共查询到18条相似文献,搜索用时 406 毫秒
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坩埚下降法生长了(Mo^6+、PbF2),(Mo^6+、Gd^3+),(PbF2,Gd^3+)组合掺杂,及PbF2单掺杂钨酸铅晶体,对样品进行了吸收光谱、光产额、x射线和紫外激发发光光谱等测试和表征,讨论了掺杂对钨酸铅发光的增强效果。掺杂钨酸铅总发光额都得到了增强;在门宽100ns内晶体的光产额都有提高,但在测试门宽在200ns内,(Gd^3+、PbF2)掺杂样品光产额有所下降。x射线激发发光显示,PbWO4:(Mo^6+、Gd^3+)的蓝发光和绿发光分量都有提高;PbWO4:(Mo^6+、PbF2)蓝发光受到拟制,提高了绿发光成分,晶体光学吸收边明显红移。PbWO4:(Gd^3+、PbF2)蓝发光得到增强,绿发光得到一定的拟制。光致发光光谱分析表明,Gd^3+掺杂对PbWO4基质发光有敏化作用。实验证实,F在PbWO4生长中非常不稳定,显示很差的掺杂均匀性。 相似文献
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以分析纯ZrO2和WO3为原料,通过原位反应法成功制备了ZrO2-ZrW2O8复合材料,研究了其热膨胀性能,并探讨了烧结助剂AJ203对其致密度的影响。采用X射线衍射仪(XRD)、扫描电镜(SEM)和热膨胀仪对制备的样品进行表征。研究结果表明:制备的复合材料的组元为α-ZrW2O8和m-ZrO2;其中ZrO2-33%(质量分数),ZrW2O8复合材料的热膨胀系数近似为零,但致密度不高;添加0.30%(质量分数)Al2O3有效地提高了ZrO2-33%(质量分数)ZrW2O8复合材料的致密度,与出现的新相Al2(WO4)3有关,而且对其零膨胀特性影响不大。 相似文献
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HPLC法测定血竭药材中血竭素的含量 总被引:1,自引:0,他引:1
本文建立了血竭药材中血竭素的测定方法,采用Agilent TC—C18柱,以乙腈-0.05mol/LKH2PO4(0.1%H3PO4水溶液)=40:60;流速:1.0mlMmin;检测浓度:440nm和270nm,回收率为96.25%~100%之间,RSD为1.67%。实验结果表明该方法简便、快速、精密度高。 相似文献
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采用垂直Bridgman法生长了In掺杂Cd0.3Mn0.2Te晶体(CdMnTe:In)和本征的Cd0.8Mn0.2Te晶体(CdMnTe)。X射线粉末衍射、X射线双晶摇摆曲线和位错密度测试表明,所生长晶体均为立方闪锌矿结构,半峰宽为40~80arc Sec,位错密度为100~100cm^-2,结晶质量良好.In掺杂不影响晶体的结构和结晶质量。电流.电压(I-V)测试表明,CdMnTe:In晶体的电阻率为1~3×10^9Ω·cm,与CdMnTe晶体相比上升了3个数量级.近红外光透过光谱(IR transmission)研究发现In掺杂后CdMnTe晶体红外透过率降低,在波数范围4000~1000cm^-1,CdMnTe晶体红外透过率为51.2%~56.4%,而CdMnTe:In的红外透光率为15.4%~6%。 相似文献
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一种新型改性PbTiO3压电陶瓷材料研究 总被引:13,自引:0,他引:13
研制了一种新型的添加Pb(Mn1/3Sb2/3)O3、碱土金属CaCO3、Bi2O3、NiO的改性钛酸铅压电陶瓷材料.该材料具有高压电活性、大压电各向异性、低介电常数及小的机械品质因素.实验确定其典型配方为Pb0.80Ca0.20[(Mn1/3Sb2/3)0.05Ti0.95]3+0.5wt%NiO+1wt%Bi2O3;在优化后的制备工艺条件下,其主要性能参数为:d33=70×10-12C·N-1;Kt=60.0;Hp≈0,Qm=43,Nt=2004Hz·m. 相似文献
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射频磁控溅射法制备Al2(WO4)3薄膜和负热膨胀性能研究 总被引:2,自引:1,他引:1
采用WO3和Al2O3陶瓷靶材,以双靶交替射频磁控溅射法,在石英基片上沉积制备了Al2(WO4)3薄膜。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM),研究了退火温度对Al2(WO4)3薄膜的相组成和表面形貌的影响,采用表面粗糙轮廓仪和划痕仪测量薄膜厚度,探索了薄膜的制备工艺以及薄膜与基片的结合力,采用高温X射线衍射和晶胞参数指标化软件,初步研究了薄膜热膨胀特性。实验结果表明:磁控溅射沉积制备的这种薄膜为非晶态,表面平滑、致密,随着热处理温度的升高,薄膜开始结晶且膜层颗粒增大,在950℃热处理10min后得到Al2(WO4)3薄膜,薄膜与基片的结合力为13.6N,薄膜物质热膨胀特性呈各向异性。 相似文献
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The solid-state reaction kinetics of a sequential reaction system were analysed theoretically and experimentally. For the reactions occurring in series, A+RB and B+QC, a multiple core–shell diffusion-controlled model has been proposed. The relations between the consumption fractions of A and B and the reaction time under isothermal conditions have been quantitatively deduced. The sequential reactions of PbWO4+PbOPb2WO5 and Pb2WO5+MgOPb(Mg1/2W1/2)O3 in the formation processes of Pb(Mg1/2W1/2)O3 were utilized as the model reactions. The unidirectional diffusion of PbO into PbWO4 to form Pb2WO5 and that of MgO into Pb2WO5 to generate Pb(Mg1/2W1/2)O3 were verified by EDS. The derived equations were confirmed to elucidate accurately the kinetics of the serial reactions in the Pb(Mg1/2W1/2)O3 system. Based on the reaction model, the activation energy for the diffusion of MgO into Pb(Mg1/2W1/2)O3 was estimated to be 161.7 kJ mol-1. © 1998 Chapman & Hall 相似文献
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采用不同粒径的Ni粉与硅橡胶(110型)按质量比2.4∶1.0制成Ni/硅橡胶复合材料, 分别测量了其压敏导电性及介电性质, 并结合扫描电镜照片对其微观导电机制进行了分析。结果表明随着填料Ni粉粒径的减小, Ni/硅橡胶复合材料的直流电阻率对外加压强更加敏感: 在低压强下, 粒径为74、48和18 μm的样品的电阻率随压强的变化率分别为1.73×104、2.59×104和3.71×10 4 Ω·m/kPa。样品直流电阻率陡降的区域随粒径的减小向压强较小的方向移动, 显示出复合材料的渗流阈值与填充粒子的粒径有关: 粒径越小, 渗流阈值也越小。Ni/硅橡胶复合材料的交流电导率、介电常数、介电损耗均随填料Ni粉粒径的减小而变大: Ni粉粒径为18 μm的Ni/硅橡胶复合材料的电导率约为10-2 S·m-1, 比74 μm粒径样品的电导率(约10-7 S·m-1)提高了5个数量级; 对应的介电常数由约102提高到约103。改变填料Ni粉粒径可以有效地调节复合材料的弹性和压敏、电输运特性。 相似文献
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以WO3粉体合成的W络合离子作为前驱液,超声喷雾热裂解法(USP)制备出WO_3薄膜,研究前驱液中H_2O_2添加量、薄膜沉积温度和薄膜退火温度对WO_3薄膜光电化学性能的影响,利用XRD、UV-vis和光电流光谱(IPCE)等对薄膜进行表征,实验结果表明,USP制备的WO_3薄膜为单斜相且沿(200)晶面优势生长;前驱液中双氧水量的增加导致WO_3薄膜禁带宽度(E_g)增加;薄膜的平带电位(Vfb)在-0.27~-0.05V之间(vs.SCE,pH=7),且掺杂浓度随退火温度升高而降低;在0.1M的Na_2SO_3溶液中,薄膜的IPCE随退火温度升高而降低,随H_2O_2量的减小IPCE增高。 相似文献
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In this work,W-Y2 O3 alloys are prepared by freeze-drying and subsequent low temperature sintering.The average size of reduced W-Y2 O3 composite powders prepared by freeze-drying method is only 18.1 nm.After low temperature sintering of these composite nanopowders,the formed W-Y2 O3 alloys possess a smaller grain size of 510 nm while maintaining a comparatively higher density of 97.8%.Besides a few submicron Y2 O3 particles(about 100-300 nm)with a W-Y-O phase diffusion layer on their surface distribute at W grain boundaries,lots of nano Y2 WO6 particles(<20 nm)exist in W matrix.Moreover,many Y6 WO12(<10 nm)particles exist within submicron Y2 O3 particles.The formation of these ternary phases indicates that some oxygen impurities in the W matrix can be adsorbed by ternary phases,resulting in the purification of W matrix and the strengthening of phase boundaries.The combined action of the above factors makes the hardness of the sintered W-Y2 O3 alloys in our work as high as 656.6±39.0 HV0.2.Our work indicates that freeze-drying and subsequent low temperature sintering is a promising method for preparing high performance W-Y2 O3 alloys. 相似文献
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通过高温熔融法和热处理制备了含有-γBi2WO6纳米晶的Er3+掺杂透明硼铋酸盐微晶玻璃.根据X射线粉末衍射结果和Scherrer公式计算得到-γBi2WO6晶粒大小约为15 nm.由于部分Er3+离子取代Bi3+进入-γBi2WO6纳米晶相中,使得Er3+离子在1.5μm的有效发射带宽由78 nm增加到85 nm,同时Er3+离子在4I13/2能级的荧光寿命由0.67 ms增加到1.43 ms.此外,与原始玻璃相比,在Er3+掺杂硼铋酸盐微晶玻璃中观察到强烈的绿光上转换发光,其上转换发光机制可以归为双光子过程. 相似文献
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Wang Z Lil G Quan Z Kong D Liu X Yu M Lin J 《Journal of nanoscience and nanotechnology》2007,7(2):602-609
Nano-submicrostructured CaWO4, CaWO4 : Pb2+ and CaWO4 : Tb3+ particles were prepared by polyol method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), thermogravimetry-differential thermal analysis (TG-DTA), photoluminescence (PL), cathodo-luminescence (CL) spectra and PL lifetimes. The results of XRD indicate that the as-prepared samples are well crystallized with the scheelite structure of CaWO4. The FE-SEM images illustrate that CaWO4 and CaWO4 : Pb2+ and CaWO4 : Tb3+ powders are composed of spherical particles with sizes around 260, 290, and 190 nm respectively, which are the aggregates of smaller nanoparticles around 10-20 nm. Under the UV light or electron beam excitation, the CaWO4 powders exhibits a blue emission band with a maximum at about 440 nm. When the CaWO4 particles are doped with Pb2+, the intensity of luminescence is enhanced to some extent and the luminescence band maximum is red shifted to 460 nm. Tb(3+)-doped CaWO4 particles show the characteristic emission of Tb3+ 5D4-7FJ (J = 6 - 3) transitions due to an energy transfer from WO4(2-) groups to Tb3+. 相似文献