Crystalline electric fields in mixed valent systems

Conference · Tue Jan 01 04:00:00 EST 1980

OSTI ID:6768928

Shapiro, S M

The inelastic neutron studies of rare-earth-based mixed valent systems have all shown remarkably similar results: a broad quasielastic line with half width on the order of 10 MeV. This width exhibits a strong temperature dependence in those systems which undergo a valence transition and is only weakly temperature dependent in those systems which show no transition. A surprising result was the absence of crystalline electric field (CEF) excitations. Recent measurements on the alloy Ce/sub .9-x/La/sub x/Th/sub .1/ have revealed the existence of CEF excitations. For x = 0, the valence transition is strongly first order and occurs near T/sub 0/ approx. 150 K. The inelastic spectra exhibit the typical broad quasielastic scattering. As x increases, T/sub 0/ decreases due to internal pressure effects, and a well-defined, but broad, excitation appears near E = 15 MeV. This is interpreted as a CEF excitation between the GAMMA/sub 7/ and GAMMA/sub 8/ levels of the Ce/sup 3/+ ion. For x = 0.40, the valence transition is almost completely suppressed and the excitation becomes even sharper.

• Research Organization: Brookhaven National Lab., Upton, NY (USA)
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6768928
• Report Number(s): BNL-28632; CONF-801134-11
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
CRYSTAL FIELD
ELECTRONIC STRUCTURE
ELEMENTS
METALS
RARE EARTHS