Mg0.15Zn0.85O:Tb合金薄膜的阴极射线发光性质研究

采用溶胶凝胶方法成功地制备了掺杂烯土铽离子的ZnO和Mg0.15Zn0.85薄膜。通过对X射线衍射结果的分析表明，稀土离子替代了Zn^2 的格位，进入了半导体基质的晶格中。从阴极射线发光结果可以发现，在Mg0.15Zn0.85O基质中，可以观察到来源于稀土铽离子各能级的发射，而ZnO:Tb的薄膜只能观察到较强的铽离子^5D4-^7F5能级的跃廷。这可能是由于Mg0.15Zn0.85O基质的能隙（3.65eV)比ZnO更宽（3.3eV），其对铽离子的能量传递更有效的缘故。     

Mg掺杂Al_(0.5)Ga_(0.5)N薄膜的发光性质研究

利用MOCVD技术在c面蓝宝石衬底上采用AlN缓冲层制备了Mg掺杂Al0.5Ga0.5N薄膜。采用CL测试方法研究了Mg掺杂对Al0.5Ga0.5N薄膜光学特性的影响。测量表明,Mg掺杂导致在Al0.5Ga0.5N薄膜的发光谱中出现了3.9eV的发光带,其发光机理为束缚的施主-受主对(DAP)间的辐射复合跃迁。     

稀土掺杂半导体纳米发光材料研究取得新进展

稀土离子和半导体纳米晶(或量子点)本身都是很好的发光材料,二者的有效结合能否生出新型高效发光或激光器件一直是国内外学者关注的科学问题。与绝缘体纳米晶相比,半导体纳米晶的激子玻尔半径要大得多,因此量子限域效应对掺杂半导体纳米晶发光性能的影响变得很显著,从而有可能通过尺寸调     

Ba3Ga(PO4)3:Dy3+荧光粉阴极射线发光研究

本文研究了采用高温固相法合成的Ba3Gd(PO4)3:Dy3 荧光粉的阴极射线发光特性.测试并比较了电子轰击前后荧光粉的CL谱、色坐标以及PL谱变化.Ba3Gd(PO4)3:0.06Dy3 荧光粉的色坐标为 x=0.454,y=0.424,Tc=2889.3 K.测试结果显示该荧光粉是一种低色温、暖白光荧光粉,并且具有高的饱和电流,有耐大电流密度电子束轰击的能力.     

掺碳SiO_2薄膜的室温可见光致发光研究

用射频共溅射技术和后退火工艺制备出了埋入ＳｉＯ２中的碳复合膜,在室温下测到了强的可见光致发光谱（峰位在２．２２ｅＶ）．研究了衬底温度、退火温度、薄膜厚度对发光谱的影响．通过喇曼散射谱、红外透射谱和Ｘ光衍射谱的测量,对复合膜的结构进行了探讨．     

纳米氧化铟和稀土共掺杂二氧化硅薄膜的结构和光学性质研究

用溶胶-凝胶法制得了In2O3纳米颗粒与Eu3 共掺的SiO2薄膜.使用X-射线衍射证实体系中形成了In2O3纳米颗粒,其数密度可以通过改变铟的掺杂浓度来进行良好的控制.在薄膜的光致发光光谱中观察到Eu3 离子的5Do-7FJ(J:O-4)特征发射峰,In2O3纳米颗粒的掺入使Eu3 的光致发光得到显著增强.通过光致发光激发光谱的测量进一步研究了In2O3纳米颗粒对Eu3 的光致发光增强的机制.     

Na_xMg_(0.2)Zn_(0.8-x)O纳米薄膜的光学性能

采用溶胶-凝胶法在玻璃衬底上以二水乙酸锌(C_4H_6O_4Zn·2H_2O)、乙酸镁(C_4H_(14)-MgO_8)、氯化钠(NaCl)为前驱体制备Na_xMg_(0.2)Zn_(0.8-x)O纳米薄膜,借助扫描电子显微镜(SEM)、X射线衍射仪(XRD)、喇曼光谱及光致发光谱(PL)等手段,对Na_xMg_(0.2)Zn_(0.8-x)O薄膜的晶格结构、表面形貌及光学性能进行表征及分析,研究了Na~+不同掺杂浓度对Na_xMg_(0.2)-Zn_(0.8-x)O薄膜的结构及光学性能的影响。研究结果表明,所有样品均为六方纤锌矿结构;Na~+的掺入弥补了MgZnO薄膜本身存在的晶格缺陷,颗粒分布均匀且紧密,晶粒尺寸增大;当x在0～0.04内,x为0.02时,Na_(0.02)Mg_(0.2)Zn_(0.78)O薄膜的结晶性能更加优秀,且缺陷减少,光致发光性能达到最佳。     

纳米SiO2基质中Eu3+的发光特性

采用溶胶凝胶法(sol-gel)制备了Eu3+掺杂SiO2基质发光材料,分别用荧光(PL)光谱、原子力显微镜(AFM)、扫描电镜(SEM)等分析手段对样品进行了表征,研究了退火温度以及掺杂浓度对发射光谱的影响,并对其发光机制进行了分析.薄膜样品在258 nm光激发下,在620 nm,667 nm处出现了比较少见的双峰红光发射,而620 nm处的光发射最强,说明Eu3+离子处在对称性较低的配位环境中.退火处理温度对样品的发射光谱影响很大,经900 ℃退火处理的样品发射强度最强.随着掺杂浓度的变化,改变了Eu3+ -O2-间的距离,在相同紫外光激发下O2-外层的电子迁移到Eu3+ 4f轨道上的能量变化,使得谱线位置出现了移动.     

Er^3＋,Yb^3＋掺杂氟氧化物微晶玻璃上转换发光的研究

测量了Er^3 掺杂氟氧化物微晶玻璃、Er^3 ,Yb^3 掺杂氟氧化物微晶玻璃退火前后3种样品的吸收光谱、激发光谱、上转换发光光谱及其强度随泵浦光强的变化,对比讨论了其上转换发光特性。     

(Ce，Yb）共掺杂氧化硅薄膜的发光特性及结构

采用磁控溅射技术在单晶硅衬底上制备了稀土（Ce,Yb）共掺杂氧化硅薄膜,研究了薄膜样品的结构和下转换发光性质。样品的发光光谱显示,在He-Cd激光器325 nm线的激发下,Ce3+离子的发光强度较弱而Yb3+离子的发光较强;Yb3+的发光随着退火温度的升高逐渐增强;这些结果加上样品的激发光谱和衰变光谱,都显示样品中发生了Ce3+ 到Yb3+的能量传递过程。X射线衍射结果表明,样品在高温退火时（大于1 000 ℃）出现晶化,形成了Ce和Yb的硅酸盐结构。笔者认为利用高温退火形成Ce的硅酸盐结构可以明显增强Yb3+的发光,从而提高薄膜的下转换发光效率。     

Blue–Green Emission in Terbium‐Doped Alumina (Tb:Al2O3) Transparent Ceramics

Alumina (Al₂O₃) is one of the most versatile ceramics, utilized in an amazing range of structural and optical applications. In fact, chromium‐doped single crystal Al₂O₃ was the basis for the first laser. Today, most photoluminescent (PL) materials rely on rare earth (RE) rather than transition‐metal dopants because RE doping produces greater efficiencies and lower lasing thresholds. RE‐doped alumina could provide an extremely versatile PL ceramic, opening the door for a host of new applications and devices. However, producing a transparent RE:Al₂O₃ suitable for PL applications is a major challenge due to the very low equilibrium solubility of RE (～10^?3%) in Al₂O₃ in addition to alumina's optical anisotropy. A method is presented here to successfully incorporate Tb³⁺ ions up to a concentration of 0.5 at% into a dense alumina matrix, achieving a transparent light‐emitting ceramic. Sub‐micrometer alumina and nanometric RE oxide powders are simultaneously densified and reacted using current‐activated, pressure‐assisted densification (CAPAD), often called spark plasma sintering (SPS). These doped ceramics have a high transmission (～75% at 800 nm) and display PL peaks centered at 485 nm and 543 nm, characteristic of Tb³⁺ emission. Additionally, the luminescent lifetimes are long and compare favorably with lifetimes of other laser ceramics. The high transparencies and PL properties of these ceramics have exciting prospects for high energy laser technology.     

Nd2O3掺杂BaZr0.2Ti0.8O3陶瓷的介电性能

在溶胶-凝胶法制备钛酸钡(BaZr0.2Ti0.8O3)超细粉体的过程中,使用液相掺杂的方式在溶胶过程中进行了稀土元素Nd的掺杂。掺杂摩尔分数为0、0.001、0.002、0.003、0.004和0.005。掺杂改性后的BaZr0.2Ti0.8O3粉体,通过X-射线衍射(XRD)测试,结果表明在摩尔分数为0.005以内的稀土Nd掺杂并未改变BaZr0.2Ti0.8O3的钙钛矿结构。粉体烧结的陶瓷介电性能得到较大的改善:介电常数由3 389提高到4 493,而介电损耗在60 Hz时由1.4%降低到0.35%。     

Solvothermal Synthesis,Cathodoluminescence, and Field‐Emission Properties of Pure and N‐Doped ZnO Nanobullets

Homogenous crystallization in solution, in the absence of external influences, is expected to lead to growth that is symmetric at least in two opposite facets. Such was not the case when we attempted to synthesize ZnO nanostructures by employing a solvothermal technique. The reaction product, instead, consisted of bullet‐shaped tiny single crystals with an abrupt hexagonal base and a sharp tip. A careful analysis of the product and the intermediate states of the synthesis reveals that one of the reaction intermediates with sheet‐like morphology acts as a self‐sacrificing template and induces such unexpected and novel growth. The synthesis was further extended to dope the nanobullets with nitrogen as previous studies showed this can induce p‐type behavior in ZnO, which is technologically complementary to the naturally occurring n‐type ZnO. Herein, a soft‐chemical approach is used for the first time for this purpose, which is otherwise accomplished with high‐temperature techniques. Cathodoluminesce (CL) investigations reveal stable optical behavior within a pure nanobullet. On the other hand, the CL spectra derived from the surfaces and the cores of the doped samples are different, pointing at a N‐rich core. Finally, even though N‐doped ZnO is known to have high electrical conductivity, the study now demonstrates that the field‐emission properties of ZnO can also be greatly enhanced by means of N doping.     

Luminescence of Nanocrystalline Erbium‐Doped Yttria

In this paper, the luminescence, including photoluminescence, upconversion and cathodoluminescence, from single‐crystalline erbium‐doped yttria nanoparticles with an average diameter of 80 nm, synthesized by a molten salt method, is reported. Outstanding luminescent properties, including sharp and well‐resolved photoluminescent lines in the infrared region, outstanding green and red upconversion emissions, and excellent cathodoluminescence, are observed from the nanocrystalline erbium‐doped yttria. Moreover, annealing by the high power laser results in a relatively large increase in photoluminescent emission intensity without causing spectral line shift. These desirable properties make these nanocrystals promising for applications in display, bioanalysis and telecommunications.     

稀土元素(Sm,Tm)掺杂ZnO的电学与光学性质

运用Materials Studio软件中的CASTEP子模块,借助第一性原理平面波超软赝势法,计算分析了稀土元素(Sm,Tm)掺杂ZnO前后的能带结构、态密度以及光学性质变化情况。计算结果表明,掺杂后体系的能带部分更加稠密,出现新的杂质能级,费米能级从价带顶处上移进入导带部分,出现载流子简并现象,形成简并半导体。掺杂体系显示出更强的金属性,呈现n型导电。同时定性分析了体系前后的光学吸收系数与介电函数的变化情况。     

(Ba_(0.85)Ca_(0.15))(Zr_(0.1)Ti_(0.9))O_3-(Ba_(0.85)Ca_(0.15))TiO_3无铅压电陶瓷的结构与性能

采用流延叠层成型工艺制备了(Ba0.85Ca0.15)(Zr0.1Ti0.9)O3-5%(Ba0.85Ca0.15)TiO3(BCZT-5%BCT)无铅压电陶瓷,研究了BCZT-5%BCT陶瓷的微观组织结构对电性能的影响规律,研究表明,BCZT-5%BCT陶瓷的晶粒尺寸对其压电、介电与铁电性能影响显著,在1 500℃下烧结时,BCZT-5%BCT陶瓷的晶粒尺寸随烧结保温时间的增加呈现先增大后减小的趋势,烧结保温时间为8h的样品中晶粒尺寸最大,此时BCZT-5%BCT陶瓷的压电与铁电性能最优,即压电常数(d33)约为218pC/N,剩余极化强度2Pr约为30.48μC/cm2,介电常数(εr)约为1 617,介电损耗(tanδ)约为0.037,居里温度(TC)约为90.6℃。     

Cathodoluminescence study of micro-crack-induced stress relief for AlN films on Si(111)

Spatially, spectrally, and depth-resolved cathodoluminescence (CL) measurements were performed for high-quality thin AlN films grown on Si(111). Cl spectra exhibited a sharp peak at 5.960 eV, corresponding to the near-band-edge excitonic emission of AlN. Depth-resolved CL analysis showed that deep level oxygen and carbon impurities are localized primarily at the AlN/Si interface and AlN outer surface. Monochromatic CL imaging of the near-band-edge emission exhibits a spotty pattern, which corresponds to high concentrations of threading dislocations and thermally induced microcracks in the thin layers. We have examined relief of the thermal stress in close proximity to single microcracks and intersecting microcracks. Local CL spectra acquired with a focused e-beam show blue-shifts as large as ∼82 meV in the AlN near-band edge excitonic peaks, reflecting defect-induced reductions in the biaxial thermal stress, which has a maximum value of ∼47 kbar.     

BNT陶瓷低温烧成与性能

采用复合添加BaCuO_2-CuO(以下简称BCC)、ZnO-B_2O_3-SiO_2(以下简称ZBS)等烧结助剂的方法,研究了Ba_4(Nd_(0.85)Bi_(0.15))_(28/3)Ti_(18)O_(54)陶瓷(以下简称BNT)低温烧结的烧结特性和微波介电性能。结果表明:复合添加(均为质量分数)2.5％BaCuO_2-CuO和5％ZnO-B_2O_3-SiO_2后可以在1050℃烧结成致密瓷,气孔率为5.73％,在5.6 GHz,相对个电常数ε_r为64.25,Q·f值为2026 GHz,频率温度系数τ_f为+26.4×10~(-6)℃~(-1),可望实现与Cu电极浆料低温共烧。