ที่มา:วิทยาสารเกษตรศาสตร์ สาขา วิทยาศาสตร์

หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Electron Spin Resonance (ESR) and Optical Absorption Spectra of a Manganese Doped Soda-Lime-Silicate Glass System)

ผู้เขียน:Nattapon Srisittipokakun, Chittra KedKaew, Jakrapong Kaewkhao, Treedej Kittiauchawal, เขมฤทัย ถามะพัฒน์, พิเชษฐ ลิ้มสุวรรณ

สื่อสิ่งพิมพ์:pdf

Abstract

A (65-x)SiO2:10CaO:25Na2O:xMnO2 glass system with 0 ? x ? 0.5 mol% was prepared and investigated by X-ray diffraction, optical absorption and ESR spectroscopies. The XRD pattern of undoped glass confirmed the formation of an amorphous vitreous structure. The optical absorption spectra exhibited a predominant broad band around 500 nm and its increase was clearly observed from 0.1 mol% of MnO2. This band corresponded to an allowed transition from 5Eg5T2g, of Mn3+ ions. When the MnO2 concentration was increased, the absorption band due to Mn3+ ions dominated. The ESR spectra results exhibited resonance signals at g ? 2.0 with a sextet of hyperfine lines and less intensity at g ? 4.3. The group of hyperfine lines at g ? 2.0 represented Mn2+ ions in octahedral symmetry. However, these lines were broader and disappeared for higher MnO2 concentrations. This behavior indicated the reduction of Mn2+ ions in the glass system as the concentration of MnO2 was increased by increasing the Mn3+ ions.

Article Info

Agriculture and Natural Resources -- formerly Kasetsart Journal (Natural Science), Volume 043, Issue 5, Dec 09 - Dec 09, Page 360 - 364 |  PDF |  Page

ที่มา:วิทยาสารเกษตรศาสตร์ สาขา วิทยาศาสตร์

หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : The Color Change of Natural Blue Sapphires by Heat Treatment)

ผู้เขียน:Treedej Kittiauchawal, พิเชษฐ ลิ้มสุวรรณ

สื่อสิ่งพิมพ์:pdf

Abstract

This research aimed to investigate the effects of heat treatment on color and clarity of blue sapphires. The blue sapphires were heated at sequentilly increasing temperature of 1300, 1400, 1500 and 1600 ?C in nitrogen atmosphere. Each temperature, the samples were treated for 12 hours, before and after heat treatment at each temperatures, the color and clarity were measured by spectrophotometer. It was found that, when blue sapphires were heated at high temperatures, the color of the untreated sapphire crystal changed to darker blue at higher temperatures. Whereas, the clarity of all samples were not significantly found in the temperature range of 1300 -1600?C

Article Info

Agriculture and Natural Resources -- formerly Kasetsart Journal (Natural Science), Volume 041, Issue 5, Jan 07 - Dec 07, Page 262 - 266 |  PDF |  Page