Оттиски доступны непосредственно от издателя Фотокопирование разрешено только в соответствии с лицензией 2014 ИМФ (Институт металлофизики им. Г. В. Курдюмова НАН Украины) Напечатано в Украине.
Изучено влияние температуры подложки и среды отжига (вакуум или атмосфера азота) на формирования фазового состава и структуры нано-размерных плёнок CoSb x (30 нм) (1,8 х 4,2) с концентрацией Sb от 65 ат.% до 81 ат.%. Определено, что при осаждении на подложки при ком-натной температуре формируется рентгеноаморфное состояние. При дальнейшем нагреве после кристаллизации область существования фазы CoSb 3 расширяется (75-80 ат.% Sb) по сравнению с массивным состояни-ем (75 ат.% Sb). При увеличении температуры подложки до 200C обра-зуются плёнки Co-Sb в кристаллическом состоянии, и закономерности формирования фазового состава в них характеризуются последовательно-стью превращений, которая соответствует диаграмме фазового равнове-сия для массивного состояния системы Co-Sb. Установлено, что плёнки на основе CoSb 3 термически стабильны до 300C. Отжиг плёнок Co-Sb как в вакууме, так и в атмосфере азота при температурах выше 300C приводит к сублимации как избыточной сурьмы, так и сурьмы из кри-сталлической фазы CoSb 3 . Показано, что влияние среды отжига для плё-нок Co-Sb проявляется в более интенсивной сублимации сурьмы при от-жиге в вакууме. Установлено, что более интенсивный процесс сублима-
fabrication of nanosize filMs on the base of scUtterUdite cosb 3 for therMoelectric devicesThe work is concerned with ascertainment of the regularities for thermostimulated formation of the phase composition and structure of CoSb 3 -scutterudite-based films deposited by the vacuum condensation method as well as the effect of the nanoscale factor on their thermoelectric properties. The influence of the substrate temperature and physical-technological parameters of heat treatment (temperature, duration, en vi ronment) on the phase composition, structure, mechanical-stress level, and thermo electric properties of the CoSb x (30 nm) (1.8 ≤ х ≤ 4.2) (65-81 at.% Sb) films is stu died. As determined, the change in the substrate temperature during the deposition of nanoscale Co-Sb films in the concentration range of 65-81 at.% Sb allows regulating the structural state. During the deposition on substrates at a room tempe rature, an X-ray amorphous state with an extended region for existence of the CoSb 3 -type phase at 75-80 at.% Sb after crystallization and further heating is formed. When the substrate temperature increases up to 200 °C, a crystalline state forms, and regularities of phase composition formation in Co-Sb films are characterized by a sequence, which is analogous to the phase equilibrium diagram for the bulk state of the Co-Sb system with the CoSb 3 -type phase formation at ≈75 at.% Sb. As found, films based on CoSb 3 are thermally stable up to ≈300 °C. Thermal treatment of Co-Sb films with an Sb concentration of 65-81 at.%, both in vacuum and under nitrogen, at the temperatures above 300 °C, leads to the occurrence of phase trans formations and a change in the structure according to the schemes: CoSb 3 + Sb → CoSb 3 (at 300 °C), CoSb 3 → CoSb 3 + CoSb 2 (at 400-500 °C), CoSb 2 → → CoSb 2 + CoSb (at 500-600 °C) because Sb atoms get rise in an ability to sublimate from the X-ray amorphous or crystalline states and cobalt antimonides, CoSb 2 and CoSb 3 , if annealing temperature increases. As determined, the presence of the nanoscale factor (i.e., the single-phase crystalline structure of CoSb 3 scutterudite with an extended area of existence in the film form with increased structural imperfection due to the sublimation of antimony and reduction in the grain size) causes an increase in the thermoelectric efficiency coefficient of Co-Sb films in ≈8 times as compared to the bulk material. This has a practical importance when these materials Yu.M. Makogon, S.I. Sidorenko, аnd R.A. Shkarban are used for providing the autonomous power supply for low-power electronic devices and creating film coolers in the elemental base of the nanoscale range for computer equipment and infrared sensors.Energy saving is an important component for the economic development of countries. Most of the electric power is produced via the thermal machines with a low efficiency factor (less than 40%). That is more than half of the energy dissipates as a heat for nothing. That is why the thermoelectricity based on the Seebeck (direct con...
It is investigated the formation of the phase composition and structure in the nanoscaled CoSb x (30 nm) (1.82 ≤ x ≤ 4.16) films deposited by the method of molecularbeam epitaxy on the substrates of the oxidated monocrystalline silicon at 200°C and following thermal treatment in vacuum in temperature range of 300-700°C. It is established that the films after the deposition are polycrystalline without texture. With increase in Sb content the formation of the phase composition in the films takes place in such sequence as this is provided by phase diagram for the bulky state of the Co-Sb system. At annealing in vacuum at temperature above 450-500°C a sublimation not only of the crystalline Sb phase but from the antimonides occurs. This is reflected on the phase composition change by following chemical reactions: CoSb 2 →(600 ∘ C) Sb↑= CoSb, CoSb 3 →(600 ∘ C) Sb↑=CoSb 2 ,CoSb 3 +Sb↑→(600 ∘ C) CoSb 3 and leads to increase in amount of the CoSb and CoSb 2 phases and decrease in amount of the CoSb 3 . CoSb x (30 nm) (1.8 < x < 4.16) films under investigation are thermostable up to ~350°C.
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