Electronic structure of rare-earth sesquioxides and oxysulfides

Mikami, Masayoshi; Nakamura, Shinichiro

doi:10.1016/j.jallcom.2005.01.068

Cited by 73 publications

(42 citation statements)

References 28 publications

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“…This value of bulk modulus is smaller compared to the reported values of 164, 134 and 188 GPa [15,17,18] with B 0 ' fixed at 4. These values of the bulk moduli are comparable with those reported for other RE 2 O 3 systems [4,[20][21][22].…”

Section: Resultssupporting

confidence: 89%

“…This bulk modulus is comparable to that observed in other rare earth oxides [18,20,21,23]. However, the transition pressure of 27 GPa for Tb 4 O 7 is much higher than that generally found in other rare-Earth oxide systems (<15 GPa) [18,[20][21][22][23][24] XPS spectra on the sample confirm the presence of Tb 4+ ions [14]. In Tb 4 O 7 , the different cation sites in the fluorite lattice are occupied by trivalent and tetravalent Tb ions, which are coordinated by 6 and 8 oxygen anions respectively.…”

Section: Resultssupporting

confidence: 78%

“…It can be seen that the C-A transition pressure increases with increasing Z of the cation [20,24]. The bulk moduli of these systems along with that of the other C-type RE 2 O 3 systems reported in the literature [18,[20][21][22][23][24] are shown in figure 4. The increase in B 0 with increasing atomic number Z of the cation can be clearly seen.…”

Section: Resultsmentioning

confidence: 99%

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High Pressure Structural Studies on Rare-Earth Sesquioxides

Sahu¹,

Lonappan

Shekar

2012

J. Phys.: Conf. Ser.

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High -pressure synchrotron x-ray diffraction study of RMnO 3 (R = Eu, Gd, Tb and Dy) upto 50 GPa D V S Muthu, A E Midgley, P R Scott et al. Abstract. The Rare-Earth sesquioxides (RE 2 O 3 ) exhibit interesting physical and chemical properties. Some of these oxides have tremendous technological applications. At ambient conditions, the RE 2 O 3 systems exist in three polymorphic forms, namely: hexagonal A-type, monoclinic B-type, and cubic C-type. The structural stability of three RE 2 O 3 systems: RE = Gd, Ho, Tm and the Tb 4 O 7 system have been studied under high pressure. All the four systems exhibited interesting pressure induced phase transitions. Gd 2 O 3 exhibited C-A transition at ~ 12 GPa, whereas Ho 2 O 3 and Tm 2 O 3 exhibited C-B transition at pressures of 9.5 and 7 GPa respectively. Tb 4 O 7 transformed from its cubic fluorite structure to probably the cotunnite phase at a relatively higher pressure of 27 GPa. The unusual large pressure stability of Tb 4 O 7 was attributed to the presence of Tb 4+ ions. The bulk moduli show systematic increase with higher cations, probably due to the enhanced influence of the 4f electron states and increased nature of covalency. However, the mechanisms of the structural transitions C-B-A with increased pressure and increased cation radii are yet to be understood.

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Section: Resultssupporting

confidence: 89%

Section: Resultssupporting

confidence: 78%

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High Pressure Structural Studies on Rare-Earth Sesquioxides

Sahu¹,

Lonappan

Shekar

2012

J. Phys.: Conf. Ser.

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“…The only competing binary oxide containing La is La 2 O 3 , which occurs in a body-centered cubic structure for the most stable phase (see Table II) and in the trigonal structure at high temperature (see Table III) [42, 44,53]. Both are non-magnetic.…”

Section: A Geometries and Energeticsmentioning

confidence: 99%

Thermodynamic stability of LaMnO3and its competing oxides: A hybrid density functional study of an alkaline fuel cell catalyst

et al. 2011

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The phase stability of LaMnO 3 with respect to its competing oxides is studied using hybridexchange density functional theory (DFT) as implemented in CRYSTAL09. The underpinning DFT total energy calculations are embedded in a thermodynamic framework that takes optimal advantage of error cancellation within DFT. It has been been found that by using the ab initio thermodynamic techniques described here, the standard Gibbs formation energies can be calculated to a significantly greater accuracy than was previously reported (a mean error of 1.6% with a maximum individual error of -3.0%). This is attributed to both the methodology for isolating the chemical potentials of the reference states, as well as the use of the B3LYP functional to thoroughly investigate the ground state energetics of the competing oxides.

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“…1 They are excellent host materials for solid state lasers 2 and improved phosphors. 3,4 They have high thermal stability and toughness suitable for their application in refractors or abrasives.…”

Section: Introductionmentioning

confidence: 99%

Anharmonic behavior and structural phase transition in Yb2O3

Pandey¹,

Samanta²,

Singh³

et al. 2013

AIP Advances

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The investigation of structural phase transition and anharmonic behavior of Yb2O3 has been carried out by high-pressure and temperature dependent Raman scattering studies respectively. In situ Raman studies under high pressure were carried out in a diamond anvil cell at room temperature which indicate a structural transition from cubic to hexagonal phase at and above 20.6 GPa. In the decompression cycle, Yb2O3 retained its high pressure phase. We have observed a Stark line in the Raman spectra at 337.5 cm−1 which arises from the electronic transition between 2F5/2 and 2F7/2 multiplates of Yb3+ (4f13) levels. These were followed by temperature dependent Raman studies in the range of 80–440 K, which show an unusual mode hardening with increasing temperature. The hardening of the most dominant mode (Tg + Ag) was analyzed in light of the theory of anharmonic phonon-phonon interaction and thermal expansion of the lattice. Using the mode Grüneisen parameter obtained from high pressure Raman measurements; we have calculated total anharmonicity of the Tg + Ag mode from the temperature dependent Raman data.

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Electronic structure of rare-earth sesquioxides and oxysulfides

Cited by 73 publications

References 28 publications

High Pressure Structural Studies on Rare-Earth Sesquioxides

High Pressure Structural Studies on Rare-Earth Sesquioxides

Thermodynamic stability of LaMnO3and its competing oxides: A hybrid density functional study of an alkaline fuel cell catalyst

Anharmonic behavior and structural phase transition in Yb2O3

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