Electrical Resistivity Peculiarities of the Nanograined Bi2Te3 Material

The hot quasiisostaic pressure method was applied to sinter the nanograined Bi2Te3 material. The samples with various mean grain size of 64, 61, 56 and 51 nm were prepared by changing the pressure of sintering. It was found that the specific electrical resistivity of the material under study increases when the mean grain size decreases. The Hall effect was measured to extract the concentration and mobility values of the charge carries. It was found that the electron concentration decreases as the mean grain size decreases while the electron mobility has extreme dependence on the grain size

Characterization of Bulk Nanostructural Bi2Te3-based Material Prepared by Microwave-solvothermal Synthesis and Hot Isostatic Pressure

The bulk nanostructural Bi2Te3-based material was prepared by microwave assisted solvothermal method and hot isostatic pressure. Optimal synthesis conditions of the Bi2Te3 nanopowder were found. It was established that hot isostatic pressing of the nanopowders at the temperature of 400 С and the pres-sures of 2, 4, 6 and 8 GPa allowed us to prepare the homogeneous and dense Bi2Te3-based material with the mean grain size of~50 nm. It is found that an electrical resistivity increases as the mean grain size of the material under study decreases. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3638

Linear Positive Magnetoresistivity of the Bi1.9Lu0.1Te3 Alloy with Inhomogeneous Micrograined Structure

Positive nonsaturating transverse magnetoresistivity (MR) has been observed below room temperature in the Bi1.9Lu0.1Te3 alloy with inhomogeneous micrograined structure. A crossover from parabolic MR ~ B2 dependence in low magnetic fields to linear MR ~ B dependence in high fields was found in the magnetoresistivity curves. The crossover field is shifted to lower magnetic fields as temperature decreases. Within the temperature range of “metal” type of conductivity, the temperature dependences of the specific electrical resistivity and MR magnitude are determined by the temperature dependence of the carrier mobility due to acoustic phonon scattering. Linear MR can be associated with microstructural inhomogeneity leading to strong electrical disorder of the Bi1.9Lu0.1Te3

Electrical Resistivity Peculiarities of the Nanograined Bi2Te3 Material

The hot quasiisostaic pressure method was applied to sinter the nanograined Bi2Te3 material. The samples with various mean grain size of 64, 61, 56 and 51 nm were prepared by changing the pressure of sintering. It was found that the specific electrical resistivity of the material under study increases when the mean grain size decreases. The Hall effect was measured to extract the concentration and mobility values of the charge carries. It was found that the electron concentration decreases as the mean grain size decreases while the electron mobility has extreme dependence on the grain size

Hopping Conductivity and Negative Magnetoresistance of the Bulk Nanograined Bi2Te3 Material

The bulk nanograined Bi2Te3 material was prepared by the microwave assisted solvothermal method and cold isostatic pressure method. It was found that above T* ≈ 190 K the temperature dependence of the specific electrical resistivity of material is of metallic type, while below this temperature a semiconductor conductivity takes place. Within the temperature ΔT ≈ 90 K-35 K interval the electrical conductivity of material can be described by the variable-range hopping conductivity mechanism. Negative magnetoresistance was observed at the same temperature interval

Plasma focus installation as a tool for the study of the interaction of high power plasma streams with condensed matter

In this work the possibilities of the use of the high-current discharges of Plasma Focus type for the investigation of the effect of plasma on the materials are discussed. From this point of view the properties of plasma streams and ion beams arising in the PF discharges are studied. Here, as an example of an application of the Plasma Focus device (PF), we studied the influence on Vanadium (perspective material in nuclear power engineering) a cumulative streams producing in the P

Unconventional ferromagnetism and transport properties of (In,Mn)Sb dilute magnetic semiconductor

Narrow-gap higher mobility semiconducting alloys In_{1-x}Mn_{x}Sb were synthesized in polycrystalline form and their magnetic and transport properties have been investigated. Ferromagnetic response in In_{0.98}Mn_{0.02}Sb was detected by the observation of clear hysteresis loops up to room temperature in direct magnetization measurements. An unconventional (reentrant) magnetization versus temperature behavior has been found. We explained the observed peculiarities within the frameworks of recent models which suggest that a strong temperature dependence of the carrier density is a crucial parameter determining carrier-mediated ferromagnetism of (III,Mn)V semiconductors. The correlation between magnetic states and transport properties of the sample has been discussed. The contact spectroscopy method is used to investigate a band structure of (InMn)Sb near the Fermi level. Measurements of the degree of charge current spin polarization have been carried out using the point contact Andreev reflection (AR) spectroscopy. The AR data are analyzed by introducing a quasiparticle spectrum broadening, which is likely to be related to magnetic scattering in the contact. The AR spectroscopy data argued that at low temperature the sample is decomposed on metallic ferromagnetic clusters with relatively high spin polarization of charge carriers (up to 65% at 4.2K) within a cluster.Comment: 19 pages, 9 figures, 1 tabl

A multi-country test of brief reappraisal interventions on emotions during the COVID-19 pandemic

The COVID-19 pandemic has increased negative emotions and decreased positive emotions globally. Left unchecked, these emotional changes might have a wide array of adverse impacts. To reduce negative emotions and increase positive emotions, we tested the effectiveness of reappraisal, an emotion-regulation strategy that modifies how one thinks about a situation. Participants from 87 countries and regions (n = 21,644) were randomly assigned to one of two brief reappraisal interventions (reconstrual or repurposing) or one of two control conditions (active or passive). Results revealed that both reappraisal interventions (vesus both control conditions) consistently reduced negative emotions and increased positive emotions across different measures. Reconstrual and repurposing interventions had similar effects. Importantly, planned exploratory analyses indicated that reappraisal interventions did not reduce intentions to practice preventive health behaviours. The findings demonstrate the viability of creating scalable, low-cost interventions for use around the world

Туннельная проводимость сверхпроводящего индия в пористом стекле

Електричний опір індію індію в пористому склі з розміром пор 7 нм було вивчено в інтервалі температур 2,3-300 K. Виявлено, що досліджуваний матеріал зазнає перехід в надпровідний стан при температурі TC = 3,9 K. Різкий асиметричний пік на кривій R(T) виявлений при температурі 6,4 K. Вперше R(T) залежність проаналізована для нормальної фази. Встановлено, що в інтервалі температур 15-80 K температурна залежність опору описується механізмом тунелювання носіїв заряду в рамках моделі Шенга. Досліджуваний матеріал можна розглядати як електрично неоднорідний матеріал, в якому металеві області в порах контактують між собою за допомогою діелектричних містком матриці зі скла. Перенесення заряду між металевими областями відбувається за допомогою тунелювання електронів через потенційні бар'єри, відповідні діелектричним містках.Электрическое сопротивление индия индия в пористом стекле с размером пор 7 нм было изучено в интервале температур 2,3-300 K. Обнаружено, что исследуемый материал претерпевает переход в сверхпроводящее состояние при температуре TC = 3,9 K. Резкий ассиметричный пик на кривой R(T) обнаружен при температуре 6,4 K. Впервые R(T) зависимость проанализирована для нормальной фазы. Установлено, что в интервале температур 15-80 K температурная зависимость сопротивления описывается механизмом туннелирования носителей заряда в рамках модели Шенга. Исследуемый материал можно рассматривать как электрически неоднородный материал, в котором металлические области в порах контактируют между собой посредством диэлектрических мостиков матрицы из стекла. Перенос заряда между металлическими областями происходит посредством туннелирования электронов через потенциальные барьеры, соответствующие диэлектрическим мостикам.Electrical resistance of indium in 7 nm-pore glass has been studied in the temperature 2.3-300 K interval. It was found that material under study undergoes the transition into the superconducting state at TC = 3.9 K. A sharp asymmetric R(T) maximum was found at temperature of 6.4 K. The R(T) dependence has been for the first time analyzed for the normal phase. It was found that the temperature dependence of the resistance in the temperature 15-80 K interval can be described by tunnelling mechanism of the charge carriers in the frames of the Sheng’s model. Material under study can be considered as electrically inhomogeneous material in which metallic domains in pores are contacting each other via dielectric bridges of glass matrix. A charge transfer between the metallic domains can be realized by the electron tunneling through the potential barriers corresponding to the dielectric bridges