Epitaxial stabilization of (110)-layered perovskites of the RE{sub 2}Ti{sub 2}O{sub 7} (RE=La, Nd, Sm, Gd) family

Journal Article · Wed Jul 15 00:00:00 EDT 2009 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2009.02.025· OSTI ID:21370457

Havelia, S; Wang, S; Balasubramaniam, K R ^[1]

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1. Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA 15213 (United States)

Thin films of RE{sub 2}Ti{sub 2}O{sub 7} (RE=La, Nd, Sm, Gd) were deposited on single crystal SrTiO{sub 3} (110) substrates at 900 deg. C using pulsed laser deposition. X-ray diffraction (XRD) results showed sharp (00k) peaks (in theta-2theta scans) with narrow rocking curves (omega-scan peak widths of 0.4-0.9{sup o}), indicating that all compositions adopted the (110)-layered perovskite structure. While this is the stable structure for RE=La and Nd, it is metastable for RE=Sm and Gd. The metastable compounds are formed directly through epitaxial stabilization at these high temperatures and are shown to be isostructural to monoclinic La{sub 2}Ti{sub 2}O{sub 7}. The a, b, and c lattice parameters decreased monotonically with decreasing size of the RE cation, while the monoclinic angle remained fairly constant. The epitaxial relationship between the (110)-layered RE{sub 2}Ti{sub 2}O{sub 7} films and the SrTiO{sub 3}(110) substrate was found by XRD and transmission electron microscopy to be {l_brace}001{r_brace}<010>{sub film}||{l_brace}110{r_brace}<11-bar0>{sub SrTiO{sub 3}}. The single-phase, metastable, epitaxial, 100 nm thick films maintained the layered perovskite structure even after annealing at 900 deg. C for two hours in 200 Torr of oxygen. - Graphical abstract: Epitaxial thin films of RE{sub 2}Ti{sub 2}O{sub 7} (RE=Gd, Sm, Nd, and La) were deposited on single crystal SrTiO{sub 3} (110) substrates using pulsed laser deposition (PLD). All compositions adopted the monoclinic (110)-layered perovskite structure, which is the stable phase for La{sub 2}Ti{sub 2}O{sub 7} and Nd{sub 2}Ti{sub 2}O{sub 7} but is metastable with respect to the pyrochlore phase for Sm{sub 2}Ti{sub 2}O{sub 7} and Gd{sub 2}Ti{sub 2}O{sub 7}.

• OSTI ID: 21370457
• Journal Information: Journal of Solid State Chemistry, Vol. 182, Issue 7; Other Information: DOI: 10.1016/j.jssc.2009.02.025; PII: S0022-4596(09)00067-X; Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANNEALING
ENERGY BEAM DEPOSITION
EPITAXY
GADOLINIUM COMPOUNDS
LANTHANUM COMPOUNDS
LASER RADIATION
MONOCLINIC LATTICES
MONOCRYSTALS
NEODYMIUM COMPOUNDS
NEUTRON DIFFRACTION
PEROVSKITE
PULSED IRRADIATION
SAMARIUM COMPOUNDS
STABILIZATION
STRONTIUM TITANATES
TEMPERATURE RANGE 1000-4000 K
THIN FILMS
TITANATES
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
ALKALINE EARTH METAL COMPOUNDS
COHERENT SCATTERING
CRYSTAL GROWTH METHODS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
DEPOSITION
DIFFRACTION
ELECTROMAGNETIC RADIATION
ELECTRON MICROSCOPY
FILMS
HEAT TREATMENTS
IRRADIATION
MICROSCOPY
MINERALS
OXIDE MINERALS
OXYGEN COMPOUNDS
PEROVSKITES
RADIATIONS
RARE EARTH COMPOUNDS
SCATTERING
STRONTIUM COMPOUNDS
SURFACE COATING
TEMPERATURE RANGE
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS