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April 6, 2009

Shear modulus and compliance in the range of the dynamic glass transitionfor metallic glasses

Filed under: Glasses 1998 — admin @ 11:45 am


The dynamic shear modulus and compliance of the dynamic glass transition wereinvestigated in two metallic glasses (Pd_(40)Ni_(40)P_(20) and Zr_(65)Al_(7.5)Cu_(17.5)Ni_(10).Isothermal measurements over four frequency decades enable the determination of shape parameters forthe proper glass transition. The real part of the dynamic shear compliance shows a step height ofapproximately a factor of 2.6 for Pd_(40)Ni_(40)P_(20), comparable to low molecular weight glassformers or the segmental mode as part of the glass transition in high molecular weight polymers. Thefrequency dependence of the imaginary part of the shear compliance at the high frequency side ofthe peak shows an exponent near the Andrade value of 1/3.

K. Schroter G. Wilde R. Willnecker M. Weiss K. Samwer E. Donth

EPR structural characterisation of some alkali phosphate glasses

Filed under: Glasses 1998 — admin @ 11:42 am

It is known that W5+, Mo5+, and Fe3+ ions are sensitive indicators for thestructural changes of the local symmetry in oxide glasses. Thus, these centres were used as EPRprobes in P2O5-A(2)MO(4)-A(2)O (M=Mo, W and A=Li, Na). The M5+ ions are located in a distortedenvironment. Their symmetry is lowered as A(2)O content is high. In iron-dopped glasses Fe3+ centresoccupy distorted octahedra. The distortion extent is less than 7%. Radiation-induced defects havebeen detected, it is concerned with a PO42- centre and peroxy radicals.

Boudlich D. Archidi ME. Haddad M. Nadiri A. Berger R. Yahiaoui EM.

Contribution of theoretical chemistry to the investigation of optical nonlinearities in glasses

Filed under: Glasses 1998 — admin @ 11:39 am

The origin of optical non-linear response has been investigated in titaniumand niobium borophosphate glasses and in tellurite glasses. Correlations between the local structureof polarizable entities within the glasses and their optical activities have been tentativelyestablished through a semi-empirical model and ab-initio calculations.

Fargin E. Cardinal T. Videau JJ. Villesuzzanne A. Le Flem G. Berthereau A.

Minimax games, spin glasses, and the polynomial-time hierarchy of complexityclasses

Filed under: Glasses 1998 — admin @ 11:28 am

We use the negative replica method, which was originally developed for thestudy of overfrustation in disordered systems, to investigate the statistical behavior of the costfunction of minimax games. These games are treated as hierarchical statistical mechanical systems,in which one of the components is at negative temperature. [References: 13]

Varga P.

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