Search results for "amorphous"

PATTERNED LASER CRYSTALLIZATION OF a-Si

2009

PATTERNED LASER CRYSTALLIZATION OF a-SiThin films of amorphous Si on glass were crystallized by pulsed nano- and picosecond lasers. Two methods for creating the desired patterns of crystallized regions were used. In the former, the pattern is produced by a focused laser beam, and in the latter it is made using a prefabricated mask. The electric conductivity of crystallized films increases by more than 4 orders of magnitude in comparison with untreated amorphous films.

Synthesis and nonlinear optical properties of novel N,N-dihydroxyethyl-based molecular organic glasses using triaryl substitutes as amorphous phase f…

2011

In given study a new structural design of molecular NLO materials is presented where amorphous phase formation is achieved by introduction of bulky trityl and triphenylsilyl substituents. Obtained materials formed stable organic glasses with good optical quality and glass transition temperatures notably exceeding ambient. NLO activity was successfully measured in samples that underwent corona discharge poling. The comparison of both enhancer groups revealed, that trityl group increases thermal sustainability of material, while triphenylsilyl group better promotes formation and stability of amorphous phase.

Effect of structure relaxation on the holographic recording in amorphous As2S3 films

1997

Abstract Results of the experimental studies of holographic recording in a-As 2 S 3 films, such as exposure and intensity dependences, spatial frequency dependence, are reported. Several peculiarities are found including recording intensity threshold, nonmonotonical intensity dependences, nonlinear exposure curves, the change of the spatial frequency response due to film aging. These peculiarities are explained in terms of the phenomenological model which is based on the simultaneous action of the photostructural changes and the relaxational structural changes.

Selective growth and optical properties of sputtered BaTiO3films

2000

we report the growth of BaTiO 3 thin films by standard Radio Frequency sputtering. Without any in situ or post annealing, these polycristalline films are oriented relative to the substrate even when it is amorphous. We show that this preferential orientation may be monitored using a DC Bias during the film growth. At room temperature, cubic films of (100) and (110) orientations have been achieved, on fused silica substrate. Some optical waveguiding properties of these films have been studied. The resulting film index is 2.26 and the optical step index at the substrate interface is sharp. This allows the use of standard RF sputtering techniques to monitor oriented BaTiO 3 films for linear op…

Characterization of thin superconducting YBaCuO-films by Raman-spectroscopy

1988

We have investigated thin sputtered films of the high Tc material YBa2Cu3O7 by means of Raman spectroscopy at different stages of the preparation process. We find that the films are amorphous after sputtering. The Raman spectra indicate that random polycrystalline layers, as well as crystalline layers with preferred orientation, are obtained by an additional thermal treatment.

Insights into the In Vitro Formation of Apatite from Mg‐Stabilized Amorphous Calcium Carbonate

2020

Molybdenum thin-film growth on rutile titanium dioxide ()

2002

Molybdenum films were deposited at room temperature on rutile TiO2(1 1 0) surfaces having different stoichiometries, surface roughnesses and crystallinities. The film structures and compositions and the substrate–film interfaces were investigated by X-ray diffraction, high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy. Different substrate pretreatments resulted in markedly different film and interface structures. Under the growth conditions studied, no amorphous molybdenum oxide interlayers were formed upon deposition in contrast to previous studies. Preferred (1 1 0) textured Mo films grew on both air-annealed and oxygen-bombarded substrates. While sh…

Oxygen K-edge x-ray absorption near-edge structure in crystalline and amorphous molybdenum trioxides

2004

X-ray absorption near-edge structure (XANES) signals at the oxygen K edge in polycrystalline α-MoO3 and amorphous a-MoO3 thin film were analysed within the full-multiple-scattering (FMS) formalism. Significantly different XANES signals were found for non-equivalent oxygen atoms in low-symmetry layered-type α-MoO3 structure. The obtained results are in agreement with the experimental data and allow us to interpret all XANES peaks for α-MoO3. Besides, the FMS XANES simulations, performed for several fragments of α-MoO3 structure, allowed us to explain the O K-edge XANES in amorphous a-MoO3 thin film. We found that although the crystallographic structures of α-MoO3 and a-MoO3 are strongly diff…

High-Temperature Stable Gold Nanoparticle Catalysts for Application under Severe Conditions: The Role of TiO2 Nanodomains in Structure and Activity

2015

Metal nanoparticles with precisely controlled size are highly attractive for heterogeneous catalysis. However, their poor thermal stability remains a major concern in their application at realistic operating conditions. This paper demonstrates the possibility of synthesizing gold nanoparticles with exceptional thermal stability. This has been achieved by using a simple conventional deposition–precipitation technique. The material employed as catalyst consists of gold supported on a TiO2-impregnated SiO2 bimodal mesoporous support. The resulting material shows gold nanoparticles with a narrow size distribution around 3.0 nm, homogeneously dispersed over the TiO2/SiO2 material. Most interesti…

Morphological and Chemical Evolution of Gradually Deposited Diamond-Like Carbon Films on Polyethylene Terephthalate: From Subplantation Processes to …

2016

Diamond-like carbon (DLC) films on polyethylene terephthalate (PET) are nowadays intensively studied composites due to their excellent gas barrier properties and biocompatibility. Despite their applicative features being highly explored, the interface properties and structural film evolution of DLC coatings on PET during deposition processes are still sparsely investigated. In this study two different types of DLC films were gradually deposited on PET by radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) using acetylene plasma. The surface morphology of the deposited samples has been analyzed by atomic force microscopy (AFM). Their chemical composition was investigated by …