Papers by Keyword: Refractive Index

Abstract: Silver-silica nanocomposites (Ag-SiO₂NCs) with various compositions were synthesized through sol-gel technique. The morphology, optical and thermal stability of the nanocomposite were investigated and was compared with pure sol-gel to determine the effects of the nanoparticles. Transmission electron microscopy (TEM) confirmed that SiO₂ was encapsulated Ag with mean size of 30 nm. Uv-vis spectroscopy shows that the surface plasmon resonance (SPR) peak show Ag-SiO₂ NCs were greatly reduce due to the SiO₂ particles. The permittivity and refractive index were decreased as the composition of Ag was increased at composition of 60% silver. The real permittivity is negative along the visible region. The trend stability of Ag-SiO₂NCs were increased with the increased amount of silver.

Abstract: A series of tellurite glass containing samarium ion and silver nanoparticles with a composition of (89.6-x)TeO₂-10MgO-(x)Sm₂O₃-0.4AgCl with 0.2 ≤ x ≤ 1.0mol% have been synthesized by a conventional melt quenching technique. The X-ray diffraction pattern verified the amorphous nature of glasses. A systematic study on the relationship between Sm₂O₃ concentration and the physical properties of the glass has been made. The effect on the progressive replacement of TeO₂ by Sm₂O₃ on density, molar volume, refractive index and electronic polarisability has been investigated. The results show that density and ionic packing density are in the range of 4.91-5.04 g cm^-3 and 0.444 – 0.455, respectively, increases as the amount of Sm₂O₃ is increased up to 0.8 mol% and decrease afterward. However, the molar volume which is in between, 29.59-30.26 m³ mol^-1 decreasing as the amount of Sm₂O₃ is increased up to 0.8 mol% and increase thereafter. Meanwhile the refractive index which is deduced from optical energy band gap is found to possess a value in the range of 2.37 to 2.45 and electronic polarisability is in the range of 7.14-7.51ų. All the results will be discussed with respect to the glass composition.

Abstract: The construction of an experimental set for measurement of refractive index of liquids using fiber optics has been described in this work. The experimental set is aimed for demonstration in physics high school class. A prototype fabricated in laboratory composes of plastic-clad-plastic (PCP) optical fiber with the length of 50 cm, fiber optic transmitter diode, fiber optic phototransistor detector, and liquid container. The diameter and refractive index of the core of PCP optical fiber were 1 mm and 1.492, respectively. The thickness and refractive index of fiber cladding were 1.2 mm and 1.417, respectively. The fiber cladding surface at the central region was removed approximately 5 cm long to form a sensor area. This sensor area was inserted into a cylindrical glass which acted as the container. One end of the fiber was connected to the transmitter diode with a wavelength of 660 nm, and the other end was connected to the detector. A digital multimeter was used to measure an output voltage from the detector. In this work, the effect of water temperature on its refractive index was determined. The results showed that the water refractive index decreased with increasing water temperature and result in the increase of measured output voltage. Furthermore, it was found that the output voltage measured at different temperatures of water depends linearly on water refractive index.

Abstract: Polydimethylsiloxanes (PDMS), (CH₃)₃SiO-[Si(CH₃)₂O]_n-Si(CH₃)₃, known as silicone oil is a tamponade liquid which is very important in vitreoretinal surgery, especially in the treatment of complicated retinal detachment. Here, we investigated the optical properties and structure of silicone oil with high viscosity silicone oil of 5500 cSt and low viscosity silicone oil of 1300 cSt in order to understand the changing of physical properties of silicone oil before and after using in vitreoretinal surgery as a tamponade liquid and analyze the relationship between the tamponade duration and changed in silicone oil properties. From UV-Vis spectroscopy and refractometer measurement, it is found some changes in transmittance and refractive index values in both silicone oil after using as a tamponade liquid. From fourier transform infrared (FT-IR) spectroscopy, some additional of functional groups of N-H and O-H bond are observed at 1634.5 cm^-1 and 3435.7 – 3764.5 cm^-1, respectively. The changes of optical and structure properties of silicone oil after using as a tamponade liquid are assumed to be responsible in emulsification of silicone oil and affect the transmittance quality at visible light spectrum. However, in this study, there is no linear corelation between tamponade duration and changed in silicone oil properties.

Abstract: Erbium doped zinc borotellurite glasses were prepared by using melt-quenching method. The structural properties of the glass samples were determined by using x-ray diffraction (XRD) method and was confirmed its amorphous nature. The density and molar volume is shown to be increased with increasing content of erbium. The refractive index is found to be increased with increasing content of erbium.

Abstract: The electronic and optical properties of tetragonal rutile TiO₂ are investigated by first principles calculations using plane-wave pseudopotentials. Generalized gradient approximation proposed by Perdew-Burke-Ernzerhof (GGA-PBE) is employed with Vanderbilt’s ultrasoft pseudopotentials (USPs) for the geometry optimization. The cutoff energy 380 eV and Monkhorst-Pack (MP) grid of size 5 x 5 x 8 is used to study the electronic properties of TiO₂. Besides, the optical properties of TiO₂ are studied using a mesh size of 9 x 9 x 9. A periodic supercell of size 2a x 2b x 2c is created and a single Copper (Cu) atom directly substitutes the titanium atom. The geometry is optimized at cutoff energy 440 eV with MP grid of size 3 x 3 x 8 and a denser k-points mesh of size 6 x 6 x 6 is used for the investigation of optical properties.

Abstract: The structural, elastic and optical properties of Ag-doped rutile TiO2 are studied using the first principles calculations method. Four different functionals are employed using the ultrasoft pseudopotentials (USPs) on a supercell of size 2a × 2b × 1c. The band gaps of un-doped TiO2 obtained using PBE, RPBE, PW91 and LDA-CA-PZ are 1.861, 1.873, 1.857 and 1.854 eVs respectively. However, after Ag substitution in the supercell, the band gaps are reduced for all of the functionals. After substitution, in the region near to the Fermi level, some new electronic states are observed. The calculated elastic constants show that the structure is mechanically stable. The obtained values of the B, G and elastic constants of un-doped TiO2 are consistent with prior published experimental findings. For Ag-doped supercell, implementing PW91, B and G are 119 and 62 GPa. For the same size of supercell, using LDA-CA-PZ, B and G are 152 and 70 GPa. Besides, the results of the optical properties show that the major absorption peaks for all of the functionals locate away from the visible region. This shows poor absorption of visible light and weak photocatalytic activity of rutile TiO2.

Abstract: A series of high refractive index of α,ω-vinyl silyl terminated polydimethylsiloxane-co-polydiphenylsiloxane was synthesized by the equilibration ring opening – anionic polymerization of cyclic organo-siloxane oligomers in the present of 1,3-divinyltetramethyldisiloxane as terminating agent. Structural modifications were characterized by use of FTIR, H-NMR, and solution viscosity. UV-visible spectroscopy was analyzed which reveal a good transmittance in the region 400 – 750 nm radiation for all polysiloxanes.The presence of diphenylsiloxane unit results in a linear increase of the refractive index of the resin. These features favor good application as encapsulant for high brightness LED (HBLED) packaging.

Abstract: Recently, the display industry is focusing on making bendable or flexible displays with higher quality and larger area. Ultimately, there is a very high possibility that future displays will be rollable. The biggest problem with rollable displays is the fabrication of a polarizer film to prevent reflection of the OLED. To develop a rollable display, the display should be made of material with a very thin thickness, like that of paper. However, the thickness of the polarizer film used for displays is only approximately 180 μm. This means that the film is too thick to be applied to rollable displays. If a polarizer of wire grid type, which we investigate in this study, is used, it can reduce the thickness of this film to a value under approximately 1 μm. One research result has been to discover that Fe₃O₄ is a very slightly absorptive material. Especially, most research into Fe₃O₄ thin films has concentrated on its characteristics in nanotubes. So, our purpose in this research is to investigate the deposition process of Fe₃O₄ thin-film under various conditions using an E-beam evaporator; we intend to compare these various processes with each other after measuring the refractive index.

Abstract: The refractive index of double-distilled water and inorganic salt solutions of concentrations varying from 0.4 to 100 ppt (‰) have been measured at 20 Celsius degrees using Abbe refractometer, respectively. The inorganic salts such as NaCl, MgSO4, KCl and MgCl2,these forming the major constituents of seawater are used as solutes of the water solution. The effect of the concentration of these constituents on the refractive index of the solution is experimentally investigated. And meanwhile, the index of refraction studies are carried out for the laser wavelength of 405nm, 450nm, 532nm and 633nm under the case of varying concentration. The results show that the refractive index of the solution will be linearly increased with the increase of the concentration of these constituents. The index of refraction differs for the different solutes when their concentration is same at a certain wavelength.