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 หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : LA-ICP-MS Study of Impurity Ion Concentrations in Zircon) ผู้เขียน: Araya Mungchamnankit, Supanee Limsuwan, Pongtip Winotai, Siwaporn Meejoo สื่อสิ่งพิมพ์:pdf AbstractLaser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) is surfacesensitive analytical technique for the estimation of element concentrations as well as their spatial distribution in the analyzed sample. In this work, LA-ICP-MS technique was used for analyzing the impurity ion concentrations in zircon. Because the presence of the impurity ions in the zircon usually caused the color in crystal, the zircon samples in this study are divided into three major groups i.e. untreated zircon (brown color), heat treated zircon in oxygen atmosphere (yellow color) and heat treated zircon in argon atmosphere (greenish blue color). For the first group, the most impurity ion concentrations are Fe (208.90 ppm) and Ti (91.24 ppm). For the second and third groups, there are Fe (965.88 ppm) and Mg (412.20 ppm), Fe (434.66 ppm) and Ti (109.26 ppm), respectively. |
หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Color Enhancement of Natural Type Ia Diamond Using a Neutron–Irradiation and Annealing Method) ผู้เขียน: นางศิวาพร สหวัฒน์, รองศาสตราจารย์ , Areeratt Kornduangkaeo, Kanphot Thongcham, Siwaporn Meejoo, ดร.วิวัฒน์ วงศ์ก่อเกื้อ, ผู้ช่วยศาสตราจารย์ , นางสุรีย์ ลิขิตตชัย, อาจารย์ สื่อสิ่งพิมพ์:pdf AbstractColor in diamonds arises from defects or impurities such as nitrogen, boron or a lattice vacancy. Therefore, suitable types and quantities of defects will assist in creating the most desirable color in a diamond. In this research, ESR spectroscopy was used to find the optimal annealing temperature for color changing in a neutron-irradiated type Ia diamond. It was found that negative vacancies (V-) became mobile above 600?C and were completely trapped by nitrogen to form color centers at 750?C. Therefore, the optimal temperature for color treatment of irradiated diamonds was 750?C. After annealing, yellow diamond was obtained. The optimal fluence of neutron irradiation to produce green diamond was then determined. This research showed that neutron irradiation could turn brown diamond into green diamond with the shading dependent on the fluence of irradiation. The optimal fluence to obtain green diamond was 1.58?1016 n/cm2, while at higher levels the diamond became opaque. After annealing at approximately 750?C, irradiated diamond turned into yellow diamond. A higher fluence of neutron irradiation provided a relatively dark yellow color after annealing. The pale or dark shade of enhanced yellow diamond seemed to be independent of the annealing time. |
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