Scientific innovations and applications- the key to growth and sustenance of quality of life in the...

Scientific innovations and applications- the key to growth and sustenance of quality of life in the 21st century

Kapila Gunasekera, Shibalik Chakraborty, Chad Holbrook, Sriram Ravindren and Vignarooban Kandasamy, and Punit Boolchand University of Cincinnati http://www.ece.uc.edu/~pboolcha/

25 new 25 new discoveries of discoveries of 2012 , 2012 ,

Time Magazine, Time Magazine, Nov. 12, 2012Nov. 12, 2012

Solar –powered distillerSolar –powered distiller

States of matter States of matter

Liquids Liquids → Solids→ Solids

water icewater ice

((disordereddisordered) () (orderedordered))

These are “These are “atomicatomic networksnetworks””

Liquid

GlassFrozen Liquid Solid

- ●Disordered- ●Flow

- ●Disordered- ●Supports Shear

- ●Ordered- ●Supports Shear

Tf or Tl

Tc

Tg GlassTransition

●●What is so special about these very What is so special about these very select melts that can bypass select melts that can bypass

crystallization and form a glasscrystallization and form a glass? ?

● ● Here I will show you that these melts Here I will show you that these melts possess an possess an ideal connectivityideal connectivity..

●●There are deep There are deep theoretical, applied and theoretical, applied and technological consequences of this technological consequences of this finding. finding.

Quartz (SiO2) Crystal

Corning Glass Corning Glass

https://www.youtube.com/watch?v=aVxj6gRYwS0

  https://www.youtube.com/watch?v=FCR8

NDq-jmw&feature=fvsr  

3 4 5 6 7

Si crystal structureSi crystal structure

Disordered- OrderedDisordered- 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. nc = 5 + 2 = 7

● nc = 2r-3 + r/2 = ( 5/2)r - 3

1

2

3

4 0

Tetrahedral Coordination

r = 2r = 2

nncc = (5/2)r – 3 = (5/2)r – 3

= 2= 2

1

2

3

Chain structure of crystalline Selenium

Degrees of freedomDegrees of freedom

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

Ideal networks ? Ideal networks ? ● ● Ideal networks form when the degrees of freedom Ideal networks form when the degrees of freedom exactly match the count of mechanical constraintsexactly match the count of mechanical constraints. . Thus, for example, a 3D network would be ideal if Thus, for example, a 3D network would be ideal if every atom in the network had 3 constraints on an every atom in the network had 3 constraints on an average.average.

● ● Si is an example of a highly over-constrained Si is an example of a highly over-constrained network. There are nnetwork. There are ncc = 7 constraints/atom. = 7 constraints/atom.

● ● On the other hand, Se is an example of an under-On the other hand, Se is an example of an under-constrained network, since nconstrained network, since ncc = 2. = 2.

How are we to get an ideal How are we to get an ideal network out Si and Se? network out Si and Se?

● ● If we were to mix 20 atoms of Si with 80-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?

●● nncc of a mixture of Si of a mixture of Si2020SeSe8080 composition, composition,

= 7 x 0.20 + 2 x 0.80 = 3.0= 7 x 0.20 + 2 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 Siglasses to show anomalies near 20% of Si. .

In nature the glass forming In nature the glass forming tendency is tendency is optimizedoptimized near this near this magic connectivity of magic connectivity of

nncc = 3 !!!! = 3 !!!!

- - J.C. Phillips 1979 (Jour. Non Cryst. Solids) J.C. Phillips 1979 (Jour. Non Cryst. Solids)

Thermally reversing window in binary GexSe100-Thermally reversing window in binary GexSe100-x bulk glassesx 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 Functional Disordered networksnetworks

Each may have at its base a self-organized phase that Each may have at its base a self-organized phase that endows these systems with unusual functionalities.endows these systems with unusual functionalities.

PB, G.Lucovsky, J.C.Phillips and M.F.Thorpe, Phil. PB, G.Lucovsky, J.C.Phillips and M.F.Thorpe, Phil. Mag.Mag.8585, 3823 (2005)., 3823 (2005).

Window GlassWindow Glass Self-organizationSelf-organization

in oxide glassin oxide glass

Electrical EngElectrical Eng.. Thin-film gateThin-film gate

dielectricsdielectrics

Biological SciencesBiological Sciences Protein foldingProtein folding

Computer ScienceComputer Science Satisfiability ProblemsSatisfiability Problems

Solid State PhysicsSolid State Physics Pairing in Oxide Pairing in Oxide SuperconductorsSuperconductors

Intermediate phasesIntermediate phases in glassesin glasses