ISSN:
1572-9605
Keywords:
La2NiO4+δ
;
La2CuO4+δ
;
structural phase transition
;
phase diagram
;
orthorhombicity
;
X-ray powder diffraction
Source:
Springer Online Journal Archives 1860-2000
Topics:
Electrical Engineering, Measurement and Control Technology
,
Physics
Notes:
Abstract The phase diagram of La2MO4+δ (M=Ni, Cu) and the temperature dependence of orthorhombicity for several orthorhombic phases were investigated byin situ X-ray powder diffraction. A successive phase transition, tetragonalI4/mmm-[second-order] → orthorhombicBmab-[ first-order] → orthorhombicPccn, was observed in La2NiO4.00. The orthorhombicity of thePccn phase decreases on cooling in contrast to that of theBmab phase. The orthorhombic La2NiO4.15 (Fmmm) shows a weak temperature dependence of orthorhombicity and exhibits a first-order phase transition to the tetragonalI4/mmm phase on heating. As judged from the temperature dependence of orthorhombicity, superconducting La2CuO4.07, which results from the phase separation in the high-pressure oxygenated sample, isBmab, while La2CuO4.07 prepared by electrochemical oxidation at room temperature isFmmm.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00730369
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