Building up of concerted electronic material possessing hybridized conduction band

在这个项目中，我们试图设计和合成新的材料，其中导带的底部由s-带和d-带或s-带和f -带之间的杂化组成。这些材料在本项目中被称为“杂化导带材料”。对这些材料进行了能带结构的解析、电子掺杂和强磁场下新性质的寻找。通过在~ 673K氧化Sn^<II>_2M^V_2O_7 （MV=Nb, Ta）前驱体焦绿石型氧化物，成功合成了Sn^<IV>M^VO_<4+x>的新型亚稳氧化物，其中Sn^<IV>和M^V的阳离子排列顺序与前驱体焦绿石结构相似。在这些氧化物中，Sn 5s和Nb 4d或Ta 5d轨道的能量非常接近。利用XRD对这些氧化物的晶体结构进行了分析，并从晶体化学的角度提出了它们的转变机理。对于ce4f和Sn5s能量非常接近的SnTaO4+x和…More的CeSnO4，在稀氢气氛下退火诱导产生氧空位的电子掺杂是成功的。例如，我们成功地合成了杂化导带材料。在7T强磁场下，测定了SnTaO_<4+x>和CeSnO_4的电导率，以期发现其磁电阻等新特性。然而，不幸的是，我们没有发现。由此推断，在现有材料中，Sn 5s与Ta 5d或Sn 5s与Ce 4f的杂化不足。萤石型SnTaO_<4+x>的氧释放是在还原气氛下670K的极低温度下开始的，而α-PbO_2型SnTaO_<4+x>的氧释放是在820K的较高温度下开始的。这种特性适用于废气净化中的储氧材料。结果表明，本项目合成的杂化导带材料在化学性质上具有独特的性能。少

In this project, we have attempted to design and synthesize novel materials in which the bottom of the conduction band consists of hybridization between s- and d-bands or s- and f -bands. These materials are termed "hybridized conduction-band materials" in this project. The elucidation of the energy band structure, electron doping and searching of novel properties under strong magnetic field have been carried out for these materials.By oxidation of precursor pyrochlore-type oxide of Sn^<II>_2M^V_2O_7 (MV=Nb, Ta) at 〜673K, novel metastable oxides of Sn^<IV>M^VO_<4+x>, in which the cations of Sn^<IV> and M^V were respectively ordered similar manor observed in the precursor pyrochlore structure, were successfully synthesized. The energy of Sn 5s and Nb 4d or Ta 5d orbital was very close in these oxides. The crystal structure of these oxides was elucidated by Rietveld analysis using XRD, and the transformation mechanism has been proposed based on the crystal chemistry. For the SnTaO4+x and … More CeSnO4, in which the energy of Ce 4f and Sn5s are very close, the electron doping by generation of oxygen vacancies, which were induced by annealing the samples under diluted hydrogen atmosphere, became successful. For instance, we have succeeded to synthesize hybridized conduction-band materials. The electrical conductivity of the SnTaO_<4+x> and CeSnO_4 were measured under strong magnetic field of 7T on a quest to finding out of novel properties such as magnetoresistance. However, we could not find out unfortunately. It was inferred that the hybridization between Sn 5s and Ta 5d or Sn 5s and Ce 4f is insufficient in the present materials. The oxygen release from fluorite related SnTaO_<4+x> was started at very low temperature of 670K under reducing atmosphere, while the α-PbO_2 type SnTaO_<4+x> was start reducing at comparatively high temperature of 820K. Such a property is available for the oxygen storage material in exhaust gas cleaning. It was shown that the hybridized conduction band materials synthesized in the present project show distinctive properties in chemical property. Less