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A comprehensive study of the crystal and electronic structures, thermodynamic, kinetic, energy, and magnetic properties of the Lu1−xVxNiSb semiconductor (x = 0÷0.10) has revealed the possibility for impurity V atoms to simultaneously occupy different crystallographic positions. At the same time, defects of the acceptor or donor nature are generated in the crystal structure of the Lu1−xVxNiSb solid solution, and the corresponding energy states appear in the band gap ϵg. The concentration ratio of donor-acceptor states determines the position of the Fermi level ϵF and the mechanisms of electrical conductivity of Lu1−xVxNiSb. The results of the modeling of thermodynamic and transport properties of the semiconductor are consistent with experimental data. Understanding the mechanism of energy state generation in the semiconductor Lu1−xVxNiSb allows the modeling and production of new thermoelectric materials with a high efficiency of converting the thermal energy into the electrical one., Комплексне дослiдження кристалiчної та електронної стру-ктур, термодинамiчних, кiнетичних, енергетичних та магнiтних властивостей напiвпровiдника Lu1−xVxNiSb, x = 0–0,10 встановило можливiсть домiшкових атомiв V одночасно займати рiзнi кристалографiчнi позицiї. При цьому у структурi Lu1−xVxNiSb генеруються дефекти акцепторної та донорної природи, а в забороненiй зонi ϵg з’являються вiдповiднi енергетичнi стани. Спiввiдношення концентрацiй донорно-акцепторних станiв визначає по-ложення рiвня Фермi ϵF та механiзми електропровiдностi Lu1−xVxNiSb. Результати моделювання властивостей напiвпровiдника узгоджуються з даними експериментальних дослiджень. Розумiння механiзму генерування енергетичних станiв у напiвпровiднику у Lu1−xVxNiSb дозволяє моделювати та отримувати новi термоелектричнi матерiали з високою ефективнiстю перетворення теплової енергiї в електричну.

The energy expediency of the existence of Er1-xScxNiSb substitutional solid solution up to the concentration x≈0.10 was established by modeling the variation of free energy ΔG(x) values (Helmholtz potential). At higher Sc concentrations, x> 0.10, there is stratification (spinoidal decomposition of phase). It is shown that in the structure of p-ErNiSb semiconductor there are vacancies in positions 4a and 4c of Er and Ni atoms, respectively, generating structural defects of acceptor nature. The number of vacancies in position 4a is twice less than in position 4c. This ratio also remains for p-Er1-xScxNiSb. Doping of p-ErNiSb semiconductor by Sc atoms by substitution of Er atoms is also accompanied by the occupation of vacancies in position 4a. In this case, Ni atoms occupy vacancies in position 4c, which can be accompanied by the process of ordering the p-Er1-xScxNiSb structure. Occupation of vacancies by Sc and Ni atoms leads to an increase of the concentration of free electrons, an enlarge of the compensation degree of semiconductor, which changes the position of the Fermi level εF and the mechanisms of electrical conductivity.

A comprehensive study of the crystal and electronic structures, thermodynamic, electrokinetic, energy, and magnetic properties of the semiconductive solid solution Lu1-xScxNiSb, x = 0 – 0.10, revealed the possibility of doping Sc atoms of different crystallographic sites depending on their concentration. This leads to the generation of structural defects of donor and/or acceptor nature and the appearance of the corresponding energy levels (bands) in the band gap єg. The ratio of ionized donors and acceptors (degree of compensation) determines the position of the Fermi level єF in Lu1-xScxNiSb. The dependence of the rate of generation of energy levels and the position of the Fermi level єF on the impurity concentration Sc, which determines the mechanism of electrical conductivity of Lu1-xScxNiSb, is established. The investigated Lu1-xScxNiSb solid solution is a promising thermoelectric material., Комплексне дослiдження кристалiчної та електронної структур, термодинамiчних, кiнетичних, енергетичних та магнiтних властивостей напiвпровiдникового твердого розчину Lu1-xScxNiSb, x = 0–0,10, виявило можливiсть зайняття легуючими атомами Sc рiзних кристалографiчних позицiй у залежностi вiд їхньої концентрацiї. Це приводить до генерування структурних дефектiв донорної i/або акцепторної природи та появи у забороненiй зонi єg вiдповiдних енергетичних рiвнiв (зон). Спiввiдношення iонiзованих донорiв та акцепторiв (ступiнь компенсацiї) визначає у Lu1-xScxNiSb положення рiвня Фермi єF. Встановлено залежнiсть швидкостi генерування енергетичних рiвнiв та положення рiвня Фермi єF вiд концентрацiї домiшки Sc, що визначає механiзм електропровiдностi Lu1-xScxNiSb. Дослiджений твердий розчин Lu1-xScxNiSb є перспективним термоелектричним матерiалом.

Samples of Er1-xScxNiSb (x = 0–0.10) solid solution were synthesized by an arc-melting and the effect of doping by Sc atoms on the electrokinetic and energetic characteristics of the half-Heusler ErNiSb phase was investigated. It was established that at the studied concentrations the main carriers of electricity in the Er1-xScxNiSb semiconductor are holes. It was shown that doping of p-ErNiSb compound by Sc atoms introduced by substitution of Er atoms in 4a position is accompanied by the occupation of presented vacancies in position 4a, which leads to the reduction and elimination of structural defects of acceptor nature and corresponding acceptor band. The concentration ratio of ionized acceptors and donors generated in Er1-xScxNiSb determines the position of the Fermi level and the mechanisms of electrical conduction. The investigated solid solution Er1-xScxNiSb is a promising thermoelectric material.

Automated The results of modeling performances of the semiconductor solid solution Er1-xScxNiSb are presented, which can be a promising thermometric material for the manufacture of sensitive elements of thermoelectric and electroresistive thermocouples. Fullprof Suite software was used to model the crystallographic characteristics of the Er1-xScxNiSb thermometric material. Modeling of the electronic structure of Er1-xScxNiSb was performed by Coring-Kon-Rostocker methods in the approximation of coherent potential and local density using the exchange-correlation potential Moruzzi-Janak-Williams and Linear Muffin-Tin Orbital in the framework of DFT density functional theory. The Brillouin zone was divided into 1000 k-points, which were used to model energetic performances by calculating DOS. The width of the energy window was 22 eV and was chosen to capture all semi-core states of p-elements. Full potential (FP) was used in the representation of the linear MT orbital in the representation of plane waves. The accuracy of calculating the position of the Fermi level was εF ± 6 meV. To verify the existence of a continuous solid solution, Er1-xScxNiSb substitution, the change in the values of the period of the unit cell a (x) was calculated within the framework of the DFT density functional theory in the range x = 0–1.0. It is presented that the calculated and experimentally obtained dependences of the period of the unit cell a(x) Er1-xScxNiSb are almost parallel, which confirms the correctness of the used tools and the obtained modeling results. To research the possibility of obtaining thermometric material Er1-xScxNiSb in the form of a continuous solid solution was performed modeling of thermodynamic calculations in the approximation of harmonic oscillations of atoms in the theory of DFT density functional for a hypothetical solid solution Er1-xScxNiSb, x = 0–1.0. It is shown that the change in the values of free energy ΔG(x) (Helmholtz potential) passes through the minimum at the concentration x≈0.1 for all temperatures of possible homogenizing annealing of the samples, indicating the solubility limit of Sc atoms in the structure of the ErNiSb compound. The presence of this minimum indicates that the substitution of Er atoms for Sc atoms in the ErNiSb compound is energetically advantageous only up to the concentration of impurity atoms Sc, x≈0.1. At higher concentrations of Sc atoms, x> 0.10, stratification occurs (spinoidal phase decay). It is shown that modeling of the mixing entropy behavior S even at a hypothetical temperature T = 4000 K shows the absence of complete solubility of Sc atoms in Er1-xScxNiSb. To model the energetic and kinetic performances of the semiconductor thermometric material Er1-xScxNiSb, particularly the behavior of the Fermi level F e , bandgap width g e the distribution of the density of electronic states (DOS) and the behavior of its electrical resistance ρ(x, T) is calculated for an ordered variant of the structure in which the Er atoms in position 4a are replaced by Sc atoms. It is shown that the ErNiSb compound is a semiconductor of the electronic conductivity type, in which the Fermi level is located near the level of the conduction band C e . The modeling showed that at higher concentrations of Sc atoms, the number of generated acceptors exceeds the concentration of uncontrolled donors, and the concentration of free holes exceeds the concentration of electrons. Under these conditions, the Fermi level F e approaches, and then the level of the valence band Er1- xScxNiSb crosses: the dielectric-metal conductivity transition occurs. The experiment should change the sign of the thermo-emf coefficient α(x, T) Er1-xScxNiSb from negative to positive, and the intersection of the Fermi level F e and the valence band changes the conductivity from activating to metallic: on the dependences ln(ρ(1/T)) the activation sites disappear, and the values of resistivity ρ increase with temperature.

The effect of doping of the TiCoSb compound (MgAgAs structure type) by Mo atoms on the features of the structural characteristics and behavior of the electrokinetic, energetic and magnetic properties of the Ti1-xMoxCoSb semiconducting solid solution (х = 0 - 0.06) in the temperature interval 80 - 400 K was studied. It was shown that including of Mo atoms (rМо= 0.140 nm) in the ToCoSb structure by substitution of Ti atoms (rТі= 0.146 нм) in 4a position is accompanied with non-monotonous variation of the lattice parameter values а(х), indicating unpredictable structural changes. Based on analysis of the variation of the electric resistivity values, thermopower coefficient, magnetic susceptibility and energetic characteristics, it was concluded that simultaneous generation in the crystal of the structural defects of the donor and acceptor nature (donor-acceptor pairs), which generate corresponding energy levels in the band gap of semiconductor and determine its electrical conductivity.

The samples of ZrNi1-хVxSn solid solution (x = 0–0.10) based on the ZrNiSn half-Heusler phase (MgAgAs structure type) were synthesized by direct arc-melting with homogenous annealing at 1073 K. The electrokinetic and energy state characteristics of the ZrNi1-хVxSn semiconducting solid solution were investigated in the temperature range T = 80–400 K. An analysis of behavior of the electrokinetic and energetic characteristics, in particular, the motion rate of the Fermi level, ΔεF/Δx for ZrNi1-xVxSn, allows to assume about the simultaneous generation of the structural defects of donor and acceptor nature in the crystal. The additional researches are required to establish the mechanisms of donor generation., Зразки твердого розчину ZrNi1-хVxSn (х=0–0.10) на основі напів-Гейслерової фази ZrNiSn (структурний тип MgAgAs) синтезовано методом електродугового плавлення з гомогенізувальним відпалюванням за температури 1073 К. Електрокінетичні та енергетичні характеристики напівпровідникового твердого розчину ZrNi1-хVxSn досліджено в інтервалі температур Т=80–400 К. На основі аналізу поведінки кінетичних та енергетичних характеристик, зокрема, швидкості руху рівня Фермі ΔεF/Δх ZrNi1-хVxSn, зроблено припущення про одночасне генерування у кристалі структурних дефектів акцепторної та донорної природи. Встановлення механізмів генерування донорів вимагає додаткових досліджень.

The peculiarities of electronic and crystal structures of Zr1-xVxNiSn (x = 0-0.10) semiconductive solid solution were investigated. To predict Fermi level εF behavior, band gap εg and electrokinetic characteristics of Zr1-xVxNiSn, the distribution of density of electronic states (DOS) was calculated. The mechanism of simultaneous generation of structural defects of donor and acceptor nature was determined based on the results of calculations of electronic structure and measurement of electrical properties of Zr1-xVxNiSn semiconductive solid solution. It was established that in the band gap of Zr1-xVxNiSn the energy states of the impurity donor and acceptor levels (donor-acceptor pairs) appear, which determine the mechanisms of conduction of semiconductor., Досліджено особливості електронної та кристалічної структур напівпровідникового твердого розчину Zr1-xVxNiSn (х=0–0.10). Для прогнозування поведінки рівня Фермі εF, ширини забороненої зони εg та кінетичних характеристик Zr1-xVxNiSn розраховано розподіл густини електронних станів (DOS). За результатами розрахунків електронної структури та вимірювання електротранспортних властивостей напівпровідникового твердого розчину Zr1-xVxNiSn визначено механізм одночасного генерування структурних дефектів донорної та акцепторної природи. Встановлено, що у забороненій зоні Zr1-хVxNiSn з’являються енергетичні стани домішкових донорної та акцепторної зон (донорно-акцепторні пари), які визначають механізми електропровідності напівпровідника.