Chemistry Department, Lomonosov Moscow State University, Leniskie Gory, 1-3, Moscow 119991, Russia.
Chemistry. 2010 Nov 8;16(42):12582-9. doi: 10.1002/chem.201001990.
The creation of thermoelectric materials for waste heat recovery and direct solar energy conversion is a challenge that forces the development of compounds that combine appreciable thermoelectric figure-of-merit with high thermal and chemical stability. Here we propose a new candidate for high-temperature thermoelectric materials, the type-III Si(172-x)P(x)Te(y) cationic clathrate, in which the framework is composed of partially ordered silicon and phosphorus atoms, whereas tellurium atoms occupy guest positions. We show that the utmost stability of this clathrate (up to 1500 K) in air is ensured by the formation of a nanosized layer of phosphorus-doped silica on the surface, which prevents further oxidation and degradation. As-cast (non-optimized) Si-P-Te clathrates display rather high values of the thermoelectric figure-of-merit (ZT=0.24-0.36) in the temperature range of 700-1100 K. These ZT values are comparable to the best values achieved for the properly doped transition-metal-oxide materials. The methods of the thermoelectric efficiency optimization are discussed.
用于废热回收和直接太阳能转换的热电材料的开发是一项挑战，它促使人们开发出兼具可观的热电优值和高热化学稳定性的化合物。在这里，我们提出了一种新型高温热电材料候选物——III 型 Si(172-x)P(x)Te(y) 阳离子笼合物，其框架由部分有序的硅和磷原子组成，而碲原子占据客体位置。我们表明，这种笼合物（高达 1500 K）在空气中的最大稳定性是通过在表面形成一层纳米尺寸的磷掺杂氧化硅来保证的，这防止了进一步的氧化和降解。铸造（非优化）的 Si-P-Te 笼合物在 700-1100 K 的温度范围内表现出相当高的热电优值（ZT=0.24-0.36）。这些 ZT 值与适当掺杂的过渡金属氧化物材料所达到的最佳值相当。还讨论了热电效率优化的方法。
