Publications (27)
Pressure Raman effects and internal stress in network glasses
Fei Wang, S. Mamedov, P. Boolchand +2
Raman scattering from binary GexSe1-x glasses under hydrostatic pressure shows onset of a steady increase in the frequency of modes of corner-sharing GeSe4 tetrahedral units when t…
Elastic flexibility, fast-ion conduction, boson and floppy modes in AgPO3-AgI glasses examined in Raman scattering, IR reflectance, MDSC, ac electrical conductivity and molar volume experiments
Deassy I. Novita, P. Boolchand, Mohammed Malki +1
Raman scattering, IR reflectance and modulated DSC measurements are performed on specifically prepared dry (AgI)x(AgPO3)1-x glasses over a wide range of compositions 0 < x < 0.60.…
Fast-ion conduction and flexibility and rigidity of solid electrolyte glasses
M. Micoulaut, M. Malki, D. I. Novita +1
Electrical conductivity of dry, slow cooled (AgPO)(AgI) glasses is examined as a function of temperature, frequency and glass composition. From these data compositi…
Pressure Raman Effects and Internal Stress in Network Glasses
Fei Wang, Sergey Mamedov, P. Boolchand +2
Raman scattering from binary GexSe1-x glasses under hydrostatic pressure shows onset of a steady increase in the frequency of modes of corner-sharing GeSe4 tetrahedral units when t…
Meeting experimental challenges to physics of network glasses: assessing role of sample homogeneity
S. Bhosle, K. Gunasekera, P. Chen +3
We introduce a Raman profiling method to track homogenization of GeSe melts in real time, and show that 2 gram melts reacted at 950°C in high vacuum homogenize in 16…
Abrupt boundaries of intermediate phases and space filling in oxide glasses
K. Rompicharla, D. I. Novita, Ping Chen +3
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…
The Intermediate Phase in Ternary GexAsxSe1-2x Glasses
Tao Qu, D. G. Georgiev, P. Boolchand +1
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 Mossb…
Designing heavy metal oxide glasses with threshold properties from network rigidity
Shibalik Chakraborty, P. Boolchand, M. Malki +1
Here we show that a new class of glasses composed of heavy metal oxides involving transition metals (VO5-TeO), can surprisingly be designed from ve…
Superstrong nature of covalently bonded glass-forming liquids at select compositions
K. Gunasekera, S. Bhosle, P. Boolchand +1
Variation of fragility (m) of specially homogenized GexSe100-x melts are established from complex specific heat measurements, and show m(x) has a global minimum at an extremely low…
Aging, Fragility and Reversibility Window in Bulk Alloy Glasses
S. Chakravarty, D. G. Georgiev, P. Boolchand +1
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, w…
Self-Organization and the Physics of Glassy Networks
P. Boolchand, G. Lucovsky, J. C. Phillips +1
Network glasses are the physical prototype for many self-organized systems, ranging from proteins to computer science. Conventional theories of gases, liquids, and crystals do not…
Origin of giant photocontraction in obliquely deposited amorphous Ge_xSe_{1-x} thin- films and the intermediate phase
Mingji Jin, Ping Chen, P. Boolchand +4
Obliquely deposited amorphous Ge_xSe{1-x} thin-films at several compositions in the 0.15 < x < 0.333 range, and at several obliqueness angles in the 0 < alpha < 80 range at each x…
The Thermally Reversing Window in Ternary GexPxS1-2x glasses
U. Vempati, P. Boolchand
GexPxS1-2x glasses in the compositional range 0.05 < x < 0.19 have been synthesized and examined in temperature modulated differential scanning calorimetry (MDSC) and Raman scatter…
Rare-earth monosulfides as durable and efficient cold cathodes
M. Cahay, S. B. Fairchild, L. Grazulis +10
In their rocksalt structure, rare-earth monosulfides offer a more stable alternative to alkali metals to attain low or negative electron affinity when deposited on various III-V an…
Melt homogenization and self-organization of chalcogenides glasses: evidence of sharp rigidity, stress and nanoscale phase separation transitions in the GexSe100-x binary
S. Bhosle, K. Gunasekera, P. Boolchand +1
A Raman profiling method is used to monitor growth of GexSe100-x melts and reveals a two step process of homogenization. Resulting homogeneous glasses show the non-reversing enthal…
Raman scattering as a probe of intermediate phases in glassy networks
P. Boolchand, Mingji Jin, D. I. Novita +1
Bulk glass formation occurs over a very small part of phase space, and "good" glasses (which form even at low quench rates ~ 10K/sec) select an even smaller part of that accessible…
Intrinsic Nanoscale Phase Seperation of bulk As2S3 Glass
D. G. Georgiev, P. Boolchand, K. A. Jackson
Raman scattering on bulk AsxS1-x glasses showes that vibrational modes of As4S4 monomer first appear near x=0.38, and their concentration increases precipitously with increasing x,…
Onset of rigidty in glasses: from random to self-organized networks
M. Micoulaut, P. Boolchand, J. C. Phillips
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…
Direct evidence of rigidity loss and self-organisation in silicate glasses
Y. Vaills, T. Qu, M. Micoulaut +2
The Brillouin elastic free energy change between thermally annealed and quenched glasses is found to decrease linearly at (floppy phase), a…
Fragility and molar volumes of non-stoichiometric chalcogenides -- the crucial role of melt/glass homogenization
R. Bhageria, K. Gunasekera, P. Boolchand +1
Melt-fragility index (m) and glass molar volumes (Vm) of binary Ge-Se melts/glasses are found to change reproducibly as they are homogenized. Variance of Vm decreases as glasses ho…
Aging, Fragility and Reversibility Window in Bulk Alloy Glasses
S. Chakravarty, D. G. Georgiev, P. Boolchand +1
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, wit…
Long term aging of Selenide glasses: Evidence of sub-Tg endotherms and pre-Tg exotherms
Ping Chen, P. Boolchand, D. G. Georgiev
Long term aging is studied on several families of chalcogenide glasses including the Ge-Se, As-Se, Ge-P-Se and Ge-As-Se systems. Special attention is given to the As-Se binary, a s…
Fast-ion conduction and flexibility of glassy networks
Deassy I. Novita, P. Boolchand, M. Malki +1
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% an…
Intermediate phase, network demixing, boson and floppy modes, and compositional trends in glass transition temperatures of binary AsxS1-x system
Ping Chen, Chad Holbrook, P. Boolchand +3
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%<x<41%) of composi…
Intermediate Phases, structural variance and network demixing in chalcogenides: the unusual case of group V sulfides
P. Boolchand, Ping Chen, U. Vempati
We review Intermediate Phases (IPs) in chalcogenide glasses and provide a structural interpretation of these phases. In binary group IV selenides, IPs reside in the 2.40 < r < 2.54…
Reversibility Window, Aging, and Nanoscale Phase Separation in GexAsxS1-2x Bulk Alloy Glasses
Tao Qu, P. Boolchand
The non-reversing enthalpy near Tg, DHnr, in bulk GexAsxS1-2x glasses is found to display a global minimum (~0) in the 0.11 < x < 0.15 range, the reversibility window. Furthermore,…
Crucial effect of glass processing and melt homogenization on the fragility of non-stoichiometric chalcogenides
Sriram Ravindren, K. Gunasekera, Z. Tucker +3
The kinetics of homogenization of binary AsSe melts in the As concentration range are followed in FT-Raman profiling experiments, and show th…