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Elastic and anelastic properties of densified vitreous B2O3: Relaxations and anharmonicity (Articolo in rivista)
- Type
- Label
- Elastic and anelastic properties of densified vitreous B2O3: Relaxations and anharmonicity (Articolo in rivista) (literal)
- Anno
- 2012-01-01T00:00:00+01:00 (literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
- 10.1103/PhysRevB.85.094201 (literal)
- Alternative label
Giovanni Carini Jr., Giuseppe Carini, Gaspare Tripodo, Gaetano Di Marco, Edmondo Gilioli (2012)
Elastic and anelastic properties of densified vitreous B2O3: Relaxations and anharmonicity
in Physical review. B, Condensed matter and materials physics (Online); APS, American physical society, College Park, MD (Stati Uniti d'America)
(literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
- Giovanni Carini Jr., Giuseppe Carini, Gaspare Tripodo, Gaetano Di Marco, Edmondo Gilioli (literal)
- Pagina inizio
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- http://adsabs.harvard.edu/abs/2012PhRvB..85i4201C (literal)
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- ISI Web of Science (WOS) (literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
- IPCF del C.N.R., Sezione di Messina, Viale Ferdinando Stagno d'Alcontres 37, I-98166 Messina, Italy; Dipartimento di Fisica, Universit`a Degli Studi di Messina, Viale Ferdinando Stagno d'Alcontres 31, I-98166 Messina, Italy; IMEM del C.N.R., Area delle Scienze, I-43010 Parma, Italy (literal)
- Titolo
- Elastic and anelastic properties of densified vitreous B2O3: Relaxations and anharmonicity (literal)
- Abstract
- The elastic and anelastic properties of densified B2O3 glasses, melt quenched under pressures of 2 and 4 GPa,
were investigated by measuring the sound velocity and the acoustic attenuation of longitudinal and shear ultrasonic
waves in the megahertz range over the temperature interval between 8 and 300 K. Densification from 1826 to
2373 kg/m3 leads to an extraordinarily large growth of both bulk and shear moduli but leaves the Poisson's ratio
nearly constant. In the glass compacted at 4 GPa, the elastic moduli become larger by a factor of five than those
characterizing normal vitreous B2O3 (v-B2O3) as a consequence of modifications of the chemical bonding in the
network. The thermally activated relaxations of intrinsic structural defects, which dominate the acoustic behaviors
of normal glass below 150 K, giving rise to an intense attenuation peak and a corresponding steep decrease in
sound velocity, are increasingly depressed by growing densification. Above 150 K, the ultrasonic velocity is
mainly regulated by the vibrational anharmonicity and shows a nearly linear decrease as the temperature is
increased, with a substantially smaller slope with increasing densification. Modeling the relaxation losses and the
related velocity variations by an asymmetric double-well potential model that has a distribution of both the barrier
potential and the asymmetry, it has been possible to separate the relaxation and the anharmonic contributions to
the sound velocity. The former has been ascribed to local motions of boroxol rings formed by connected BO3
planar triangles, the basic units building up the network of v-B2O3, while the latter has been interpreted in terms
of the Akhiezer mechanism concerning the \"thermal vibration viscosity.\" (literal)
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