ALLOY THEORY OF VALENCE TRANSITION

1976 ◽  
Vol 37 (C4) ◽  
pp. C4-289-C4-292
Author(s):  
S. K. GHATAK ◽  
M. AVIGNON ◽  
K. H. BENNEMANN
Keyword(s):  
Valence Transition ◽  
Alloy Theory

HREM Study of electron-induced surface radiation damage in ReO3

1991 ◽  
Vol 49 ◽  
pp. 636-637
Author(s):  
R. Ai ◽  
H.-J. Fan ◽  
L. D. Marks
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Oxides ◽  
Electron Irradiation ◽  
Transition Metal Oxides ◽  
Carbon Film ◽  
Transition Metal Ions ◽  
Surface Radiation ◽  
Valence Transition ◽  
Electron Microscopes

It has been known for a long time that electron irradiation induces damage in maximal valence transition metal oxides such as TiO2, V2O5, and WO3, of which transition metal ions have an empty d-shell. This type of damage is excited by electronic transition and can be explained by the Knoteck-Feibelman mechanism (K-F mechanism). Although the K-F mechanism predicts that no damage should occur in transition metal oxides of which the transition metal ions have a partially filled d-shell, namely submaximal valence transition metal oxides, our recent study on ReO3 shows that submaximal valence transition metal oxides undergo damage during electron irradiation.ReO3 has a nearly cubic structure and contains a single unit in its cell: a = 3.73 Å, and α = 89°34'. TEM specimens were prepared by depositing dry powders onto a holey carbon film supported on a copper grid. Specimens were examined in Hitachi H-9000 and UHV H-9000 electron microscopes both operated at 300 keV accelerating voltage. The electron beam flux was maintained at about 10 A/cm2 during the observation.

scholarly journals Negative thermal expansion in YbMn2Ge2 induced by the dual effect of magnetism and valence transition

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Yongqiang Qiao ◽  
Yuzhu Song ◽  
Andrea Sanson ◽  
Longlong Fan ◽  
Qiang Sun ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Intermetallic Compound ◽  
Cell Volume ◽  
Valence State ◽  
Unit Cell Volume ◽  
Negative Thermal Expansion ◽  
Combined Effect ◽  
Dual Effect ◽  
Valence Transition ◽  
Magnetovolume Effect

AbstractNegative thermal expansion (NTE) is an intriguing property, which is generally triggered by a single NTE mechanism. In this work, an enhanced NTE (αv = −32.9 × 10−6 K−1, ΔT = 175 K) is achieved in YbMn2Ge2 intermetallic compound to be caused by a dual effect of magnetism and valence transition. In YbMn2Ge2, the Mn sublattice that forms the antiferromagnetic structure induces the magnetovolume effect, which contributes to the NTE below the Néel temperature (525 K). Concomitantly, the valence state of Yb increases from 2.40 to 2.82 in the temperature range of 300–700 K, which simultaneously causes the contraction of the unit cell volume due to smaller volume of Yb3+ than that of Yb2+. As a result, such combined effect gives rise to an enhanced NTE. The present study not only sheds light on the peculiar NTE mechanism of YbMn2Ge2, but also indicates the dual effect as a possible promising method to produce enhanced NTE materials.

Comment on “Pressure-induced structural and valence transition in AgO” by C. Hou, J. Botana, X. Zhang, X. Wang and M. Miao, Phys. Chem. Chem. Phys., 2016, 18, 15322

2016 ◽  
Vol 18 (46) ◽  
pp. 31973-31974 ◽  
Author(s):  
Mariana Derzsi ◽  
Wojciech Grochala
Keyword(s):  
Electronic Structure ◽  
Recent Article ◽  
Theoretical Study ◽  
Mixed Valence ◽  
Chem Phys ◽  
External Pressure ◽  
Valence Transition ◽  
Mixed Valence Compound ◽  
Phys Chem Chem Phys

The recent article by Hou et al. has focused on a theoretical study of mixed valence compound AgO in order to elucidate the nature of the electronic structure of this system as a function of external pressure.

Valence transition in polycrystalline Eu(Rh 1–x Co x ) 2 Si 2 studied by hard x-ray photoemission spectroscopy

2017 ◽  
Vol 220 ◽  
pp. 28-32 ◽  
Author(s):  
Katsuya Ichiki ◽  
Takayuki Matsumoto ◽  
Hiroaki Anzai ◽  
Ryohei Takeshita ◽  
Kodai Abe ◽  
...  
Keyword(s):  
Photoemission Spectroscopy ◽  
Valence Transition ◽  
X Ray

scholarly journals Eu valence transition behavior in the nano form of EuPd2Si2

2018 ◽  
Vol 465 ◽  
pp. 515-518
Author(s):  
Kartik K. Iyer ◽  
Tathamay Basu ◽  
P.L. Paulose ◽  
E.V. Sampathkumaran
Keyword(s):  
Valence Transition ◽  
Transition Behavior

First-order valence transition and barocaloric effect in EuNi2(Si1−xGex)2

2004 ◽  
Vol 272-276 ◽  
pp. 2352-2354 ◽  
Author(s):  
Z. Hossain ◽  
Th. Strässle ◽  
C. Geibel ◽  
A. Furrer
Keyword(s):  
Valence Transition ◽  
First Order

The effect of high pressure upon the valence transition in EuPd2Si2

1991 ◽  
Vol 3 (29) ◽  
pp. 5465-5468 ◽  
Author(s):  
D M Adams ◽  
A E Heath ◽  
H Jhans ◽  
A Norman ◽  
S Leonard
Keyword(s):  
High Pressure ◽  
Valence Transition

scholarly journals High Field X-ray Diffraction Study on a Magnetic-Field-Induced Valence Transition in YbInCu4

2006 ◽  
Vol 75 (2) ◽  
pp. 024710 ◽  
Author(s):  
Y. H. Matsuda ◽  
T. Inami ◽  
K. Ohwada ◽  
Y. Murata ◽  
H. Nojiri ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Diffraction Study ◽  
High Field ◽  
X Ray Diffraction ◽  
Valence Transition ◽  
X Ray
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