Reserch Of Thermoluminescence In Identifing Crystals

The gemological characteristics of synthetic crystals are similar to that of natural crystals.In the absence of obvious internal characteristics,how to identify them quickly and accurately is an urgent problem in the gem industry.Thermoluminescence?TL?is a kind of phosphorescence,also one of the microscopic characteristics of minerals.TL technology can be used effectively to reveal the physical properties of minerals,study its lattice parameters and crystal defects,and analyze the causes and behaviors of electron traps.This thesis takes rock crystal,amethyst,smoky quartz and synthetic crystal as experimental objects,using the TL measuring instrument,Infrared spectrometer and X-ray fluorescence spectrometer,to make a summary on the TL characteristics of samples,hope to get meaningful conclusions in gem identification,and explore its potential applications in the field of the gem identification and development trend in future.Getting the TL curve of samples by slow linear temperature,due to irradiation from nature,the natural crystal samples have a low intensity light emitting peak in 110-125?,may be associated with Fe-O^-center,synthetic crystal samples show no TL phenomenon;natural amethyst have no TL phenomenon,that is because Fe inhibitory effect on low temperature zone,luminous,synthetic amethyst have low intensity light emitting peak appears at 75?and 115?by a short time and large-scale of irradiation;natural smoke quartz show no TL phenomenon,it is speculated that element Fe and Ti inhibit TL in low temperature area,a short time and large-scale irradiation effect make synthetic smoky quartz a large number of lattice defects,then show relatively strong TL phenomenon,and photoluminescence peak appear at 95?and 155?.Therefore,the natural crystal and synthetic crystal can be distinguished by the characteristics of thermoluminescence.By testing FT-IR spectrometry of samples,the rock crystals have the characteristics of3595cm^-11 and 3481cm^-11 absorption peaks,while the synthetic crystals have 3584cm^-1absorption peaks to be different with the rock crystals.Amethyst has a wide absorption band in the 3550cm^-1-3250cm^-11 range,yet synthetic amethyst has 3540cm^-11 of characteristic absorption peak,but this peak of some synthetic amethyst is not obvious.The two absorption peaks of 3595cm^-11 and 3481cm^-11 lost in the synthetic smoke quartz,the characteristics can be used to identify Smoke quartz and the synthetic one.X-ray fluorescence spectrometers are used to analyze the content of microelement within the samples,and no significant difference found in the types and contents of microelement in the rock crystal,smoke quartz and the synthetic crystals.The content of K in synthetic amethyst is a little more than amethyst.