钽酸锂晶体宽带滤波器

本文简要介绍钽酸锂晶体及器件的一些特性,对用该材料制作的21.4MHz宽带滤波器的设计、制作和测试结果作了较详细的介绍,滤波器的带宽达225kHz,矩形系数(BW_(?0dB)/BW_(3dB)为2.66,带外衰减在50dB以上。该材料在做宽带滤波器和压控振荡器方面具有优越性。     

生长MCT晶体的改进型Bridgman方法：ACRT—B

本文介绍一种经改进的采用加速坩埚旋转技术的Bridgman方法(ACRT-B)及ACRT-B用于生长MCT晶体得到的重要结果。与传统Bridgman方法生长的晶体相比,ACRT-B生长的晶体的径向组份均匀性得到很大改善;有用组份的晶片较多;晶体的结晶度好;主晶粒数目减少。ACRT-B工艺中,影响晶体质量最重要的旋转参数是最大旋转速率,而保持在最大旋转速率的时间和停止时间及反向旋转对结果的影响都很小。     

Magnetic field influenced growth kinetics in chemical CdS thin-film deposition

The kinetics of growth for the deposition of CdS thin films from chemical solutions has been studied without and under the action of an external magnetic field. It has been established that the growth takes place out of a narrow near-surface transition layer between liquid and solid, where mobile ions are moved by the field, resulting in thin, adherent and specularly reflecting films. The presence of an external magnetic field affects the formation process of the CdS films in a characteristic manner, and allows to control thickness, grain size and optical quality of the grown layers. Optical transmission spectroscopy measurements reveal, that the band gap energy of 2.36 eV for films grown without the application of a magnetic field, increases to 2.51 eV for the highest field strength applied. The film thickness under otherwise identical conditions increases by about a factor of 3, while the medium grain size shrinks to almost half the value of about 70 nm found without external field action. AFM images are applied in the study, showing an improved smoothness of the films.     

磷矿共生含钾页岩特征及蚀变法浸钾过程

本文测试和计算了磷矿底板共生的含钾页岩的化学成分、矿物成分，并研究了钾的赋存状态。从天然浸钾过程得到启示，在热力学、晶体结构和反应动力学等三个方面研究了蚀变法的浸钾过程。浸钾后的副产品可作为优良的陶瓷原料。     

用于电能计量的串联型晶体振荡器的设计

提出了一种用于电能计量的串联型晶体振荡电路,着重分析了串联型晶体振荡电路的起振条件、起振时间、动态功耗、振荡频率稳定性等,并利用EDO模拟器作了验证,最后给出了应用此振荡器作为时钟发生器在单相电能计量集成电路产品中的测试结果。     

Substituent Effects on Crosslike Packing of 2′,7′‐Diaryl‐ spiro(cyclopropane‐1,9′‐fluorene) Derivatives: Synthesis and Crystallographic,Optical, and Thermal Properties

A series of 2′,7′‐diarylspiro(cyclopropane‐1,9′‐fluorene) derivatives are efficiently synthesized and characterized to determine the reason for the “green‐light” emission of these compounds. These compounds exhibit bright‐violet to blue photoluminescence (PL) (λ^PL_max = 353–419 nm) with excellent PL quantum efficiencies (Φ_PL = 83–100 %) in solution and show high thermal stabilities (T_d = 267–474 °C). The variation of the optical properties of these molecules in the solid state depends on the different stacking modes of these compounds containing different substituents, which are revealed by crystallographic analysis. CH…π hydrogen bonds instead of intermolecular π–π interactions act as the driving force between adjacent fluorenes, even though a very small dialkyl group (cyclopropane) is introduced at the C‐9 position of fluorene. The crosslike molecular stacking efficiently reduces the energy transfer between the herring‐like aggregates and therefore results in the absence of a “green‐light” emission tail. In order to determine the cause of the “green‐light” emission tails, the fluorescence spectra of the films annealed in N₂ or in air are recorded. Broad green‐light emission tails were observed for the films annealed in air, which might be caused by fluorenone defects generated during processing or during the course of the photophysical analysis by reaction with residual oxygen.     

LED生产过程中的质量控制

对LED封装过程可能出现的问题逐一指出，并提出解决的办法，着重介绍封装位置对LED发光亮度的影响。以期引起LED封装管理人员及工作人员的注意。     

Hg1—xCdxTe晶体密度和组分的关系

根据Hg1-xCdxTe晶体结构、组分和点阵常数的关系，导出Hg1-xCdxTe晶体密度和组分的关系式。讨论了温度对晶体密度的影响，与参考文献中的密度公式进行了比较。     

The effect of different lattice sites substitution on photoluminescence characteristics of Eu2+/Ce3+ doped M5(ZO4)3X

The empirical formula of Van Uitert is applied to calculating the emission wavelengths of haloapatite and silicon apatite phosphors doped with Eu²⁺/Ce³⁺. The relationship between emission wavelengths and occupied lattice sites of Eu²⁺/Ce³⁺ is discussed in haloapatite crystal. For phosphors of haloapatite and silicon apatite doped with Eu²⁺, the emission bands of the long-wave region are interpreted reasonably. Phosphors Sr₅(PO₄)₂SiO₄ doped with Eu²⁺/Ce³⁺ are synthesized by high temperature solid state reaction under two different atmospheres, the spectral characteristics of Eu²⁺/Ce³⁺ occupying different lattice sites are studied. The luminescent materials Sr₅(PO₄)₂SiO₄ doped with Eu²⁺/Ce³⁺ are promising blue-green phosphors for application in white-LEDs.     

Room-temperature synthesis of nanocrystalline titanium dioxide via electrochemical anodization

This paper presents a study of the growth of nanoporous anatase and rutile phases of titanium dioxide (TiO₂) subjected to electrochemical anodization at room temperature without post-thermal treatment, using sulfuric acid as the electrolyte. Effects of the applied voltage on the morphological, structural, and photoelectrochemical (PEC) properties were examined. Images from field emission scanning electron microscopy reveal that pore size could be manipulated by changing the anodization voltage. In addition, X-ray diffraction (XRD) results indicate that anatase and rutile phases of TiO₂ appeared in samples subjected to minimum anodization voltages of 100 V and 150 V. The Scherrer method was used to calculate the mean crystallite size, and the interplanar d-spacing formula was used to obtain the in-plane and out-of-plane strains. XRD measurements reveal that the amount of anatase and rutile crystallinity and their mean crystallite sizes were affected significantly by the anodization voltage. Results of the PEC studies reveal that the photocurrent density and photoconversion efficiency increased with increasing anodization voltage. In addition, the synthesized nanoporous TiO₂ showed stable photoresponse where only a small decay of photocurrent density is observed in numerous on-to-off illumination cycles.