导模法生长晶体研究进展

导模法是一种极具应用潜力的晶体生长方法,具有生长速度快,加工成本低的优点,广泛用于生长各种形状的晶体.对导模法的原理、特点和发展历史进行了简单介绍.着重论述了导模法在生长有形蓝宝石和硅晶体中的发展和应用,对目前导模法生长晶体过程中存在的问题做了简单的介绍.     

Nd：GGG晶体生长、光谱性能及激光性能（英文）

采用提拉法生长掺钕钆镓石榴石（neodymium-doped gadolinium gallium garnet,Nd：GGG）激光晶体,选择最佳工艺参数：提拉速率为2～4mm/h;转速为20～40r/min;冷却速率为20℃/h。测试了晶体的吸收和荧光光谱,结果表明：主吸收峰位于808nm,主发射峰位于9430cm^–1,对应于Nd3＋的4F3/2–4I11/2跃迁。对晶体样品进行了激光性能测试。结果表明：当泵浦功率为900mW时,对泵浦光的吸收效率为85%,激光输出波长约为1μm,激光输出功率为305mW,激光阈值功率为380mW,光–光转换效率达57.8%,斜效率达57.6%。     

γ射线辐照及其后退火MgAl2O4透明陶瓷中缺陷运动行为的研究

用不同剂量的γ射线辐照镁铝尖晶石透明陶瓷，并对辐照后的样品进行等时退火，UV－VIS和FT－IR，PAT测试表明，辐照前3360cm^-1处有吸收峰，它是由VOH^-心吸收引起的，通过γ射线辐照，样品在370nm处产生吸收带，它是由辐照产生的V型色心吸收引起的，通过退火可以使V型色心吸收带消除。结果表明：对陶瓷γ射线辐照及退火，将使样品中的空位团发生分裂和空位聚集。较低剂量的γ射线辐照能降低陶瓷紫外到红外透过率，大剂量的γ射线辐照能在陶瓷中产生局域退火效应，它能阻止可见和紫外透过率随剂量增加而下降并能增加陶瓷红外透过率。     

热交换法生长掺锆蓝宝石单晶及其光谱性能研究

采用热交换法(Heat-Exchange Method,HEM)生长出无色透明的掺锆蓝宝石(Zr∶ sapphire)单晶.通过辉光放电质谱(GD-MS)、傅里叶变换红外光谱(FTIR)、紫外-可见-近红外(UV-VIS-NIR)吸收光谱、紫外-可见(UV-VIS)透过率等测试手段研究了Zr∶ sapphire的光谱性能.目前研究表明,采用HEM成功地将ZrO2掺入蓝宝石晶体中,掺入量可达3.3 ppm;蓝宝石晶体中掺入ZrO2后能消除晶体的F+色心缺陷,提高晶体在波长257 nm处的透过率;Zr∶sapphire晶体在可见、红外波段的透过率分别为83.41％、83.20％,掺入ZrO2后蓝宝石晶体依然保持其良好的可见、红外光学性能.     

热交换法生长掺锆蓝宝石单晶及其光谱性能研究

采用热交换法(Heat-Exchange Method,HEM)生长出无色透明的掺锆蓝宝石(Zr:sapphire)单晶.通过辉光放电质谱(GD-MS)、傅里叶变换红外光谱(FTIR)、紫外-可见-近红外(UV-VIS-NIR)吸收光谱、紫外-可见(UV-VIS)透过率等测试手段研究了Zr:sapphire的光谱性能.目前研究表明,采用HEM成功地将ZrO2掺入蓝宝石晶体中,掺入量可达3.3 ppm;蓝宝石晶体中掺入ZrO2后能消除晶体的F+色心缺陷,提高晶体在波长257 nm处的透过率;Zr:sapphire晶体在可见、红外波段的透过率分别为83.41％、83.20％,掺入ZrO2后蓝宝石晶体依然保持其良好的可见、红外光学性能.     

ZnWO4晶体着色和消色机理的研究

生长不掺杂但原料纯度不同的ZnwO_4晶体和掺人Sb_2O_2、CeO_2、Ag_2O等杂质的掺杂znwO_4晶体。晶体在氧气中高温退火,测试晶体退火前后的性能,探讨ZnwO_4晶体着色和消色机理;提出ZoWO_4晶体的颜色是由于色心复合体“Fe~(2+)+[O~(2-)]+电子”引起的。     

钼酸铅晶体中包裹体的组态和散射

本文着重研究了钼酸铅晶体中包裹体的组态和散射特征。实验结果指出:在钼酸铅晶体中的包裹体主要由气泡和片状包裹体组成。通过光学显微术、X射线和电子探针等分析,定性地认为片状包裹体是由另一种晶相——Pb_2MoO_5组成。对一批正交试验法生长的钼酸铅晶体的光学测试以及对包裹体的分布密度和散射率的测量结果表明:包裹体是影响钼酸铅晶体光学质量和器件性能的主要因素,并指出了钼酸铅晶体的光学质量与生长工艺参数之间的密切关系。 最后,从钼酸铅晶体生长中的原料组分配比和工艺参数的分析中,初步探讨了包裹体的成因。     

氟化钡晶体点阳极电注入着色光谱特性

利用自行研制的电注入实验装置,在不同温度和电压条件下,对氟化钡(BaF2)晶体进行点阳极电注入着色。测定了点阳极电注入着色时的电流随时间的变化关系;测量和分析了着色BaF2晶体室温下的吸收光谱。结果表明:着色BaF2晶体中产生大量F色心。按照传统电注入机理,晶体经点阳极电注入不可能产生F色心。借助电流–时间曲线对经点阳极电注入BaF2晶体中F色心的形成机理进行了分析,即V色心首先在阳极附近被产生,F色心是由V色心吸收光子转化而来。     

Nd:GGG晶体生长、光谱性能及激光性能

采用提拉法生长掺钕钆镓石榴石(neodymium-doped gadolinium gallium garnet, Nd: GGG)激光晶体,选择最佳工艺参数:提拉速率为2～4mm/h:转速为20～40r/min;冷却速率为20℃/h.测试了晶体的吸收和荧光光谱,结果表明:主吸收峰位于808nm,主发射峰位于9430cm-1,对应于Nd3 的4F3/1-4I11/2跃迁.对晶体样品进行了激光性能测试.结果表明:当泵浦功率为900mW时,对泵浦光的吸收效率为85%,激光输出波长约为1μm,激光输出功率为305mW,激光阈值功率为380mW,光-光转换效率达57.8%,斜效率达57.6%.     

纳米棒状氧化铁红的制备及表征

以尿素为沉淀剂,采用缓慢滴加方式,用均匀沉淀法制备了纳米棒状氧化铁红。考察了Fe^2＋浓度、反应时间、反应温度、尿素与Fe^2＋物质的量比等因素对产品粒径、形貌及收率的影响,并用TG,XRD,IR,UV-VIS,TEM等对样品进行了表征。确定了制备纳米棒状氧化铁红的最佳工艺条件：Fe^2＋浓度为0.50 mol/L,反应时间为180 min,反应温度为80℃,尿素与Fe^2＋物质的量比为20∶1,在此条件下制得前驱体,将前驱体在350℃下煅烧2 h,即可得到纳米棒状氧化铁红。样品的XRD,TEM表征结果为六方晶系的纳米棒状α-Fe2O3,其长轴约为300-500 nm,短轴约为20-40 nm,产品收率为75.90%,颜色为鲜红色,含质量分数5%样品的清漆对紫外线具有很好的吸收性能,而对可见光具有良好的透明性,其透光率在85%以上,可作为透明氧化铁红颜料使用。     

导模法和温度梯度法生长r面蓝宝石

r面(0112)蓝宝石晶体可用作制备非极性GaN薄膜的衬底.采用温度梯度法(temperature gradient technique,TGT)和导模法(edge-defined film-fedcrystal growth,EFG)生长了质量良好的r面蓝宝石晶体.利用双晶衍射、光学显微镜、光谱仪观察和分析了晶体的结构和缺陷.结果表明:TGT法生长的r蓝宝石晶体的双晶摇摆曲线对称性好,半高宽值仅为18rad·s.位错密度为4×103cm-2,透过率达83%,晶体质量好.与TGT法相比,EFG法生长的r面蓝宝石晶体的结构完整性较差.位错密度为5×105cm-2,透过率仅为75%.但是EFG法具有晶体生长速度快,后期加工成本低的优点.     

High quality sapphire crystal by advanced chemical transport process

Single crystal sapphire was synthesized by chemical transport of Al-O generated by the reaction of polycrystalline Al₂O₃ ceramic and carbon. Using C-axis oriented polycrystalline Al₂O₃ ceramics as a seed crystal in the deposition temperature range, a C-axis sapphire crystal (Φ5xL35 mm) was grown at a temperature range of 700–1000 °C, and the growth rate in the C-axis direction was about 3.5 mm/h. The transmittance in the visible to infrared region of the synthesized sapphire is a theoretical value (transmission loss is lower than 0.1 %/cm), and the absorption edge was less than 200 nm (the band gap is 6.2 eV), which is shorter than the absorption edge (240 nm) of the commercially available single crystal (band gap 5.2 eV) synthesized by the Czochralski method. The dislocation density in this material was extremely low, and it was confirmed by lattice image observation that it was a high-quality single crystal with very few defects.     

The change of Fe–Ni alloy inclusions in synthetic diamond crystals due to annealing

The influence of annealing under high P–T parameters on the inclusions of Fe–Ni alloys in synthetic diamond crystals was studied. The experimental annealing of the grown diamond crystals was held under a pressure of 6.5–7.0 GPa, at temperatures of 1700–2200°C and the duration of the experiments was 1–30 h. Depending on the annealing temperature, the color of diamonds changed, along with the corresponding variations of their IR spectra, i.e. diamond of Ib type transformed into Ia type. The form of metal inclusions, entrapped by diamonds, varied, they experienced change of their faces with their orientation in one direction, in accordance with the temperature gradient in the reaction cell. Besides, the migration of the inclusions of the Fe–Ni alloy within diamond volume in the direction of higher temperatures took place. The mechanism of metal inclusions’ migration in diamond as a result of recrystallization in the gradient field of temperatures is considered. The assumption about possible participation of carbon-containing melt of transition metals at the early stage of natural diamonds crystallization with further recrystallization and self-purification of diamonds from the transition metals’ inclusions during the long period of their existence in the Earth’s mantle at high temperatures and pressures was made.     

钛宝石晶体中的位错以及退火对位错的影响

用化学腐蚀剂腐蚀出样品的 (0 0 0 1)表面上的位错蚀坑 ,在原生态和退火样品的对应径向线上测量了位错腐蚀坑的密度分布 .由位错腐蚀坑的形成理论确定出原生态晶体中很可能有 3种位错类型 ,即Burgers矢量b =13〈112 0〉 ,13〈110 1〉和〈10 10〉的位错线 ,然而长时间在还原性高温气氛中的退火难以降低晶体中的总的位错密度 .在晶体的放肩至等径生长阶段 ,沿着晶体的生长方向 ,晶体棒中心的位错密度由高变低 ,这显示出 :在晶体的放肩至等径生长的转变过程中 ,生长界面发生了翻转 ,由凹形界面转变为凸形界面 ,位错线随之从晶体棒的中心向边缘发散 .     

Effects of annealing on the optical and scintillation properties of reddish Bi4Ge3O12 single crystals

Large-size and -scale bismuth germanate (Bi₄Ge₃O₁₂, BGO) crystals were grown in an oxidizing atmosphere using the modified Bridgman method. Although the growth condition has been optimized, we found a few reddish crystals, resulting in poor performance. In this work, the red-color-induced characteristic absorption bands corresponding to 506, 389, and 332 nm were studied by measuring the optical transmission and absorption spectra. A modified oxygen-annealing was applied to eliminate the reddish in BGO single crystal. Based on the comparison of the optical performance, the absorption band in the visible range of the reddish crystals disappeared after annealing. This phenomenon greatly improved the light output and energy resolution. The effects of annealing in reducing atmosphere were studied. The formation mechanism of crystal coloration was also discussed.     

南宋官窑青瓷釉呈色机理研究

本文将南宋官窑青瓷釉的颜色分釉色色调（颜色种类）与釉色饱和度（颜色鲜艳程度）两方面进行研究，釉色色调与主波长位置对应，釉色饱和度与刺激纯度对应，用穆斯堡尔谱分析，配以反射光谱测定，ＣＩＥ色品图．及配位场理论分析研究南宋官窑青瓷釉的釉色色调，并试验烧成温度和釉层厚度对釉色饱和度的影响。主要结论如下：（１）南宋官窑青瓷釉的颜色主要受六配位Ｆｅ（２＋）离子的ｄｄ跃迁与Ｆｅ（３＋）离子的荷移光谱控制，前者的吸收带位置在１０００ｎｍ左右近红外区，后者在２３０ｎｍ左右紫外区，两者共同决定南宋官窑釉在可见光区的吸收光谱。（２）实验表明，控制南宋官窑青瓷釉色色调，关键是控制／Ｆｅ（３＋）比值。／Ｆｅ（３＋）比值增大，主波长位置移向短波方向，反之则移向长波方向。（３）实验表明，烧成温度提高和釉层厚度增大都使南宋官窑青瓷釉色饱和度增大。     

反应温度对溶胶-凝胶法制备CuFeMnO_4光学性能的影响

采用溶胶-凝胶法制备了CuFeMnO4复合金属氧化物,用X射线衍射仪(XRD)、扫描电镜(SEM)、紫外-可见-近红外分光光度计(UV-Vis-NIR)对试样的物相结构、微观形貌和光谱吸收性能进行了表征。结果表明,反应温度为50℃和70℃得到的试样含有CuO、Fe2O3和MnO杂质相,这些杂质相不利于试样对光线的吸收。随着反应温度的升高,积分平均吸收率随着下降。在反应温度25℃、pH=6.5、煅烧温度700℃、煅烧时间1 h的工艺条件下制备的CuFeMnO4复合金属氧化物对200~2 500 nm波长范围光线的平均吸收率达88.34%。     

胃蛋白酶在体外对转移因子生化特性及生物活性的影响

当胃蛋白酶与猪脾转移因子在体外模拟胃酸（pH2．0）的情况下，于37℃水浴中作用1h及2h后，其紫外（A254nm）吸收值及对经45℃处理1h的T淋巴细胞EaRFC和EtRFC形成率与对照PS－TF之间均无显著差异（p＞0．05）。200nm～300nm扫描曲线表明，PS－TF经胃蛋白酶作用2h后，在230nm以下主要由肽键形成的吸收峰明显下降。表明胃蛋白酶对PS－TF中多肽链某些部分的水解与PS－TF的生物活性无关。     

结晶紫-硼酸复配物的固相合成及其热变色性能

采用固相法合成了结晶紫-硼酸系列可逆热致变色颜料。研究结果表明,m(结晶紫)∶m(硼酸)=1∶(200～600),研制的颜料在60～65℃时由紫红色开始变为蓝色,加热到95～100℃时变为黄色,冷却时恢复为紫红色,复色时间小于3min。重复进行20次实验,颜料的色泽、变色温度和复色时间保持不变。还研究了MgO、Al2O3、硅藻土、硅胶、CaCO3等无机填料对颜料变色性能的影响,结果表明:以Al2O3和硅胶为填料,m(结晶紫)∶m(硼酸)∶m(填料)=1∶200∶(100～200),颜料的两个变色温度降低到56℃和85℃,复色时间为105s。DSC检测颜料的热变色过程得出:该系列变色颜料在40～60℃、100～130℃、130～150℃出现3个吸热峰。     

Diamond-like carbon nanocrystals formed by implanting fused quartz and sapphire (α-Al2O3) with carbon ions

In an attempt to synthesize diamond nanocrystals 1 MeV carbon ions were implanted into fused quartz and sapphire to several different doses and annealed in a furnace at 1100°C for different durations in different annealing ambients. We observe a peak in the optical absorption spectrum at around 5 eV in carbon-implanted quartz and sapphire samples after thermal annealing. We studied the behaviour of the absorption peak as a function of carbon ion dose, annealing time and ambient. Raman spectroscopy using the 514.5 nm line of an argon ion laser was used to elucidate the nature of the chemical bonding in the carbon-implanted samples. Several sharp hitherto unknown Raman peaks are observed in carbon-implanted and annealed sapphire which are consistent with the presence of diamond-like carbon clusters.