Neutron diffraction and Mossbauer spectroscopy studies of the mixed valent Tl-1212 ferrite (Tl0.5Pb0.5)Sr3Fe2O8

被引：2

作者：

Nguyen, N ^{[1
]}

Groult, D ^{[1
]}

Caignaert, V ^{[1
]}

Ducouret, A ^{[1
]}

Raveau, B ^{[1
]}

机构：

[1] ISMRA UNIV, LAB CRISMAT, URA CNRS 1318, F-14050 CAEN, FRANCE

来源：

PHYSICA B-CONDENSED MATTER | 1996年 / 228卷 / 3-4期

关键词：

neutron diffraction; Mossbauer spectroscopy; ferrite; mixed valent iron;

D O I：

10.1016/S0921-4526(96)00488-7

中图分类号：

O469 [凝聚态物理学];

学科分类号：

070205 ;

摘要：

The mixed valent 1212-ferrite (Tl0.5Pb0.5)Sr3Fe2O8 has been characterized using powder neutron diffraction data collected at 1.5 and 293 K. The structure is confirmed to be close to that of the Tl-1212 superconductor (Tl0.5Pb0.5)Sr2CaCu2O7 but with no deviation from a full occupancy of (Tl, Pb) and oxygen sites. Fe-57-Mossbauer spectroscopy data depend upon the temperature between 4.2 and 293 K. They have been explained on the basis of a mixture of trivalent and tetravalent iron states at 4.2 and 150 K. At temperature higher than 150 K the existence of intermediate iron states Fe-n+ (3 < n < 4) due to electron transfer between Fe3+ and Fe4+ sites has to be taken into account to fit the data. EFG calculations based upon neutron diffraction results at 293 K confirm that local displacements of the apical oxygen O (2) can be considered to explain the appearance of three Mossbauer iron sites instead of the structure expected one.

引用

页码：251 / 260

页数：10