Research On Influencing Factors Of Infrared Spectrum Of Nephrite

Nephrite is formed in the process of geological action,mainly composed of tremolite-actinolite,a high-grade jade that is loved by consumers at home and abroad.Because it is derived from nature,it often contains impurity minerals such as serpentine,calcite,diopside,talc,and epidote in addition to its main components.The content of these impurity minerals has a great influence on the quality of nephrite.Therefore,quantitative calculation of impurity mineral content in nephrite is of great significance for nephrite quality evaluation.When quantitatively calculating the content of impurity minerals in nephrite,it will be affected by many factors.In this paper,through a large number of experiments,according to the mineral composition of natural nephrite,multiple sets of series of standard samples are configured.The quantitative calculation of nephrite composition by infrared spectroscopy was studied,such as baseline painting,selection of characteristic peaks,experimental conditions and other influencing factors.According to the mineral composition of natural nephrite,tremolite was used in combination with minerals such as serpentine,calcite,diopside,talc and epidote to prepare ST(serpentine-tremolite),CT(calcite-tremolite),DT(diopside-tremolite),TT(talc-tremolite)and ET(epidenite-tremolite)five sets of standard sample series with different binary mineral content.Infrared spectrum analysis was carried out on the prepared standard samples,and infrared spectra of the binary series samples of each group were obtained.Using MATLAB to fit the obtained data,a quantitative analysis model of each group of binary series samples was obtained,and a quantitative analysis of each binary model was carried out.The influence of baseline drawing on the quantitative calculation of each group of binary series of standard samples was studied.For each binary series of standard samples,the quantitative calculation model was established by using the connection method and the single shoulder method,and the results of quantitative calculation using different baseline drawing methods were evaluated.The results show that,for the binary component series of CT,ST,and TT,the calculation error of the absorbance using the one-shoulder methodis smaller;for the binary component series of DT,ET,it is more suitable for the calculation of absorbance by the connection method.For each set of binary series models,the influence of the selection of characteristic peaks on quantitative calculation was studied.The same mineral may have multiple characteristic absorption peaks,and quantitative analysis models have been established for different characteristic absorption peaks in different matrices.The method of selecting the characteristic peak with the smallest error in the content of tremolite was studied when the symbiosis of different contents of tremolite with serpentine,calcite,diopside,talc and epidote was studied.According to the research on the factors that affect the quantitative analysis of nephrite,the quantitative calculation process of nephrite composition containing different impurity minerals,namely nephrite composition BP calculation method,is proposed.CST(calcite-serpentine-tremolite)three-component series standard samples and DETT(diopside-epidote-talc-tremolite)four-component series standard samples were prepared.The content of tremolite in CST and DETT series samples were calculated by BP calculation method and traditional calculation method respectively.Comparing the calculation results,the error of the BP calculation method is only 6%-82% of the error of the traditional calculation method,with an average of 40%.