Lusitra Munisa

Infrared absorption in a-SiC:H alloy prepared by d.c. sputtering

Abstract Infrared absorption and hydrogen effusion were measured on silicon rich a-SiC:H films deposited by d.c. sputtering. Hydrogen concentration was changed by hydrogen implantation. The results show that the shift of the SiH stretching absorption from 2000 to 2100 cm−1 with increasing carbon concentration is mainly due to hydrogen-related void formation. The absorption strength of SiH stretching and wagging absorptions are found to be independent of carbon concentration. The data suggest that both 720 and 780 cm−1 absorptions are due to CSi stretching vibrations with the 720 cm−1 absorption presumably related to HSiC groups. Under the deposition condition applied, these HSiC groups are the predominant sites for hydrogen and carbon incorporation.

Helium effusion measurements for studying the microstructure of a-SiC:H films deposited by d.c. sputtering

Abstract The effusion of helium was used for microstructure characterisation of d.c. sputtered amorphous silicon carbon (a-SiC:H) alloys. The results show that up to carbon concentrations of approximately 25 at.%, helium effuses mainly in two stages: a lower temperature effusion peak near 500 °C is attributed to the out-diffusion of He from network sites while higher temperature He effusion is attributed to the release of He precipitated in isolated voids present from the deposition process. At carbon concentrations exceeding 25 at.%, helium is found to effuse predominantly in a single stage at lower temperature indicating the presence of interconnected voids. The results are in agreement with effusion results of implanted neon, argon as well as hydrogen.

Sono- and photocatalytic activities of SnO2 nanoparticles for degradation of cationic and anionic dyes

The current research work focuses on the catalytic activity of SnO2 nanoparticles (NPs) against degradation of both cationic dye (methylene blue) and anionic dye (Congo-red). SnO2 NPs were synthesized under the sol-gel method and were characterized by performing X-ray diffraction, Fourier Transform Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM) Brunauer-Emmet-Teller (BET) surface area analysis and UV-Vis spectroscopy. The results demonstrate that SnO2 NPs has well crystalline structure with the crystallite size of 44 nm. The degradation of dyes was studied under ambient temperature using ultrasonicator and UV light, respectively. The sono- and photocatalytic activities of SnO2 NPs on dyes were analyzed by measuring the change in absorbance of dyes under UV-spectrophotometer. The degradation of the organic dyes has been calculated by monitoring the degradation in the concentration of the dyes before and after irradiation of ultrasonic and light, respectively. The influence of other p...

The influence of two-type graphene material on photocatalytic activity of ZrO2 nanoparticles under UV light irradiation

In this study, ZrO2/nanographene platelets (NGP) and ZrO2/graphene composites were fabricated by depositing ZrO2 nanoparticles onto nanographene platelets and graphene surfaces to develop photocatalysts. ZrO2/NGP and ZrO2/graphene were successfully synthesized using the co-precipitation method. The physicochemical characteristics were studied through X-ray diffraction, transmission electron microscope, energy dispersive X-ray analysis, Brunauer-Emmett-Teller method and infrared absorption. The X-ray diffraction results revealed that the ZrO2 nanoparticles have a typical tetragonal structure and the average crystallite size was found to be approximately 13 nm by using the Debye-Scherrer’s equation. The results are also confirmed by TEM measurements. The photocatalytic activity of ZrO2/NGP and ZrO2/graphene composites was evaluated by degrading methylene blue under UV light irradiation which confirmed that ZrO2/graphene composites have better catalytic performance than ZrO2/NGP composites and pure ZrO2 nanoparticles. An effort has been made to correlate the physicochemical characteristic of ZrO2/NGP and ZrO2/graphene composites to the rate of photocatalytic degradation of methylene blue. The results demonstrated that graphene incorporation in ZrO2 nanoparticles could greatly improve the photocatalytic activity. In addition, the influence of catalyst dosage, initial concentration, and scavengers of reactive species on the photocatalytic activity was investigated. Moreover, the composites were found to be reusable photocatalyst.In this study, ZrO2/nanographene platelets (NGP) and ZrO2/graphene composites were fabricated by depositing ZrO2 nanoparticles onto nanographene platelets and graphene surfaces to develop photocatalysts. ZrO2/NGP and ZrO2/graphene were successfully synthesized using the co-precipitation method. The physicochemical characteristics were studied through X-ray diffraction, transmission electron microscope, energy dispersive X-ray analysis, Brunauer-Emmett-Teller method and infrared absorption. The X-ray diffraction results revealed that the ZrO2 nanoparticles have a typical tetragonal structure and the average crystallite size was found to be approximately 13 nm by using the Debye-Scherrer’s equation. The results are also confirmed by TEM measurements. The photocatalytic activity of ZrO2/NGP and ZrO2/graphene composites was evaluated by degrading methylene blue under UV light irradiation which confirmed that ZrO2/graphene composites have better catalytic performance than ZrO2/NGP composites and pure ZrO2 nano...

Structural characterization of a-Si:C:H alloys prepared by dc sputtering

Abstract The microstructure of dc sputtered amorphous silicon carbon (a-Si:C:H) films have been studied using infrared absorption, hydrogen effusion as well as secondary ion mass spectroscopy (SIMS) profiling of hydrogen–deuterium (H/D) inter-diffusion measurements. A comparison of the three methods shows the presence of a structural transition at a carbon concentration of about 25 at.% and it is attributed to hydrogen-induced void formation. Effusion measurements of implanted inert gases suggest giving information about sizes of microstructure.

Infrared and hydrogen effusion studies of amorphous silicon carbon (a-Si:C:H) films prepared by DC magnetron sputtering (DCMS)

Infrared and effusion of hydrogen, as well as of the inert gases, were studied for dc magnetron sputtered a-Si:C:H films. A structural transition from compact to void-rich material is observed and attributed to hydrogen-induced void formation. Inert gas atoms were incorporated into the material by ion implantation. It is shown that the inert gas effusion spectra give the information about sizes of microstructure.

Pengaruh Peningkatan Flow Rate Gas Metan Terhadap Sifat Optis L

Methane Flow Rate Effects On The Optical Properties of Amorphous Silicon Carbon (a-SiC:H) Films Deposited By DC Sputtering Methods. We have investigated the refractive index (n) and the optical absorption coeffi cient (α) from refl ection and transmission measurements on hydrogenated amorphous silicon carbon (a-SiC:H) fi lms. The a-SiC:H fi lms were prepared by dc sputtering method using silicon target in argon and methane gas mixtures. The refractive index (n) decreases as the methane fl ow rate increase. The optical absorption coeffi cient (α) shifts to higher energy with increasing methane flowrate. At higher methane fl ow rate, the fi lms tend to be more disorder and have wider optical gap. The relation of the optical properties and the disorder amorphous network with the compositional properties will be discussed. Keywords: Refractive index, optical absorption coeffi cient, optical gap, amorphous silicon carbon, sputtering