Fast-ion conduction and flexibility and rigidity of solid electrolyte glasses (2009)
Micoulaut, M., Malki, M., Novita, D. I., Boolchand, P.
Electrical conductivity of dry, slow cooled (AgPO$_3$)$_{1-x}$(AgI)$_x$ glasses is examined as a function of temperature, frequency and glass composition. From these data compositional trends in...
Understanding amorphous phase-change materials from the viewpoint of Maxwell rigidity (2009)
Micoulaut, M., Raty, J-Y., Otjacques, C., Bichara, C.
Phase-change materials (PCMs) are the subject of considerable interest because they have been recognized as potential active layers for next-generation non-volatile memory devices, known as Phase...
Atomic structure of the two intermediate phase glasses SiSe4 and GeSe4 (2009)
Massobrio, C., Celino, M., Salmon, Philip S, Martin, R A, Micoulaut, M., Pasquarello, A.
The microscopic origin of the intermediate phase in two prototypical covalently bonded A(x)B(1-x) network glass forming systems, where A=Ge or Si, B=Se, and 0
The role of the exchange-correlation functional on the network structure of liquid GeSe$_2$ (2008)
Micoulaut, M., Vuilleumier, R., Massobrio, C.
The structural properties of liquid GeSe$_2$ are studied by using first-principles molecular dynamics in conjuncton with the Becke, Lee, Yang and Parr (BLYP) generalized gradient approximation for...
Chen, Ping, Holbrook, Chad, Boolchand, P., Georgiev, D. G., Jackson, K. A., Micoulaut, M.
The structure of binary As_xS_{1-x} glasses is elucidated using modulated-DSC, Raman scattering, IR reflectance and molar volume experiments over a wide range (8%
Abrupt boundaries of intermediate phases and space filling in oxide glasses (2008)
Rompicharla, K., Novita, D. I., Chen, Ping, Boolchand, P., Micoulaut, M., Huff, W.
Modulated DSC measurements on bulk (Na2O)x(GeO2)1-x glasses show a sharp reversibility window in the 14% < x < 19% soda range, which correlates well with a broad global minimum in molar volumes....
Fast-ion conduction and flexibility of glassy networks (2007)
Novita, Deassy I., Boolchand, P., Malki, M., Micoulaut, M.
We observe two thresholds in the variations of electrical conductivity of dry solid electrolyte (AgI)x(AgPO3)1-x glasses, when the AgI additive concentration x increases to 9.5% and to 37.8%. Raman...
Aging, Fragility and Reversibility Window in Bulk Alloy Glasses (2007)
Chakravarty, S., Georgiev, D. G., Boolchand, P., Micoulaut, M.
Non-reversing relaxation enthalpies (DHnr) at glass transitions Tg(x) in the PxGexSe1-2x ternary display wide, sharp and deep global minima (~ 0) in the 0.09 < x < 0.145 range, within which Tgs...
The structure of amorphous, crystalline and liquid GeO2 (2006)
Micoulaut, M., Cormier, L., Henderson, G. S.
Germanium dioxide ($GeO_2$) is a chemical analogue of $SiO_2$. Furthermore, it is also to some extent a structural analogue, as the low and high-pressure short-range order (tetrahedral and...
Onset of rigidty in glasses: from random to self-organized networks (2006)
Micoulaut, M., Boolchand, P., Phillips, J. C.
We review in this paper the signatures of a new elastic phase that is found in glasses with selected compositions. It is shown that in contrast with random networks, where rigidity percolates at a...
Micoulaut, M., Mechkov, S., Retraint, D., Viot, P., Francois, M.
The behavior of an ultrasonic shot peening process is observed and analyzed by using a model of inelastic hard spheres in a gravitational field that are fluidized by a vibrating bottom wall...
Direct evidence of rigidity loss and self-organisation in silicate glasses (2005)
Vaills, Y., Qu, T., Micoulaut, M., Chaimbault, F., Boolchand, P.
The Brillouin elastic free energy change $DF$ between thermally annealed and quenched $(Na_2O)_x(SiO_2)_{1-x}$ glasses is found to decrease linearly at $x > 0.23$ (floppy phase), and to nearly vanish...
Correlation between floppy to rigid transitions and non-Arrhenius conductivity in glasses (2005)
Malki, M., Micoulaut, M., Chaimbault, F., Vaills, Y.
Non-Arrhenius behaviour and fast increase of the ionic conductivity is observed for a number of potassium silicate glasses $(1-x)SiO_2-xK_2O$ with potassium oxide concentration larger than a certain...
Raman thresholds and rigid to floppy transitions in calcium silicate glasses (2004)
Micoulaut, M., Malki, M., Simon, P., Canizares, A.
Alkaline earth silicate glasses $xCaO-(1-x)SiO_2$ exhibit a well marked threshold in Raman lineshapes which can be related to the onset of network rigidity as the concentration of calcium oxide $x$...
Direct evidence of rigidity loss and self-organisation in silicate glasses (2004)
Vaills, Y., Qu, T., Micoulaut, M., Chaimbault, F., Boolchand, P.
The Brillouin elastic free energy change $DF$ between thermally annealed and quenched $(Na_2O)_x(SiO_2)_{1-x}$ glasses is found to decrease linearly at $x > 0.23$ (floppy phase), and to nearly vanish...
Direct evidence of rigidity loss and self-organisation in silicate glasses (2004)
Vaills, Y., Qu, T., Micoulaut, M., Chaimbault, F., Boolchand, P.
The Brillouin elastic free energy change $DF$ between thermally annealed and quenched $(Na_2O)_x(SiO_2)_{1-x}$ glasses is found to decrease linearly at $x > 0.23$ (floppy phase), and to nearly vanish...
Direct evidence of rigidity loss and self-organisation in silicate glasses (2004)
Vaills, Y., Qu, T., Micoulaut, M., Chaimbault, F., Boolchand, P.
The Brillouin elastic free energy change $DF$ between thermally annealed and quenched $(Na_2O)_x(SiO_2)_{1-x}$ glasses is found to decrease linearly at $x > 0.23$ (floppy phase), and to nearly vanish...
Ageing, fragility and the reversibility window in bulk alloy glasses
Percolative conductivity in alkaline earth silicate melts and glasses (2003)
Malki, M., Micoulaut, M., Chaimbault, F., Vaills, Y., Simon, P.
Ion conducting $(CaO)_x(SiO_2)_{1-x}$ glasses and melts show a threshold behaviour in dc conductivity near $x=x_t=0.50$, with conductivities increasing linearly at $x>x_t$. We show that the behaviour...
The Intermediate Phase in Ternary GexAsxSe1-2x Glasses (2003)
Qu, Tao, Georgiev, D. G., Boolchand, P., Micoulaut, M.
Melt-quenched AsxGexSe1-2x glasses over the composition range, 0 < x < 0.26, are examined in Raman scattering, T-modulated Differential Scanning Calorimetry (MDSC), and 119Sn Mossbauer spectroscopy...
Aging, Fragility and Reversibility Window in Bulk Alloy Glasses (2003)
Chakravarty, S., Georgiev, D. G., Boolchand, P., Micoulaut, M.
Non-reversing relaxation enthalpies (DHnr) at glass transitions Tg(x) in the PxGexSe1-2x ternary display a wide, sharp and deep global minimum (~0) in the 0.09 < x < 0.145 range, within which Tg...
Tao Qu, D. G. Georgiev, P. Boolch, M. Micoulaut
Melt-quenched AsxGexSe1-2x glasses over the composition range, 0 < x < 0.26, are examined in Raman scattering, T-modulated Differential Scanning Calorimetry (MDSC), and 119 Sn Mossbauer...
Rings and rigidity transitions in network glasses (2002)
Micoulaut, M., Phillips, J. C.
Three elastic phases of covalent networks, (I) floppy, (II) isostatically rigid and (III) stressed-rigid have now been identified in glasses at specific degrees of cross-linking (or chemical...
Glass structure, rigidity transitions and the intermediate phase in the Ge -As -Se ternary (2000)
Y. Wang, P. Boolch, M. Micoulaut
Abstract. – The non-reversing heat flow, ∆Hnr(x) nearTg in ternary GexAsxSe1−2x glasses is examined by temperature-modulated differential scanning calorimetry. The ∆Hnr(x) term shows a deep...
On the glass transition temperature in covalent glasses (1998)
We give a simple demonstration of the formula relating the glass transition temperature, $T_g$, to the molar concentration $x$ of a modifier in two types of glasses: binary glasses, whose composition...
We give in this letter a set of general rules which allow the prediction of the value of the glass transition temperature $T_g$ in network glasses. Starting from the Gibbs-Di Marzio law which gives a...