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Title: M$sub 4$ $sub 5$ spectrum of Ce and the $gamma$--$alpha$ phase transition

Abstract

Absolute absorption coefficients in the region of the M/sub 4/ and M/sub 5/ edges are presented for cerium in CeF/sub 3/, CeO/sub 2/, and in the metal. Strong line absorptions (3d yields 4f) occur to the low energy side of weak M/ sub 4/ and M/sub 5/ edges.'' At each edge'' the absorption passes through a weak broad peak attributed to transitions into a band of higher f states. The spectra of CeF/sub 3/ and the metal at room temperature are structurally similar but differ clearly from the quadrivalent oxide. A shift to higher energy is found for both absorption lines and edges in the sequence fluoride- oxide--metal at room temperature. On cooling the evaporated metal absorption foil ( gamma phase) to 77 deg K both M/sub 4/ and M/sub 5/ line profiles change into forms accurately resolvable into a combination of trivalent (CeF/sub 3/ like) and quadrivalent (CeO/sub 2/ like) curves, suitably displaced in energy, in the proportions 59% to 43%, respectively. This is interpreted as evidence for the transfer of localized 4f electrons from some of the 3+ ions of the gamma phase when the gamma -- alpha transformation occurs. The line structure exhibits hysteresis and reverts tomore » that of the original gamma phase after repeated cycling between 77 deg K and room temperature. The possibility of superlattice structure in alpha -cerium is discussed. (auth)« less

Authors:
; ;
Publication Date:
Research Org.:
Univ. of Leicester, Eng.
OSTI Identifier:
4378137
NSA Number:
NSA-29-008642
Resource Type:
Journal Article
Journal Name:
J. Phys., B (London), v. 6, no. 10, pp. 2184-2196
Additional Journal Information:
Other Information: Orig. Receipt Date: 30-JUN-74; Bib. Info. Source: UK (United Kingdom (sent to DOE from))
Country of Publication:
United Kingdom
Language:
English
Subject:
N60200* -Physics (Atomic & Molecular)-Atomic & Molecular Properties; N50230 -Metals, Ceramics, & Other Materials-Metals & Alloys-Properties, Structure & Phase Studies; *CERIUM FLUORIDES- ABSORPTION SPECTRA; *CERIUM OXIDES- ABSORPTION SPECTRA; *CERIUM- PHASE TRANSFORMATIONS; HYSTERESIS; LOW TEMPERATURE; MEDIUM TEMPERATURE; SUPERLATTICES

Citation Formats

Ottewell, D, Stewardson, E A, and Wilson, J E. M$sub 4$ $sub 5$ spectrum of Ce and the $gamma$--$alpha$ phase transition. United Kingdom: N. p., 1973. Web.
Ottewell, D, Stewardson, E A, & Wilson, J E. M$sub 4$ $sub 5$ spectrum of Ce and the $gamma$--$alpha$ phase transition. United Kingdom.
Ottewell, D, Stewardson, E A, and Wilson, J E. Mon . "M$sub 4$ $sub 5$ spectrum of Ce and the $gamma$--$alpha$ phase transition". United Kingdom.
@article{osti_4378137,
title = {M$sub 4$ $sub 5$ spectrum of Ce and the $gamma$--$alpha$ phase transition},
author = {Ottewell, D and Stewardson, E A and Wilson, J E},
abstractNote = {Absolute absorption coefficients in the region of the M/sub 4/ and M/sub 5/ edges are presented for cerium in CeF/sub 3/, CeO/sub 2/, and in the metal. Strong line absorptions (3d yields 4f) occur to the low energy side of weak M/ sub 4/ and M/sub 5/ edges.'' At each edge'' the absorption passes through a weak broad peak attributed to transitions into a band of higher f states. The spectra of CeF/sub 3/ and the metal at room temperature are structurally similar but differ clearly from the quadrivalent oxide. A shift to higher energy is found for both absorption lines and edges in the sequence fluoride- oxide--metal at room temperature. On cooling the evaporated metal absorption foil ( gamma phase) to 77 deg K both M/sub 4/ and M/sub 5/ line profiles change into forms accurately resolvable into a combination of trivalent (CeF/sub 3/ like) and quadrivalent (CeO/sub 2/ like) curves, suitably displaced in energy, in the proportions 59% to 43%, respectively. This is interpreted as evidence for the transfer of localized 4f electrons from some of the 3+ ions of the gamma phase when the gamma -- alpha transformation occurs. The line structure exhibits hysteresis and reverts to that of the original gamma phase after repeated cycling between 77 deg K and room temperature. The possibility of superlattice structure in alpha -cerium is discussed. (auth)},
doi = {},
journal = {J. Phys., B (London), v. 6, no. 10, pp. 2184-2196},
number = ,
volume = ,
place = {United Kingdom},
year = {1973},
month = {10}
}