5 instead of both Sb5+ and V5+, while the charge compensation occurs by a formation of cation defects (□) at Sb5+ and V5+. The phases Sb1-6x□xV1-6x□xMo10xO5 are stable in the solid-state up to 69010C and the limit of solubility of MoO3 in SbVO5 does not exceed 20.00 mol%.
Authors:W. Wolski, E. Wolska, J. Kaczmarek, and P. Piszora
Products of hydrothermal treatment of the initial amorphous system MnxFe2−2x(OH)6−4x for 0≤x1 in 0.1x intervals, and products of their further thermal treatment, were examined by chemical analysis, X-ray, IR, and DTA techniques supported by magnetic measurements. After hydrothermal growth for lowx, hematite and goethite phases occurred. Although the goethite phase was still identifiable atx=0.6, formation of a solid solution with the isostructural groutite was not found. The ferrimagnetic spinel phase, which resists heating up to 400‡C, was present at 0.5≤x≤0.9. At higher temperatures, it transformed into the rhombohedral hematite type phase or into the cubic bixbyite phase. AtT≥900‡C, a ferrimagnetic spinel structure reappeared up tox=0.8. For x=0.9, the low- and high-temperature forms of the hausmannite phase occurred, forx= 1 passing from one form into another through Mn5O8 and partritgeite.
In the systems Ca3(PO4)2-MSO4 (M = Sr, Ba), the series of single phase Ca21−3xM2xI(PO4)14−2x(SO4)2x with 0<x<0.15 forM=Sr and 0<x<0.1 forM = Ba have been prepared. These solid solutions, respectively strontium phosphosulfate and barium phosphosulfate, are isostructural with anhydrous tricalcium orthophosphate. They have been characterized by their infrared spectra and their crystallographic unit cell parameters.
The thermotropic phase transitions in the perovskite type layer compound (n-C10H21NH3)2MnCl4 and (n-C14H29NH3)2MnCl4 were synthesized and, at the same time, a series of their mixtures C10Mn-C14Mn were prepared. The experimental binary phase diagram of C10Mn-C14Mn was established by differential thermal analysis (DTA), IR and X-ray diffraction. In the phase diagram new material (n-C10H21NH3)(n-C14H29NH3)MnCl4 and two eutectoid invariants were observed, two eutectic points temperatures are about 29.8 and 27.9°C. Contrasting other
similar system, there are three noticeable solid solution ranges (α, β, γ) at the left and right boundary and middle of the
Authors:K. Kakinuma, H. Yamamura, H. Haneda, and T. Atake
The structural characterization, thermogravimetric analysis and electrical properties for solid solution system, (Ba1–xLax)2In2O5+x with perovskite-type structure were investigated. X-ray diffraction showed that the orthorhombic phase was in the range of 0.0<x
0.3, the tetragonal phase 0.3<x
0.5, and the cubic phase 0.5<x. The sharp transition of electrical conductivity shifted to a lower temperature with increasing x and disappeared at the phase boundary between the orthorhombic and tetragonal phases. This perovskite-related oxide exhibited a pure oxide-ion conduction over the oxygen partial pressure range of 1 atm to 10–3.5 atm, and the electrical conductivity reached the value of 1.610–1 (S cm–1) at 1073 K, which was nearly equal to that of the yttria stabilized zirconia. These properties were successfully explained in terms of disordered oxygen ions.