Alexey Babich

В работе исследована кинетика кристаллизации тонких пленок материала Ge2Sb2 Te 5. Показано, что время кристаллизации, а значит, и время работы устройств на основе данного материала в значительной степени зависят от температуры, что открывает возможность оптимизации режимов работы устройств.

A promising method for increasing the efficiency of thermoelectric energy converters as alternative energy sources is nanostructuring of thermoelectric materials used to manufacture thermoelements. The widespread use of thermoelectric devices is hampered by their low efficiency, which is determined by the thermoelectric figure of merit ZT of thermoelectric materials. The paper investigates the stability of the properties of low-temperature nanostructured thermoelectric materials based on solid solutions of Bi₂Te_2.8Se_0.2 (0.16 wt % CdCl₂) of the n-type and Bi_0.5Sb_1.5Te₃ (2.2 wt % Te and 0.16 wt % TeI₄) of the p-type obtained as a result of grinding in a planetary ball mill and subsequent compaction by spark plasma sintering. Thermoelectric materials Bi₂Te_2.8Se_0.2 and Bi_0.5Sb_1.5Te₃ have high maximum values of thermoelectric figure of merit ZT, equal to 1.17 and 1.23, respectively. Thermal stability of the properties of Bi₂Te_2.8Se_0.2 and Bi_0.5Sb_1.5Te₃ materials was investigated using multiple measurements using differential scanning calorimetry and thermogravimetry. Thermoelectric and electrophysical characteristics of thermoelectric materials were obtained at temperatures up to 500 K. It was established that nanostructuring does not have a significant effect on the thermal stability of the studied low-temperature nanostructured thermoelectric materials.

Binary chalcogenides have found a wide range of applications due to the possibility of fast and reversible phase transitions, tunable band gap, and high charge carrier mobility. This paper presents the results of thermal and laser crystallization of InSe thin films deposited by vacuum thermal evaporation of synthesized material and covered with a protective SiO2 layer. The amorphous state of as-deposited InSe thin films was confirmed by Raman spectroscopy. Thermal and laser crystallization processes were studied using electrical resistivity measurements and optical microscopy respectively. The temperature and laser power ranges required for the crystallization of the InSe thin film were determined. The Raman spectroscopy showed that the degree of crystallinity of modified regions of InSe thin films can be tuned by varying the power of laser irradiation. Бинарные халькогенидные соединения нашли широкий спектр применения благодаря возможности быстрого и обратимого фазового перехода, перестраиваемой ширины запрещенной зоны, высокой подвижности носителей заряда. Рассматриваются результаты термической и лазерной кристаллизации тонких пленок InSe, сформированных методом вакуумно-термического испарения синтезированного материала и покрытых защитным слоем SiO2. Аморфное состояние тонких пленок InSe было подтверждено спектроскопией комбинационного рассеяния света. Процессы термической и лазерной кристаллизации были изучены путем измерения электрического сопротивления и с применением оптической микроскопии соответственно. Были получены диапазоны температур и мощностей лазерного воздействия, необходимые для кристаллизации тонкой пленки InSe. Результаты спектроскопии комбинационного рассеяния показали, что степень кристалличности тонких пленок InSe можно подстраивать, варьируя мощность лазерного излучения.

—The development of flexible thermoelectric generators (alternative energy sources) using screen-printing technology is a promising direction. To produce such generators, low-temperature thermoelectric materials of the Bi-Te-Se and Bi-Te-Sb systems are used. The properties of thick-film samples can be improved by introducing nanodispersed highly conductive copper-oxide powder CuO. However, the thermal stability of such materials has still not been studied. This work investigates the thermal properties and stability of thick films based on low-temperature thermoelectric-material of the systems Bi-Te-Se (n-type) and Bi-Te-Sb (p-type), doped by CuO. It is determined that thick-film samples containing 0.1% CuO additive have the best thermoelectric characteristics. It is shown that in the studied temperature range (from room temperature to 550 K) the samples are stable, there are no pronounced thermal effects and changes in the mass of the samples. In addition, repeated measurements do not lead to phase separation or other undesirable processes. It is established that thick films based on low-temperature thermoelectric materials of the Bi-Te-Se and Bi-Te-Sb systems, modified with copper-oxide additives, can be used for the manufacture of flexible thermoelectric devices.

A novel biologically active organic ligand L (N’-benzylidenepyrazine-2-carbohydrazonamide) and its three coordination compounds have been synthesized and structurally described. Their physicochemical and biological properties have been thoroughly studied. Cu(II), Zn(II), and Cd(II) complexes have been analyzed by F-AAS spectrometry and elemental analysis. The way of metal–ligand coordination was discussed based on FTIR spectroscopy and UV-VIS-NIR spectrophotometry. The thermal behavior of investigated compounds was studied in the temperature range 25–800 °C. All compounds are stable at room temperature. The complexes decompose in several stages. Magnetic studies revealed strong antiferromagnetic interaction. Their cytotoxic activity against A549 lung cancer cells have been studied with promising results. We have also investigated the biological effect of coating studied complexes with silver nanoparticles. The morphology of the surface was studied using SEM imaging.

In this work, thermoelectric properties of Ge ₂ Sb ₂ Te ₅ thin films obtained by magnetron sputtering were investigated. Deposition was carried out at room temperature, the thickness of the films was 500 nm. The resistivity, Seebeck coefficient and thermal conductivity of thin films were measured. The resistivity of as-deposited layers was about 3500 Ohm·cm and dropped sharply after annealing at a temperature of 260°C for 30 minutes, which is due to the phase transition of the material. The Seebeck coefficient for the as-deposited films was about 1000 μV/K, and the thermal conductivity was 0.16 W/(m·K). It has been established that the highest power factor of 0.13 mW/(m·K ² ) have Ge ₂ Sb ₂ Te ₅ thin films heat treated at 260°C.