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采用高温固相反应及共沉淀法合成Y3-xAl5O12∶Ce3x (x=0.01,0.03,0.05,0.07,0.09)黄色系列粉末状发光材料。经X射线衍射分析产物为单相,属立方晶系,其结果与JCPDS标准卡(88-2047)相符。分析了两种方法合成的粉末样品的SEM照片,发现共沉淀法不仅能降低合成温度,对细化粉体晶粒粒度也有较大作用。检测了材料的真空紫外激发光谱和发射光谱。发现,Y3Al5O12∶Ce3 的真空紫外激发光谱,在100~300nm范围内呈三个带状峰,峰值分别在126,177,230nm附近。随着Ce3 含量x由0.01增加到0.05,YAG∶Ce3 发射强度逐渐增加到最大值,之后随着x继续增加其发射强度逐渐下降,呈现明显的浓度猝灭现象。 相似文献
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Visible upconversion emission intensities are investigated in Er3+-doped Y203 nanocrystals. We also find that the upconversion intensity varies nonlinearly with the excitation power with a threshold of 110 mW, which indicates that the green and red emissions would be photon avalanche upconversion when the excitation power exceeds the threshold. 相似文献
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基于密度泛函微扰理论(DFPT)结合模守恒赝势方法进行晶格动力学模拟.得到了钇铝石榴石(YAG)的声子态密度、分波声子态密度和声子的色散谱.利用第一Brillouin区的特殊点取样方法,计算了YAG的比热容和布局数平均的声子群速度.在非谐相互作用下,利用Fermi黄金公式结合第一Brillouin区的特殊点取样方法,得出了YAG非谐声子平均自由程.综合考虑了两种声子散射机制,得到了YAG陶瓷的热导率.结果表明,对于YAG陶瓷,在低温时,晶界散射将对热阻起主要作用;在高于一定温度时,三声子相互作用对热阻的贡献将占主导地位.同时也从理论上证明了Sato等提出的在室温以上,YAG陶瓷与单晶的热导率的差异可以忽略的观点.所得到的热导率、比热容随温度的变化与实验结果很好地符合.
关键词:
声子平均自由程
密度泛函微扰理论
3Al5O12声子结构')" href="#">Y3Al5O12声子结构
热导率 相似文献
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The synthesized monoclinic(B-type) phase of Y_2O_3 has been investigated by in situ angle-dispersive x-ray diffraction in a diamond anvil cell up to 44 GPa at room temperature. A phase transition occurs from monoclinic(B-type) to hexagonal(A-type) phase at 23.5 GPa and these two phases coexist even at the highest pressure. Parameters of isothermal equation of state are V_0= 69.0(1) ~3, K_0= 159(3) GPa, K_0= 4(fixed) for the B-type phase and V_0= 67.8(2) ~3, K_0= 156(3) GPa,K'_0= 4(fixed) for the A-type phase. The structural anisotropy increases with increasing pressure for both phases. 相似文献
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《中国光学快报(英文版)》2015,(5)
High-quality holmium-doped Y3Al5O12(YAG) ceramic is fabricated in sequence by tape-casting and vacuum sintering. The average grain size of the Ho:YAG ceramic is around 20 μm with a fully dense microstructure. The inline transmittance of the sample is ~82% in visible and IR region. The fluorescence lifetime at 2088 nm is8.17 ms. The excellent properties of the Ho:YAG ceramic demonstrate the tape-casting is a novel candidate process for the fabrication of Ho:YAG-based thin-chip or composite ceramics. 相似文献
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The photoluminescence(PL) properties of Y2O3:Eu3+nanophosphors were systematically investigated with the goal of improving the color quality and quantum efficiency of Y2O3:Eu3+nanophosphors for potential applications in nanoscale devices. The emission spectra, excitation spectra and fluorescence decay curves were employed to trace the energy transfer process from Eu3+at C3isite to Eu3+at C2site. The experimental results show that the energy transfer process becomes more and more efficient with the increase in the Eu3+concentration. The emission of Eu3+at C2site is favorable because it has high radiative efficiency and better color quality. The successful suppress of the emission Eu3+at C3iis especially important for its applications in general illumination or display technology. The quantum efficiency and color quality of Y2O3:Eu3+can be improved by controlling the energy transfer between the Eu3+at S6site and Eu3+at C2site. 相似文献
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《中国光学快报(英文版)》2016,(1)
We report on the continuous-wave(CW) and passive Q-switching performance of a miniature Yb:Y_3Ga_5O_(12)crystal laser end pumped by a 935-nm diode laser. A maximum CW output power of 12.03 W is produced with an optical-to-optical efficiency of 54.4%, while the slope efficiency is 63%. In the passively Q-switched operation achieved with a Cr~(4+):YAG saturable absorber, an average output power of 2.12 W at 1025.2 nm is generated with a slope efficiency of 46% at a pulse repetition rate of 5.0 kHz. The pulse's energy, duration, and peak power are 424 μJ, 2.3 ns, and 184.3 k W, respectively. 相似文献
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Y_2O_3和Gd_2O_3对含La_2O_3硼酸盐玻璃析晶性能的影响 总被引:4,自引:1,他引:3
用差热分析(DTA)、X射线衍射分析(XRD)方法研究了Y2O3和Gd2O3对70B2O325La2O35ZnO(mol%)玻璃析晶性能的影响;用梯温炉测定比较了Y2O3和Gd2O3对玻璃失透倾向的影响;用红外光谱(IR)研究了Y2O3和Gd2O3在玻璃中的结构作用。结果表明,适量用Y2O3或Gd2O3取代La2O3可以减轻玻璃的失透倾向,但没有改变玻璃的析晶相。玻璃的析晶相是LaB3O6,Y2O3和Gd2O3在玻璃结构中为网络修饰体。玻璃的折射率nd高于1.70,色散系数υ低于55。 相似文献
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纳米晶Y2O3:Eu3+的合成及其光谱性质研究 总被引:3,自引:0,他引:3
本文报道了草酸作为沉淀剂并添加表面活性剂合成了纳米晶Y2O3:Eu^3 的方法,其一次粒径为15-109nm。对样品的激发光谱、发射光谱及色坐标的测定结果表明:与微米晶比较该纳米晶的发射光谱发生蓝移,激发光谱未见明显变化,猝灭浓度明显提高。荧光粉色坐标x=0.6479,y=0.3442,研究发现了发光亮度随团聚尺寸增大而增强。 相似文献
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《中国光学快报(英文版)》2015,(6)
Cr3t∕Yb3tcodoped Y3Al5O12(i.e., YAG) thin films are prepared by pulsed laser deposition. The films are characterized by X-ray diffraction, atomic force microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and photoluminescence spectra. Excitation at 446 or 587 nm, a broadband emission in the range of 610–800 nm, and an intense near-infrared at 1030 nm are obtained, showing cooperative energy transfer from Cr3 tto Yb3tions in the Cr3t∕Yb3tcodoped YAG thin films; energy transfer efficiency is 71%. The YAG films may have potential application to enhance the efficiency of silicon solar cells. 相似文献
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掺杂Gd^3+对Y2O2S:Eu^3+发光特性的影响 总被引:6,自引:0,他引:6
在红色荧光粉Y2O2S:Eu^3+的制备过程中掺入了不同浓度的Ga2O3;发现在掺入适当浓度的Ga2O3的情况下,可以增强发射强度并改善其电压特性,即在保证所要求的发光颜色、粒径和其它物理及化学特性的条件下,可改善发射强度与激发电压间的关系,讨论和分析了强度被增强的起因。Ga^3+对Y^3+的置换,减少了因Eu^3+对Y^3+转换所引起的晶格的畸变,从而减弱了无辐射过程及因晶格畸变所造成的能量损失 相似文献
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采用原位脱氯化氢缩合聚合法制备了聚(2-甲氧基-5-辛氧基)对苯乙炔/Y_2O_3:E~(3+)(PMOCOPV/Y_2 O_3:Eu~(3+))纳米复合材料。红外光谱证实了在Y_2O_3:Eu~(3+)表面的包覆层为PMOCOPV。紫外-可见吸收光谱表明与PMOCOPV相比,PMOCOPV/Y_2O_3:Eu~(3+)的最大吸收峰发生红移且强度提高。荧光光谱研究表明PMOCOPV/Y_2O_3:Eu~(3+)的最大发射波长发生红移且强度提高,荧光寿命得到增强,Y_2O_3:Eu~(3+)与PMOCOPV之间形成了光致电子转移体系,使得π电子离域程度增加,并且导致荧光量子效率提高。根据E_g与入射光子能量hv的关系,拟合了PMOCOPV/Y_2O_3:Eu~(3+)薄膜的光学禁带宽度,发现E_g减小。采用简并四波混频方法测试它们的三阶非线性极化率x~((3)),结果发现与PMOCOPV相比,PMOCOPV/Y_2O_3:Eu~(3+)纳米复合体的非线性光学响应逐渐增强,进一步说明PMOCOPV与Y_2O_3:Eu~(3+)之间形成了分子间光致电子转移体系,产生了复杂的分子间离域π电子非线性运动。 相似文献
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在团簇近似的基础上,利用分子动力学和密度泛函计算相结合的手段,在Y2O3:Eu3+中研究了随Li+掺杂浓度的变化,缺陷形成情况以及C2位处Y-O键长的变化对电子态密度的影响.结果表明,随着Li+掺杂浓度的增加,与C2格位相关团簇的Y-O键平均键长出现了增加-减小-增加的变化趋势,这可能是引起此类材料发光强度随Li+浓度出现类似变化的原因. 相似文献
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Y_2O_3稳定Z_rO_2相结构的拉曼光谱研究 总被引:5,自引:0,他引:5
测试了Z_rO_2+nmol%Y_2O_3系统多种陶瓷样品的拉曼光谱,发现随着Y_2O_3含量的增加,在常温下,Z_rO_2即可发生由单斜相到四方相再到立方相的结构相变,常温下稳定的四方相Z_rO_2是我们所希望的。测试结果表明,当Y_2O_3含量为2~2.25mol%时,可获得常温下稳定的四方相Z_rO_2。研究不同工艺条件对样品相结构的影响,找出了制造样品的最佳工艺条件。 相似文献