Igor Burmistrov

Potassium polytitanate gas-sensor study by impedance spectroscopy

Nanocrystalline potassium polytitanates K2O·nTiO2·mH2O represent a new type of semiconducting compounds which are characterized by a high specific surface that makes them promising for use in gas sensors. In this work, we have studied potassium polytitanate mesoporous nanoparticle agglomerates placed over a SiO2/Si substrate equipped with multiple coplanar electrodes to measure the electrical response to various organic vapors, 1000xa0ppm of concentration, mixed with air by impedance spectrometry in range of the 10(-2)-10(6)xa0Hz. The recorded impedance data for each sensor segment are associated with RC components of an equivalent circuit which are applied to selectively recognize the test vapors exploiting a multisensor array approach.

The Potentiodynamic Bottom-up Growth of the Tin Oxide Nanostructured Layer for Gas-Analytical Multisensor Array Chips

We report a deposition of the tin oxide/hydroxide nanostructured layer by the potentiodynamic method from acidic nitrate solutions directly over the substrate, equipped with multiple strip electrodes which is employed as a gas-analytical multisensor array chip. The electrochemical synthesis is set to favor the growth of the tin oxide/hydroxide phase, while the appearance of metallic Sn is suppressed by cycling. The as-synthesized tin oxide/hydroxide layer is characterized by mesoporous morphology with grains, 250–300 nm diameter, which are further crystallized into fine SnO2 poly-nanocrystals following heating to 300 °C for 24 h just on the chip. The fabricated layer exhibits chemiresistive properties under exposure to organic vapors, which allows the generation of a multisensor vector signal capable of selectively distinguishing various vapors.

The effects of liquid-phase oxidation of multiwall carbon nanotubes on their surface characteristics

The development of new sorbents based on nanostructured carbon materials recently became a perspective field of research. Main topic of current study is to investigate the effect of different regimes of multiwall carbon nanotubes (MWCNT) surface modification process on their structural characteristics. MWCNT samples were treated with nitric acid at high temperature. Structural properties were studied using low temperature nitrogen adsorption and acid-base back titration methods. The study showed that diluted nitric acid does not affect MWCNT structure. Concentrated nitric acid treatment leads to formation of 2.8 carboxylic groups per 1 nm2 of the sample surface.

The room-temperature chemiresistive properties of potassium titanate whiskers versus organic vapors

The development of portable gas-sensing units implies a special care of their power efficiency, which is often approached by operation at room temperature. This issue primarily appeals to a choice of suitable materials whose functional properties are sensitive toward gas vapors at these conditions. While the gas sensitivity is nowadays advanced by employing the materials at nano-dimensional domain, the room temperature operation might be targeted via the application of layered solid-state electrolytes, like titanates. Here, we report gas-sensitive properties of potassium titanate whiskers, which are placed over a multielectrode chip by drop casting from suspension to yield a matrix mono-layer of varied density. The material synthesis conditions are straightforward both to get stable single-crystalline quasi-one-dimensional whiskers with a great extent of potassium replacement and to favor the increase of specific surface area of the structures. The whisker layer is found to be sensitive towards volatile organic compounds (ethanol, isopropanol, acetone) in the mixture with air at room temperature. The vapor identification is obtained via processing the vector signal generated by sensor array of the multielectrode chip with the help of pattern recognition algorithms.

Potassium layered polytitanates influence on low-pressure polyethylene properties in wide concentrations range

Thermoplastic composites based on low-pressure polyethylene and layered potassium titanates have been made in the work. We have shown the possibility to processing the composites into the products by injection molding at polytitanates content up to 50%wt. Technological properties of composites at low concentrations of filler are established. Layered potassium polytitanates influence on the mechanical and thermophysical properties of low-pressure polyethylene in a wide range of concentrations is investigated: from 1 to 50 %wt. Essential increase of complex of mechanical properties of polyethylene at introduction of small amounts of layered potassium polytitanates is shown. Due to the layered structure of the potassium polytitanates with particle size of about 500u2005nm in diameter and a thickness of less than 10u2005nm durability to shock loads increase comparable to the results of the introduction of fibrous potassium hexatitanates is reached.

A new gas-analytical device concept via implementation of impedance spectroscopy

Here we discuss the concept of new gas-analytical device based on a.c. driven chemiresistive semiconducting layer. We test the approach utilizing quasi-amorphous potassium polytitanates, K2O·nTiO2·mH2O, which are characterized by high specific surface. In this work, we placed the polytitanate layer over a set of electrodes at the multielectroded chip and measured its impedance under exposure to various gas mixtures. The obtained data allow one to make an equivalent circuit for these structures where the combination of each active/reactive component can be used for selective gas identification.