Turquoise, a hydrated phosphate of copper and aluminum, is an opaque, blue-to-green mineral with the chemical formula CuAl6(PO4)(4)(OH)(8)0.4 H2O. Owing to its unique hue, turquoise is rare and valuable, and it has been appraised as a gemstone for thousands of years. However, with high porosity, low specific gravity, fracturable, and low hardness of just under six or slightly more than window glass, treatments are required before use as jewelry. Nowadays, imitations, and synthetics from glass, plastic, or pressed turquoise powder bonded with resin, are generally found in the market. In our present study, we aim to investigate an alternative method to form glass-ceramic for turquoise imitation by using a direct sintering method based on the soda-lime-silica glass waste with kaolin mixer and coloring oxide additives. In the preparation, the pre-mixed powders were poured into a stainless-steel die, then, the die was brought to the pressing machine for sample forming. A conventional furnace was applied for heating the samples to similar to 1000 degrees C with a soaking time of 4 h. The obtained ingots were characterized by several techniques. The chemical compositions were determined by the Energy Dispersive X-ray Fluorescence (ED-XRF), and their chemical structures were evaluated by the X-ray diffractometer. Meanwhile, their chemical fingerprints were obtained by Raman spectroscopy. As for comparison, the natural turquoise, as well as the commercial imitation samples, selected from the local market were undergone the same characterization. We have found that with the proper content of the metal oxide additives, the products in unique blue and brown-turquoise appearances can be formed and cut to decorate the jewelry set for the niche market. Thus, an alternative method for recycling soda lime-silica waste glass based on a single-step sintering process at relatively low temperature enabled jewelry applications.

Ruby is a mineral in the corundum (Al2O3) family and it is remarkably valuable as a gemstone. From the physics point of view, the ruby coloration depends on the balance of trace or chromophore impurities and defect complexes in the Al2O3 lattice. Shifting this balance into right direction is of paramount importance for the ruby value as the gemstone and ion implantation can be applied for this purpose. Thus, in the present study, we explored the influence of high dose oxygen ion implants on the natural ruby coloration. By performing quantitative colorimetry analysis, we detected prominent coloration changes unambiguously attributed to the effect of the implants, even though the implanted oxygen profile was located at the near surface region of the sample. Moreover, applying near surface sensitive cathodoluminescence measurements we observed spectacular changes in the spectra correlated with the implants. Importantly, the trends observed in the colorimetry and cathodoluminescence as a function of the implantation parameters were consistent. As such, the present paper provides both the scientific perspective and quantitative interpretations potentially paving the way for the ion beams applications in the gemstone industry.

Rubellite, one of the most attractive members of the colorful family of tourmalines, has its colors ranging from fine red hues to pinkish and violetish nuances. Some of them are very light while others are so dark that the real hue can only be identified when the stones are held against the light. Fine jewelry-grade rubellites are relatively rare; therefore, color enhancement are normally required on natural samples. In present study, pink tourmaline samples from Mozambique were enhanced using two methodologies, i.e., gamma irradiation and heat treatment. The samples were characterized before and after the color enhancements. Conclusive remarks were drawn upon the modification of their color appearance, optical absorption, and oxidation states of the chromophores. After preparation, the samples were divided into two groups: The first group were irradiated with 400, 500 and 600 kGy of gamma while the second group were heat treated at 350, 450 and 550 degrees C. After irradiation, the slightly pink tourmaline samples turned saturated pink. The color of heat-treated samples, however, were faded from initially very slightly pink to colorless with increasing temperatures. It was noticed that both gamma irradiation and heat treatment at current conditions did not affect any inclusions in the specimens. FTIR spectra of untreated samples displayed several bands at 3300-3700 cm(-1) for OH-stretching, 5200 cm(-1) for H2O and 4200-4400 cm(-1) for Fe-OH. After both treatments, all bands were decreased, especially, for the OH band. UV-vis-NIR spectra of the untreated samples displayed the absorption band at 520 nm related to Mn3+. Upon treatments, this band was increased with peak height depended on the treatment conditions. Mn K-edge x-ray absorption spectra of the samples exhibited the shift of Mn oxidation to a higher number after both treatments.

Soda lime glass (SLG) is one type of glass mainly used in beverage and food packaging industries. SLG has high potential as starting materials for glass-ceramics (GC) production as SLG consists of large proportion of silicate and has considerably low of melting temperature. In addition, large consumption of beverages and foods, SLG makes up a large bulk of the waste. Producing glass-ceramics (GC) from SLG is thus interesting. Processing of SLG to GC is strongly dependent on their thermal property. Before processing, thermal profile of SLG was analyzed by differential scanning calorimetry; crystallization temperature at 711 °C was identified at the heating rate of 5 °C/min. It was also possible to extract information about crystallization kinetic by applying the Kissinger and the Ozawa relations. It was found that crystallization activation energies were 365.06 and 381.60 kJ/mol, respectively. For the GC processing, SLG powder was mixed with precursors to the ratio of 60SLG-35SiO2-2TiO2-2ZnO-1CuO before sintering with single step method at 711, 800, 850, 900, 950, 1,000 °C. An analysis by XRD has shown that there were two phases; beta-quartz and beta-cristobalite, in the sintered samples. Different sintering temperatures have yielded different proportion of alpha-to beta-phases. SEM/EDX has also revealed uneven distribution of different oxides in the produced glass-ceramics.

Ion implantation of gemstones for gemological modification is a new development of ion beam technology applications in materials science. At Chiang Mai University, ion implantation of gemstones has been emphatically carried out with using ion species such as nitrogen and oxygen at the ion energy in a range of 20 to 120 keV to the ion beam fluences in a range of 1017 to 1019 ions/cm2. After ion implantation treatments, the gemological properties and thus qualities of gemstones were found improved in various degrees, such as changes in colors and tones, enhancements in transmittance, glittering and brilliance, homogenization of color distribution, and removal of inclusions and flaws. The ion-beam-treated gemstones were judged by gemologist professionals to confirm promotions of the gem grades. Ion implantation has advantages over conventional HTs, such as fast treatment, low temperature, and localized modification. Our work has been cited and commented by GIA (Gemology Institute of America) in their recent review. Although there have been impressive achievements, there is a commonly recognized puzzle in ion implantation induced color changes of gemstone, that is the ion range puzzle. The ion range is short; however, the gemological modification induced seems of bulk. Mechanisms involved in the color modifications are not yet well revealed and understood and they only remain in speculation. Ion beam parameters seem influential to the effects. Further research issues are proposed accordingly.

Natural opal, an amorphous, hydrous form of silica (SiO2-n-H2O), has been one of the favored precious gemstones for many centuries. Though beautiful, opal is very fragile and is damaged quite easily. Thus, opals of all varieties have been synthesized experimentally and commercially. The objective of this project was to synthesize and to compare crystalline opals. In this work, the development of powder sintered glass ceramics process based on soda lime silica glass waste with metal oxide powder enable jewelry applications. The substantial viscous flow of the glass led to dense products for rapid treatments at relatively low temperatures (900–1,000°C), whereas glass/metal powder interactions resulted in the formation of color agent crystals, provide enhancing optical properties. Several techniques were applied for characterization of the ingots. The chemical analysis was performed by Energy Dispersive X-ray Fluorescence (ED-XRF). The mineralogical compositions of the samples were determined by X-ray diffraction analysis. Raman spectroscopy was applied for optical characterization. The results were compared with a natural common opal. The present investigation demonstrated that the common opal with both color and colorless appearance can be synthesized by the technique, as the crystalline phase of opal structure was identified by XRD measurement. There is a great potential for such materials with novel functionalities for artificial gemstone application, i.e. opal forming.

Sawdust is a waste from furnitureindustry which is mostly left in the garbage or burn for landfill in hugequantities every year. Efforts to find utilization of this material haveresulted mostly in low value. However, sawdust waste can be considered as analternative to fabricate fiber reinforced polymer composites for furniturefunction. This study was undertaken to determine the physical and mechanicalproperties of wood plastic composites, which were made under laboratoryconditions by hot pressing of high-density polyethylene (HDPE) with teakwoodsawdust as filler. Seven levels of mixed flour, 10, 20, 30, 40, 50, 60 and 70%,based on the composition by weight was added to the HDPE powder with palm oilas coupling agent. A flat pressing technology, the simplest method for capableof large dimension wood plastic panel production, was used to manufacturetesting specimens in dimensions 5.8 x 7.3 cm2. Investigation of themechanical property of the composites material, according to the Americansociety for testing and materials (ASTM) method, was done by impact strengthtester. The measurement results were found that impact strength was decreased uponthe increasing of the sawdust up to 30 % mixing then gradually increased. However,by increasing mixed flour content, water resistance of the panels wasnegatively influenced. The best appearance of composites material in comparisonwith the natural woods was ~30% sawdust powder mixing. The woodplastic panels were utilized for construction of a Thai spirithouse as an outdoor decoration.

The technique of stone-in-place casting has been established in jewelry production for three decades. However, the process is not widely used since it is limited to precious stones with high hardness and high stability at high temperature. This experiment tested tourmaline, which is a semi-precious gemstone having less hardness and less stability compared with precious stones. The objective was to achieve the conditions of a lost-wax casting process with tourmaline placed in waxes in the casting process. The experiment was divided into two parts. The first part was to understand the tolerance of tourmaline under the heating conditions. Natural tourmaline stones were investigated and compared inclusions tested at a temperature of 700°C. Tourmaline with ion-implantation was also heated to 700°C for comparison. The second part was to test tourmaline in-place casting with tree conditions of flask casting at 550°C, 625°C, and 700°C. The results showed that stones were able to tolerate as much as at 700°C. The inclusion growth of ion-implantation under heating to 700°C also observed the growth of inclusion in the same way as untreated tourmaline. The casting condition at 550°C showed better results. The highest probability of stones breaking after casting occurred in bezel settings.

For photovoltaic applications in dye-sensitised solar cells (DSSC), used as a wide band semiconductor layer, titanium dioxide (TiO2) nano-films were formed by the filtered cathodic vacuum arc deposition (FCVAD) technique using Ti as the cathode and controlled oxygen (O2) gas inlet under varied deposition and post-deposition annealing conditions. The deposition conditions included the O2 pressure as the key parameter and others such as deposition time and bias. The work was aimed at investigating the FCVAD condition effect on the TiO2 film characteristics and thus the solar cell efficiency. The formed films were characterised using optical microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy and scanning photoemission microscopy (SPEM) techniques. All the characterisations revealed that the film transparency increased and thickness decreased to a nanoscale with increasing of the O2 pressure, the transparent deposited films contained stoichiometric titanium and oxygen under the medium O2 pressure, the as-deposited films were TiO2 containing some rutile but without anatase, and the annealing improved the film quality by introducing anatase and increasing the Ti-oxide. Test of the films for the DSSC-photovoltaic property efficiency showed that the efficiency of using the annealed films was 104 times that of using the as-deposited films, indicating the crucial significance of the anatase.

The rising concern towards environmental issue underscores the “greenproducts” based on natural resources for a wide range of applications. Theseefforts include white rice husk ash (WRHA) considering as an alternative rawmaterial for lignocellulosic filler in green composite. We present the propertiesevaluation of composite WRHA dispersing into polyvinyl-chloride (PVC) with di-isononyl-phthalate(DINP) as compatibilizing agent by compression molding method. The XRD analysisshows typical main peak of silica crystalline, the strengthening materials asreinforcement within the composite structure. The SEM demonstrated that WRHAfillers were well embedded in PVC matrix and better adhesion occurred between themand the matrix. Thus, the adhesion between the reinforcing fiber and the matrixplays an important role in the mechanical properties of the materials. The positiveachievement for fire resistance and its mechanism were specially discussed forceiling board in/outdoor environment applications.

This research was focused on the study of the synthesis process, and the physical and mechanical properties, of the composite material prepared from Poly(vinyl chloride) (PVC) and natural fiber extracted from reed, scientific namely Cyperus corymbosus Rotth, leading to the development of a new type of low cost material for the furniture function. Reed is chosen to be a source of natural fiber due to its ease of finding and ease of growth along water reservoir which can provide a cheap material for composite production. In the study, the samples were divided into four groups based on the addition of reed powder loading, ranged from a weight ratio of 0%, 20, 40 to 50%, respectively. The composite materials were pre-mixed, using white oil as coupling agent, by the single screw extruder, and the wood plastic was produced by compression molding method. The flat plate panels were tested by several standard techniques, including impact testing, bending testing and tensile testing. Morphology of the fracture surfaces and the dispersion of filler particles were observed by using scanning electron microscopy (SEM). The testing measurement revealed the decreasing of impact strength, tensile strength and flexural strength in all WPCs in comparison with pure PVC. This negative effect may be ascribed to the poor compatibility between the fibers and polymer matrix.

This study presents the progression of nucleation and crystallization from composition of soda lime glass (SLG) and oxides as 60SLG-35SiO 2 -2TiO 2 -2ZnO-1CuO through single step sintering at 850° C. X-ray diffraction (XRD) showed a higher degree of crystallinity and larger crystallite size of a-SiO 2 after sintering. It was also observed that plane (100) shrank to a smaller d 100 spacing after sintering. XRD peaks from other oxides than SiO 2 decreased dramatically after sintering; possibly signifying a transition into the silica network. The microstructure of the sintered samples was analysed using scanning electron microscope (SEM) and SEM/energy dispersive X-ray spectroscopy (SEM/EDX). The SEM/EDX analysis revealed SiO 2 grains and whiskers of crystalline phase in many areas. A lower concentration of zinc and higher concentration of titanium were found to be associated with whiskers. This work has shown a possibility to utilize single-stage heat treatment for nucleation and crystallization of soda lime glass (SLG). Article history Submitted: 24 March 2017 Revised: 8 May 2017 Accepted: 10 July 2017 Available online: 28 July 2017

Preparation of ultrathin alumina (Al2O3) films through Plasma-Enhanced Atomic Layer Deposition (PE-ALD) at low substrate temperature is discussed. The present work aims to investigate the physical mechanism of the PE-ALD deposition process and also the characteristics of the ultrathin alumina films on silicon 〈100〉 wafer deposited using the technique. The deposition was performed using trimethyl aluminum (Al (CH3)3) as the precursor and argon gas for purging. During deposition, the target temperature was kept constant at ~80, 100 and 150°C and the pressure was ~1.3×10−2Pa. Two deposition cycles were tested, 400 and 800 cycles. As for understanding the process, the films deposited with and without oxygen plasma were compared. Various thin film characterization techniques, including Atomic Force Microscope (AFM), ellipsometry, Raman spectrometry measurement, X-ray diffraction (XRD), and indentation technique, were applied for investigating the film properties. A transmission electron microscope (TEM) equipped with high-angle annular dark-field imaging line scan modes and energy-dispersive X-ray spectroscopy acquisition was used for imaging thin film cross-sections. We found that the number of deposition cycles did not affect the substrate surface roughness as evidenced by AFM images. The mechanical property, the hardness of the film deposited with 800 cycles and plasma was the best. Raman spectroscopy measurements showed that a Al-O-Si phase exists when the films were deposited at 100°C and 150°C for 400 and 800 cycles under oxygen plasma atmosphere. While no Al-O-Si phase existed after the same number of ALD deposition cycle without plasma. Results from XRD measurements indicated that the films deposited at 100°C and 150°C for 400 and 800 cycles under oxygen plasma atmosphere has an Al-O structure. TEM images clearly displayed the interface between the thin films, SiO2 interface layers and Si substrates. As for the sample deposited at 80°C, an Al2O3 film was hardly seen, but when increasing the deposition temperature to 100°C and 150°, films started to build on top of the substrate. However, for all deposition conditions, TEM revealed that the amounts of carbon atoms in the reaction site remained relatively high.

Natural spinel (MgAl2O4) can be found in several colors resembling corundum, i.e. rubies and sapphires. In particular, spinels with saturated red appearance, called spinel-rubies or balas rubies, are the most appreciated. However, the beautiful rich red spinels are very rare, they can be found in a range of pastel shades blended with either brown, orange or purple. Therefore, the objectives of the present studies are to investigate the origins of the color blending and to improve the optical property of this gemstone by ion beam techniques. Two non-destructive ion beam analysis techniques, i.e., particle induced X-ray emission (PIXE) and iono-luminescence (IL), have been employed for geochemical analysis of the gems. As an alternative method, ion beam treatment using N2-ion was applied for improving optical appearance and color enhancement of the red Burmese (Myanmar) spinel. For each run, samples were implanted at ion energy of 70keV to a fluence of ~1×1017ions/cm2 and subsequently surface cleaning. UV-Vis spectroscopy, Raman spectroscopy and photoluminescence spectroscopy were selected for sample characterization. As for comparison, the spinel samples from the same origin were heated in air and undergone the same measurement. We have found that the color appearance of spinel can be engineered by both techniques. However, the heating has transformed the normal or the ordered spinel to the inverse or the disordered one, and thus disorder might be used as criteria to determine if the stone has been heated. On the other hand, the crystalline structure of the spinel remains almost the same or slightly disordered after ion implantation. This finding leads to future applications for jewelry.

Article history: Received 2 February 2016 Revised 8 August 2016 Accepted in revised form 10 August 2016 Available online 12 August 2016 Natural corundum, a crystalline form of aluminiumoxide (Al2O3)with impure elements, is an allochromaticmineral whose color varies based on the presence of impurities in the composition. Ion implantation technology can be utilized for enhancing the optical properties of corundum by selecting the implanted ion type leading tomodification of the composition and defects. As for the appearance of corundumdepending onmany factors including brilliance, color, fire (light dispersion), and luster, this research attempted to find out an alternative method for improving the optical appearance and color enhancement of corundum by using ion implantation. Ion beam treatments with 70 keV nitrogen and argon ions and 23 keV oxygen ion at fluence of 10 ions/cmwere applied to ruby and sapphire from Thailand,Myanmar, Cambodia, Sri Lanka, Africa, andUSA. Additionally, ion beamanalysis techniques, i.e., particle-induced X-ray emission (PIXE), together with conventional gemological observations such as optical microscope and UltraViolet-Visible and Near Infrared (UV–Vis-NIR) spectroscopy were applied to understand the phenomena observed. The results revealed the possibility of color changing by ion beams resulting from variation in the ionic stage of trace elements as seen from UV–Vis-NIR absorption spectra. The advantages of ion implantation appear to be new and sustainable for improving corundum properties. © 2016 Elsevier B.V. All rights reserved.

Natural corundum, a crystalline form of aluminium oxide (Al2O3) with impure elements, is an allochromatic mineral whose color varies based on the presence of impurities in the composition. Ion implantation technology can be utilized for enhancing the optical properties of corundum by selecting the implanted ion type leading to modification of the composition and defects. As for the appearance of corundum depending on many factors including brilliance, color, fire (light dispersion), and luster, this research attempted to find out an alternative method for improving the optical appearance and color enhancement of corundum by using ion implantation. Ion beam treatments with 70keV nitrogen and argon ions and 23keV oxygen ion at fluence of 1017 ions/cm2 were applied to ruby and sapphire from Thailand, Myanmar, Cambodia, Sri Lanka, Africa, and USA. Additionally, ion beam analysis techniques, i.e., particle-induced X-ray emission (PIXE), together with conventional gemological observations such as optical microscope and UltraViolet-Visible and Near Infrared (UV–Vis-NIR) spectroscopy were applied to understand the phenomena observed. The results revealed the possibility of color changing by ion beams resulting from variation in the ionic stage of trace elements as seen from UV–Vis-NIR absorption spectra. The advantages of ion implantation appear to be new and sustainable for improving corundum properties.

Ion implantation technique has been used for improving the quality of natural ruby. The implantation was performed by using 90keV N2-ion and 50keV O-ion beams. Either kind of ion species could eliminate tiny inclusions in the ruby as observed from an optical microscope. The red color of the ruby was intensified after O-ion implantation. N2-ion implantation changed the color of red ruby to be violet-red. UV–vis and X-ray absorption spectroscopic techniques were employed for investigating the mechanism behind the optical quality improvement of the ruby. The results from both measurement techniques are reported and discussed.

In our efforts in developing ion beam technology for novel applications in biology and gemmology, an economic simple compact ion implanter especially for the purpose was constructed. The designing of the machine was aimed at providing our users with a simple, economic, user friendly, convenient and easily operateable ion implanter for ion implantation of biological living materials and gemstones for biotechnological applications and modification of gemstones, which would eventually contribute to the national agriculture, biomedicine and gem-industry developments. The machine was in a vertical setup so that the samples could be placed horizontally and even without fixing; in a non-mass-analyzing ion implanter style using mixed molecular and atomic nitrogen (N) ions so that material modifications could be more effective; equipped with a focusing/defocusing lens and an X–Y beam scanner so that a broad beam could be possible; and also equipped with a relatively small target chamber so that living biological samples could survive from the vacuum period during ion implantation. To save equipment materials and costs, most of the components of the machine were taken from decommissioned ion beam facilities. The maximum accelerating voltage of the accelerator was 100kV, ideally necessary for crop mutation induction and gem modification by ion beams from our experience. N-ion implantation of local rice seeds and cut gemstones was carried out. Various phenotype changes of grown rice from the ion-implanted seeds and improvements in gemmological quality of the ion-bombarded gemstones were observed. The success in development of such a low-cost and simple-structured ion implanter provides developing countries with a model of utilizing our limited resources to develop novel accelerator-based technologies and applications.