METASTABLE BEHAVIOR OF THE SUPERCONDUCTING PHASE IN THE BABI1-XPBXO3 SYSTEM
METASTABLE BEHAVIOR OF THE SUPERCONDUCTING PHASE IN THE BABI1-XPBXO3 SYSTEM
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DOI：
10.1103/physrevb.46.1144
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发表时间：
1992-07-01
影响因子：
3.7
通讯作者：
DABROWSKI, B
中科院分区：
文献类型：
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作者：
MARX, DT;RADAELLI, PG;DABROWSKI, B
用中子粉末衍射研究了BaBi_（1-x）Pb_xO_3系统的结构相。由于铅被取代在铋的位置上，室温结构是单斜的0.00小于或等于x小于或等于0.20，斜方的0.25小于或等于x小于或等于0.65，双相（斜方和四方）的0.70小于或等于x小于或等于0.80，和单斜的x = 1.0。在0.70小于或等于x小于或等于0.80的组成范围内观察到样品的超导电性。超导相为四方相。原位中子粉末衍射测量结果表明，在低于425 K的温度下，它是不稳定的。所有超导样品都由亚稳态四方相和半导体斜方晶系菱形相组成，因为四方相到斜方晶系的转变没有进行到完成。Ba 1-yKyBi 1-xPbxO 3样品的T（c）与组成区域（0.5小于或等于x + y小于等于0.9）中的总掺杂剂浓度x + y成反比，其中材料是金属的。
The structural phases of the BaBi1-xPbxO3 system have been studied using neutron powder diffraction. As lead is substituted on the bismuth site, the room-temperature structure is monoclinic for 0.00 less-than-or-equal-to x less-than-or-equal-to 0.20, orthorhombic for 0.25 less-than-or-equal-to x less-than-equal-to 0.65, diphasic (orthorhombic and tetragonal) for 0.70 less-than-or-equal-to x less-than-or-equal-to 0.80, and monoclinic for x = 1.0. Superconductivity is observed for samples in the composition range 0.70 less-than-or-equal-to x less-than-or-equal-to 0.80. The superconducting phase is the tetragonal phase. In situ neutron-powder-diffraction measurements versus temperature show that it is not stable at temperatures below about 425 K. All superconducting samples consist of the metastable tetragonal phase and a semiconducting orthorhombic rhombic phase because the tetragonal-to-orthorhombic transition does not proceed to completion. Samples of Ba1-yKyBi1-xPbxO3 have T(c)'s that are inversely proportional to the total dopant concentration, x + y, in the composition region (0.5 less-than-or-equal-to x + y less-than-equal-to 0.9), where the material is metallic.