1 Section of Chemistry, The Faculty of Engineering and Science, Aalborg University, VBN2 Department of Chemistry and Bioscience, The Faculty of Engineering and Science, Aalborg University, VBN3 Inorganic Amorphous Materials, The Faculty of Engineering and Science, Aalborg University, VBN4 The Faculty of Engineering and Science, Aalborg University, VBN5 European Synchrotron Radiation Facility6 Università di Trento7 Forschungszentrum Jülich GmbH8 Area delle Scienze9 UOS di Messina10 Università di Messina11 Università di Perugia12 Goethe-Universität13 334 Cambridge Science Park14 STFC Rutherford Appleton Laboratory15 Queen Mary University of London16 University of Bayreuth17 Universität Bayreuth18 Max Planck Institut for the Science of Light19 European Synchrotron Radiation Facility20 Queen Mary University of London
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 higherdensity 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.