Pichet LimsuwanSiwaporn MeejooAsanee SomdeeKheamrutai ThamaphatTreedej KittiauchawalAtitaya SiripinyanondJurek KrzystckKing Mongkuts University of Technology ThonburiMahidol UniversityNational High Magnetic Field Laboratory2018-07-122018-07-122008-06-01Chinese Physics Letters. Vol.25, No.6 (2008), 1976-1979174135400256307X2-s2.0-46749147192https://repository.li.mahidol.ac.th/handle/20.500.14594/19893Blue sapphires are treated with Be in oxidizing atmosphere to change the blue colour into yellow. Untreated and Be-treated samples are examined using laser ablation inductively coupled-plasma-mass spectrometry (LA-ICP-MS), electron spin resonance (ESR) and ultraviolet-visible (UV-vis) spectroscopy. The results show that the yellow colouration in Be-heated blue sapphires is not due to Be diffusion from the surface of sapphire. Be behaves as a sole catalyst in this process. We find that the charge transfer between the ferrous (Fe2+) and ferric (Fe3+) is the reason of the colour change. The above conclusions are confirmed by ESR measurements to determine the connections between the Fe3+ions before and after Be-treated heat treatments. © 2008 Chinese Physical Society and IOP Publishing Ltd.Mahidol UniversityPhysics and AstronomyArticleSCOPUS10.1088/0256-307X/25/6/015