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Building up of concerted electronic material possessing hybridized conduction band

具有杂化导带的协同电子材料的构建

基本信息

批准号：
15360346
负责人：
OMATA Takahisa
金额：
$ 9.86万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

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

在这个项目中，我们试图设计和合成新型材料，其中导带底部由s-和d-带或s-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”。通过对前驱体焦绿石型氧化物Sn ^2M^V_2O_7（MV = Nb，Ta）在673K下的氧化，成功地合成了新型亚稳氧化物Sn ^M^VO_（4 + x），其中Sn ^和M^V的阳离子分别具有与前驱体焦绿石结构相似的有序结构。<II><IV><IV>Sn的5s轨道能量与Nb的4d或Ta的5d轨道能量非常接近。利用Rietveld分析和XRD表征了这些氧化物的晶体结构，并从晶体化学的角度提出了转变机理。对于SnTaO 4 + x和 ...更多信息 CeSnO_4中Ce_（4f）和Sn_（5s）的能量非常接近，通过在稀氢气氛下退火诱导产生氧空位来实现电子掺杂。例如，我们已经成功地合成了杂化导带材料。在7T的强磁场下测量了SnTaO_（4 + x）和CeSnO_4的电导率，以探索其磁电阻等新特性。然而，我们很不幸地无法找到答案。推测在现有材料中Sn 5s和Ta 5d或Sn 5s和Ce 4f之间的杂化是不充分的。萤石型SnTaO_（4 + x）在670K的低温还原气氛下开始释氧，而α-PbO_2型SnTaO_（4 + x）在820K的高温还原气氛下开始释氧。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在化学性质上具有独特的性质。少