79 research outputs found
Effect of cluster size of chalcogenide glass nanocolloidal solutions on the surface morphology of spin-coated amorphous films
Amorphous chalcogenide thin film deposition can be achieved by a spin-coating
technique from proper solutions of the corresponding glass. Films produced in
this way exhibit certain grain texture, which is presumably related to the
cluster size in solution. This paper deals with the search of such a
correlation between grain size of surface morphology of as-deposited
spin-coated As33S67 chalcogenide thin films and cluster size of the glass in
butylamine solutions. Optical absorption spectroscopy and dynamic light
scattering were employed to study optical properties and cluster size
distributions in the solutions at various glass concentrations. Atomic force
microscopy is used to study the surface morphology of the surface of
as-deposited and thermally stabilized spin-coated films. Dynamic light
scattering revealed a concentration dependence of cluster size in solution.
Spectral-dependence dynamic light scattering studies showed an interesting
athermal photo-aggregation effect in the liquid state.Comment: 15 pages, 8 figure
Intermediate phase, network demixing, boson and floppy modes, and compositional trends in glass transition temperatures of binary AsxS1-x system
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 compositions. We observe a reversibility window
in the calorimetric experiments, which permits fixing the three elastic phases;
flexible at x<22.5%, intermediate phase (IP) in the 22.5%<x<29.5% range, and
stressed-rigid at x>29.5%. Raman scattering supported by first principles
cluster calculations reveal existence of both pyramidal (PYR, As(S1/2)3) and
quasi-tetrahedral(QT, S=As(S1/2)3) local structures. The QT unit concentrations
show a global maximum in the IP, while the concentration of PYR units becomes
comparable to those of QT units in the phase, suggesting that both these local
structures contribute to the width of the IP. The IP centroid in the sulfides
is significantly shifted to lower As content x than in corresponding selenides,
a feature identified with excess chalcogen partially segregating from the
backbone in the sulfides, but forming part of the backbone in selenides. These
ideas are corroborated by the proportionately larger free volumes of sulfides
than selenides, and the absence of chemical bond strength scaling of Tgs
between As-sulfides and As-selenides. Low-frequency Raman modes increase in
scattering strength linearly as As content x of glasses decreases from x = 20%
to 8%, with a slope that is close to the floppy mode fraction in flexible
glasses predicted by rigidity theory. These results show that floppy modes
contribute to the excess vibrations observed at low frequency. In the
intermediate and stressed rigid elastic phases low-frequency Raman modes
persist and are identified as boson modes. Some consequences of the present
findings on the optoelectronic properties of these glasses is commented upon.Comment: Accepted for PR
The Proceedings of the Fourth International Conference of the Association of Architecture Schools of Australasia
The Proceedings of the Fourth International Conference of the Association of Architecture
Schools of Australasia.
Each paper in the Proceedings has been double refereed by members of an independent panel
of academic peers appointed by the Conference Committee. Papers were matched, where
possible, to referees in the same field and with similar interests to the authors
Materiály pro paměti založených na optických a elektrických fázových změnách - struktura, vlastnosti a aplikace
A review of materials and principles used in optical and electrical data storage based on phase changes is given, the composition structure, properties and the ways of preparation of thin films of the materials already used, or potentially applicable, are discussed. The problems of fast crystallization and amorphization as well as problems of stability of amorphous state and of the storage at elevated temperatures are mentioned
Poslední výsledky studia materiálů pro paměti s fázovými změnami
Recent results of the study of phase change materials, of their structure, composition, properties and models fast crystallization and amorphization are discussed
Structure and optically induced changes of reactivity and optical properties of amorphous chalcogenides
Recent results of authors and other laboratories were reviewedand relations among structure, its changes, reactivity and otherphysical, chemical properties of amorphous chalcogenide werepresented
Photoinduced changes of structure and properties of amorphous chalcogenides, description, interpretation
Changes of properties and structure of thin films of amorphous chalcogenides were disscused, a model proposed and possible applications described
Photoinduced surface deformations in ion-conducting Ag–As–S glasses. I. Isotropic deformations produced by small light spots
Prominent surface deformations appear in Ag–As–S chalcogenide glasses when exposed to focused laser beams. Deformation behaviors change with the beam diameter, the photon energy, the temperature at which illumination is provided, and the sample composition. In thin AgAsS2 films exposed at room temperature to a 2.0 eV light spot with a diameter of 2 µm, an isotropic convex structure with a height of ~0.1 µm appears. The expanded region accompanies an Ag-content enhancement by ~3 at. %, which suggests that the deformation is caused by photoinduced accumulation of Ag + ions
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