硬脂酸凝胶法制备CeO2纳米粉体

采用硬脂酸凝胶法制备了CeO2纳米晶。XRD分析表明,当焙烧温度为450～900℃时,所合成的CeO2纳米晶均属于单相立方晶系,空间群为O5H-FM3M;计算表明,随焙烧温度的升高,平均晶粒度增大,而平均晶格畸变率则随平均晶粒度的增大而减小,表明粒子越小,晶格畸变越大,晶粒发育越不完整。TEM分析表明,CeO2纳米晶呈球形,粒度随焙烧温度的增加而增大。热失重分析表明,当焙烧温度高于750℃时,CeO2中的杂质基本挥发完毕。相对密度分析表明,随CeO2纳米晶粒度的增大,粉末的密度增加。,CeO2 nanocrystalline particulates of different sizes were prepared by stearic acid gel method.XRD patterns showed that the synthesized CeO2 was cubic in structure with single-phase when calcination temperature was 450-900℃,space group was O5H-FM3M.Calcination revealed that the mean crystalline size increased with the increase of calcinstion temperature,but average crystal lattice distortion rate decreased with the increasing in the average crystalline size.This indicated that the smaller the particle size,the bigger crystal lattice distortion,the worse the crystal growed.TEM photos revealed that CeO2 particles were spherical in shape,and the mean sizes of the C eO2 particles increased with the increase of calcination temperatures.Weight loss analysis indicated that the impurity in CeO2 completely volatilized when calcination temperature was above 750℃.The density of nanocrystalline CeO2 powders analysis showed that the density of CeO2 nanocrystalline powders increased with the increasing in CeO2 particles sizes.     

火炬气回收用螺杆压缩机的防腐和冷却

水冷式螺杆压缩机用于火炬气回收系统，将火炬气升压后送到燃料气管网利用。由于火炬气中引入冷却水，对螺杆和机壳腐蚀严重。采用石油液化气作冷剂取代水冷却，用润滑油隔绝火炬气与螺杆表面、机壳内表面的接触，起到了防癌和冷却作用，延长了螺杆压缩机的使用寿命。     

Growth,structure and spectral characteristics of KEr_(0.1)Yb_(0.9)(WO_4)_2 laser crystal

The 10 at.% Er3+-doped KYb(WO4)2(KEr0.1Yb0.9(WO4)2) laser crystal with dimensions up to 25 mm×15 mm×10 mm was grown by the Kyropoulos method.The crystal structure was identified as β-KEr0.1Yb0.9(WO4)2 by XRD analysis.Through TG-DTA curves,the melting point and transition point of the crystal were determined to be 1058 and 1031 °C,respectively.Infrared spectrum and Raman spectrum were measured,and the vibration frequencies of infrared and Raman active modes for the crystal were assigned.The absorption cross section is 3.1×10-20 cm2 at chief peak of 981 nm with the absorption line width of 26 nm.Based on the Judd-Ofelt theory,the intensity parameters ?λ(λ=2,4,6) calculated were:?2=16.34×10-20 cm2,?4=4.18×10-20 cm2,and ?6=1.26×10-20 cm2.There was a strong emission peak near 1533 nm and the emission line width at the main peak at 1533 nm run up to 55 nm with the emission cross section of 3.47×10-20 cm2 .These optical parameters indicated the potential of this crystal used as an excellent laser material for 1540 nm nearby human-eye safe.     

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YbKGd(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YbKGW(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WO42-、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-YbKGd(WO4)2.     

Nd:NaBi(WO4)2晶体光谱性能研究

采用提拉法生长出了四方晶系白钨矿结构的掺钕钨酸铋钠[分子式Nd:NaBi(WO4)2,简称Nd:NBW]晶体.通过TG-DTA分析得到晶体的熔点为936.2℃,从XRD分析得到晶胞参数a=b=0.5275nm,c=1.1493nm.测试了该晶体的红外光谱和拉曼光谱,讨论了晶体的振动归属.由吸收光谱可以看出,该晶体在802nm有较强的吸收峰,半峰宽约16nm,并计算了晶体中Nd3 的吸收截面积.     

掺镱钇铝石榴石激光透明陶瓷超细粉体的研究

钇铝石榴石(YAG)透明陶瓷是制造大功率、发光效率高的小型激光器的良好材料.而制备掺镱钇铝石榴石(Yb:YAG)透明陶瓷的关键在于制备出粒度均匀、化学纯度高、分散性好的YAG超细粉体.本文以Y2O3、Yb2O3、Al2(NO3)3·9H2O为原料,以Yb:Y:Al=0.06:2.94:5的配比掺杂2%的Yb取代Y,配成硝酸盐溶液,用NH4HCO3作为沉淀剂,用碳酸盐共沉淀法制备Yb:YAG前驱超细粉体,并用TG-DTA、XRD、IR、SEM等测试方法对其粉体结构和形貌进行分析.结果表明:在1 100℃煅烧过程中,失重约为41%.所得到的Yb:YAG粉体结晶好,烧结性高、纯度较好、形状规则,粒径均匀,均在200～300 nm之间.     

溶胶—凝胶法制备Li_2B_4O_7薄膜的研究

本文主要研究溶胶—凝胶法制备Li2B4O7薄膜的工艺过程，并就影响因素进行了分析和讨论。     

大尺寸BaF_2晶体开裂的研究

本文指出了大尺寸(φ100mm)BaF_2单晶生长过程中的开裂因素,分析了大尺寸BaF_2单晶生长时能允许的最大轴向温度梯度,降温速率以及由于热应力引起的最大合成应变。相应地改善了温场,确定了最佳晶体生长工艺,采用坩埚下降法生长出了无开裂的φ100mm的完整晶体。     

Y—Ba—Cu—O超导薄膜溅射靶材的研制

本文按136;134和123名义配比研制了用于磁控溅射制膜的超导靶材,其中134和136配比的超导靶材增加了Cu和Ba的比例,在烧制过程中增加了BaCuO_2相,使制备出的超导薄膜表面电阻小,136组分要优于134组分、用136组分靶材制备出了高Tc超导薄膜,起始转变温度为94K,零电阻转变温度为86.5K的样品。     

Tm:Yb:KY(WO4)2晶体蓝光上转换

利用顶部籽晶提拉(TSSG)法生长了Yb3 ,Tm3 共掺KY(WO4)2晶体,在室温下测量了290～1200nm内晶体的吸收光谱。根据上转换模型研究了晶体中Yb3 向Tm3 进行能量传递的机制并对晶体中跃迁能级进行了指认,建立了简单的速率方程。计算得出Yb3 离子向Tm3 离子的能量传递效率接近于1。在974nm激光二极管抽运下观察到Tm3 离子的波长为476nm蓝色上转换发光。利用Fadenbrug-luechtbauer方法计算了1G4到3H6能级跃迁的发射截面积,其最大发射截面积约为1.51×10-20cm2。