Hydrogen catalyzed crystallization of strontium titanate

Journal Article · Thu Sep 01 00:00:00 EDT 1994 · Journal of Applied Physics; (United States)

DOI:https://doi.org/10.1063/1.357574· OSTI ID:7005156

Simpson, T W; Mitchell, I V ^[1]; McCallum, J C ^[2]; Boatner, L A ^[3]

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1. Department of Physics, University of Western Ontario, London, Ontario N6A 3K7 (Canada)
2. Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200 (Australia)
3. Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

The crystallization rate of amorphous strontium titanate is enhanced by more than an order of magnitude during thermal annealing in water vapor as compared to a dry ambient. Time resolved optical reflectivity (TRR) has been combined with Rutherford backscattering spectrometry (RBS) and ion channelling to investigate this effect. Thin amorphous films (0.6 [mu]m) were produced on single-crystal substrates of (100) strontium titanate by bombardment with 1.9 or 2.0 MeV Pb ions. Specimens were annealed under controlled ambient conditions (H[sub 2]O, D[sub 2]O, vacuum, 265--430 [degree]C) and the solid phase epitaxial crystallization monitored [ital in] [ital situ] by TRR (633 nm). The TRR data were calibrated [ital ex] [ital situ] by transmission electron microscopy and RBS measurements. Isotope substitution, nuclear reaction analysis, and secondary-ion-mass spectrometry were utilized to reveal the uptake of hydrogen and oxygen into the implanted layer. Hydrogen is identified as the only species which penetrates to the crystal/amorphous interface. It is shown that the crystallization rate is proportional to the concentration of diffusing hydrogen (H or D) at the interface. The data show that the effect of water vapor, or more precisely, hydrogen, is to reduce the activation energy of crystallization from 2.1 to 1.0 eV. It is concluded that hydrogen, provided by the dissociation of water molecules at the surface, is a catalyst in the crystallization of amorphous strontium titanate.

• OSTI ID: 7005156
• Journal Information: Journal of Applied Physics; (United States), Vol. 76:5; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
HYDROGEN
DIFFUSION
STRONTIUM TITANATES
CRYSTALLIZATION
AMORPHOUS STATE
ANNEALING
ION CHANNELING
LEAD IONS
NUCLEAR REACTION ANALYSIS
OPTICAL REFLECTION
PHYSICAL RADIATION EFFECTS
RUTHERFORD SCATTERING
THIN FILMS
ALKALINE EARTH METAL COMPOUNDS
CHANNELING
CHARGED PARTICLES
CHEMICAL ANALYSIS
ELASTIC SCATTERING
ELEMENTS
FILMS
HEAT TREATMENTS
IONS
NONMETALS
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
RADIATION EFFECTS
REFLECTION
SCATTERING
STRONTIUM COMPOUNDS
TITANATES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
360602* - Other Materials- Structure & Phase Studies
665300 - Interactions Between Beams & Condensed Matter- (1992-)