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Titolo: SECONDARY RELAXATIONS AND THE CONSTANT DENSITY OF SLATES IN QUADRUPOLAR GLASSES
Autore: SOLF MP; KLEIN MW;
 Indirizzi:
 WORCESTER POLYTECH INST,DEPT PHYS,100 INST RD WORCESTER MA 01609 ROME LAB BEDFORD MA 01731
 Titolo Testata:
 Journal of noncrystalline solids
,
volume: 172,
anno: 1994,
parte:, 1
pagine: 531  537
 SICI:
 00223093(1994)172:<531:SRATCD>2.0.ZU;2C
 Fonte:
 ISI
 Lingua:
 ENG
 Soggetto:
 ORIENTATIONALLY DISORDERED CRYSTALS; LOWTEMPERATURE PROPERTIES; LOWENERGY EXCITATIONS; MIXEDCRYSTALS; STATE; (KBR)1X(KCN)X; M(CN)XX1X; (NACN)1X(KCN)X; REORIENTATIONS; BEHAVIOR;
 Tipo documento:
 Article
 Natura:
 Periodico
 Settore Disciplinare:
 Science Citation Index Expanded
 Citazioni:
 32
 Recensione:
 Indirizzi per estratti:



 Citazione:
 M.P. Solf e M.W. Klein, "SECONDARY RELAXATIONS AND THE CONSTANT DENSITY OF SLATES IN QUADRUPOLAR GLASSES", Journal of noncrystalline solids, 172, 1994, pp. 531537
Abstract
The Hamiltonian for a set of interacting quadrupoles (QPs) randomly distributed in a nonpolar host is considered. One such system is (KCN)(x)(KBr)(1x), where x denotes the fractional concentration of the CN()QPs; x is assumed to be in the regime where KCNKBr exhibits glasslike properties, i.e., 0.2 less than or similar to x less than or similar to 0.6. The model Hamiltonian considers the QPQP interaction between the CN QPs and the interaction of CN with elastic random fields caused by random fluctuations in the local environment of the CN ions. For low temperatures, T, we assume that QPs freeze into a state of quenched orientational disorder. However, the ground state of a system of N interacting QPs is still 2(N)fold degenerate. A perturbation approach is used to lift the degeneracy and it is shown that the QPs can be described in terms of an effective twolevel system Hamiltonian and that the density of states for low energies is constant. The constant density arises from 180 degrees tunneling QPs coupled with a center ofmass displacement of the QPs and is not related to the electric dipole moment of CN, as was suggested previously by Sethna et al.
ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 21/09/20 alle ore 06:37:27