Glow Discharge Mass Spectrometry Quantitative Analysis Of Doping Elements Of Synthetic Crystals

In this paper, the direct current glow discharge mass spectrometry (dc-GD-MS) was applied for the determination of doping elements in some synthetic crystals, such as BaF2, Y3Al5O12(YAG), Bi4Si3O12(BSO), La3Ga5SiO14(LGS), CsI, Pb(Mg1/3Nb2/3)O3-PbTiO3(PMN-PT), CaF2and γ-Al2O3. To get stable discharge, the surface coating method and tantalum carrier method were used to support the sputtering and ionization of samples respectively.The stable discharge current and the matrix signals were investigated by using these two methods. For the analysis of BaF2, YAG, BSO, LGS, Csl and PMN-PT, both the surface coating method and tantalum carrier method could achieve stable discharge and fine intensity of matrix elements. While for the analysis of CaF2and γ-Al2O3, the tantalum carrier method could sustain much stable discharge to achieve fine intensity of matrix elements compared to the surface coating method in a very short time. As conductive host, the Ta carrier method could not cause any interference to most of the rare elements. Compared to the secondary cathode method and mixing method, the surface coating method and Ta carrier method could sustain stable discharge and enhance the stability of signals. Furthermore, the results of two similar YAG samples could also validate the precision, accuracy and reproducibility of the surface coating method and Ta carrier method.The experimental results showed that the dc-GD-MS could be better applied for the determination of doping elements in synthetic crystals by combing the surface coating method and Ta carrier method, this developed the application field of dc-GD-MS.This paper consists of the following three chapters. Chapter one: PrefaceFirstly, we generally introduced the type and properties of the crystal materials, described the types of crystal defects and its effects to crystal materials. Meanwhile, we described the application of crystal defects in the crystal material synthesis, and the importance of the quantitative analysis of the doping elements. Then we reviewed the progress of researches of methods for determination of doping elements in synthetic crystals. The advantages and disadvantages of the methods of atomic spectroscopy, X ray fluorescence spectrometry, mass spectrometry and electron probe micro-analyzer have been compared. Finally, we illustrated dc-GD-MS, in which the basic principle, experimental device and its application in non-conductive materials were highlighted. At last, we pointed out the purpose and significance of this paper.Chapter Two:Studies for determination of doping elements in synthetic crystals by the surface coating method of glow discharge mass spectrometryIn this chapter, the direct current glow discharge mass spectrometry (dc-GD-MS) was applied for the determination of doping elements in BaF2, YAG, PMN-PT, BSO, LGS, CsI, CaF2and γ-Al2O3by using the surface coating method. The raw materials were manufactured into pin samples (20mm×2mm×2mm). The pure indium was melted in a clean ceramic crucible at a temperature of around200℃. Then, the pin sample was held by titanium tweezers and dipped into the indium, submerging around75%of the length, and the surface coating layer thickness of indium was about400μm, thus making the new samples. Under the optimized conditions, the doping elements in these crystals were analyzed by the dc-GD-MS. Compared to the secondary cathode method and mixing method, the surface coating method could sustain stable discharge and enhance the stability of signals. Furthermore, the results of two similar YAG samples could also validate the precision, accuracy and reproducibility of the surface coating method. The results suggested that the dc-GD-MS would be a good choice to determine the doping elements in synthetic crystals by using the surface coating method. Chapter Three: Studies for determination of doping elements in synthetic crystals by the Ta carrier method of glow discharge mass spectrometryIn this chapter, the direct current glow discharge mass spectrometry (dc-GD-MS) was applied for the determination of doping elements in these crystals by using the Ta carrier method. The raw materials were manufactured into pin samples (5-10mm×2mm×2mm), and Ta carrier (20mm×2mm×2mm) was made from high-purity tantalum. The pin sample was put in the Ta carrier for analysis. Under the optimized conditions, the doping elements in these crystals were analyzed by the dc-GD-MS. Compared to the secondary cathode method and mixing method, the Ta carrier method could also sustain stable discharge and enhance the stability of signals. While for the analysis of CaF2、γ-Al2O3and rare earth elements, the Ta carrier method would be a better choice compared to the surface coating method. Furthermore, the precision, accuracy and reproducibility of the Ta carrier method were validated by the results of two similar YAG samples. The results suggested that the dc-GD-MS would also be a good choice to determine the doping elements in synthetic crystals by using the Ta carrier method.