ZnS电致发光磷光体制备过程中掺入微量Cu和Mn对微晶结构的影响

本文用X射线粉末衍射法研究了在600—1200℃范围内煅烧制成的纯ZnS,以及掺杂有不同浓度激活剂Cu和Mn的ZnS微晶结构,用X射线绝标法确定ZnS中α相(六角)和β相(立方)的重量比,并标定ZnS的绝标法常数K_β^α,结果表明,低温β相到高温α相的相变温度对纯ZnS为1020℃,与公认的一致,当加入Cu量超过1×10^-3后,相变温度明显向高温移动;当Cu量为2×10^-3时,相变温度已高于1200℃,这可被解释为当在Z     

18 MeV质子辐照对TiNi形状记忆合金R相变的影响

 研究了用HZ-B串列加速器的18MeV质子辐照对TiNi形状记忆合金R相变的影响，辐照在奥氏体母相状态下进行。示差扫描量热法（DSC）表明，辐照后R相变开始温度T^s_R和逆马氏体相变结束温度T^f_A随辐照注量的增加而降低。当注量为1.53×10¹⁴/cm²时，T^sR和T^f_A分别下降6K和13K，辐照未引起R相变结束温度T^s_R和逆马氏体相变开始温度T^f_A的变化。表明辐照后母相(奥氏体相)稳定。透射电镜（TEM）分析表明辐照后没有引起合金可观察的微观组织变化。辐照对R相变开始温度T^s_{R和逆马氏体相变结束温度Af的影响可能是由于质子辐照后产生了孤立的缺陷团，形成了局部应力场，引起晶格有序度的下降所造成的。}     

衬底温度对类金刚石薄膜力学性能的影响

 采用脉冲激光沉积方法在不同衬底温度下制备了最高硬度与弹性模量分别达45 GPa和290 GPa,且表面十分光滑的类金刚石薄膜。在相对湿度为80%的条件下,薄膜最低的摩擦系数与磨损率分别为0.045与5.74×10^-10 mm³·N^-1·m^-1。实验结果表明,硬度与弹性模量随衬底温度升高而降低,摩擦系数与磨损率随衬底温度升高而增大。拉曼光谱表明:在室温下制备的薄膜为典型类金刚石结构,sp³含量高达76.8%,而随温度升高,薄膜结构逐渐经无定形碳结构向纳米晶石墨结构方向发展,sp³含量也随之降低,力学性能变差。     

中子星内部非奇异-奇异夸克物质的相变

研究了中子星内部从两味夸克物质到三味夸克物质的相变过程。发现这个过程的时标短至10^-7s,并且在相变中奇异夸克所参加的半轻子过程是中微子能量损失的主要过程。这样,1.4M_⊙质量的中子星内部的非奇异-奇异夸克物质相变会有几个10⁵¹erg的能量以中微子形式发射出去,这将表现为一种中微子爆现象。     

热核破碎中相变现象的质量依赖性

本文研究了热核破碎特有的模式相变现象随热核质量数的变化.在所研究的从⁵⁶Ni*到²³⁸U*六个热核中,⁶³Cu*以及重于它的热核,其破碎瞬时的总激发能对温度曲线T(E*)上,都有两个明显的温度平台结构;比⁶³Cu*轻的⁵⁶Ni,其第一平台结构则退化为斜率的微小改变.     

表面热透镜技术测量3.8μm和2.8μm激光薄膜的微弱吸收

 采用表面热透镜技术，对3.8μm和2.8μm激光辐照下镀制在Si基底上的单层ZnS，YbF₃和YBC薄膜及不同膜系的YbF₃/ ZnS多层分光膜和多层高反膜，以及镀制在CaF₂基底上的增透膜进行了吸收测量，并对3.8μm和2.8μm 激光的测量结果进行了比较分析。实验结果表明，2.8μm波长下的吸收比3.8μm的大得多，两者之间约相差一个量级，测得的多层高反膜YbF₃/ZnS薄膜在的3.8μm处的最低吸收为4.57×10^－4，测量系统的灵敏度约为10^-5。     

外类杂质在氧化亚铜中的扩散

在640—960℃温度范围内研究了放射性铊和钽在结晶粒结构的氧化亚铜晶体中的扩散。结果指出,它们分别满足下列关系式:D_Tl=2.29×10^-2e^-37000/(RT)+7.73×10^-9e^-6100/(RT)厘米²/秒;D_Ta=8.95e^-49500/(RT)+1.85×10^-8e^-7200/(RT)厘米²/秒。logD～1/T图线在760±10℃有一转折点,在这个温度以上和以下由曲线斜率求出的激活能是不同的。根据实验结果可以认为,在760℃以下,杂质原子主要是沿着晶粒间界发生扩散的,而在760℃以上是沿着单晶体的空位式扩散机构。并且认为空位式的扩散机构是舆空格点本身的位移相伴随着。放射性钽在氧化过程中的浓度分布指出:在760℃以下,在氧化过程中,氧和铜的相对扩散佔同等重要地位;而在760℃以上,随着温度的升高,铜的扩散逐渐佔优势,在继续氧化过程中,由於氧的扩散生成的氧化层逐渐减少。     

光纤Bragg光栅热敏力敏效应研究及应用探讨

本文报道了光纤Bragg光栅热敏力敏效应的实验研究结果,测量所得的光纤Bragg光栅温度系数和应力系数分别为6.84×10^-6/℃和7.27×10^-6/gf,与理论值6.85×10^-6/℃和7.32×10^-6/gf符合得很好.在20～180℃和0～50gf的温度应力测量范围内,光纤Bragg光栅透射谱中心波长移动量同温度应力具有良好的线性关系.基于光纤Bragg光栅的热敏力敏效应,本文还讨论了光纤Bragg光栅温度应变传感器实用化时必须首先考虑的一些关键问题.     

克里奇中间体CH2OO与CF3CF=CF2反应的动力学研究

本文使用OH激光诱导荧光方法研究了结构最简单的克里奇中间体CH₂OO和CF₃CF=CF₂的反应动力学. 在压强为10 Torr条件下，测量了温度在283，298，308和318 K的反应速率常数，分别为(1.45±0.14)×10^-13，(1.18±0.11)×10^-13，(1.11±0.08)×10^-13和(1.04±0.08)×10^-13 cm³·molecule^-1·s^-1. 根据阿伦尼乌斯方程，获得该反应的活化能为(-1.66±0.21) kcal/mol. 在6.3∽70 torr压力范围内，未观察到该反应的速率常数存在压力相关.     

对苯二酚-甲醛碳气凝胶的制备

 溶胶-凝胶法制备了高HC比（10~40,对苯二酚与催化剂(Na₂CO_{3/sub>)的物质的量之比）的对苯二酚-甲醛有机气凝胶,并经高温碳化处理得到其碳气凝胶。借助有机气凝胶的红外光谱研究了其化学结构,说明其网孔结构形成的可能性;研究了有机气凝胶的扫描电镜图像、比表面积及孔径分布等,并得到碳化前后的一些对比数据：有机气凝胶颗粒大小30~50 nm,碳化后约为10 nm,比表面积从341.77 m²/g增大到452.75 m²/g,密度从0.170 8 g/cm^{3/sup>增大到0.335 6 g/cm3/sup>。}}     

激活剂Cu和Mn对ZnS相变和微结构的影响

为了深入研究交流粉末电致发光粉的发光机理,增加对荧光粉激发能量的输入,提高它的发光亮度,研究这种材料的微结构极为必要。但要在原子尺度上研究材料的结构和成分,目前仍十分困难。至今,人们对电致发光机理还没有统一认识,不能不说与此有关。     

Diffusional relaxation in ZnS after thermal doping at 800°C

Photoluminescence spectra of powdered ZnS thermally doped with MnS are studied. Correlations are demonstrated between variations in the luminescence characteristics of ZnS:Mn, on one hand, and some features of radiation center formation and the diffusion of Mn in ZnS after processing, on the other. It is found that after manganese doping at a temperature (T = 800°C) lower than the phase transition temperature of ZnS, relaxation processes owing to diffusion of Mn in ZnS take place in the material over times as long as 6.10³ h. It is shown that 6.10³ h after doping the α-MnS phase is essentially completely dissolved in the volume of the ZnS. Diffusion of Mn in powdered ZnS is found to occur via several channels, rapid diffusion along interior boundaries and slow diffusion via interstitial space, which indicates the existence of different activation energies for diffusion of Mn depending on its localization within the ZnS lattice.     

Structural phase transformation in ZnS nanocrystalline thin films by swift heavy ion irradiation

Zinc sulfide (ZnS) thin films in zinc-blende (ZB) and wurtzite (W) phases have been fabricated by pulsed laser deposition. 150 MeV Ni ion beam irradiation has been carried out at different fluences ranging from 10¹¹ to 10¹³ ions/cm² at room temperature for ion induced modifications. Structural phase transformation in ZnS from W to ZB phase is observed after high energy ion irradiation which leads to the decrease in bandgap. Generation of high pressure and temperature by thermal spike during MeV ion irradiation along the ion trajectory in the films is responsible for the structural phase transformation.     

Enhanced ionic conduction and disproportionation in pure CuCl at high pressure

The optical and electrical properties of pure cuprous chloride (CuCl) single crystals have been studied under pressure up to 12 GPa. The transition pressures for the three crystallographic phases have been determined as 5.1 ± 0.1 GPa (ZnS → tetragonal) and 8.8 ± 0.4 GPa (tetrag.-NaCl). During the transition at 5.1 GPa, where the coordination number changes, the formation of cupric ions is observed. This is interpreted as a result of a partial, transient, and reversible disproportionation. In the ZnS and NaCl phase, an enhanced ionic conductivity is found following the first transformation into the tetragonal structure. The concentration of the mobile ions is typically 10¹⁸ cm^?3 and their diffusivity is ～ 4×10^?7 cm²s^?1. An applied voltage in excess of 0.7 V causes anodic oxidation of Cu⁺ which mimics much higher conductivity.     

Influence of Fe doping on the structural,optical and magnetic properties of ZnS diluted magnetic semiconductor

Fe doped ZnS nanoparticles with different concentrations of Fe, synthesized by microwave assisted co-precipitation method have been reported. The incorporation of Fe²⁺ and Fe³⁺ ions into ZnS lattice are confirmed by X-ray diffraction (XRD) and Electron Paramagnetic resonance (EPR) study. XRD and High Resolution Transmission electron Microscope (HRTEM) results confirm the phase purity of the samples and indicate a reduction of the particle size with increase in Fe concentration. EDAX analysis confirms the presence of Zn, S and Fe in the samples. A yellow–orange emission peak is observed in Photoluminescence (PL) spectra which exhibits the Characteristic ⁴T₂ (4G)–⁶A₁ (6S) transition of Fe³⁺ ion. The room temperature magnetic studies as analyzed from M–H curves were investigated from vibrating samples magnetometer (VSM) which shows a weak ferro and superparamagnetic like behavior in 1% and 3% Fe-doped ZnS nanocrystals, whereas; at 10% Fe-doping concentrations, antiferromagnetism behavior is achieved. The ZFC-FC measurement reveals that the blocking temperature of the nanoparticle is above the room temperature.     

含12mol%铈的四方氧化锆多晶的变温喇曼散射研究

对含12mol％铈的四方氧化锆多晶耐高温材料从17—505K温度范围进行了50—800cm^-1的喇曼散射研究,同时还实测了线膨胀系数随温度的变化。降温时,在165±1K观察到了类四方相向类单斜相的转变,而升温时,在450土2K发生了与之相反的转变。为了探讨该转变的原因,对布里渊区声子凝聚和可能引起的相转变做了较仔细的说明。 关键词：     

Highly luminescent undoped and Mn-doped ZnS nanoparticles by liquid phase pulsed laser ablation

In this paper we report the synthesis of highly luminescent ZnS and Mn-doped ZnS nanoparticles with uniform particle size distribution by liquid phase pulsed laser ablation. The formation of nanosized ZnS crystallites was confirmed by high-resolution transmission electron microscopy (HRTEM) images. The optical properties of these nanoparticles were studied by room temperature photoluminescence (PL) spectra. The PL emission from the ZnS nanoparticles shows a sharp peak in the UV region (334 nm) corresponding to the band edge and a broad peak in the visible region which can be attributed to the sulphur vacancies, cation vacancies and surface states in the nanocrystals. The yellow emission from the Mn-doped ZnS nanoparticles can be attributed to the radiative transition between ⁴T₁ and ⁶A₁ levels within the 3d⁵ orbital of Mn²⁺.     

Phase transition of [(C6H5)3PCH3]+(TCNQ)-2 and electrical transport properties

The electrical conductivity at 10GHz, the dielectric constant, and the thermoelectric power (TEP) of [(C₆H₅)₃PCH₃]⁺(TCNQ)^-₂, from 230 up to 400 K, have been measured. This organic quasi-one-dimensional solid undergoes a first order phase transition at 314 K. At the transition the conductivity increases by a factor of 2.2 and the activation energy drops to 0.26 from 0.31 eV. At 314 K TEP decreases abruptly from -75 to -60μVK^-1 and remains almost constant for T > 314 K. The dielectric permeability ?₀ is constant and equal to 5 in the low temperature phase, increases abruptly by 7% at the transition, and then depends strongly on temperature in the high temperature phase. Results of the high temperature phase are interpreted in terms of a strongly correlated salt.     

B+注入HgCdTe快速热退火的研究

借助二次离子质谱和俄歇电子能谱对B⁺注入HgCdTe有无ZnS膜包封在快速热退火条件下表层的Hg损失进行了深入的分析-快速热退火温度为300，350和400℃，退火时间为10s-ZnS膜厚度为160nm-结果表明，300℃，10s快速热退火后，有ZnS膜包封的HgCdTe表层没有Hg损失-对B⁺注入HgCdTe N⁺-P结快速热退火工艺流程进行了优化-结果表明，快速热退火放在光刻金属电极之后进行，可以改善结的特性- 关键词：     

Luminescence enhancement of Mn doped ZnS nanocrystals passivated with zinc hydroxide

Mn-doped ZnS nanocrystals prepared by solvothermal method have been successfully coated with different thicknesses of Zn(OH)₂ shells through precipitation reaction. The impact of Zn(OH)₂ shells on luminescent properties of the ZnS:Mn nanocrystals was investigated. X-ray diffraction (XRD) measurements showed that the ZnS:Mn nanocrystals have cubic zinc blende structure. The morphology of nanocrystals is spherical shape measured by transmission electron microscopy (TEM). ZnS:Mn/Zn(OH)₂ core/shell nanocrystals exhibited much improved luminescent properties than those of unpassivated ZnS:Mn nanocrystals. The luminescence enhancement was observed with the Zn(OH)₂ shell thickening by photoluminescence (PL) spectra at room temperature and the luminescence lifetime of transition from ⁴T₁ to ⁶A₁ of Mn²⁺ ions was also prolonged. This result was led by the effective, robust passivation of ZnS surface states by the Zn(OH)₂ shells, which consequently suppressed nonradiative recombination transitions.