A5104977402- Glass properties and applications
- Material Dynamics and Properties
- Phase-change materials and chalcogenides
- Conducting polymers and applications
- Polymer Nanocomposites and Properties
- Polymer crystallization and properties
- High-pressure geophysics and materials
- Solid-state spectroscopy and crystallography
- Polymer composites and self-healing
- Advanced Battery Materials and Technologies
- Aerogels and thermal insulation
- TiO2 Photocatalysis and Solar Cells
- Ultrasonics and Acoustic Wave Propagation
- Ga2O3 and related materials
- Polymer Science and PVC
- Laser-induced spectroscopy and plasma
- Optical and Acousto-Optic Technologies
- Geophysics and Gravity Measurements
- Geomagnetism and Paleomagnetism Studies
- Graphene research and applications
- Advanced Photocatalysis Techniques
- Theoretical and Computational Physics
- Luminescence Properties of Advanced Materials
- Quantum and electron transport phenomena
- ZnO doping and properties
University of Messina
2006-2022
Institute for Chemical and Physical Processes
2012-2020
Quaid-i-Azam University
2008
Malaysian Nuclear Agency
2008
Ghulam Ishaq Khan Institute of Engineering Sciences and Technology
2008
Istituto di Metodologie Chimiche
1993-1995
Istituto Nazionale per la Fisica della Materia
1990
Azienda Ospedaliera Ospedali Riuniti Papardo Piemonte
1987
Institute of Structure of Matter
1976
We measured the density of vibrational states (DOS) and specific heat various glassy crystalline polymorphs ${\mathrm{SiO}}_{2}$. The typical (ambient) glass shows a well-known excess relative to crystal ($\ensuremath{\alpha}$-quartz). This, however, holds when comparing lower-density higher-density crystal. For with matched densities, DOS appears as smoothed counterpart corresponding crystal; it reveals same number Debye model, all in low-energy region, provides heat. This that glasses have...
Low-frequency Raman spectra of metaphosphate glasses (${\mathrm{Sm}}_{2}$${\mathrm{O}}_{3}$${)}_{\mathit{x}}$(${\mathrm{P}}_{2}$${\mathrm{O}}_{5}$${)}_{1\mathrm{\ensuremath{-}}\mathit{x}}$, (${\mathrm{Eu}}_{2}$${\mathrm{O}}_{3}$${)}_{\mathit{x}}$(${\mathrm{P}}_{2}$${\mathrm{O}}_{5}$${)}_{1\mathrm{\ensuremath{-}}\mathit{x}}$, (${\mathrm{Gd}}_{2}$${\mathrm{O}}_{3}$${)}_{\mathit{x}}$(${\mathrm{P}}_{2}$${\mathrm{O}}_{5}$${)}_{1\mathrm{\ensuremath{-}}\mathit{x}}$, and ${\mathrm{GeO}}_{2}$ have...
The dependence of the boson peak on alkaline ion in modified borate glasses ${({M}_{2}\mathrm{O})}_{0.14}{({\mathrm{B}}_{2}{\mathrm{O}}_{3})}_{0.86}$ $({M}^{+}={\mathrm{Li}}^{+},{\mathrm{Na}}^{+},{\mathrm{K}}^{+},{\mathrm{Cs}}^{+})$ was analyzed by performing Raman spectroscopy, inelastic neutron scattering, and low-temperature specific-heat measurements. It is found that distribution vibrations merging into shifts to higher frequency going from cesium lithium. A linear correlation between...
A study of low temperature specific heat capacity (1–30 K) has been performed on samples vitreous SiO2, which have compacted under pressures up to 8 GPa explore different glassy phases having growing density. Increasing densification by more than 21% leads a progressive reduction the C p and shift from 10 K about 17 broad hump, calorimetric Boson peak (BP), observed above 1 in (T)/T 3 vs. T plot. The revealed changes are not accounted for modifications elastic continuum, implying nature...
A comparative study of Raman scattering and low temperature specific heat capacity has been performed on samples B2O3, which have high-pressure quenched to go through different glassy phases having growing density the crystalline state. It revealed that excess volume characterizing networks favors formation structural units, boroxol rings, produce boson peak, a broad band energy vibrational states. The decrease rings with increasing pressure synthesis is associated progressive depression...
Comparative measurements of Brillouin light scattering and ultrasounds in a wide class silica aerogels xerogels show the existence distinct mechanisms governing temperature behaviors acoustic attenuation different frequency ranges. In MHz range is mainly regulated by dynamical due (i) to thermally activated local motions structural defects typical vitreous at low temperatures (ii) relaxations ``extrinsic'' high temperatures, i.e., hydroxyl groups covering inner surface pores aerogels. range,...
The attenuation and velocity of ultrasonic waves frequencies in the range $10\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}70\phantom{\rule{0.3em}{0ex}}\mathrm{MHz}$ have been measured ${({\mathrm{Li}}_{2}\mathrm{O})}_{x}{({\mathrm{B}}_{2}{\mathrm{O}}_{3})}_{1\ensuremath{-}x}$ borate glasses as a function temperature between 1.5 $300\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Two distinct features characterize behavior: (i) plateau at temperatures below...
The fragility and the anharmonicity of (Ag2O)x(B2O3)1−x borate glasses have been quantified by measuring change in specific heat capacity at glass transition temperature Tg room-temperature thermodynamic Grüneisen parameter. Increasing silver oxide content above X = 0.10 leads to an increase both parameters, showing that a growing glass-forming liquid is predictive increasing overall its glassy state. attenuation velocity ultrasonic waves frequencies range 10–70 MHz also measured as function...
Abstract The Raman spectra of metaphosphate glasses, which contain very high concentrations either Eu3+ or Gd3+ ions, have been measured over a wide range temperatures (10–300 K). high-frequency part the spectrum (above 200 cm−1) is similar to that found for other phosphate indicating these glasses share common structural feature skeleton built up from (PO4)2 tetrahedral units. low-frequency region determined by two spectral contributions are characteristic disordered topology vitreous...
The elastic and anelastic properties of densified B${}_{2}$O${}_{3}$ glasses, melt quenched under pressures 2 4 GPa, were investigated by measuring the sound velocity acoustic attenuation longitudinal shear ultrasonic waves in megahertz range over temperature interval between 8 300 K. Densification from 1826 to 2373 kg/m${}^{3}$ leads an extraordinarily large growth both bulk moduli but leaves Poisson's ratio nearly constant. In glass compacted at become larger a factor five than those...
Low-temperature experiments of Raman scattering and heat capacity have been performed in a B2O3 glass, pressure quenched from 1200 °C order to obtain the density as largest possible (ρ = 2373 kg/m3). When compared those compacted glasses having smaller density, spectrum this glass exhibits strong decrease intensities Boson peak band at 808 cm−1, both features being determined by boroxol ring population. Moreover, large shift 68 cm−1 (from 26 observed normal vitreous B2O3). The high atomic...
The physical properties of disordered systems are in the focus a large research effort. In particular, one open problems related to glasses is their excess modes THz frequency range over vibrational contribution predicted by Debye model. fact, could expect continuum approximation underlying model hold at long wavelengths least as well crystalline solids. Experiments, instead, seem indicate that specific heat low temperature (a few Kelvin) and density states terahertz) very different from...
Polymeric electrolytes of the poly(ethylene) oxide (PEO) potassium thiocyanate system have been studied by analyzing temperature dependence low-frequency (0.3–30 Hz) mechanical characteristics. It is found that local and cooperative molecular motions characterizing host polymer are strongly influenced addition salt, as a result strong interactions between polymeric chains alkaline salt molecules, which ensure formation homogeneous complexes. In low-concentration region (molar fraction...
We describe the neutron diffraction patterns of a series alkaline borate glasses at different metal oxide content. Strong differences are observed in intermediate range order as function specific ion and its concentration. On these results, we propose that first sharp peak arises from correlations atoms voids show compositional variation this intensity is due to changes distribution void sizes within three-dimensional network. argue our interpretation terms interstitial (empty and/or filled)...
The attenuation and velocity of ultrasonic waves frequencies in the range 10 to 90 MHz have been measured ${\mathrm{La}}_{2}$${\mathrm{O}}_{3\mathrm{\ensuremath{-}}}$${\mathrm{P}}_{2}$${\mathrm{O}}_{5}$ ${\mathrm{Sm}}_{2}$${\mathrm{O}}_{3\mathrm{\ensuremath{-}}}$${\mathrm{P}}_{2}$${\mathrm{O}}_{5}$ glasses with high lanthanide concentrations as a function temperature between 1.5 400 K. Two distinct features characterize behavior: (i) plateau at temperatures below 15 K (ii) broad...
Abstract A study of the thermal and mechanical properties new semi-interpenetrating polymer networks (IPN's) based on linear polyurethane (PU) crosslinked trimerized dicyanate (TDC) reveals existence structures characterized by absence chemical interactions. Two distinct glass transitions are observed in thermograms, as an indication fact that two polymeric components preserve their molecular structure. The interpenetration affects markedly transition temperatures revealed pure consequence...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation M. K. Ahmad, N. A. Rasheid, Zain Ahmed, S. Abdullah, Rusop; Effect of Annealing Temperature on Titanium Dioxide Thin Films Prepared by Sol Gel Method. AIP Conf. Proc. 20 May 2008; 1017 (1): 109–113. https://doi.org/10.1063/1.2940607 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends...
Specific heat was measured over the temperature range 0.4–25 K in GeO2 glasses, compacted at pressures of 2 and 6 GPa to achieve more than 20% densification. Above 1 K, specific C reduced by up a factor 2.5 with increasing density; variation being stronger that observed below K. The broad peak above C/T 3 vs. T plot shifted higher temperatures density, exhibiting changes which cannot be explained modifications elastic continuum. In addition, showed no shape, clearly indicating overall...