O. G. Gromov

Preparation of LiTaO3 , LiNbO3 , and NaNbO3 from Peroxide Solutions

A procedure is described for preparing peroxide solutions of LiTaO3 and LiNbO3 . It is shown that the use of peroxide solutions makes it possible to obtain stoichiometric LiTaO3 , LiNbO3 , and NaNbO3 and LixNa1 – xNbО3 solid solutions.

Sol-gel synthesis of Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte

A modified sol-gel process was studied as applied to synthesize a lithium-conducting solid electrolyte of composition Li1.3Al0.3Ti1.7(PO4)3 (LATP) using water-soluble salts Al(NO3)3 · 9H2O, LiNO3 · 3H2O, and (NH4)2HPO4 and a titanium(IV) citrate complex. As-synthesized samples were characterized using X-ray powder diffraction, DSC/TG, SEM, and impedance spectroscopy. Sintering of as-synthesized amorphous powders at 700°C was found to yield LATP with crystallite sizes of 42–48 nm. Ionic conductivity of the electrolyte measured in the frequency range 25–106 Hz in disks having 86–90% density that were sintered at 1000°C was (3–4) × 10−4 S/cm. Temperature-dependent ionic conductivity was studied in the range 25–200°C. The activation energy of conduction was determined for LATP.

High-pressure synthesis, structure, and electrical properties of LixNa1 − xNbO3 solid solutions

The dielectric permittivity of LixNa1 − xNbO3 ferroelectric solid solutions prepared at high pressures has been measured as a function of temperature and frequency, and their structural properties have been studied. The results demonstrate that ceramics samples of the LixNa1 − xNbO3 (x = 0.17, 0.25) ferroelectric perovskite solid solutions exhibit superionic conduction at relatively low temperatures (T ≥ 400 K). In the temperature range of superionic conduction, we observe significant dielectric dispersion and anomalies in permittivity, corresponding to structural transformations of the high-pressure solid solutions.

Preparation of powders and films of the lithium ion conducting solid electrolyte Li1.3Al0.3Ti1.7(PO4)3

This paper describes a process for the preparation of powders and films of the lithium ion conducting solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 from peroxide solutions. The use of peroxide solutions ensures the preparation of Li1.3Al0.3Ti1.7(PO4)3 with a room-temperature electrical conductivity of (4–5) × 10−4 S/cm by calcining a precursor at 800°C. The synthesized Li1.3Al0.3Ti1.7(PO4)3 powders were characterized by X-ray diffraction, thermal analysis (DTA/TG), and ionic and electronic conductivity measurements. The growth of Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte films is described.

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.

Synthesis of ZnTa2O6 from peroxide solutions

We have studied the formation of zinc metatantalate from peroxide solutions. The results indicate that the use of peroxide solutions enables stoichiometric ZnTa2O6 to be prepared. The crystal structure of the low-temperature phase of ZnTa2O6 forms at a calcination temperature of 700°C. The synthesized ZnTa2O6 powders have been characterized by X-ray diffraction, differential thermal analysis, thermogravimetry, and scanning electron microscopy.

Preparation of powder barium titanate

Phase-pure BaTiO3 powder (free of Ba2TiO4, BaCO3, Ba(NO3)2, and OH impurities) with an average particle size of about 100 nm is prepared by solid-state reaction between titanium oxyhydroxide and barium hydroxide ground and mixed by sonication in an inert organic liquid.

Preparation of high-voltage ZnO varistor ceramics

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.

Production of an electrode material modified by a lithium-conducting solid electrolyte

The process for producing the electrode material LiCoPO4 modified by the lithium-conducting solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 (LATP) was studied. To create a composite consisting of an electrochemically active substance and an electrically conductive additive distributed uniformly between LiCoPO4 particles, a peroxide solution of a LATP precursor was used. After annealing at 700°C, the two-phase composite LiCoPO4/LATP was obtained, the conductivity of which was two orders of magnitude higher than that of binary lithium cobalt phosphate at room temperature.

Synthesis and Ionic Conductivity of Lithium-conducting Titanium Phosphate Solid Electrolytes

Solid electrolytes were synthesized in the systems Li2O-Al2O3-TiO2-P2O5 and Li2O-Al2O3-TiO2-P2O5-H2O-H2O2. Their ionic conductivities were studied and compared. The possibility of obtaining a film of Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte on a sapphire substrate from an aqueous peroxide solution of a precursor was analyzed.