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.

钙钛矿型BaBiO_3具有BiO_6八面体倾斜的单斜结构，是具有Bi^<3+>和Bi^<5+>有序网络的CDW绝缘体，在低温下Tc与Tc之间存在关系。对Ba_<1-x>Rb_xBiO_3的研究发现，超导性更倾向于立方对称性和小的晶格参数。由于转移能量的增加，Bi 6s 轨道上的局域电子预计会进行循环，从而抑制 CDW 并过渡到金属。在高压下，BaBiO_3 的晶格参数预计会变小，如果晶体结构。 BaBiO_3在高压下会转变为立方体，预计会出现更高Tc的超导性，已测量了半导体在高达8 GPa的高压下的电阻率。 Ba_<1-x>K_xBiO_3 然而，它仍然保持半导体性，这是因为 BiO_6 八面体的倾斜角在高压下可能变大。电子掺杂的 Ba^<2+>_<0.6>Bi^<3+>。 _<0.4>BiO_3 是一种绝缘体，其原因之一可能是氧空位的存在。制备了不显示CDW的层状结构的Li插层铌氧化物作为参考材料，其Tc〜5K为Li_xRbSr_2Nb_3O_<10>和Li_xCsSr_2Nb_3O_<10。 > 已经找到了目前Nb氧化物中Tc值低于的原因。 Bi氧化物中的这一点尚不清楚。

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