Al~(3+)杂质对KDP晶体光学质量影响的研究

用传统降温法和快速生长法生长了Al3+离子掺杂的磷酸二氢钾(KDP)晶体,并对掺杂的KDP晶体的光学质量进行了测试和分析。实验表明,Al3+掺杂对KDP晶体的透光率没有明显的影响,但会使晶体的光散射加剧,光学均匀性和激光损伤阈值下降。     

Ca2+离子对 KDP晶体生长习性及性能的影响

Ca^2＋是KDP原料中一种常见的杂质离子，通过传统降温法和“点籽晶”快速生长法研究了Ca^2＋离子对KDP晶体生长习性及性能的影响、实验表明，Ca^2＋低浓度掺杂时对溶液的稳定性及生长过程没有明显的影响；高浓度时溶液稳定性有所降低，经常出现杂品；快速生长时，晶体柱面易出现包藏，晶体的紫外透过呈下降趋势，晶体中散射颗粒密度随掺杂浓度的增加而增大、     

硫酸盐掺杂对KDP晶体生长的影响

SO2-4是KDP原料中一种常见的杂质离子,通过传统降温法和“点籽晶”快速生长法研究了掺杂K2SO4的KDP晶体的生长.实验表明,硫酸根低浓度掺杂时可提高溶液的稳定性,促进晶体的生长,造成柱面扩展;高浓度时溶液稳定性遭到破坏,出现杂晶,晶体生长速度变慢,晶体出现开裂,柱面发生“楔化”.     

化学组成对EMD电化学行为的影响

为了了解化学组成对电解二氧化锰(EMD)电化学行为的影响,分析了三种商品 EMD的组成,它们分别为Mn_0.881⁴⁺Mn_0.044³⁺O_1.655^2-(OH)_0.345^-、Mn_0.880⁴⁺Mn_0.048³⁺O_1.666^2-(OH)_0.334^-和 Mn_0.879⁴⁺Mn_0.054³⁺O_1.677^2-(OH)_0.322^-, X射线衍射表明晶型为γ-MnO₂.通过循环伏安、恒流放电、 电位-时间关系等实验研究其电化学行为,结果表明,EMD中结合水含量(即阳离子空位数) 增加时,样品开路电压升高、放电容量增大、第1电子还原的峰电位正移.     

六偏磷酸盐对KDP晶体快速生长及光学性能的影响研究

在掺杂不同浓度的六偏磷酸盐溶液中,利用"点籽晶"快速生长法生长了KDP晶体,生长速度约20 mm/d。研究了六偏磷酸盐对快速生长的KDP晶体的生长及光学性能的影响,并与传统慢速生长的晶体进行了对比。实验表明,溶液中掺杂少量六偏磷酸盐就会显著降低生长溶液的稳定性,抑制晶体的生长,生长的晶体容易出现包藏、添晶、粉碎性裂纹等缺陷;生长的晶体光学质量也明显下降,例如晶体内部的光散射加重,激光损伤阈值降低;相比传统生长法生长的晶体,同等浓度的六偏磷酸盐对"点籽晶"快速生长法生长的晶体影响更为严重。结合KDP的晶体结构和六偏磷酸盐的分子特点,对其影响机理进行了讨论。     

Yb:KGd(WO4)2激光晶体结构与振动光谱

用顶部籽晶提拉法, 以K₂W₂O₇为助溶剂, 生长Yb:KGd(WO₄)₂激光晶体. 经热重-差热分析, 确定晶体熔点为1086℃, 相变温度为1021℃. 晶体结构分析确定Yb:KGW(WO₄)₂晶体由WO₆八面体连接而成, WO₆八面体是由(WOOW)双氧桥及(WOW)单氧桥构成. 晶体粉末样品室温下的红外及拉曼光谱测试, 确定WO₄^2-、双氧桥及单氧桥的振动范围, 并对其进行了归属. X射线粉末衍射测试, 验证所生长的晶体为β-Yb:KGd(WO₄)₂.     

高阻In掺杂CdZnTe晶体缺陷能级的研究

利用低压垂直布里奇曼法制备了不同In掺杂量的CdZnTe晶体样品, 采用低温光致发光谱(PL)、深能级瞬态谱(DLTS)以及霍尔测试等手段研究了In掺杂CdZnTe晶体中的主要缺陷能级及其可能存在的补偿机制. PL测试结果表明, 在In掺杂样品中, In原子占据了晶体中原有的Cd空位, 形成了能级位于E_c-18meV的替代浅施主缺陷[In_Cd^+], 同时 [In_Cd⁺]还与[V_Cd^2-]形成了能级位于E_v+163meV的复合缺陷[(In_Cd⁺-V_Cd^2-)^-]. DLTS分析表明, 掺In样品中存在导带以下约0.74eV的深能级电子陷阱能级, 这个能级很可能是Te反位[Te_Cd]施主缺陷造成的. 由此, In掺杂CdZnTe晶体的电学性质是In掺杂施主缺陷、Te反位深能级施主缺陷与本征受主缺陷Cd空位和残余受主杂质缺陷补偿的综合结果.     

共沉淀法制备掺杂氧化锌压敏陶瓷粉料热力学分析

本文通过对Ｍｅ^ｎ＋（Ｚｎ^２＋;Ｃｒ_３^＋,Ｍｎ^２＋;Ｓｂ^３＋,Ｂｉ^３＋,Ｃｏ^２＋）－ＮＨ_３－ＣＯ_３^２－－Ｈ_２Ｏ体系进行热力学分析的基础上,获得了Ｍｅ－ＮＨ_３－ＣＯ_３^２－Ｈ_２Ｏ体系中的ｌｇ［Ｍ］_T－ｐＨ关系图,得到了用ＮＨ_４ＨＣＯ_３和ＮＨ_３·Ｈ_２Ｏ作沉淀剂,用共沉淀法制备掺杂氧化锌压敏陶瓷粉料时,最佳共沉淀ｐＨ为７．０左右．     

不同籽晶对KDP晶体质量的影响

采用Z片籽晶和锥头籽晶分别进行传统降温法生长KDP晶体,并对其高分辨摇摆曲线、锥光干涉图以及消光比进行测试研究。实验发现,KDP晶体在不同籽晶下均能实现较好的生长稳定性,采用锥头籽晶生长的KDP晶体具有相对更好的晶体质量。     

水热法制备碱式硫酸镁晶须的过程机制

以MgSO₄和NaOH为原料,采用常温合成-水热反应方式制备出直径0.5-1.0μm、长30-50μm的碱式硫酸镁(5Mg(OH)₂·MgSO₄·3H₂O)晶须。电导率实验表明:添加氢氧化镁可显著提高硫酸镁水热溶液的电导率,由此初步推测晶须的水热合成属溶解-结晶机制:氢氧化镁首先溶解,然后溶液中Mg²⁺、SO₄^2-和OH^-发生反应生成碱式硫酸镁晶须。晶须的水热合成过程受晶体生长控制,宏观动力学方程为:-dc/dt=0.438(c-0.417)4     

Growth habit and transparency of sulphate doped KDP crystal

KDP crystals were grown from the aqueous solution with different concentrations of sulphate by both the traditional temperature-lowering method and the rapid growth method. Sulphate showed a great effect on the growth and the properties of KDP crystals. With the rise of the dopant concentration, many defects occur such as mother liquid inclusions, parasite crystals and cracks. When the dopant concentration of sulphate reaches a certain value, the ultraviolet transmittance of crystals decreases a lot compared with crystals at low dopant concentration.     

添加剂DTPA对KDP晶体快速生长及性能的影响研究

在添加1×10^-4 (mol/mol KDP) 二乙烯三胺五乙酸(DTPA)的溶液中, 利用“点籽晶”快速生长法生长了KDP晶体. 实验发现, 添加少量DTPA即可使不同饱和温度下的KDP生长溶液的亚稳区宽度均得到提高. 利用激光偏振干涉装置研究了不同浓度的DTPA对KDP晶体(100)面生长动力学的影响. 发现随DTPA掺杂量增加, 临界过饱和度(死区)一直降低, 生长速度则是先增加经过一个最大值后减小. 表征了晶体的光学透过率和晶体内部的杂质金属离子含量, 发现掺杂1×10^-4 (mol/mol) DTPA大幅提高了快速生长的KDP晶体在紫外区的透过率, 并有效地减少了进入晶体内部的杂质金属离子含量.     

Growth of unidirectional potassium dihydrogen orthophosphate single crystal by SR method and its characterization

Unidirectional <100> potassium dihydrogen orthophosphate (KDP) single crystals were grown for the first time by Sankaranarayanan-Ramasamy (SR) method. The <100> oriented seed crystals were mounted at the bottom of the glass ampoules and the crystal of 15 mm diameter, 65 mm height were grown by SR method. The grown crystals were characterized by high-resolution X-ray diffraction (HRXRD), etching studies. The HRXRD analysis indicates that the crystalline perfection is excellent without having any very low angle internal structural grain boundaries. Dislocation density is less in SR grown KDP compared to conventional method grown KDP.     

硫酸盐掺杂导致KDP晶体开裂的研究

采用传统降温法生长了掺杂不同浓度的SO42-离子KDP晶体,研究分析了晶体的宏观缺陷及开裂形式,从晶体生长角度初步分析了硫酸盐掺杂导致KDP晶体开裂的主要原因。实验表明,随着SO42-离子掺杂浓度的增大,KDP晶体的主要开裂形式是垂直于生长层{101}面的裂纹;晶体中裂纹存在的区域都分布有大量层层平行于生长层的母液包藏。随着SO42-离子掺杂浓度的进一步增大,晶体内包藏呈云雾状分布,裂纹不规则,晶体质量严重下降,透明度降低。     

Effects of Cl- and SO2-4 Ions on Corrosion Behavior of X70 Steel

Corrosion behaviors of X70 steel were studied by means of electrochemical experiments and morphology observation.First, through potentiodynamic polarization in solution of various Cl- ions concentration, it was found that Epit began to appear in solution of Cl- concentration above 0.1 mol/L, and there was a critical point of Cl- concentration between 0.05 mol/L and 0.1 mol/L, below which the extent of pitting and general corrosion were trivial, while in solution of Cl- concentration above 0.1 mol/L, general and pitting corrosion became greater as the increasing of Cl- concentration. All of them were confirmed by the SEM observations after anodic polarization. Second, via the potentiodynamic polarization curves of X70 steel in 0.5 mol/L Cl- solution with 0, 0.05, 0.5 and 1 mol/L SO42-ions, it was found SO42- ions were able to inhibit corrosion aroused from Cl- ions, accordingly a model was set up to describe the process. In addition, to further explore the inhibited effect of SO42- ions, EIS was used in solutions of different Cl- and SO42- concentrations, the results revealed that the e(ectrochemical resistance has a relation with the [SO42-]/[Cl-], that was, the bigger the value of [SO42-]/[Cl-], the greater the electrochemical resistance.     

Cr3+掺杂对快速生长KDP晶体的生长习性和光学性能的影响

采用快速法生长了掺杂不同Cr3+浓度的KDP晶体,测试了KDP晶体(100)面在不同Cr3+掺杂浓度下的生长速度及死区,表征了Cr3+掺杂的KDP晶体的Cr3+元素分布、透过光谱、散射颗粒分布和光损伤阈值.实验表明Cr3+易吸附在晶体(100)面,从而增大了(100)生长死区,并降低了(100)面生长速度.Cr3+使快...     

Investigation of SR method grown 0 0 1 directed KDP single crystal and its characterization by high-resolution X-ray diffractometry (HRXRD), laser damage threshold, dielectric, thermal analysis, optical and hardness studies

0 0 1 directed potassium dihydrogen orthophosphate (KDP) single crystal was grown by Sankaranarayanan–Ramasamy (SR) method. The 0 0 1 oriented seed crystals were mounted at the bottom of the platform and the size of the crystals were 10 mm diameter, 110 mm height. Two different growths were tried, in one the crystal diameter was the ampoule's inner diameter and in the other the crystal thickness was less than the ampoule diameter. In the first case only the top four pyramidal faces were existing whereas in the second case the top four pyramidal faces and four prismatic faces were existing through out the growth. The crystals were grown using same stoichiometric solution. The results of the two growths are discussed in this paper. The grown crystals were characterized by high-resolution X-ray diffractometry (HRXRD), laser damage threshold, dielectric, thermal analysis, UV–vis spectroscopy and microhardness studies. The HRXRD analysis indicates that the crystalline perfection is excellent without having any very low angle internal structural grain boundaries. Laser damage threshold value has been determined using Nd:glass laser operating at 1054 nm. The damage threshold for the KDP crystal is greater than 4.55 GW cm⁻². The dielectric constant was higher and the dielectric loss was less in SR method grown crystal as against conventional method grown crystal. In thermal analysis, the starting of decomposition nature is similar in SR method grown KDP crystal and conventional method grown crystal. The SR method grown KDP has higher transmittance and higher hardness value compared to conventional method grown crystals.     

室内外细粒子PM_(2.5)和总悬浮颗粒物污染水平的对比研究

为了解室内外空气颗粒物PM2.5和总悬浮颗粒物(TSP)的污染状况,自2008年3月24日～4月3日在西安交通大学学生办公室、教师办公室、化学实验室和室外同时采集PM2.5和TSP样品,对其质量浓度及无机水溶性离子组分(Na+、NH4+、K+、Mg2+、Ca2+、Cl-、NO3-和SO42-)进行了分析。结果表明,室内外PM2.5和TSP浓度都远远高于美国空气质量标准规定的35μg/m3。室内外颗粒物浓度具有相同的变化趋势,且室内总体上低于室外。室内PM2.5在TSP中所占比例在65%～85%,室外在40%左右。室内外TSP和PM2.5中二次污染离子SO42-、NO3-和NH4+占总离子质量的50%以上,主要富集在细颗粒中。NH4+、K+和Cl-在总离子中的比例均为室内大于室外,PM2.5中大于TSP。Ca2+、Mg2+主要富集在粗颗粒上,室外含量远远高于室内。     

离子色谱法测定饮用水中常见阴离子

本文主要介绍离子色谱法检测饮用水中常见阴离子的方法。本方法采用瑞士万通的761型离子色谱仪。分离柱为METROSEPAnionDual2,淋洗液为2.0mmol/LNaHCO3和1.3mmol/LNa2CO3抑制液为20mmol/LH2SO4在测定范围内,F-、Cl-、NO2-、NO32-;-SO42-的峰面积和质量浓度呈线性关系,相关系数均大于0.999。回收率F-为101.5%,CL-O101.6%,NO2-为108.0%.NO32-为97.7%,SO42-为103.3%。相对标准偏差在0.7%-4.3%之间。