Scientific innovations and applications- the key to growth and sustenance of quality of life in the 21 st century Kapila Gunasekera, Shibalik Chakraborty, Chad Holbrook, Sriram Ravindren and Vignarooban Kandasamy, and Punit Boolchand University of Cincinnati

25 new discoveries of 2012, Time Magazine, Nov. 12, 2012

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States of matter Liquids → Solids Liquids → Solids water ice water ice (disordered) (ordered) (disordered) (ordered) These are “atomic networks” These are “atomic networks”

Liquid Glass Frozen Liquid Solid -●Disordered -●Flow -● Disordered -● Supports Shear -● Ordered -● Supports Shear T f or T l TcTc TgTg Glass Transition

● What is so special about these very select melts that can bypass crystallization and form a glass? ● Here I will show you that these melts possess an ideal connectivity. ● There are deep theoretical, applied and technological consequences of this finding.

Quartz (SiO 2 ) Crystal

Corning Glass   RYwS0 RYwS0     NDq-jmw&feature=fvsr NDq-jmw&feature=fvsr  

Si crystal structure Si crystal structure

Disordered- Ordered

● “r”, Coordination number, = 4 ●6 bond angles but only 5 are independent ●4 bonds ●Each bond-angle and bond-length serves as mechanical constraints. n c = = 7 ● n c = 2r-3 + r/2 = ( 5/2)r Tetrahedral Coordination

r = 2 n c = (5/2)r – 3 = 2 = Chain structure of crystalline Selenium

Degrees of freedom An atom moving in a 3D space can move either along the x- axis, or the y-axis or the z- axis. “An atom in 3D space has 3 degrees of freedom”.

Ideal networks ? ● Ideal networks form when the degrees of freedom exactly match the count of mechanical constraints. Thus, for example, a 3D network would be ideal if every atom in the network had 3 constraints on an average. ● Si is an example of a highly over-constrained network. There are n c = 7 constraints/atom. ● On the other hand, Se is an example of an under-constrained network, since n c = 2.

How are we to get an ideal network out Si and Se? ● If we were to mix 20 atoms of Si with 80- atoms of Se, what would be the count of atoms of Se, what would be the count of constraints for such a mixture? constraints for such a mixture? ● n c of a mixture of Si 20 Se 80 composition, ● n c of a mixture of Si 20 Se 80 composition, = 7 x x 0.80 = 3.0 = 7 x x 0.80 = 3.0 would become ideal !!!! would become ideal !!!! ● And one might expect these binary melts/ ● And one might expect these binary melts/ glasses to show anomalies near 20% of Si. glasses to show anomalies near 20% of Si.

In nature the glass forming tendency is optimized near this magic connectivity of In nature the glass forming tendency is optimized near this magic connectivity of n c = 3 !!!! n c = 3 !!!! - J.C. Phillips 1979 (Jour. Non Cryst. Solids) - J.C. Phillips 1979 (Jour. Non Cryst. Solids)

Thermally reversing window in binary GexSe100-x bulk glasses X.Feng et al. Phys. Rev. Lett. 78,4422(1997). S.Bhosle et al. Sol.St. Commun. 151, 1851(2011 ) P.B et al. in Rigidity and IPs, Chapter 1, Pp1-36 (2009).

Functional Disordered networks Each may have at its base a self-organized phase that endows these systems with unusual functionalities. Each may have at its base a self-organized phase that endows these systems with unusual functionalities. PB, G.Lucovsky, J.C.Phillips and M.F.Thorpe, Phil. Mag.85, 3823 (2005). PB, G.Lucovsky, J.C.Phillips and M.F.Thorpe, Phil. Mag.85, 3823 (2005). Window Glass Window Glass Self-organization Self-organization in oxide glass in oxide glass Electrical Eng. Electrical Eng. Thin-film gate Thin-film gate dielectrics dielectrics Biological Sciences Protein folding Protein folding Computer Science Computer Science Satisfiability Problems Satisfiability Problems Solid State Physics Solid State Physics Pairing in Oxide Pairing in Oxide Superconductors Superconductors Intermediate phases in glasses in glasses