TY - JOUR
T1 - The glassy state of matter
T2 - Its definition and ultimate fate
AU - Zanotto, Edgar D.
AU - Mauro, John C.
N1 - Funding Information:
Throughout four decades of working on glass research and teaching, EDZ has been asked many times by students and colleagues of different backgrounds to explain the concept of “glass.” JCM has encountered the same experience numerous times. Hence, we made an effort to put together this article, which hopefully can be educative and useful, not only for the general public and students, but also for the scientific community. The authors are grateful to the CeRTEV (www.certev.ufscar.br) researchers for their critique and insights about the above described concepts, and to Joachim Deubener for suggesting and translating from German some classical references, and also for his useful comments. Profs. A. Varshneya, A. C.M.Rodrigues, E. B. Ferreira and M. L. F. Nascimento made relevant suggestions. Daniel R. Cassar helped us in producing Fig. 2. We are also grateful to Kenneth L. Burns from the Rakow Research Library at the Corning Museum of Glass for help with the Chihuly reference. Funding by the São Paulo State Foundation, FAPESP (#2013/07793-6) is deeply appreciated.
Publisher Copyright:
© 2017 Elsevier B.V.
PY - 2017/9/1
Y1 - 2017/9/1
N2 - The objective of this communication is to clarify the meanings of solid and liquid, to dwell on the ultimate fate of glass in the limit of infinitely long time, and to propose a modern, improved definition of glass. We review the four characteristic states of matter related to vitrification: the stable equilibrium liquid (L), the metastable supercooled liquid (SCL), the unstable nonequilibrium glass (G), and the stable crystal (C). We also discuss some relevant terms and phenomena, including glass transition, crystallization, non-crystalline, amorphous, solid, and frozen. We review several previously published definitions of glass and finally propose an improved definition in two alternative forms. The first improved definition is: “Glass is a nonequilibrium, non-crystalline state of matter that appears solid on a short time scale but continuously relaxes towards the liquid state.” This is an intuitive description for the general public and young students. An alternative, more detailed definition to be understood and used by advanced students, researchers, and professors is: “Glass is a nonequilibrium, non-crystalline condensed state of matter that exhibits a glass transition. The structure of glasses is similar to that of their parent supercooled liquids (SCL), and they spontaneously relax toward the SCL state. Their ultimate fate, in the limit of infinite time, is to crystallize.” This definition is for experts who understand the meaning of glass transition.
AB - The objective of this communication is to clarify the meanings of solid and liquid, to dwell on the ultimate fate of glass in the limit of infinitely long time, and to propose a modern, improved definition of glass. We review the four characteristic states of matter related to vitrification: the stable equilibrium liquid (L), the metastable supercooled liquid (SCL), the unstable nonequilibrium glass (G), and the stable crystal (C). We also discuss some relevant terms and phenomena, including glass transition, crystallization, non-crystalline, amorphous, solid, and frozen. We review several previously published definitions of glass and finally propose an improved definition in two alternative forms. The first improved definition is: “Glass is a nonequilibrium, non-crystalline state of matter that appears solid on a short time scale but continuously relaxes towards the liquid state.” This is an intuitive description for the general public and young students. An alternative, more detailed definition to be understood and used by advanced students, researchers, and professors is: “Glass is a nonequilibrium, non-crystalline condensed state of matter that exhibits a glass transition. The structure of glasses is similar to that of their parent supercooled liquids (SCL), and they spontaneously relax toward the SCL state. Their ultimate fate, in the limit of infinite time, is to crystallize.” This definition is for experts who understand the meaning of glass transition.
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U2 - 10.1016/j.jnoncrysol.2017.05.019
DO - 10.1016/j.jnoncrysol.2017.05.019
M3 - Article
AN - SCOPUS:85020280890
SN - 0022-3093
VL - 471
SP - 490
EP - 495
JO - Journal of Non-Crystalline Solids
JF - Journal of Non-Crystalline Solids
ER -