Low-temperature structural phase transition in La sub 2 NiO sub 4+. delta
Journal Article
·
· Physical Review, B: Condensed Matter; (USA)
- IBM Research Division, Thomas J. Watson Research Center, Yorktown Heights, NY (USA)
- Department of Chemical Engineering, Colburn Laboratory, University of Delaware, Newark, DE (USA)
- E.I. du Pont de Nemours and Company, Wilmington, DE (USA)
La{sub 2}NiO{sub 4+{delta}} ({delta}=0) has a high-temperature tetragonal (HTT) phase ({ital T}{gt}680 K), a low-temperature orthorhombic (LTO) phase, and a low-temperature tetragonal (LTT) phase ({ital T}{lt}70 K); that is, HTT{r arrow}LTO{r arrow}(LTT). These phases are isomorphic to those of La{sub 2{minus}{ital x}}Ba{sub {ital x}}CuO{sub 4} ({ital x}=0.12). Using Raman spectroscopy, we have measured the {ital c}-axis-polarized phonons. The {sup 2}{ital A}{sub 1{ital g}} modes of the HTT phase occur in all three phases at 155 and 445 cm{sup {minus}1}, with energies and widths only weakly dependent on temperature. The low-energy NiO{sub 6}-octahedra tilting modes (which drive the phase transitions) have been observed and clearly show the first-order nature of the LTO{r arrow}LTT phase transition. The lowest-energy Raman mode observed (at 70 cm{sup {minus}1} with {ital B}{sub 1{ital g}} symmetry), allowed only in the LTT phase, involves rocking motion of the undisplaced in-plane oxygen atoms.
- OSTI ID:
- 5854908
- Journal Information:
- Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 42:16; ISSN 0163-1829; ISSN PRBMD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
CHALCOGENIDES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
CRYSTALS
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
LOW TEMPERATURE
MONOCRYSTALS
NICKEL COMPOUNDS
NICKEL OXIDES
ORTHORHOMBIC LATTICES
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHONONS
POLARIZATION
QUASI PARTICLES
RAMAN SPECTRA
RARE EARTH COMPOUNDS
SPECTRA
TETRAGONAL LATTICES
TRANSITION ELEMENT COMPOUNDS
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
CHALCOGENIDES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
CRYSTALS
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
LOW TEMPERATURE
MONOCRYSTALS
NICKEL COMPOUNDS
NICKEL OXIDES
ORTHORHOMBIC LATTICES
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHONONS
POLARIZATION
QUASI PARTICLES
RAMAN SPECTRA
RARE EARTH COMPOUNDS
SPECTRA
TETRAGONAL LATTICES
TRANSITION ELEMENT COMPOUNDS