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Title: HYBRIDIZATION AND PRESSURE EFFECTS IN UTX COMPOUNDS

Abstract

No abstract prepared.

Authors:
; ;
Publication Date:
Research Org.:
Los Alamos National Lab., NM (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
787673
Report Number(s):
LA-UR-01-5643
TRN: US0200390
DOE Contract Number:
W-7405-ENG-36
Resource Type:
Conference
Resource Relation:
Conference: Conference title not supplied, Conference location not supplied, Conference dates not supplied; Other Information: PBD: 1 Oct 2001
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; HYBRID SYSTEMS; URANIUM COMPOUNDS; TRITIDES; PRESSURE DEPENDENCE

Citation Formats

A. ALSAMDI, V. SECHOVSKY, and ET AL. HYBRIDIZATION AND PRESSURE EFFECTS IN UTX COMPOUNDS. United States: N. p., 2001. Web.
A. ALSAMDI, V. SECHOVSKY, & ET AL. HYBRIDIZATION AND PRESSURE EFFECTS IN UTX COMPOUNDS. United States.
A. ALSAMDI, V. SECHOVSKY, and ET AL. Mon . "HYBRIDIZATION AND PRESSURE EFFECTS IN UTX COMPOUNDS". United States. doi:. https://www.osti.gov/servlets/purl/787673.
@article{osti_787673,
title = {HYBRIDIZATION AND PRESSURE EFFECTS IN UTX COMPOUNDS},
author = {A. ALSAMDI and V. SECHOVSKY and ET AL},
abstractNote = {No abstract prepared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Oct 01 00:00:00 EDT 2001},
month = {Mon Oct 01 00:00:00 EDT 2001}
}

Conference:
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  • No abstract prepared.
  • Uranium, along with other actinides and lanthanides, forms a large group of ternary intermetallic compounds of stoichiometry UTX (T = transition metal, X = p-electron metal). These compounds are formed in several structure types and the occurrence and stability of particular structures with respect to the transition metal content suggests reasonable systematics. The authors have also investigated the magnetic structures of selected UTX compounds and it is revealing to relate the crystallographic and magnetic structures, because of the relationship between the magnetic symmetry and that of the U-atom environment produced by the 5f-ligand hybridization, and the consequent anisotropic exchange. Thosemore » of ZrNiAl structure type are collinear, with moments along the hexagonal c-axis. In the orthorhombic NiSiTi structure type, the moments are confined to the b- c plane (perpendicular to the uranium chains) and the structures are often incommensurate. In the hexagonal CaIn{sub 2} (or GaGeLi) structure type, the magnetic structures form in an orthorhombic cell, and at least in the disordered centric group, again the moments lie perpendicular to the nearest-neighbor uranium spacing. This work presents a phenomenology of trends in UTX ternary compounds. It is shown that there is an apparent strong hybridization parallel to nearest neighbor U-U directions, with ferromagnetic coupling in the same directions. There may be a systematic relationship between the hybridization anisotropy and the magnetic anisotropy, in which the quantization axes are the same and the moments point along directions of relatively weak hybridization.« less
  • The rare earth element Ce and a number of rare earth compounds exhibit valence transition under pressure. This has been one of the most active research topics in recent years. There also exist several intermetallic compounds of Ce that do not unergo abrupt valence changes. Instead, the valence varies continuously with pressure or temperature. A systematic high pressure study of these compounds will further elucidate the phenomenon of valence fluctuation. For these materials, the single parameter which is most sensitive to the pressure is the position of the Ce 4f level relative to the conduction bands. Therefore, it should bemore » possible to monitor the valence with pressure and follow the evolvement of the system from a local moment state to a nonmagnetic state. The latter may be a spin compensated Kondo lattice state of a lattice of virtual bound states. The experimental evidence of these exotic states is reviewed, and new experiments to investigate their physical properties are suggested.« less
  • The role of hybridization of f-electrons with non-f ligands is discussed as a primary cause for determining the electronic properties of Ce and U compounds. From this point of view, systematic variation of heavy-fermion and related behavior can be observed in isostructural compounds where the non-f component is varied. A specific discussion of data for the UX/sub 3/ compounds is presented.
  • Computational analysis and modeling of spectroscopic properties of trivalent uranium in crystals of hexagonal symmetry have been conducted with inclusion of the crystal-field induced orbital hybridization between the 5f{sup 3} and 5f{sup 2}6d configurations. It is shown that, in the absorption spectrum with energy above 20,000 cm{sup -1}, the mixing of 5f{sup 3} and 5f{sup 2}6d states is significant. The spectrum in this region cannot be interpreted by the conventional model of crystal field theory. The Judd-Ofelt theory fails completely in predicating the intensities of optical absorption from the ground state to the configuration mixed excited states. A new Hamiltonianmore » including the odd ranks of crystal field interaction is diagonalized on the bases of all 5f{sup 3} and 5f{sup 2}6d states. A simulation of absorption spectrum is optimized in comparison with the experimental spectrum for determination of the Hamiltonian parameters. (authors)« less