添加剂对季戊四醇（PET）晶体生长的影响研究

发布时间：2018-10-24 10:36

【摘要】：季戊四醇(C(CH2OH)4,简称PET)晶体是一种重要的X射线分光晶体,具有衍射强度大,背景低和热稳定性高等优点。是X射线荧光光谱、激光等离子体X射线光谱等分析与检测领域的重要材料,摄谱范围为0.55~0.8 nm,主要检测元素范围为Al13~Zr40。本文以水为溶剂,分别进行了无添加剂、多种浓度的弱酸(硼酸、草酸、柠檬酸)、乙醇添加的PET结晶性状实验,发现添加硼酸和低浓度(1~2%)的乙醇能够有效改善其结晶习性,所得晶粒完整、透明,从而选定硼酸和乙醇作为PET晶体生长的添加剂;分别测定了这两种添加剂存在下PET在水中的溶解度和溶液亚稳区,结果显示,在添加硼酸和乙醇的溶液中PET具有更大的溶解度和溶解度温度系数,亚稳区也有所增宽;再分别添加硼酸和乙醇条件下,采用常温溶液降温法生长PET晶体,与其在无添加剂的溶液中生长相比,溶液更加稳定,晶体的宏观完整性明显提高。通过对所培养晶体的(001)晶面摇摆曲线测试及晶体光轴向干涉图观测分析晶体的晶面完整性与光学均匀性,得出在添加浓度为0.8mol/L的硼酸溶液中自然降温培养的PET晶粒(001)面衍射峰半高宽最窄,单晶的结构完整性最好,适合做籽晶;添加浓度为1.5%~2%的乙醇所生长PET晶体的衍射峰半高宽较窄且差别较小,说明晶面结构完整性较好;不同条件下所生长PET晶体的光轴向干涉图除了添加乙醇(1%、1.25%)没有明显差别,都比较规则,无明显扭曲、变形现象,只因加工方式不同而略有不同,证明晶体的光学均匀性很好,且不受生长时添加条件变化的影响。
[Abstract]:Pentaerythritol (C (CH2OH) 4 (PET) crystal is an important X-ray spectroscopic crystal with the advantages of large diffraction intensity, low background and high thermal stability. It is an important material in the field of X-ray fluorescence spectrum, laser plasma X-ray spectrum and so on. The spectrum range is 0. 55 ~ 0. 8 nm, and the main detection element range is Al13~Zr40.. In this paper, using water as solvent, the crystallization properties of PET with different concentrations of weak acids (boric acid, oxalic acid, citric acid) and ethanol were studied. It was found that the addition of boric acid and low concentration of ethanol (1%) could effectively improve its crystallization habit. Boric acid and ethanol were selected as additives for PET crystal growth. The solubility and metastable region of PET in water were determined in the presence of these two additives. In the solution with boric acid and ethanol, PET has greater solubility and solubility temperature coefficient, and the metastable region is also widened, and then the PET crystal is grown by cooling method in normal temperature solution under the condition of boric acid and ethanol, respectively. Compared with the solution without additive, the solution is more stable and the macroscopic integrity of the crystal is improved obviously. By measuring the rocking curve of (001) crystal plane and observing the crystal axial interferogram, the crystal plane integrity and optical uniformity are analyzed. The results show that in boric acid solution with concentration of 0.8mol/L, the diffractive peak width of PET crystal (001) surface is narrowest and the structure integrity of single crystal is the best, which is suitable for seed crystal. The diffractive peak width of the PET crystal grown by adding 1.5% and 2% ethanol is narrow and the difference is small, which indicates that the crystal plane structure integrity is better, and the optical axial interferogram of the PET crystal grown under different conditions has no obvious difference except the addition of ethanol (1.25%). It is proved that the optical uniformity of the crystal is very good and is not affected by the change of the growth conditions.
【学位授予单位】：北京工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O78

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