N. L. Mikhailova

Double complex salts [Ni(NH3)6]3[Fe(CN)6]2 and [Ni(NH3)6]3[Cr(CNS)6]2: Synthesis and properties

The double complex salts [Ni(NH3)6]3[Fe(CN)6]2 and [Ni(NH3)6]3[Cr(CNS)6]2 were synthesized and their thermal decomposition in air was studied. The values of interplanar distances in crystal lattices were determined. The compounds are proposed as precursors for producing homogeneous bimetallic nanodimensional powders.

Phase formation along sections of the HfO(NO3)2-H3PO4-RbF-H2O system

The phase formation in the system HfO(NO3)2-H3PO4-RbF-H2O was studied along the sections at the molar ratios PO43−/Hf = 0.5, 1.0, 1.5, 2.0, and 3.0 and RbF: Hf = 1−5. The initial solutions contained 2–10 wt % HfO2. The synthesis was performed at room temperature. The following substances were obtained for the first time: crystalline fluorophosphatehafnate RbHfF2PO4 · 0.5H2O, crystalline triple salt HfF4 · Rb(PO4)0.33 · RbNO3, crystalline solvate Rb3Hf3(PO4)5 · 3HF, and amorphous fluorophosphate Hf3O2F2(PO4)2 · 8H2O (formula is conditional). The compounds were studied by crystal-optical, elemental, X-ray diffraction, thermogravimetric, IR spectroscopic, and electron microscopic analyses.

Binary complexes [Co(A)6][M(C2O4)3] (A = NH3, 1/2C2H8N2, M = Fe, Cr): Synthesis, properties, and thermal decomposition

Binary complexes [Co(A)6][M(C2O4)3] (A = NH3, 1/2C2H8N2, M = Fe, Cr) are synthesized, and their physicochemical properties and thermal decomposition in air, argon, and hydrogen are studied. The qualitative and quantitative analyses are carried out for the solid and gaseous thermolysis products. Similar regularities are revealed in the behavior of complexes [Co(NH3)6][Fe(C2O4)3] (I), [Co(En)3][Fe(C2O4)3] (II), [Co(NH3)6][Cr(C2O4)3] (III), and [Co(En)3][Cr(C2O4)3(IV). The solid thermolysis product for complexes I and III in argon at 225 and 300°C is Co(NH2)2M(C2O4)2, respectively; and that for complexes II and IV at 280 and 380°C is Co(En)2M(C2O4)2. The gaseous thermolysis products are CO and CO2, NH3, En partially isolated upon thermal destruction, other products of En destruction, and En itself. Complex III forms the most highly dispersed solid products in a range of 300–400°C.

Effect of ligands on the thermolysis of the double complexes [Co(NH3)6]2C2O4[Cu(C2O4)2]2 and [Co(NH3)6]Cl[Cu(C7H4O3)2]

The thermolysis of the complexes [Co(NH3)6]2C2O4[Cu(C2O4)2]2 (I) and [Co(NH3)6]Cl[Cu(C7H4O3)2] (II) in air and hydrogen at 200, 350, and 500°C and the composition and properties of the thermolysis products are considered. The oxidative thermolysis of the complexes yields mixtures of cobalt and copper oxides, including mixed ones. The reductive thermolysis of the complexes yields a Co + Cu bimetallic powder in the case of compound I and a Co + Cu + C powder in the case of compound II. The thermal behavior of the complexes is governed by the nature of the ligand coordinated to the copper atom. The observed data are explicable in terms of the properties of this ligand. The chemistry of the oxidative and reductive thermolysis is discussed.

Thermal stability and X-ray luminescence properties of cesium fluorophosphatohafnates

The thermal stability of cesium fluorophosphatohafnates (crystalline CsHf2F2(HPO4)2PO4 · 2H2O, CsHfF2PO4 · 0.5H2O, CsHf2F6PO4 · 4H2O and X-ray amorphous Cs2Hf3O1.5F5(PO4)2 · 5H2O, Cs5H4Hf3F7(PO4)3.66(NO3)3 · 5H2O) was determined. The weight ratios Cs+/Hf and PO43−/ZrHf in CsHf2F2(HPO4)2PO4 · 2H2O were confirmed by identifying the calcination production CsHf2(PO4)3 (∼1000°C). A new crystalline compound CsHf2F(HPO4)(PO4)2 was found by thermogravimetric and X-ray powder diffraction analysis during heating. A new method for hydrothermal synthesis of CsHf2(PO4)3, which was different from the already known one, was proposed. It was ascertained that CsHf2(PO4)3 possesses a significant X-ray luminescence; whereas in fluorophosphatehafnates show low luminescence intensity.

Interaction of components of electrode coatings with liquid glass during heating

Structural and chemical changes are considered at contact of some coating materials and sodium–potassium or sodium liquid glass solutions. Behaviour and phase composition of stock mix for the welding electrode coating ingredients are determined by the methods of thermal and roentgen-phase analyses.

Phase formation in the ZrO(NO3)2-NaF(HF)-H3PO4-H2O system at 20°C

Phase formation in the ZrO(NO3)2-NaF(HF)-H3PO4-H2O system was studied at 20°C and 2.0–14.5 wt % ZrO2 in the initial solution along sections with molar ratios PO43−/Zr = 0.5 and 1.5 and also in the presence of hydrogen fluoride at Na/Zr = 1 and PO43−/Zr = 0.5, 1.0, and 1.5. Crystalline zirconium hydrophosphate Zr(HPO4)2 · H2O, fluorozirconates Na5Zr2F13 and Na7Zr6F31 · 12H2O, fluorophosphatozirconates NaH2Zr3F3(PO4)4 · 3H2O and NaZr2F6(PO4) · 4H2O, and amorphous NaZrO0.5F(PO4) · 4H2O (provisional composition) were separated at room temperature. NaH2Zr3F3(PO4)4 · 3H2O and NaZr2F6(PO4) · 4H2O were prepared for the first time and were studied by crystal-optical, elemental, and thermal analyses, X-ray powder diffraction, IR spectroscopy, scanning electron microscopy (SEM), and X-ray microanalysis. Na7Hf6F31 · 12H2O was found to exist in a mixture with the hydrophosphate.

Thermal stability and X-ray-luminescent properties of fluorozirconates and fluorosulfatozirconates

The thermolysis of fluorozirconates (M2ZrF6, M5Zr4F21 · 3H2O, MZrF5 · H2O, Rb2Zr3OF12, and Cs2Zr3F14 · 1.5H2O) and fluorosulfatozirconates (M2ZrF4SO4, Rb3Zr2F9SO4 · 2H2O, and Cs8Zr4F2(SO4)11 · 16H2O) with M = K, Rb, or Cs in undried air was studied by thermal analysis in tandem with X-ray powder diffraction. The X-ray luminescence (XRL) intensity was determined for these compounds and their thermolysis products. A mixture of Rb2Zr3OF12 and Rb2ZrF6 luminescent phases was detected in the thermolysis products of Rb5Zr4F21 · 3H2O and RbZrF5 · H2O for the first time. After heat treatment, a considerable quantum yield was observed for ZnZrF6 · 5H2O, ZnZrF6 · 6H2O, and ZnZr2F10 · 7H2O. The XRL luminescence was affected by the composition of the phase and the density of excited states (F* and O*).