skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Structure stability of epitaxial MgO-CaO solid-solution films: effect of diffusion

Abstract

The nonequilibrium epitaxial growth process of Mg{sub x}Ca{sub 1-x}O solid-solution films at 600 degree sign C is carefully investigated. No obvious phase separation is observed until annealing at 800 degree sign C despite a large miscibility gap. The solid-solution film is featured with disorder alloy as confirmed by transmission electron microscopy (TEM). Spinodal decomposition caused by uprising diffusion happens after short-time annealing which explicitly indicates the structure stability of the metastable solid-solution films does result from diffusion quenching.

Authors:
; ; ; ; ;  [1];  [2];  [2]
  1. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)
  2. (China)
Publication Date:
OSTI Identifier:
20982905
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 10; Other Information: DOI: 10.1063/1.2732411; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANNEALING; CALCIUM OXIDES; CRYSTAL GROWTH; DECOMPOSITION; DIELECTRIC MATERIALS; DIFFUSION; LAYERS; MAGNESIUM OXIDES; MOLECULAR BEAM EPITAXY; PLASMA; SOLID SOLUTIONS; SOLUBILITY; THIN FILMS; TRANSMISSION ELECTRON MICROSCOPY

Citation Formats

Li, H. D., Zhang, X. N., Zhang, Z., Mei, Z. X., Du, X. L., Xue, Q. K., Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100022, and Institute of Physics, Chinese Academy of Sciences, Beijing 100080. Structure stability of epitaxial MgO-CaO solid-solution films: effect of diffusion. United States: N. p., 2007. Web. doi:10.1063/1.2732411.
Li, H. D., Zhang, X. N., Zhang, Z., Mei, Z. X., Du, X. L., Xue, Q. K., Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100022, & Institute of Physics, Chinese Academy of Sciences, Beijing 100080. Structure stability of epitaxial MgO-CaO solid-solution films: effect of diffusion. United States. doi:10.1063/1.2732411.
Li, H. D., Zhang, X. N., Zhang, Z., Mei, Z. X., Du, X. L., Xue, Q. K., Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100022, and Institute of Physics, Chinese Academy of Sciences, Beijing 100080. Tue . "Structure stability of epitaxial MgO-CaO solid-solution films: effect of diffusion". United States. doi:10.1063/1.2732411.
@article{osti_20982905,
title = {Structure stability of epitaxial MgO-CaO solid-solution films: effect of diffusion},
author = {Li, H. D. and Zhang, X. N. and Zhang, Z. and Mei, Z. X. and Du, X. L. and Xue, Q. K. and Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100022 and Institute of Physics, Chinese Academy of Sciences, Beijing 100080},
abstractNote = {The nonequilibrium epitaxial growth process of Mg{sub x}Ca{sub 1-x}O solid-solution films at 600 degree sign C is carefully investigated. No obvious phase separation is observed until annealing at 800 degree sign C despite a large miscibility gap. The solid-solution film is featured with disorder alloy as confirmed by transmission electron microscopy (TEM). Spinodal decomposition caused by uprising diffusion happens after short-time annealing which explicitly indicates the structure stability of the metastable solid-solution films does result from diffusion quenching.},
doi = {10.1063/1.2732411},
journal = {Journal of Applied Physics},
number = 10,
volume = 101,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}
  • The epitaxial growth of CaO films on mechanical-damage-free MgO(001) surface using low-temperature buffer technique has been carefully investigated. The strain is effectively relaxed in the CaO/MgO interfacial layers by lattice distortion and misfit dislocations as confirmed by transmission electron microscopy, which facilitates the subsequent growth of smooth CaO film at high temperature. The strain relaxation mechanism of the heterointerface is discussed in detail.
  • The stability of solid solutions of ZrO/sub 2/ and HfO/sub 2/ with MgO and CaO was investigated. The starting materials were HfO/sub 2/ (97.2% pure), ZrO/ (98.45% pure), and chemically pure alkaline-earth carbonates. The chemical phase analysis of the pressed samples consisting of 80% HfO/sub 2/ (or ZrO/suyb 2/ ) and 20% alkaline-earth oxide which were anneaIed at 1750 deg C for 2 hr disclosed the formation of solid solutions in all samples. After additional annealing at 1200 C for 24 hr the solid solutions which cortained MgO were decomposed. In order to study the kinetics of this decomposition, samplesmore » of solid solutions were heated at 1200 C for various lengths of time. X-ray analysis and phase analysis confirmed the instability of the solid solutions in the systems ZrO/- MgO and HfO/-MgO, and a higher stability of the solid solutions with CaO. In the radiograph, the decomposition is manifest by the appearance of a monoclinic HfO/sub 2/ or ZrO/sub 2/ phase. On the assumption that the impurities contained in ZrO/sub 2/ and HfO/sub 2/ may influence the decomposition of solid solutions, special ZrO/sub 2/ and HfO/sub 2/ reagents of particularly high degree of purity were prepared (9S.5 to 99.8 ZrO/sub 2/; 99.5 HfO/sub 2/). After annealing of these reagents with 20 mole% MgO or 20 mole% CaO no difference was found as compared with the initially used samples (98.45% ZrO/sub 2/, 97.2 HfO/sub 2/). After heating at 1200 deg C, x-ray analysis and chemical phase analysis disclosed, however, a higher stability of the solid solutions which were prepared from high-purity reagents. WWhile at 1200 deg C the solid ZrO/sub2/MgO solutions from commercial ZrO/sub 2/ (98.3% pure) completely decomposed into their components already after 15 to 20 hr, only 30% of the solid solution prepared from 99.8% ZrO/sub 2/ was decomposed after 200 hr. There was no substantial difference between the solid solutions of ZrO/sub 2/ and HfO/sub 2 with MgO and CaO. (OTS)« less
  • The refractive indices and optical birefringence of the films were measured as a function of wavelength using the film-prism coupling method. Both the ordinary and extraordinary refractive indices for films grown on MgO(001) and LaAlO{sub 3}(001) were higher than that of single-crystal PbTiO{sub 3}; however, the optical birefringence of films grown on MgO(001) was reduced from that of the bulk. For films grown on SrTiO{sub 3}(001), the ordinary refractive index was very close to that of single-crystal PbTiO{sub 3}. We correlate the refractive index values and the reduced birefringence to the degree of residual strain and the volume fraction ofmore » 90{degree} domains in the samples, respectively. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.« less
  • Single-crystal epitaxial thin films of {gamma}-Fe{sub 2}O{sub 3}(001) have been grown on MgO(001) using oxygen-plasma-assisted molecular beam epitaxy. The structure and magnetic properties of these films have been characterized by a variety of techniques, including reflection high-energy electron diffraction (RHEED), low-energy electron diffraction (LEED), x-ray photoelectron spectroscopy and x-ray photoelectron/Auger electron diffraction (XPD/AED), vibrating sample magnetometry, and ferromagnetic resonance. Real-time RHEED reveals that the film growth occurs in a layer-by-layer fashion. The {gamma}-Fe{sub 2}O{sub 3}(001) film surface exhibits a (1{times}1) LEED pattern. The growth of {gamma}-Fe{sub 2}O{sub 3} films at 450 {degree}C is accompanied by significant Mg outdiffusion. AED ofmore » Mg KLL Auger emission reveals that Mg substitutionally incorporates in the {gamma}-Fe{sub 2}O{sub 3} lattice, occupying the octahedral sites. Magnetic moments are {approximately}2300 G and {approximately}4500 G for {gamma}-Fe{sub 2}O{sub 3} films grown at 250{degree}C and 450{degree}C, respectively. The high magnetic moment for the films grown at 450{degree}C could be attributed to the high degree of structural order of the films and Mg substitution at octahedral sites. {copyright} {ital 1997 American Institute of Physics.}« less