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型的材料，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”。通过前驱体焦绿石型氧化物Sn^&lt；II&Gt；_2m^V_2O_7(MV=Nb，Ta)在~673K的氧化，成功地合成了新型亚稳态氧化物Sn^&lt；IV&Gt；M^VO_&lt；4x&gt；其中，Sn^&lt；IV&GT；和M^V的阳离子在前驱体焦绿石结构中分别观察到了有序的类似的压痕。在这些氧化物中，Sn5s和Nb4d或Ta5d轨道的能量非常接近。用X射线衍射仪进行Rietveld分析，确定了这些氧化物的晶体结构，并从晶体化学的角度提出了它们的转化机理。对于SnTaO4x和…当CeSnO4中Ce4f和Sn5s的能量接近时，通过在稀氢气氛中热处理产生氧空位的方式实现了电子掺杂。例如，我们已经成功地合成了杂化导带材料。在7T强磁场下测量了SnTaO_4x&GT；和CeSnO_4的电导率，以寻找诸如磁阻等新的性质。然而，不幸的是，我们无法找到答案。推测在目前的材料中，Sn5s与Ta5d或Sn5s与Ce4f的杂交是不够的。在还原气氛下，与萤石有关的SnTaO_4 x&gt；在670K的很低温度下开始放氧，而α-PbO_2型SnTaO_4 x&gt；这种性质可用于废气净化中的储氧材料。结果表明，本课题合成的杂化导带材料具有独特的化学性质。较少

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