Oxygen intercalation, stage ordering, and phase separation in La[sub 2]NiO[sub 4+[delta]] with 0. 05[approx lt][delta][approx lt]0. 11

Journal Article · Thu Sep 01 00:00:00 EDT 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.50.6340· OSTI ID:7051561

Tranquada, J M; Kong, Y; Lorenzo, J E ^[1]; Buttrey, D J; Rice, D E; Sachan, V ^[2]

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1. Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)
2. Department of Chemical Engineering, University of Delaware, Newark, Delaware 19716 (United States)

We report neutron diffraction studies on a series of La[sub 2]NiO[sub 4+[delta]] single crystals with 0.05[approx lt][delta][approx lt]0.11. At 300 K, all of the crystals have an average tetragonal structure (space group [ital I]4/[ital mmm]). On cooling below 290 K, one or more orthorhombic phases appear, characterized by incommensurate superlattice peaks at (0,[ital k],[ital l][plus minus][Delta]) with [ital k] odd, [ital l] even, and 1/4[lt][Delta][le]1/2. The positions, widths, and intensities of the superlattice peaks are quite sensitive to the cooling rate. We show that the incommensurate peaks are evidence of intercalated layers of oxygen spaced periodically along the [ital c] axis, with a one-dimensional ordering similar to the staging of intercalates in graphite. The structure of the La[sub 2]NiO[sub 4] lattice between the interstitial layers is of the [ital Bmab]-type; the superlattice peaks result from the ordered antiphase domain boundaries induced by the interstitial oxygens, which sit at (1/4,[ital 1] / 4 , 1/4)-type positions. Observed orderings involve interstitial layers separated by two to four Ni-O layers. Peak shapes and positions are modelled quantitatively using the formulas of Hendricks and Teller for one-dimensional disorder in a layer lattice. Besides the one-dimensional ordering of the intercalant layers, temperature-dependent phase separations are observed. Because of the slow ordering kinetics, phase separation can be suppressed by rapid cooling.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 7051561
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 50:9; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
LANTHANUM OXIDES
PHASE STUDIES
NICKEL OXIDES
CRYSTAL-PHASE TRANSFORMATIONS
MONOCRYSTALS
NEUTRON SPECTROSCOPY
ORTHORHOMBIC LATTICES
SUPERLATTICES
TEMPERATURE DEPENDENCE
TETRAGONAL LATTICES
CHALCOGENIDES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
LANTHANUM COMPOUNDS
NICKEL COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
RARE EARTH COMPOUNDS
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies