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对云南产铁-镁电气石单晶进行了定向切片和加热处理,测定了加热处理前后电气石的热释电系数和铁的价态变化,研究了铁-镁电气石结构中铁价态变化对其热释电性能的影响。结果表明,850℃热处理48 h,电气石中Fe2+已经基本被氧化,电气石热释电系数由6.4μC m-2K-1提高到8.0μC m-2K-1;850℃热处理72 h,电气石FeO含量只继续降低了0.02%,但热释电系数进一步提高至8.9μC m-2K-1。热处理提高铁-镁电气石热释电系数的主要原因是Fe2+的氧化,其次是Fe3+占位的变化。推测热处理前期以Y八面体中Fe2+的氧化为主,后期以Y八面体中的Fe3+转移至Z八面体为主。
The single crystal of iron-magnesium tourmaline in Yunnan was sliced and heat-treated. The pyrolytic coefficient and the valence state of the tourmaline before and after heat treatment were measured. The change of iron valence in the iron-magnesium tourmaline structure Its pyroelectric properties. The results show that Fe2 + in tourmaline has been basically oxidized and the pyroelectric coefficient of tourmaline increased from 6.4μC m-2K-1 to 8.0μC m-2K-1 after heat treatment at 850 ℃ for 48 h. After heat treatment at 850 ℃ for 72 h, tourmaline FeO content only continued to decrease 0.02%, but the pyroelectric coefficient further increased to 8.9μC m-2K-1. The main reason for improving the pyroelectric coefficient of Fe-Mg tourmaline by heat treatment is the oxidation of Fe2 +, followed by the change of Fe3 + occupancy. It is presumed that the oxidation of Fe2 + in Y octahedron is predominant in the early stage of heat treatment, and that of Fe3 + in Y octahedron in late stage is mainly dominated by Z octahedron.