E. L. Tikhomirova

Synthesis of a magnesium aluminum spinel by the burning method

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.

Reaction of niobium pentoxide with ammonium hydrodifluoride

The reaction between Nb2O5 and NH4HF2 is studied by thermogravimetric analysis, IR spectroscopy, and crystal-optical analysis. Intermediates and their formation temperatures are determined.

Hydrofluoride Synthesis of Fluorides of Some Rare-Earth Elements

Thermal gravimetric, X-ray phase, IR spectroscopic, and chemical analyses were applied to study the reaction of yttrium and neodymium oxides with NH4HF2.

Synthesis of varistor powders by accelerated combustion and properties of ceramics based on them

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 Ub = 4.2 kB mm–1, α = 54, and Ileak = 0.2 μA cm–2.

Optimization of the composition and sintering conditions of high-voltage ZnO varistor ceramics

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 Vb = 4.5 kV/mm, α = 50, Il = 1.1 μA/cm2, density ρ = 5.67 g/cm3 (relative density of 96.1%).

Synthesis of lithium hexafluorotitanate

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 magnesium aluminum spinel from carbonate hydroxyde precursors

Three ways to synthesize MgA12O4 precursor were studied with use of a two-step precipitation at the beginning of ions Mg2+ and then Al3+ with ammonium hydroxide, ammonium carbonate, and mixture thereof. Efficiency of these ways was evaluated with the aid of a residual amount of cations Mg2+ and Al3+ in the mother liquor.