Role of disorder in the thermodynamics and atomic dynamics of glasses.
We measured the density of vibrational states (DOS) and the specific heat of various glassy and crystalline polymorphs of SiO2. The typical (ambient) glass shows a well-known excess of specific heat relative to the typical crystal (α-quartz). This, however, holds when comparing a lower-density glass to a higher-density crystal. For glassy and crystalline polymorphs with matched densities, the DOS of the glass appears as the smoothed counterpart of the DOS of the corresponding crystal; it reveals the same number of the excess states relative to the Debye model, the same number of all states in the low-energy region, and it provides the same specific heat. This shows that glasses have higher specific heat than crystals not due to disorder, but because the typical glass has lower density than the typical crystal.
European Synchrotron Radiation Facility, F-38043 Grenoble, France.
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Chumakov
European Synchrotron Radiation Facility, F-38043 Grenoble, France and Dipartimento di Fisica, Università di Trento, I-38123 Povo, Trento, Italy.
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Monaco
Dipartimento di Fisica, Università di Trento, I-38123 Povo, Trento, Italy and IPCF-CNR, UOS di Roma, c/o Roma University La Sapienza, I-00185 Roma, Italy.
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Fontana
European Synchrotron Radiation Facility, F-38043 Grenoble, France.
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Bosak
Jülich Centre for Neutron Science JCNS and Peter Grünberg Institut PGI, JARA-FIT, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany and Faculté des Sciences, Université de Liège, B-4000 Liège, Belgium.
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Hermann
Jülich Centre for Neutron Science JCNS and Peter Grünberg Institut PGI, JARA-FIT, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany and Faculté des Sciences, Université de Liège, B-4000 Liège, Belgium.
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Bessas
European Synchrotron Radiation Facility, F-38043 Grenoble, France.
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Wehinger
European Synchrotron Radiation Facility, F-38043 Grenoble, France.
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Crichton
European Synchrotron Radiation Facility, F-38043 Grenoble, France.
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Krisch
European Synchrotron Radiation Facility, F-38043 Grenoble, France.
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Rüffer
IMEM-CNR, Area delle Scienze, I-43124 Parma, Italy.
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Baldi
IPCF-CNR, UOS di Messina, Viale F. Stagno d'Alcontres 37, I-98158 Messina, Italy.
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Carini
Dipartimento di Fisica e Scienze della Terra, Università di Messina, Viale F. Stagno d'Alcontres 31, I-98166 Messina, Italy.
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Carini
Dipartimento di Fisica e Scienze della Terra, Università di Messina, Viale F. Stagno d'Alcontres 31, I-98166 Messina, Italy.
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D'Angelo
IMEM-CNR, Area delle Scienze, I-43124 Parma, Italy.
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Gilioli
Dipartimento di Fisica e Scienze della Terra, Università di Messina, Viale F. Stagno d'Alcontres 31, I-98166 Messina, Italy.
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Tripodo
IPCF-CNR, UOS di Roma, c/o Roma University La Sapienza, I-00185 Roma, Italy and Dipartimento di Fisica, Università di Perugia, I-60123 Perugia, Italy.
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Zanatta
Geowissenschaften, Goethe-Universität, Altenhoeferallee 1, D-60438, Frankfurt a.M., Germany.
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Winkler
Accelrys, 334 Cambridge Science Park, Cambridge CB4 0WN, United Kingdom.
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Milman
STFC Rutherford Appleton Laboratory, Chilton, Didcot Oxfordshire OX11 0QX, United Kingdom.
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Refson
Materials Research Institute and School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom.
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Dove
Material Physics and Technology at Extreme Conditions, Laboratory of Crystallography, University of Bayreuth, D-95440 Bayreuth, Germany.
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Dubrovinskaia
Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth, Germany.
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Dubrovinsky
Max Planck Institut for the Science of Light, D-91058 Erlangen, Germany.
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Keding
Section of Chemistry, Aalborg University, DK-9000 Aalborg, Denmark.
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Yue