Clathrate and its preparation method and application
A technology of clathrates and reaction raw materials, applied in the field of clathrates and their preparation, can solve the problems of many boundaries, reduced carrier mobility, difficult to improve the ZT value of materials, etc., and achieves large single crystal size and excellent thermoelectric performance. , the effect of high thermoelectric figure of merit
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[0040] As a possible implementation, the preparation method of the present invention includes the following steps:
[0041] S100: According to Ba 8 Cu x Ge 46-x The stoichiometric ratio of each component in (0.5≤x≤6) is the reaction raw material containing Ba element, Cu element and Ge element.
[0042] The reaction raw materials weighed in this step can be Ba, Cu, Ge elementary substances, or Ba 6 Ge 25 The compound and the simple substance of Cu and Ge.
[0043] S200: Put the weighed reaction raw materials into the crucible, and add flux.
[0044] Preferably, the crucible is a quartz tube coated with carbon or a quartz tube without carbon coating.
[0045] The function of the flux is to reduce the melting temperature of the reaction raw materials and promote the progress of the reaction. Preferably, the melting point of the flux selected in the present invention is lower than the melting point of the lowest melting point component in the reaction raw material. Preferably, the presen...
Embodiment 1
[0072] (1) The bulk Ba element, Cu element and Ge element are weighed in a molar ratio of 8:0.5:45.5. At the same time, the granular flux Sn is weighed according to the molar ratio of Ba element to 1:1 Proportional weighing;
[0073] (2) Put the weighed Ba element, Cu element, Ge element and flux Sn into a quartz tube without carbon plating;
[0074] (3) Vacuum the quartz tube in step (2) (the vacuum degree is 10 -3 below torr), and use an oxyacetylene flame to seal the evacuated quartz tube;
[0075] (4) Put the sealed quartz tube in a high-temperature furnace, heat up to 1200°C at a rate of 5°C / min, and keep it for 12h; then cool down to 900°C at a rate of 5°C / h; Cooling rate to 700℃ to get Ba 8 Cu 0.5 Ge 45.5 Mixture of single crystal clathrate and flux Sn;
[0076] (5) Take out the quartz tube at 700°C, and separate the crystal and flux in the quartz tube with a centrifuge.
[0077] (6) Naturally cool the quartz tube to room temperature, break the quartz tube to obtain Ba with a s...
Embodiment 2
[0079] (1) The bulk Ba element, Cu element and Ge element are weighed at a molar ratio of 8:3:43. At the same time, the granular flux Sn is weighed at a molar ratio of 3:1 to Ba element. Proportional weighing;
[0080] (2) Put the weighed Ba element, Cu element, Ge element and flux Sn into a quartz tube without carbon plating;
[0081] (3) Vacuum the quartz tube in step (2) (the vacuum degree is 10 -3 below torr), and use an oxyacetylene flame to seal the evacuated quartz tube;
[0082] (4) Put the sealed quartz tube in a high-temperature furnace, heat it up to 1100°C at a rate of 5°C / min, and keep it warm for 24h; then reduce the temperature to 850°C at a rate of 10°C / h; Cooling rate to 600℃; get Ba 8 Cu 3 Ge 43 Mixture of single crystal clathrate and flux Sn;
[0083] (5) Take out the quartz tube at 600°C, and use a centrifuge to separate the crystals and flux in the quartz tube.
[0084] (6) Naturally cool the quartz tube to room temperature, break the quartz tube to obtain Ba with...
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