Hatipoǧlu M.Tuncer Y.Kibar R.Çetin A.Karal T.Can N.2024-07-222024-07-22201009214526http://akademikarsiv.cbu.edu.tr:4000/handle/123456789/18206In this study, thermal properties and thermal decompositions of dehydration behaviour of gem-quality translucent blue chalcedonies, without banding or crystalline centre structure, from the Sarcakaya-Eskiehir region in Turkey were studied by means of X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometry (ICP-AES), Fourier transform infrared (FT-IR), thermoluminescence (TL), and simultaneously two thermal analyses of (DTA/TGA) spectroscopy. X-ray diffraction patterns of the blue chalcedony indicate the presence of two important chalcedonic silica phases with overlapped peaks at 4.26, 3.34, 2.28, 2.13, 1.82, 1.54, 1.38, and 137 . During heating from the room temperature to 300 °C, the thermoluminescence pattern of the blue chalcedony shows a characteristic peak at 210 °C. This peak may be due to unusually high traces of the impurities S, Th, Tl, U, and W. During heating from the room temperature to 1400 °C, the TGA pattern of the blue chalcedony indicates that the weight loss is due to the silanol water loss only, and that this loss occurs in a wide temperature range between about 170 and 954 °C. In addition, after making some corrections concerning the artefact mass gain, being due to the drift with buoyancy effect of the atmosphere in its TGA curve, the moganite-rich blue chalcedony shows a relatively lower mass loss of 0.202%. The DTA pattern of the blue chalcedony displays both endothermic and exothermic behaviours because of silica phase transformations. There are one distinctive sharp endotherm and three weaker endotherms at 806 °C. In addition, there is one distinctive sharp exotherm and one weaker exotherm at 1270 °C. © 2010 Elsevier B.V. All rights reserved.EnglishAtomic emission spectroscopyAtomic spectroscopyBuoyancyDecompositionDiffractionElectromagnetic inductionFourier transformsGemsHeatingHolographic interferometryInductively coupled plasmaPhase transitionsSilicaThermoanalysisThermodynamic propertiesX ray diffractionX ray diffraction analysisBuoyancy effectCharacteristic peaksDehydratial behavioursExothermsFourier transform infraredInductively coupled plasma-atomic emission spectrometryMass gainMass lossMoganite-rich gem quality blue chalcedonyOverlapped peaksPhase transformationRoom temperatureSilanolsSilica phasisTemperature rangeTGA curvesThermal analysisThermal decompositionsThermal propertiesTurkeyWater lossWeight lossXRDThermoluminescenceArticle10.1016/j.physb.2010.08.048