Pr和Nb共掺杂Bi_4Ti_3O_(12)陶瓷材料电行为特性研究

采用高温固相法制备了Pr和Nb共掺杂Bi_4Ti_3O_(12)铁电陶瓷.利用XRD分析表征了样品物相结构,利用阻抗分析仪和铁电性能测量仪测试了样品的电性能,并通过对样品电导率与温度的关系进行Arrhenius拟合分析了材料的导电机理.结果表明:Pr和Nb已经完全固溶进入Bi_4Ti_3O_(12)晶格中,制备的样品均为单一的层状钙钛矿结构.Nb的引入使样品的介电常数变大,介电损耗明显降低,但居里温度变化不大.在Nb掺杂量较小(x≤0.09)时,材料的剩余极化值随着Nb掺杂量增加而增大,当x=0.09时2P_r达到极大值为26 μC/cm~2,矫顽场为50.3 kV/cm.这主要是由于高价态的Nb~(5+)取代B位Ti~4+能有效的抑制氧空位的产生.     

Na+掺杂KLaF4∶Er3+/yb3+纳米晶上转换发光性能的研究

采用水热法,以乙二胺为络合剂合成了Na+离子掺杂的六方相KLaF4∶Er3+/yb3纳米晶.利用X射线衍射谱(XRD)、透射电子显微镜(TEM)、红外光谱(FT-IR)对样品的晶体结构、形貌和表面吸附进行了表征;测量了不同含量Na+掺杂样品在980 nm近红外光激发下的上转换发射光谱和4R/2能级的荧光寿命.结果表明:随着Na+掺杂浓度的增加,KLaF4∶Er3+/yb3+纳米晶上转换红绿光的发光强度均呈现出先增大后减小的趋势,红绿光发射最强强度分别为未掺Na+样品的7.3倍和5.2倍.Na+掺杂使Er3+离子周围晶场的不对称性降低和纳米晶表面吸附基团的减少是发光增强的主要原因.针对Na+掺杂样品的荧光寿命低于未掺样品的原因作了简要讨论.     

TiO2∶Fe的EPR谱及其光催化特性研究

采用溶胶-凝胶法制备了TiO2∶ Fe材料,测试并分析了材料的电子顺磁共振谱,其结果显示溶胶凝胶法制备的Fe掺杂TiO2粉末在g=1.99和4.3处具有明显信号峰,归属于信号对应离子,并利用其积分值半定量分析了掺杂到晶体表面和内部Fe离子数目的多少及二者比值,发现对离子掺杂到内部而言直至掺杂浓度为0.6;仍未达到饱和,而对离子掺杂到表面而言,当掺杂浓度为0.4;时,该信号强度不再增强,掺杂到晶体表面的Fe离子数量达到饱和.使用紫外可见光谱仪测定了所制材料的光催化性能,所制的Fe掺杂TiO2纳米材料最佳掺杂浓度为0.1;,对甲基橙降解率是17.83;,比未掺杂材料降解率(16.31;)提高了9.32;,增强了光催化活性,其余掺杂浓度(0.0372;,0.2;,0.4;和0.6;)样品的光催化活性均比未掺杂样品的低,降低了光催化活性.     

表面处理对蓝宝石衬底的影响

蓝宝石衬底是目前最为普遍的一种衬底材料,是生长GaN、ZnO材料最常用的衬底.本文用光学显微镜、原子力显微镜(AFM)和高分辨X射线双晶洐射对蓝宝石衬底进行了分析测试,系统研究了经过机械抛光、化学机械抛光、化学腐蚀等表面处理对蓝宝石衬底表面性能的影响.结果表明经过化学机械抛光随后再经腐蚀后的蓝宝石衬底的表面性能最好.     

阳离子表面活性剂对A向蓝宝石晶片化学机械抛光效率的影响

为了探究阳离子表面活性剂对A向(1120)蓝宝石晶片化学机械抛光效率的影响,采用失重法计算蓝宝石的材料去除率(MRR)、原子力显微镜观察抛光后蓝宝石晶片表面粗糙度(Ra).结果表明:纯二氧化硅磨粒抛光液中,蓝宝石晶片的MRR在pH8时最优(MRR=1984/h),此时Ra为0.867 nm;添加一定浓度的阳离子表面活性剂可以提高蓝宝石晶片的抛光效率,其MRR在pH =9时达到最大(MRR=2366 nm/h),此时Ra =0.810 nm.通过粒径和Zeta电位分析,阳离子表面活性剂改变了二氧化硅磨粒表面的Zeta电位值,进而改变了磨粒与磨粒及磨粒与蓝宝石晶片的作用力,且在碱性条件下可以获得较高的MRR.     

蓝宝石单晶窗口材料空间粒子辐照效应研究

蓝宝石单晶(α-Al2O3)窗口材料服役于空间环境中将不可避免地受到各种不同射线及离子流的辐照作用,影响其使用性能.本文研究了蓝宝石单晶经不同剂量质子流、电子流以及综合流辐照后其表面粗糙度、透过率以及面形精度等光学性能和结构的变化.实验表明空间粒子辐照使蓝宝石表面粗糙度增大且具有剂量效应,其中综合流对表面粗糙度影响最大,质子次之,电子影响最小;UV-Vis-VIR及FTIR测试实验表明空间粒子辐照使蓝宝石透过率下降,在紫外波段下降最明显,且在不同波段范围内不同辐照粒子种类对蓝宝石单晶透过率的影响程度也不同;粒子辐照对面形精度的影响不明显.     

Ti离子注入对ZnO纳米棒阵列性能的影响

本文研究了Ti离子注入对ZnO纳米棒阵列结构、形貌、光学特性和疏水性的影响.XRD测试表明注入前后ZnO纳米棒均为六方纤锌矿晶体结构.然而,随着对ZnO纳米棒阵列注入剂量的增加,样品沿(002)晶面优先生长的趋势降低,而且当注入剂量达到5×1017/cm2时,甚至出现ZnTiO3( 104)晶面衍射峰,说明了这种物质的存在,而后面的XPS表征也进一步证明了Ti-Zn-O化学键的存在.样品形貌测试表明,离子注入后由于受刻蚀和溅射的作用,不仅使得ZnO纳米棒表面形貌发生了很大的变化,透光率也显著下降.离子注入后ZnO纳米棒表面疏水性受形貌变化的影响也发生了改变,使得其疏水性增强,当Ti离子注入量为1×1017/cm2时ZnO纳米棒表面接触角达到了151.4°.总之,离子注入作为一种较新颖的表明改性方法,通过对ZnO纳米棒阵列改性处理可以明显扩展其潜在应用价值.     

改进共沉淀法制备SrMoO_4∶Eu~(3+)荧光粉及其荧光性能研究

采用改进的共沉淀法在修饰剂的修饰下合成了一系列SrMoO_4∶Eu~(3+)红色荧光材料,通过X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)和荧光分光光度计(PL)等手段对合成样品进行表征。深入探究了其荧光性能与修饰剂种类、修饰剂添加量、反应物浓度、激活离子掺杂量等反应参数之间的关系。结果表明:在波长271 nm的激发光的激发下SrMoO_4∶Eu~(3+)在420~750 nm有四组Eu~(3+)的激发峰,其中最强峰在616 nm处发射红光。在聚乙二醇(PEG)修饰下且添加量为3 m L时荧光性能最佳;随着Eu~(3+)掺杂量的提高,样品在616 nm处的特征发射峰呈现出先升高,后下降的趋势,当Eu~(3+)掺杂量为11%时达到最大值。Eu~(3+)掺杂的SrMoO_4荧光粉在616 nm处发射峰的发光强度最强,表明SrMoO_4∶Eu~(3+)是一种能很好应用于白光LED的红色荧光材料。     

固结磨料研磨蓝宝石衬底的工艺研究

为获得高材料去除率和优表面质量的蓝宝石衬底,采用固结磨料研磨蓝宝石衬底提高加工效率,研究研磨压强、工作台转速、三乙醇胺(TEA)浓度和研磨垫类型四个因素对材料去除率和表面粗糙度的影响,并综合优化获得高材料去除率和优表面质量的工艺参数.结果表明:有图案的研磨垫、研磨压强为100 kPa、工作台转速为120 r/min、三乙醇胺的浓度为5;为最优研磨工艺参数组合,固结磨料研磨蓝宝石的材料去除率为31.1 μm/min,表面粗糙度为0.309 μm.     

超声辅助共沉淀法合成CaMoO4:Eu3+红色荧光粉及其发光性能研究

采用超声辅助共沉淀法合成了以Eu3+为激活离子的CaMoO4荧光粉.通过X-射线衍射、扫描电镜(SEM)、荧光分光光度计对样品进行了表征和分析,研究了溶剂浓度、表面活性剂种类、表面活性剂添加量、超声时间等反应参数对CaMoO4:Eu3+发光性能的影响.结果表明:制备的样品为球形纯相四方晶系CaMoO4晶体,在CaMoO4:Eu3+中存在MoO2-4到Eu3+的能量传递.以50;丙酮溶液作为溶剂、PEG添加量为9 mL、Eu3+掺杂浓度为10;、超声时间为10 min时,制备的样品在393 nm光激发下,CaMoO4:Eu3+的最强峰所在位置是616 nm,实现了有效的红光发射,样品在紫外灯下呈现出明亮的红色.     

Ti:Al2O3透明多晶陶瓷光谱特性分析

采用传统无压烧结工艺制备出透明性良好的掺Ti氧化铝陶瓷;测定了该陶瓷的吸收光谱、荧光光谱和激发光谱.结果表明,掺Ti氧化铝透明陶瓷样品在Mg与Ti掺入离子的摩尔比(NMg/NTi)较小时,表现出Ti3+离子的490nm特征吸收峰,即2T2→2E跃迁产生的宽带吸收;NMg/NTi较大时,陶瓷样品吸收光谱中不存在Ti3+离子吸收,其250nm处吸收为O2-→Ti4+的转移吸收.掺Ti氧化铝透明陶瓷样品Ti3+离子的发射谱线与单晶的相吻合,同时Ti3+在氧化铝陶瓷中分布很均匀,且Ti3+浓度较高时仍处于未畸变的八面体格位当中.氢气氛下烧结的陶瓷样品因MgO添加剂的存在而在410nm处产生Ti4+离子荧光发射;而280nm、420nm左右的荧光发射分别是由F+和F心造成的.     

温梯法生长的Ti:Al2O3晶体的光谱分析

本文研究了不同掺Ti^3＋浓度对温梯法生长的Ti：Al2O3晶体吸收光谱、荧光光谱和X射线衍射光谱的影响。根据吸收光谱提出了一个色心模型。对比了样品各处420nm荧光谱，发现掺Ti^3＋浓度越大，该处荧光强度越弱，同时解释了420肿处荧光峰的起源。对比了样品各处720nm处的荧光谱，发现掺Ti^3＋浓度越大，该处荧光强度越强。X射线衍射谱（XRD）表明，衍射峰强度随掺Ti^3＋浓度的增大而逐渐增强。     

Ion-implanted treatment of (Ba,Sr)TiO3 films for DRAM applications

The effects of ion implantation on the properties of spin-on sol–gel Ba_0.7Sr_0.3TiO₃ (BST) thin films were studied by implanted Ar⁺, N⁺, and F⁺ doses. The F⁺-implanted BST samples present leakage current density <10⁻⁶ A/cm² at 2.5 V and dielectric constant 450. The leakage current of F⁺-implanted BST samples was reduced about one order of magnitude as compared with that of samples with implanted Ar⁺, N⁺ or without implantation. The thickness shrinkage from 135 to 115 nm was observed in F⁺-implanted BST films (before annealing treatment) and a respective increase in the refractive index from 1.84 to 2.05 was measured. After annealing the implanted samples, the changes of thickness and refractive index depend on the concentration of implanted dose. Based on an infrared transmission study of the samples we suggest that the ion-implanted samples with smaller dose (5×10¹⁴ cm⁻²) have fewer −OH contaminants than the non-implanted or implanted samples with the larger doses (1×10¹⁵ cm⁻²). Based on the results presented, we conclude that suitable ion implantation densifies the spin-on sol–gel BST films and reduces the −OH contaminants in the films.     

镁/钛离子注入对蓝宝石微结构和机械性能的影响

离子注入已被证明是改善蓝宝石光学和机械表面性能的一种可靠方法.本文选择不同能量和剂量的镁/钛离子注入蓝宝石.利用TRIM(Transport of Ion Matter)程序分析了镁/钛离子在蓝宝石晶体中的射程分布.利用拉曼光谱和掠入射X射线衍射分析了损伤层深度和微结构变化.离子注入结果显示,蓝宝石的纳米硬度、纳米划痕和红外性能等均呈现出可调节的特性.     

On the Analysis of Hydrogen in as grown and Ion Implanted GaAs Single Crystals

Hydrogen detection and analysis was carried out on the undoped semi‐insulating (S.I.) gallium arsenide (GaAs) single crystal using conventional elastic recoil detection analysis (ERDA) technique with high energy, heavy ion beam. Presence of hydrogen (nearly 3 x 1020 atoms/cc) has been observed on the as‐grown samples and further high concentration of atomic hydrogen (total concentration of 7 x 1020 atoms/cc) was found at the surface and was found to be decreasing with depth after 100 nm. Further the low energy hydrogen and oxygen ions implanted separately in GaAs at room temperature were also analysed by ERDA technique. From the analysis, the projected range (Rp) of 100 keV hydrogen and oxygen ions in GaAs was determined to be 891 nm (with Δ Rp equal to 320 nm), 170 nm (with Δ Rp equal to 120 nm) respectively. The experimentally determined values of both Rp and Δ Rp are more as compared with the values obtained using the TRIM theoretical program. Low temperature (4K) photoluminescence (PL) measurements of un‐implanted and H⁺ implanted samples show the passivation of intrinsic deep level defect EL2 and shallow acceptor impurity carbon by the low energy implanted hydrogen ions. The low energy hydrogen implantation may be used as a method of hydrogenation for passivation.     

Annealing effect on electrical and photoconductive properties of Si implanted GaSe single crystal

GaSe single crystals grown by Bridgman method have been doped by ion implantation technique. The samples were bombarded in the direction parallel to c‐axis by Si ion beam of about 100 keV to doses of 1 × 10¹⁶ ions/cm² at room temperature. The effects of Si implantation with annealing at 500 and 600 °C on the electrical properties have been studied by measuring the temperature dependent conductivity and photoconductivity under different illumination intensities in the temperature range of 100–320 K. It is observed that Si implantation increases the room temperature conductivity 10⁻⁷ to 10⁻³ (Ω‐cm)⁻¹ depending on the post annealing temperature. The analysis of temperature dependent conductivity shows that at high temperature region above 200 K, the transport mechanism is dominated by thermal excitation in the doped and undoped GaSe samples. At lower temperatures, the conduction of carriers is dominated by variable range hopping mechanism in the implanted samples. Annealing of the samples at and above 600 °C weakens the temperature dependence of the conductivity and photoconductivity. This indicates that annealing of the implanted samples activates Si‐atoms and increases structural deformations and stacking faults. The same behavior was observed from photoconductivity measurements. Hence, photocurrent‐illumination intensity dependence in the implanted samples obeys the power low I_pc ∝ Φⁿ with n between 1 and 2 which is an indication of continuous distribution of localized states in the band gap. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

多片导模法蓝宝石晶体的缺陷研究

使用导模法(EFG)生长了多片a面蓝宝石晶体。显微拉曼光谱结合电感耦合等离子体发射光谱(ICP-AES)测试得出晶体的气泡中可能存在含S化合物。晶体表面明显的生长条纹主要与温度、生长速度的波动以及模具的加工精度有关。化学腐蚀分析表明晶体位错密度在4.2×10⁴ cm^-2,未存在小角度晶界缺陷,双晶摇摆曲线半峰宽(FWHM)为70.63″。由于采用石墨保温材料,晶体中存在F心与F⁺色心。晶体在400~3 000 nm波段透过率高于80%,空气中退火后可减弱色心吸收。本文研究结果可为蓝宝石晶体缺陷形成理论研究提供参考,也可为导模法蓝宝石工业生产技术改进提供借鉴。     

Formation of nanoparticles in soda-lime glasses by single and double ion implantation

Structural characteristics and optical properties of monometallic and bimetallic Ag and Au nanoparticles in the surface region of soda-lime glass fabricated by ion implantation have been studied by transmission electron microscopy and optical spectroscopy. As a result it has been found that both, implantation dose and process temperature, strongly influence the metal nanoparticle formation governed by ion diffusion and metal precipitation as well as the involved stress generation around the particles. Thus, the mean size of metal nanoparticles and the width of the particle containing region beneath the glass surface increase with increasing temperature as well as implanted dose. Upon sequential high-dose double implantation to form bimetallic Ag–Au nanoparticles a rather complex configuration has been obtained. Particles of sizes above a threshold of 5–10 nm exhibit distinct image contrast features indicating the development of central voids whose sizes are proportional to the outer particle diameter.     

Y_2O_3:Er~(3+)上转换纳米纤维的制备与性质研究

采用静电纺丝技术制备了PVA/[Y(NO_3)_3+Er(NO_3)_3]复合纳米纤维,将其在适当的温度下进行热处理,得到Y_2O_3∶Er~(3+)上转换纳米纤维.XRD分析表明,PVA/[Y(NO_3)_3+Er(NO_3)_3]复合纳米纤维为无定型,Y_2O_3∶Er~(3+)上转换纳米纤维属于体心立方晶系,空间群为Ia3.SEM分析表明,PVA/[Y(NO_3)_3+Er(NO_3)_3]复合纳米纤维的平均直径约为130 nm;经过600 ℃焙烧后,获得了直径约60 nm Y_2O_3∶Er~(3+)上转换纳米纤维.TG-DTA分析表明,当焙烧温度高于600 ℃时,PVA/[Y(NO_3)_3+Er(NO_3)_3]复合纳米纤维中水分、有机物和硝酸盐分解挥发完毕,样品不再失重,总失重率为80;.FT-IR分析表明,PVA/[Y(NO_3)_3+Er(NO_3)_3]复合纳米纤维的红外光谱与纯PVA的红外光谱基本一致,600 ℃时,生成了Y_2O_3∶Er~(3+)上转换纳米纤维.该纤维在980 nm激光激发下发射出中心波长为522 nm、561 nm的绿色和658 nm的红色上转换荧光,对应于 Er~(3+)的~2H_(11/2)/~4S_(3/2)→~4I_(l5/2)跃迁和~4F_(9/2)→~4I_(l5/2)跃迁.对Y_2O_3∶Er~(3+)上转换纳米纤维的形成机理进行了讨论,该技术可以推广用于制备其他稀土氧化物上转换纳米纤维.     

X-ray electrono-optical and SIMS characterization of Si crystals implanted with Bi ions before and after rapid thermal annealing

The purpose of the presented paper is to find out what kinds of information on surface layer structure of implanted silicon after rapid thermal annealing can be acquired by such non-destructive methods as X-ray diffractometry and its complementary RHEED technique. The experiments were performed on Si crystals implanted with Bi ions. The studies showed that using the anomalous X-ray transmission of the wavelength of 1.54 Å we are able to determine the defect concentration introduced by ion implantation with different doses as well as the effects of defect annealing. It was also shown using the REED that the surface layer of ca. 50 Å thick remains amorphous after RTA probably due to the oxidation. The measurements by using SIMS pointed also out that at the crystal surface there was a small amount of Bi atoms accumulated after RTA.