LOW-TEMPERATURE STRUCTURAL PHASE-TRANSITION IN LA2NIO4+DELTA

被引：40

作者：

BURNS, G

DACOL, FH

RICE, DE

BUTTREY, DJ

CRAWFORD, MK

机构：

[1] UNIV DELAWARE,DEPT CHEM ENGN,COLBURN LAB,NEWARK,DE 19716

[2] DUPONT CO,WILMINGTON,DE 19880

来源：

PHYSICAL REVIEW B | 1990年 / 42卷 / 16期

关键词：

D O I：

10.1103/PhysRevB.42.10777

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

La2NiO4+ (=0) has a high-temperature tetragonal (HTT) phase (T>680 K), a low-temperature orthorhombic (LTO) phase, and a low-temperature tetragonal (LTT) phase (T<70 K); that is, HTTLTOLTT). These phases are isomorphic to those of La2-xBaxCuO4 (x=0.12). Using Raman spectroscopy, we have measured the c-axis-polarized phonons. The 2A1g modes of the HTT phase occur in all three phases at 155 and 445 cm-1, with energies and widths only weakly dependent on temperature. The low-energy NiO6-octahedra tilting modes (which drive the phase transitions) have been observed and clearly show the first-order nature of the LTOLTT phase transition. The lowest-energy Raman mode observed (at 70 cm-1 with B1g symmetry), allowed only in the LTT phase, involves rocking motion of the undisplaced in-plane oxygen atoms. © 1990 The American Physical Society.

引用

页码：10777 / 10780

页数：4

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