The use of sorbents based on titanium(IV) oxohydroxophosphates for deep purification of liquid radioactive waste of complex chemical composition from Ag(I) and Sb(III) ions is shown to be promising. It has been established that Ag(I) cations are effectively extracted in an alkaline medium, Sb(III) cations - in an acidic region as a result of ionic substitution of H+ hydrophosphate groups for metal cations. Since Sb(III) is present in the anionic form in an alkaline medium, the Sb(III) anions are extracted as a result of ion exchange for the OH--groups of the sorption matrix.

Using a model solution, we have demonstrated the feasibility of using titanium(IV) oxyhydroxyphosphate-based ion-exchange materials for extraction of Cs+ and Sr2+ cations from multicomponent high-salt bottom residues. Conditions for the use of the ion exchangers have been optimized experimentally: liquid : solid = 50, t = 25°C. It has been shown that Cs+ is effectively extracted at pH 2, whereas Sr2+, at pH 8. The zirconium-modified sorbent has been shown to have a higher affinity for metal cations. The modified sorbent is especially selective for cesium in the acid pH region owing to the higher mobility of the protons of its hydrogen phosphate groups in comparison with the unmodified sorbent composition.

Studies were carried out to reduce the leakage current of high-voltage ZnO varistor ceramics by varying Sb2O3 and NiO content in a ZnO-Bi2O3-Sb2O3-Al2O3-Co3O4-NiO. It was found that the ceramic composition (wt %): ZnO 80, Bi2O3 5.83, Sb2O3 2.62, A12O3 4.66, Co2O3 3.80, NiO 3.09, has a minimum leakage current density Iout ≤ 0.1 μA cm-2, breakdown voltage Ub = 4.1kV mm-1, nonlinearity coefficient α = 65. The resulting ceramics are promising for the production of varistors with high stability of performance.

— This paper presents a study aimed at determining the weight ratio of oxide additives for obtaining high-voltage ceramics in the ZnO–Bi 2 O 3 –Sb 2 O 3 –Al 2 O 3 –Co 3 O 4 system containing 90 wt % ZnO, with a leakage current density under 1 μA/cm 2 . The ceramic containing the oxide additives in the ratio Bi 2 O 3 : Sb 2 O 3 : Al 2 O 3 : Co 3 O 4 = 0.25 : 0.17 : 1.4 : 1.4 has a nonlinearity coefficient as high as α = 69, a leakage current density as low as I l = 0.4 μA/cm 2 , and a breakdown voltage V b = 4.1 kV/mm.

Varistor powders were synthesized by accelerated combustion of an aqueous solution of hydrated zinc, bismuth, aluminum, cobalt, and nickel nitrates, antimony tartrate, and sugar at 500°С with isothermal heating for 10 min, followed by grinding and calcination at 700°С for 1 h. The varistor powders obtained have high specific surface area and allow preparation of a ceramic with high values of the breakdown voltage and nonlinearity coefficients and with low leakage current density. The ceramic of the optimum composition (wt %), ZnO 75, Bi2O3 7.36, Sb2O3 5.1, Al2O3 7.19, Co2O3 4.8, and NiO 0.61, sintered at 975°С for 4 h, has U b = 4.2 kB mm–1, α = 54, and I leak = 0.2 μA cm–2.

This paper presents a study aimed at optimizing the composition and sintering conditions of highvoltage ZnO varistor ceramics. We demonstrate that, with allowance for the cost of starting materials, the optimal composition of high-voltage ZnO varistor ceramics is as follows (wt %): ZnO, 90; Bi2O3, 2.76; Sb2O3, 1.92; Al2O3, 3.32; and Co2O3, 2. The optimal sintering conditions are isothermal holding at a temperature of 975°C for 2 h. The ceramics thus prepared have V b = 4.5 kV/mm, α = 50, I l = 1.1 μA/cm2, density ρ = 5.67 g/cm3 (relative density of 96.1%).

We have examined the effect of dopant concentration on the properties of ZnO varistor ceramics and determined the composition and conditions of the synthesis of ceramic powders and sintering of ceramics at a temperature of 925°C. We obtained a breakdown voltage of 2.8–3.0 kV/mm and nonlinearity coefficient in the range 48–55.

It was found in using anatase titanium oxide for the preparation litium hexafluorotitanate by interaction of titanium hydroxide or oxide and lithium fluoride with hydrofluoric acid an output of Li2TiF6 reached 97.1% at “reverse” synthesis, 100% consumption of LiF and 200% consumption of 54% HF.

Synthesis of MgAl2O4 from a stoichiometric mixture of aluminum and magnesium nitrates by its burning with urea, glycine, sugar, and mixtures of these as a fuel was studied.

Three ways to synthesize MgA1 2 O 4 precursor were studied with use of a two-step precipitation at the beginning of ions Mg 2+ and then Al 3+ with ammonium hydroxide, ammonium carbonate, and mixture thereof. Efficiency of these ways was evaluated with the aid of a residual amount of cations Mg 2+ and Al 3+ in the mother liquor.

The reaction between Nb 2 O 5 and NH 4 HF 2 is studied by thermogravimetric analysis, IR spectroscopy, and crystal-optical analysis. Intermediates and their formation temperatures are determined.

Reactions of crushed wastes from lithium tantalate (niobate) production with lithium carbonate were studied by thermal and X-ray analyses. Conditions for their most complete conversion into lithium orthotantalate (orthoniobate) were determined.