Charge Ordering, Superconductivity and Dimensionality in Perovskite-type Bismuth Oxides

钙钛矿型氧化铋的电荷有序性、超导性和维度

• 批准号: 12640332
• 负责人: KOIKE Yoji
• 金额: $ 2.56万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12640332/
• 关键词: Bismuth Oxide; Superconductivity; Charge Ordering Dimensionality; Crystal Structure; Substitution Carrier; 置換; キャリア; ペロブスカイト; 粉末X線回折; 磁化率

Perovskite-type BaBiO_3 has a monoclinic structure with a tilt of the BiO_6octahedra. It is a CDW insulator with an ordered network of Bi^<3+>and Bi^<5+>. The relation between Tc and the structure at low temperatures has been investigated for Ba_<1-x>Rb_xBiO_3. It has been found that the appearance of superconductivity prefers a cubic symmetry and small lattice parameters. The localized electrons in Bi 6s orbit are expected to itinerate due to the gain of transfer energy, which leads to the suppression of CDW and the transition to metal.Under high pressures, the lattice parameters of BaBiO_3 are expected to become small. If the crystal structure of BaBiO_3 will transform to cubic under high pressures, the appearance of superconductivity with higher Tc is expected. The electrical resistivity under high pressures up to 8 GPa has been measured for semiconductive Ba_<1-x>K_xBiO_3. However, it still remains semiconductive. This is because the tilt angle of BiO_6 octahedra may become large under high pressures.Electron-doped Ba^<2+>_<0.6>Bi^<3+>_<0.4>BiO_3 has been prepared. However, this sample is an insulator. One of the reasons of non-superconductivity may be the existence of oxygen vacancies. Another may be the existence of the CDW in a short range.Li-intercalated Nb oxides with the layered structure, which does not show the CDW, have been prepared as referential material. New superconductors with Tc〜5K of Li_xRbSr_2Nb_3O_<10> and Li_xCsSr_2Nb_3O_<10> have been found. The reason why the value of Tc in the present Nb oxides is lower than that in Bi oxides is not clear yet.

Perovskite型BABIO_3具有单斜结构，并带有bio_6octahedra的倾斜。它是一个CDW绝缘子，具有BI^<3+>和BI^<5+>的有序网络。已经研究了BA_ <1-x> rb_xbio_3的低温下TC与结构之间的关系。已经发现，超导性的出现更喜欢立方对称性和小晶格参数。由于传递能量的增益，预计BI 6S轨道中的局部电子被预期会导致CDW的抑制，并过渡到金属。在高压下，Babio_3的晶格参数预计将变得很小。如果BABIO_3的晶体结构将在高压下转变为立方体，则预期具有更高TC的超导性。对于半导体BA_ <1-x> k_xbio_3，测量了高压高压下的电力抗性。但是，它仍然是半导体的。这是因为在高压下，bio_6的倾斜角可能变大。但是，该样品是一个绝缘子。非责任性的原因之一可能是氧空位的存在。另一个可能是CDW在短范围内的存在。与没有显示CDW的分层结构的LI嵌入NB氧化物已作为参考材料制备。已经找到了带有li_xrbsr_2nb_3o_ <10>和li_xcssr_2nb_3o_ <10>的新的超导体。目前NB氧化物中TC的值低于BI氧化物中TC的值尚不清楚。

项目成果

I.Nagai, Y.Abe, M.Kato, Y.Koike, M.Kakihana: "Electrochemical Intercalation of Lithium in Layered Niobates AB_2Nb_3O_<10> (A : alkaline metal, B : alkaline earth metal) and Their Superconductivity"Physica C. 357-360. 393-396 (2001)

I.Nagai、Y.Abe、M.Kato、Y.Koike、M.Kakihana：“锂在层状铌酸盐 AB_2Nb_3O_<10> 中的电化学插层（A：碱金属，B：碱土金属）及其超导性”Physica C

I.NagaiM.Kato, Y.Koike, M.Kakihana: "Synthessis and superconducting properties of Li-intercalated niboum oxide Li_xAB_2Nb_3O_<10>(A : alkaline metal, B : alkaline earth metal) by electrochemical tecnique"Solid State Ionics. (in press).

I.NagaiM.Kato、Y.Koike、M.Kakihana：“通过电化学技术合成嵌锂铌氧化物 Li_xAB_2Nb_3O_<10>（A：碱金属，B：碱土金属）及其超导性能”固态离子学。

Y. Abe, M. Kato and Y. Koike: "Li-Intercalation into the Bi-Based Oxychlorides with the Layered Structures"Advances in superconductivity XII. 134-136 (2000)

Y. Abe、M. Kato 和 Y. Koike：“锂嵌入具有层状结构的双基氯氧化物中”超导性的进展 XII。

Y.Abe, M.Kato, Y.koike: "Li-Intercalation into the Bi-Based Oxychorides with the Layered Structures"Advances in Superconductivity. XII. 134-136 (2000)

Y.Abe、M.Kato、Y.koike：“锂嵌入具有层状结构的双基氯氧化物中”超导性的进展。

I.Nagai, Y.Abe, M.Kato, Y.Koike, M.Kakihana: "Electrochemical Intercalation of Lithium in Layered Niobates AB_2Nb_3O_<10>(A : alkaline metal, B : alkaline earth metal) and Their Superconductivity"Physica C. 357-360. 393-396 (2001)

I.Nagai、Y.Abe、M.Kato、Y.Koike、M.Kakihana：“锂在层状铌酸盐 AB_2Nb_3O_<10>（A：碱金属，B：碱土金属）中的电化学插层及其超导性”Physica C