Phase diagram of La2NiO4+δ (0 ≤ δ ≤ 0.18)
1993; Elsevier BV; Volume: 216; Issue: 1-2 Linguagem: Inglês
10.1016/0921-4534(93)90636-5
ISSN1873-2143
AutoresHiroyasu Tamura, Akihiko Hayashi, Yutaka Ueda,
Tópico(s)Advanced Condensed Matter Physics
ResumoLa2NiO4+δ was prepared with δ in the range of 0.00≤δ≤0.18. Oxygen stoichiometry, structure and phase transition were studied by TG-DTA and powder X-ray diffraction measurements. Five phases, i.e. orthorhombic Bmab (δ=0.00), pseudo-tetragonal (δ=0.02), orthorhombic (0.05<δ<0.09), tetragonal I4/mmm (0.1<δ<0.15) and orthorhombic Fmmm (δ≥0.15), appeared in the sequence of δ's with intervals of coexistence at room temperature. The orthorhombic phase (Fmmm) showed a first-order phase transition to a tetragonal phase (I4/mmm) with increasing transition temperatures from 320 K for δ=0.15 to 430 K for δ=0.18. A tentative phase diagram of La2NiO4+δ is also given.
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