Nm In Glass Research Articles

Nanomechanical and Microstructural Characterization of Biocompatible Ti3Au Thin Films Grown on Glass and Ti6Al4V Substrates.

Ti-Au intermetallic-based material systems are being extensively studied as next-generation thin film coatings to extend the lifetime of implant devices. These coatings are being developed for application to the articulating surfaces of total joint implants and, therefore, must have excellent biocompatibility combined with superior mechanical hardness and wear resistance. However, these key characteristics of Ti-Au coatings are heavily dependent upon factors such as the surface properties and temperature of the underlying substrate during thin film deposition. In this work, Ti3Au thin films were deposited by magnetron sputtering on both glass and Ti6Al4V substrates at an ambient and elevated substrate temperature of 275 °C. These films were studied for their mechanical properties by the nanoindentation technique in both variable load and fixed load mode using a Berkovich tip. XRD patterns and cross-sectional SEM images detail the microstructure, while AFM images present the surface morphologies of these Ti3Au thin films. The biocompatibility potential of the films is assessed by cytotoxicity tests in L929 mouse fibroblast cells using Alamar blue assay, while leached ion concentrations in the film extracts are quantified using ICPOEMS. The standard deviation for hardness of films deposited on glass substrates is ∼4 times lower than that on Ti6Al4V substrates and is correlated with a corresponding increase in surface roughness from 2 nm for glass to 40 nm for Ti6Al4V substrates. Elevating substrate temperature leads to an increase in film hardness from 5.1 to 8.9 GPa and is related to the development of a superhard β phase of the Ti3Au intermetallic. The standard deviation of this peak mechanical hardness value is reduced by ∼3 times when measured in fixed load mode compared to the variable load mode due to the effect of nanoindentation tip penetration depth. All tested Ti-Au thin films also exhibit excellent biocompatibility against L929 fibroblast cells, as viability levels are above 95% and leached Ti, Al, V, and Au ion concentrations are below 0.1 ppm. Overall, this work demonstrates a novel Ti3Au thin film system with a unique combination of high hardness and excellent biocompatibility with potential to be developed into a new wear-resistant coating to extend the lifetime of articulating total joint implants.

Lithium concentration effect on crystallization kinetics and spectral properties of Cr-doped Li2O–K2O–Al2O3–B2O3 glass-ceramics

Alkali-aluminaborate glass-ceramics doped with Cr ions are synthesized by volume crystallization. According to non-isothermal DSC method three parallel processes occur in material: 2D Avrami-Yerofeev nucleation, 2D and 3D crystallization. During the heat treatment, the LiAl7B4O17 crystalline phase is formed. With Li2O content rising crystallinity of the material increases from 27 to 69% and the crystalline field strength Dq/B of Cr3+ increases from 2.25 to 3.55. The photoluminescence spectra possess intense bands at 685, 700, and 715 nm for glass with 6.8 mol.% Li2O and higher and its decay kinetics is described by the sum of two exponentials. The maximum luminescence QY obtained is 50% at 16.1 mol.% Li2O. The highest conversion efficiency of the 532 nm LED luminescence obtained by glass-ceramics with chromium is 10%. Thus, Cr-doped alkali-alumina-borate glass-ceramics are a promising material for use in the design of radiation sources for the red and NIR spectral regions.

Fundamental studies of magneto-optical borogermanate glasses and derived optical fibers containing Tb3+

New magnetic glass compositions, based on system (100-x) (60GeO2 -25B2O3 –4Al2O3 -10Na2O–1PbO) – xTb4O7 were prepared by the melt-quenching technique. The materials were systematically characterized with respect to their structural (XRD, EXAFS, XANES and Raman), thermal (DSC), morphological, optical, magnetic and magneto-optical (MO) properties. Morphological and magnetic measurements show the homogeneous distribution of the Tb3+ ions as the magnetic susceptibility increases proportionally to the rare earth content. The optical window covers the range from 0.5 up to 1.6 μm, limited by absorption due to 4f8 -> 4f7 5 d 1and 4f8 -> 4f8 transitions of Tb3+. XANES and EXAFS measurements at the Ge–K edge show that the germanium atoms are always tetrahedrally coordinated, while results at the Tb-LIII edge shows terbium atoms to be eight-coordinated and exclusively present in the oxidation state 3+ independently of the glass composition. MO measurements show that the Verdet constant (VB) increases linearly with the Tb3+ concentration reaching the value of −83.9 rad T−1m−1 at 650 nm for glass containing 8 mol% of Tb4O7. Good thermal stability (ΔT = 200 °C) allowed obtaining an optical fiber of a glass containing 4 mol% of Tb4O7 featuring VB values of −37.9, −23.6 and −5.89 rad T−1 m−1, at 500, 650 and 1550 nm, respectively.

Low-Loss Multimode Glass Waveguides With Beam-Expanded Fiber Connectors Enabling On-Board Optical Links

Ion-exchange glass waveguides are a very promising technology with a balanced trade-off between optical loss, integration density, and fabrication costs. Graded-index multimode waveguides show low propagation loss of only 0.035 dB/cm at wavelength of 1310 nm in glass, compatible with large scale manufacturing. For fiber cable connectivity, expanded beam connectors were used to terminate the waveguides by passive pick-and-place assembly, resulting in a coupling loss of ∼1 dB per interface. Design and fabrication of glass waveguides are studied, and 2-m-long spiral waveguides along with 12 × 12 optical shuffle waveguide layouts made on a 9′′ × 12′′ area glass sheet are demonstrated experimentally.

Effect of different stabilizers on dispersion of gold nanoparticles in bismuth borosilicate glass and their intensity dependent nonlinear behaviour

Here, we report the role of different stabilizers (Eu2O3, EuF3 and KSCN) in stabilizing gold nanoparticles (AuNPs) embedded in Bismuth-Borosilicate glasses. The prepared nanocomposites are characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), UV–Visible transmission spectroscopy, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), ellipsometery and Z-scan. From FESEM, it has been observed that the morphology of AuNPs is highly dependent on the type of stabilizer. Also HRTEM confirms the covering of AuNPs by stabilizer that prevents the coagulation of NPs. The localized surface plasmon resonance related transmission dip is observed around 585 nm for glass containing Eu2O3 as a stabilizer. The linear and nonlinear refractive index of the prepared glasses is obtained from ellipsometery and Z-scan measurements, respectively. All the Z-scan measurements have been carried out at different input peak intensities varying from 1.9 to 14.38 GW/cm2. Nonlinear optical studies with open aperture Z-Scan shows the switching between saturable absorption and two photon absorption as the laser intensity is increased. The existence of third order nonlinearity has been detected using closed aperture Z-scan in the prepared glasses.

Synthesis and deposition of (200)-oriented CdTe thin films on transparent substrates

Cadmium Telluride nanoparticles were synthesized by the sonochemical method (ST) and deposited on the glass and ITO glass as transparent substrates at 100 °C. X-ray diffraction (XRD) analysis indicated the formation of CdTe cubic phase with a strong preferential orientation of (200) crystalline plane. The obtained particle size in this orientation was about 13.56 nm. The grain size of the prepared CdTe thin films was 12.33 nm and 12.42 nm for glass and ITO glass substrates, respectively. Scanning electron microscopy (SEM) analysis used to investigate the morphology of CdTe nanoparticles. The Ultraviolet-visible (UV–vis) spectroscopy measurements showed increasing of the optical band gap from 1.49 eV for CdTe powder to 1.51 and 1.61 eV for CdTe thin films on glass and ITO glass, respectively.

The Structural and Compositional Evaluation of Some Calcium Phosphate Glasses with Bioactive Potential

This paper shows the experimental results of two compositional phosphocalcic glasses: 50% SiO2 - 45% CaO - 5% P2O5 and 47% SiO2 - 45% CaO - 5% P2O5 - 3% Ag2O obtained through sol-gel method. In order to study their bioactivity, the two compositions were structural analyzed by X-ray diffraction method. In this case the apatite formation was highlighted after 14 days of soaked in simulated body fluid, but also other compounds (CaCO3, AgCl and Ag) resulting from the same process were highlighted. The first glass composition is more bioactive than composition doped with silver. The pores of the hydrated silica network are partially clogged by the AgCl formed, which can reduce the rate of hydroxyapatite formation but this process does not cancel the bioactivity of the doped glass. The functional groups present in the structure of those two glasses before and after soaking (PO43-, CO32- and HO-) were highlighted by the Fourier Transform Infrared Spectroscopy (FTIR). The elemental chemical composition was confirmed by elemental analysis WD-XRF. The particle size and the two samples stability was analyzed by Dynamic Light Scattering (DLS), Thermogravimetric Analysis (TG) and Differential Scanning Calorimetry (DSC). The granulometric analysis shows that the glass particles have average diameters of 647.9 nm for the first composition, respectively 380.4 nm for glass doped with silver. TG analysis show a total loss of weight of 8.3% for the first glass, respectively 3.72% for doped glass, which demonstrates that the two compositions are thermally stable.

A Rapid Method for Deposition of Sn-Doped GaN Thin Films on Glass and Polyethylene Terephthalate Substrates

We report the influence of Sn doping on microstructure, surface, and optical properties of GaN thin films deposited on glass and polyethylene terephthalate (PET) substrate. Sn-doped GaN thin films have been deposited by thermionic vacuum arc (TVA) at low temperature. TVA is a rapid deposition technology for thin film growth. Surface and optical properties of the thin films were presented. Grain size, height distribution, roughness values were determined. Grain sizes were calculated as 20 nm and 13 nm for glass and PET substrates, respectively. Nano crystalline forms were shown by field emission scanning electron microscopy. Optical band gap values were determined by optical methods and photoluminescence measurement. The optical band gap values of Sn doped GaN on glass and PET were determined to be approximately ∼3.40 eV and ∼3.47 eV, respectively. As a result, TVA is a rapid and low temperature deposition technology for the Sn doped GaN deposited on glass and PET substrate.

The electrical, elemental, optical, and surface properties of Si-doped ZnO thin films prepared by thermionic vacuum arc

The purpose of this work is to study the properties of Si-doped ZnO (SZO) thin films, which were prepared using the non-reactive thermionic vacuum arc technique. The analysis of the elemental, optical, and surface properties of ZnO:Si thin films was carried out using energy dispersive x-ray spectroscopy, UV–VIS spectrophotometry, atomic force microscopy, and scanning electron microscopy, respectively. The current–voltage measurement was employed in order to study the electrical properties of the films. The effect of Si doping on the physical properties of ZnO films was investigated. The film thicknesses were measured as 55 and 35 nm for glass and PET substrates, respectively. It was clearly observed from the x-ray diffraction results that the Si and ZnO peaks were present in the coated SZO films for all samples. The morphological studies showed that the deposited surfaces are homogenous, dense, and have a uniform surface, with the existence of some cracks only on the glass substrate. The elemental composition has confirmed the existence of Zn, Si, and O elements within the prepared films. Using a UV–VIS spectrophotometer, the optical parameters such as transmittance, absorbance, refractive index, and reflectance were calculated. It should be noted that the transparency and refractive indices obtained from the measurements decrease with increasing Si concentration. The obtained optical bandgap values using transmittance spectra were determined to be 3.74 and 3.84 eV for the glass and PET substrates, respectively. An increase in the bandgap results demonstrates that the Si doping concentration is comparable to the pure ZnO thin films. The current versus voltage curves revealed the ohmic nature of the films. Subsequently, the development and fabrication of excellent transparent conducting electrodes enabled the appropriate use of Si-doped ZnO thin films.

Room temperature gas-solid reaction of titanium on glass surfaces forming a very low resistivity layer

Titanium films were deposited on quartz, glass, polyamide and PET substrates in a high vacuum system at room temperature and their electrical resistance monitored in vacuo as a function of thickness. These measurements indicate that a low electrical resistance layer is formed in a gas-solid reaction during the condensation of the initial layers of Ti on glass and quartz substrates. Layers begin to show relative low electrical resistance at around 21 nm for glass and 9nm for quartz. Samples deposited on polyamide and PET do not show this low resistance feature.

Influence of silver nanoparticles on the photovoltaic parameters of silicon solar cells

Influence of Ag nanoparticles on optical and photovoltaic properties of, silicon substrates, silicon solar cells and glass have been investigated. Silver nanoparticles have been fabricated by evaporation of thin Ag layers followed by the thermal annealing. The surface plasmon resonance peak was observed in the absorbance spectrum at 470 nm of glass with deposited silver nanoparticles. It is demonstrated that deposition of silver nanoparticles on silicon substrates was accompanied with a significant decrease in reflectance at the wavelength 360-1100 nm and increase of the absorption at wavelengths close to the band gap for Si substrates. We studied influence of Ag nanoparticles on photovoltaic characteristics of silicon solar cells without and with common use antireflection coating (ARC). It is shown that silver nanoparticles deposited onto the front surface of the solar cells without ARC led to increase in the photocurrent density by 39% comparing to cells without Ag nanoparticles. Contrary to this, solar cells with Ag nanoparticles deposited on front surface with ARC discovered decrease in photocurrent density. The improved performance of investigated cells was attributed to Ag-plasmonic excitations that reduce the reflectance from the silicon surface and ultimately leads to the enhanced light absorption in the cell. This study showed possibility of application of Ag nanoparticles for the improvement of the conversion efficiency of waferbased silicon solar cells instead of usual ARC.

The giant mottled eel, Anguilla marmorata, uses blue-shifted rod photoreceptors during upstream migration.

Catadromous fishes migrate between ocean and freshwater during particular phases of their life cycle. The dramatic environmental changes shape their physiological features, e.g. visual sensitivity, olfactory ability, and salinity tolerance. Anguilla marmorata, a catadromous eel, migrates upstream on dark nights, following the lunar cycle. Such behavior may be correlated with ontogenetic changes in sensory systems. Therefore, this study was designed to identify changes in spectral sensitivity and opsin gene expression of A. marmorata during upstream migration. Microspectrophotometry analysis revealed that the tropical eel possesses a duplex retina with rod and cone photoreceptors. The λmax of rod cells are 493, 489, and 489 nm in glass, yellow, and wild eels, while those of cone cells are 508, and 517 nm in yellow, and wild eels, respectively. Unlike European and American eels, Asian eels exhibited a blue-shifted pattern of rod photoreceptors during upstream migration. Quantitative gene expression analyses of four cloned opsin genes (Rh1f, Rh1d, Rh2, and SWS2) revealed that Rh1f expression is dominant at all three stages, while Rh1d is expressed only in older yellow eel. Furthermore, sequence comparison and protein modeling studies implied that a blue shift in Rh1d opsin may be induced by two known (N83, S292) and four putative (S124, V189, V286, I290) tuning sites adjacent to the retinal binding sites. Finally, expression of blue-shifted Rh1d opsin resulted in a spectral shift in rod photoreceptors. Our observations indicate that the giant mottled eel is color-blind, and its blue-shifted scotopic vision may influence its upstream migration behavior and habitat choice.

Local crystallization of glasses aided by copper vapor laser

It is shown that a copper vapor laser can be used effectively for local crystallization of glasses with precipitation of active phases on a surface or in the interior volume of glass depending on its composition. Aprocedure is proposed for using a laser beam to form nanostructural waveguides with broadband near-IR luminescence peaking at 1300 – 1450 nm in glass with composition (mol.%) 7.5 Li2O, 2.5 Na2O, 20 Ga2O3, 35 GeO3 and 35 SiO2 doped with 0.1 – 0.5% NiO. A mechanism of self-limited laser heating, impeding subsequent growth of the nanocrystals formed, is demonstrated. The results of the investigations are of interest for developing active elements of integrated optics.

Fabrication of IZO transparent conducting thin films by the use of magnetron sputtering equipped with ion‐beam system

Abstract— Indium zinc oxide (IZO) thin films have been prepared on glass, polycarbonate (PC), and polyethylene terephthalate (PET) substrates by using a radio‐frequency (RF) magnetron sputtering system equipped with an ion gun, and a simple OLED device was made by using IZO film. The influence of the RF power, the Ar gas volume, and the substrate temperature during the deposition process on the roughness and the electrical and optical properties of the films have been investigated. In addition, End‐Hall ion‐beam treatment of the substrates is applied before the sputtering deposition process. The sheet resistance of the IZO films is 25 Ω/□ for the glass, 21 Ω/□ for the PC, and 20 Ω/□ for the PET substrate with a thickness of 150 nm, and the lowest root‐mean‐square (rms) roughness of these IZO films were measured to be 0.58, 0.35, and 0.32 nm for glass, PC, and PET substrate, respectively. The decrease in the sheet resistance of the IZO films becomes evident after the ion‐beam treatment and makes the surface of the thin film more hydrophilic. Relative to non‐treated IZO film, the ion‐beam‐treated IZO anode in the OLED device seems to inject holes into the emitting layer to enhance the current density.

X-ray induced nonbridging oxygen hole center in soda-lime silicate glass

Abstract Defects induced by X-ray irradiation in the soda-lime silicate glass were studied by means of optical spectrophotometric and electron spin resonance measurements. The defects attributed to three absorption peaks at 610, 425 and 305 nm which were observed in the glass after X-ray radiation. The induced defects were unstable at room temperature or after thermal annealing treatment. The Smakula's formula was applied to calculate the induced defects, and the concentration of induced NBOHC correlating the absorption band at 610 nm in glass after X-ray irradiation for 35 min was calculated to be about 9.80 × 1018/cm3. The linear relationship between NBOHC number and absorption at 610 nm confirmed that the absorption at 610 nm may attribute to the induced NBOHCs.

Structural Characterization of Self-Assembled Polypeptide Films on Titanium and Glass Surfaces by Atomic Force Microscopy

Chemically modified biomaterial surfaces (titanium and glass) covered with polyelectrolyte self-assembled films formed by the alternating adsorption of cationic poly-L-lysine (PLL) and anionic poly-L-glutamic acid (PGA) were structurally characterized by atomic force microscopy. Complementary information concerning the thickness and layer-by-layer growth of the films was provided by optical waveguide light-mode spectroscopy. The frequently used ex situ and the rarely used in situ build-up methods were compared. Important aspects of the industrial applicability of these films, their stability in time, and possible differences in their morphology were investigated. The films revealed a granular pattern, with grain diameters of 270 +/- 87 nm for glass (up to 8 bilayers) and 303 +/- 89 nm for titanium (up to 10 bilayers), independently of the build-up procedure. Both surfaces displayed a rehydration capability, the titanium surface exhibiting a better stability in time. The high roughness values observed at acidic or basic pH are related to the degree of ionization of PGA and PLL.

Proton conductivity in sol–gel-derived P 2O 5–TiO 2–SiO 2 glasses

The sol–gel method was applied to prepare the P 2O 5–TiO 2–SiO 2 glasses with high proton conductivities and chemical stability. The glasses were prepared by the reaction of the Ti- and Si-alkoxides with PO(OCH 3) 3 or H 3PO 4, followed by heating at 600 °C. The obtained glasses were porous, the average pore diameter of which was <2 and 4 nm for glasses prepared using PO(OCH 3) 3 and H 3PO 4, respectively. The phosphorous ions, occurring as PO(OH) 3 in the TiO 2-free glass, were polymerized with one or two bridging-oxygen ions per PO 4 unit with the increasing TiO 2 content. Despite the P 2O 5–SiO 2 binary glasses exhibiting high conductivities of ∼10 −2 S/cm at room temperature, they also dissolved after immersing for 24 h in water. The chemical stability of these glasses increased significantly on the addition of TiO 2.

Environments of lead cations in oxide glasses probed by X-ray diffraction

The structural behavior of oxygen environments of Pb 2+ cations in binary lead oxide glasses is studied by X-ray diffraction using high-energy photons from a synchrotron. Samples of different PbO content and of different type of network-forming oxide such as SiO 2 and V 2O 5 are used. For comparison, earlier data obtained of Pb phosphate glasses are included. The oxygen environments strongly depend on the type of network-forming oxide but they do not vary with PbO content. Numbers and distances of oxygen atoms at the shortest separations are three, four and five with lengths of 0.230, 0.252 and 0.247 nm for glasses with SiO 2, V 2O 5 and P 2O 5, respectively. The numbers of further oxygen atoms at distances of ∼0.275 nm are about one, two and three. The excentric positions of Pb 2+ cations in the oxygen environments of silicate and vanadate networks are attributed to non-uniform distributions of negative charge on the surrounding oxygen atoms. In case of lead vanadate glasses the Pb 2+ cations stabilize VO 5 units which is not known of vanadate glasses of other network-modifying oxides MeO.

Femtosecond measurements of two-photon absorption coefficients at λ = 264 nm in glasses, crystals, and liquids: erratum

Femtosecond measurements of two-photon absorption coefficients at λ = 264 nm in glasses, crystals, and liquids: erratum

Femtosecond measurements of two-photon absorption coefficients at lambda = 264 nm in glasses, crystals, and liquids.

Using ultraviolet femtosecond pulses with high irradiance stability, we measured the two-photon absorption (TPA) coefficients in a number of substances with a total accuracy of approximately 10%. Six commercial fused-silica samples (KU-1, Coming 7940, SQ, Suprasil, Herasil, and Infrasil) possess TPA coefficients (beta values) of approximately 2 x 10(-11) cm/W. For crystalline quartz and sapphire, the following beta values were obtained: (1.2 +/- 0.2) x 10(-11) and (9.4 +/- 1.2) x 10(-11) cm/W, respectively. In beta-barium borate crystal the TPA coefficient depends on crystal cut, beam polarization, or both and varies from (47 +/- 5) x 10(-11) to (68 +/- 6) x 10(-11) cm/W. For eight liquids that were studied (water, heavy water, ethanol, methanol, hexane, cyclohexane, 1,2-dichloroethane, and chloroform) the beta value lies from (34 +/- 3) x 10(-11) to (95 +/- 11) x 10(-11) cm/W.