Crystallography and microstructural studies of phase transformations in the Dy2O3 system

Youn Joong Kim; Waltraud M. Kriven

doi:10.1557/JMR.1998.0399

Crystallography and microstructural studies of phase transformations in the Dy₂O₃ system

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Abstract

The crystallography, microstructures, and phase transformation mechanisms in dysprosia (Dy₂O₃) have been studied. The lattice parameters of B and C phases were refined by x-ray diffraction (XRD). The modulated structures and decomposed structures in the CaO-doped samples were characterized by transmission electron spectroscopy (TEM). A new twin was observed in the modulated B phase. Contrary to the previous studies, the B to C transformation was induced by grinding. The A to B transformation was considered to be ferroelastic and the spontaneous strain was calculated. The major driving force for the B (monoclinic) to C (cubic) transformation is suggested to be the release of lattice strains and cation charge repulsions in the B structure, which is analogous to the β (monoclinic) to γ (orthorhombic) transformation in Ca₂SiO₄. This transformation can be displacive, if some conditions are provided to overcome the bonding energy of the interlayer oxygens in the B structure.

Original language	English (US)
Pages (from-to)	2920-2931
Number of pages	12
Journal	Journal of Materials Research
Volume	13
Issue number	10
DOIs	https://doi.org/10.1557/JMR.1998.0399
State	Published - Oct 1998

ASJC Scopus subject areas

General Materials Science
Condensed Matter Physics
Mechanics of Materials
Mechanical Engineering

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10.1557/JMR.1998.0399

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Cite this

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title = "Crystallography and microstructural studies of phase transformations in the Dy2O3 system",

abstract = "The crystallography, microstructures, and phase transformation mechanisms in dysprosia (Dy2O3) have been studied. The lattice parameters of B and C phases were refined by x-ray diffraction (XRD). The modulated structures and decomposed structures in the CaO-doped samples were characterized by transmission electron spectroscopy (TEM). A new twin was observed in the modulated B phase. Contrary to the previous studies, the B to C transformation was induced by grinding. The A to B transformation was considered to be ferroelastic and the spontaneous strain was calculated. The major driving force for the B (monoclinic) to C (cubic) transformation is suggested to be the release of lattice strains and cation charge repulsions in the B structure, which is analogous to the β (monoclinic) to γ (orthorhombic) transformation in Ca2SiO4. This transformation can be displacive, if some conditions are provided to overcome the bonding energy of the interlayer oxygens in the B structure.",

author = "Kim, {Youn Joong} and Kriven, {Waltraud M.}",

note = "Funding Information: This work was supported by a grant from the Department of Energy (DE-AC02-76ER 01198) through the Materials Research Laboratory of the UIUC. The use of the facilities in its Center for Microanalysis of Materials and at the Center for Electron Microscopy is gratefully acknowledged.",

year = "1998",

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doi = "10.1557/JMR.1998.0399",

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AU - Kim, Youn Joong

AU - Kriven, Waltraud M.

N1 - Funding Information: This work was supported by a grant from the Department of Energy (DE-AC02-76ER 01198) through the Materials Research Laboratory of the UIUC. The use of the facilities in its Center for Microanalysis of Materials and at the Center for Electron Microscopy is gratefully acknowledged.

PY - 1998/10

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N2 - The crystallography, microstructures, and phase transformation mechanisms in dysprosia (Dy2O3) have been studied. The lattice parameters of B and C phases were refined by x-ray diffraction (XRD). The modulated structures and decomposed structures in the CaO-doped samples were characterized by transmission electron spectroscopy (TEM). A new twin was observed in the modulated B phase. Contrary to the previous studies, the B to C transformation was induced by grinding. The A to B transformation was considered to be ferroelastic and the spontaneous strain was calculated. The major driving force for the B (monoclinic) to C (cubic) transformation is suggested to be the release of lattice strains and cation charge repulsions in the B structure, which is analogous to the β (monoclinic) to γ (orthorhombic) transformation in Ca2SiO4. This transformation can be displacive, if some conditions are provided to overcome the bonding energy of the interlayer oxygens in the B structure.

AB - The crystallography, microstructures, and phase transformation mechanisms in dysprosia (Dy2O3) have been studied. The lattice parameters of B and C phases were refined by x-ray diffraction (XRD). The modulated structures and decomposed structures in the CaO-doped samples were characterized by transmission electron spectroscopy (TEM). A new twin was observed in the modulated B phase. Contrary to the previous studies, the B to C transformation was induced by grinding. The A to B transformation was considered to be ferroelastic and the spontaneous strain was calculated. The major driving force for the B (monoclinic) to C (cubic) transformation is suggested to be the release of lattice strains and cation charge repulsions in the B structure, which is analogous to the β (monoclinic) to γ (orthorhombic) transformation in Ca2SiO4. This transformation can be displacive, if some conditions are provided to overcome the bonding energy of the interlayer oxygens in the B structure.

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