共查询到20条相似文献，搜索用时 15 毫秒
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Liu Bo Li Chunliang Bi Jiancong Sun Liang Xu Yuheng 《Crystal Research and Technology》2008,43(3):260-265
Hf(2mol%):Fe(0.05wt%):LiNbO3 crystals with various [Li]/[Nb] ratios of 0.94, 1.05, 1.2 and 1.38 have been grown. The photorefractive resistant ability increases with the accretion of [Li]/[Nb] ratio. When the ratio of [Li]/[Nb] is 1.20 or 1.38, the OH‐ absorption band shifts to about 3477cm‐1. The mechanisms of the photorefractive resistant ability increase and the absorption band shift have been discussed. The exponential gain coefficient (Γ) of the crystals was measured with two‐beam coupling method and the effective charge carrier concentration (Neff) was calculated. The results show that Γ and Neff increase with the accretion of [Li]/[Nb] ratio. The temperature effect of codoped Hf:Fe:LiNbO3 crystals was also studied, it was found that the exponential gain coefficient increase dramatically at about 55°C, 70°C and 110°C, this is due to the inner electric field which is resulted from structure phase change. (© 2007 WILEY ‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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The near sotichiometric Ce:LiNbO3 (Ce:SLN) crystals were grown by the top seeded solution growth (TSSG) method by adding K2O flux to Li2O‐Nb2O5 melt. Their UV‐vis absorption spectra and IR spectra were measured and discussed to investigate their defect structure. The results showed that the grown crystals were near stoichiometric and Ce ions in the crystals located the Li site. Photorefractive properties of Ce:SLN crystals were studied by two‐wave coupling experiment. The results of the two‐wave coupling experiments of the crystals showed that as the CeO2 doping concentrations increased, the diffraction efficiency increased, photoconductivity decreased and the writing time and erasure time increased. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Chang‐Hung Chiang Jyh‐Chen Chen Jenq‐Yang Chang Chung‐Wei Lu 《Crystal Research and Technology》2007,42(12):1302-1307
The effect of post treatment on the photorefractive properties of Ru‐doped lithium niobate was studied. The absorption spectra examination of Ru‐doped LiNbO3 crystals with different post treatments showed that the absorption coefficient at 530 nm increased after the reduced treatment was employed and the absorption edge of the reduced crystal shifted towards the infrared band. On the contrary, the trend reversed after the oxidized treatment was employed. In addition, the photorefractive properties were investigated with the two‐beam coupling method conducted via a 532 nm solid state laser. It was found that the oxidized Ru:LiNbO3 had smaller exponential gain coefficient and diffraction efficiency because the charges in the shallow level were exchanged to the deep level. On the other hand, the reduced Ru:LiNbO3 crystals had larger exponential gain coefficient and diffraction efficiency due to the increase of the Ru3+ which existed in the shallow level. The response times of both oxidized and reduced Ru:LiNbO3 were longer than those of the as‐grown ones. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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In this paper, photorefractive properties of Mg:Ce:Cu:LiNbO3 crystals were studied. The crystals doped with different concentration of Mg ions have been grown by the Czochralski method. Mg concentrations in grown crystals were analyzed by an inductively coupled plasma optical emission spectrometry (ICP‐OE/MS). The crystal structures were analyzed by the X‐ray powder diffraction (XRD), ultraviolet‐visible (UV‐Vis) absorption spectra and infrared (IR) transmitatance spectra. The photorefractive properties of crystals were experimentally studied by using two‐beam coupling. In this experiment we determined the writing time, maximum diffraction efficiency and the erasure time of crystals samples with He‐Ne laser. The results showed that the dynamic range (M/#), sensitivity (S) and diffraction efficiency (η) were dependent on the Mg doping concentration, and the Mg(4.58mol%):Ce:Cu:LiNbO3 crystal was the most proper holographic recording media material among the six crystals studied in the paper. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Chao Xu Zhaopeng Xu Yexia Fan Lei Xu Chunhui Yang Yuheng Xu 《Crystal Research and Technology》2012,47(8):863-867
Mg:Ru:Fe:LiNbO3 crystals with various doping concentration of MgO have been grown by Czochralski method. The type of charge carriers and photorefractive properties in Mg:Ru:Fe:LiNbO3 crystals were measured by two‐wave coupling method using Kr+ laser (476 nm) and He‐Ne laser (633 nm) as light sources. We found that holes were the dominant charge carriers under blue light irradiation while electrons were the dominant charge carriers under red light irradiation. Mg2+ ions behaved no longer as damage resistant, but promoter to the photorefractive properties at 476 nm wavelength. The photorefractive properties under blue light improved with the increase concentration of Mg2+ ions. The enhancement mechanisms of the blue photorefractive were suggested. Experimental results definitely showed that Mg‐doped two‐centre Ru:Fe:LiNbO3 was a promising blue photorefraction material for holographic volume storage. 相似文献
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Chao Xu Chunhui Yang Yang Mo Yijie Wang Liang Sun Liangcai Cao Yuheng Xu 《Crystal Research and Technology》2010,45(11):1123-1126
Near‐stoichiometric LiNbO3 single crystal tri‐doped with ZrO2, MnO and Fe2O3 was grown from Li‐riched melt by Czochralski method. The defect structures and composition of these crystals were analyzed by means of ultraviolet‐visible and infrared transmittance spectra. The appearance of 3466 cm‐1 peak in infrared spectra showed that the crystal grown from Li‐riched melt was near stoichiometric. The photorefractive properties at the wavelength of 488 nm and 633 nm were investigated with two‐beam coupling experiment, respectively. The experimental results showed that the response speed and sensitivity were enhanced significantly and the high diffraction efficiency was obtained at 488 nm wavelength. This manifested that near‐stoichiometric LiNbO3:Mn:Fe:Zr crystal was an excellent candidate for holographic storage. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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S. H. Yao X. B. Hu J. Y. Wang H. Liu L. Gao X. F. Cheng X. Yin X. F. Chen 《Crystal Research and Technology》2007,42(2):114-118
A near stoichiometric LiNbO3 single crystal has been grown by the Czochralski method from a 58.5% Li melt hold in a large platinum crucible. High resolution X‐ray rocking curves of 30 0 and 0006 reflections indicated that the near stoichiometric LiNbO3 crystal possesses the high structural quality. Compared with the congruent LiNbO3, the near stoichiometric LiNbO3 possesses shorter ultraviolet absorption edge, thus higher Li concentration. The OH– infrared absorption band analyses showed that the Li concentration in the near stoichiometric LiNbO3 crystal is higher than that in the congruent LiNbO3 crystal. This result is in good agreement with that of the ultraviolet absorption edge. The electro‐optic (EO) coefficient γ22 of the near stoichiometric LiNbO3 crystal was measured to be 6.75 pm/V higher than that of congruent LiNbO3 crystal. It also proves the near stoichiometric LiNbO3 electro‐optic Q‐switched requires a low driving voltage and it is advantageous for the device performance. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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以K_2O为助熔剂,应用坩埚下降法生长出了Co~(2+) 初始浓度为0.5 mol;,以及ZnO分别为3 mol;与6 mol;的单掺与双掺杂SLN晶体(分别用SLN0, SLN3, SLN6表示).测定了晶体上下部位的吸收与发射光谱.在晶体的吸收光谱中均可观察到520 nm,549 nm,612 nm,1447 nm四个吸收峰,表明Co~(2+)处于晶体的八面体场中.ZnO的掺入明显地改变了吸收峰的相对强度.在520 nm光的激发下,观察到776 nm的荧光发射,其荧光强度的相对强弱也与ZnO的掺杂量有明显的联系.从吸收边带估算出SLN0, SLN3, SLN6晶体中Li2O的含量分别为49.06 mol;,49.28 mol;, 49.10 mol;.ZnO的掺杂量对Co~(2+)在铌酸锂晶体中的浓度分布有很大的影响作用,当ZnO的掺入量为3 mol;时,明显地抑制了Co~(2+)在LiNbO_3晶体中的掺入,当ZnO掺杂量达到6 mol;时,抑制作用减弱.本文从Zn~(2+)在LiNbO_3中随浓度变化的分凝情况以及对Co~(2+)的排斥作用解释了Co~(2+)在晶体中的分布特性以及光谱的变化情况. 相似文献
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J.W. Shur W.S. Yang S.J. Suh J.H. Lee T. Fukuda D.H. Yoon 《Crystal Research and Technology》2002,37(4):353-358
Erbium doped LiNbO3 (Er:LiNbO3) single crystal fibers were grown free of cracks along c‐axis by the micro‐pulling down (μ‐PD) method. We have investigated the up‐conversion property with the change of doped Er2O3 concentration and the starting melt composition. An enhancement of green upconversion according host matrix is also observed the stoichiometric LiNbO3. And, the dependence of the green emission according to Er3+ concentration is analyzed. The possible application of the Er3+ doped stoichiometric LiNbO3 single crystal fiber for up‐conversion based optical devices is discussed. 相似文献
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M. P. Sampedro M. A. Cerezo Jcome D. Ramírez Martínez M. Mndez Otero M. Palomino Ovando 《Crystal Research and Technology》2006,41(7):683-688
It is, well know that some, optical materials to change his refractive index when these exposed to light, depending on particular conditions, they can generate several distributions of refractive index. In this work, an experimental periodic arrangement of refractive index generated on the Bi12TiO20 photorrefractive crystal is presented, the initial condition used was generated by superposing two He‐Ne laser linearly polarized beams in a perpendicular direction to the external field applied to the crystal at 632.8 nm. The diagrams of bands generated with this arrangement is studied, based on the similarities presented by the periodic refractive index with the photonic bandgap (PBG) diagrams one‐dimensional superlattices composed of alternating layers of two distinct materials. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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以K2O为助熔剂,在较大的温度梯度(90～100℃/cm)条件下进行引种和晶体生长,应用坩埚下降法成功地生长出了初始CO2+掺杂浓度为0.5mol;的近化学计量比的铌酸锂晶体.测定了该晶体的红外光谱与吸收光谱,与同成份的LiNbO3晶体相比,其紫外吸收边向短波方向移动,OH-红外吸收峰的位置发生变化.观测到520,549,612nm三个分裂的尖吸收峰以及1400nm左右为发光中心的吸收带.从吸收特性可以判断,Co离子在铌酸锂晶体中呈现+2价.比较上部与下部晶体的吸收强度,可以推测出沿着晶体生长方向Co2+离子浓度逐渐降低,Co2+离子在晶体中有效的分凝系数大于1. 相似文献
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La3Ga5SiO14单晶的生长、性能及SAW应用 总被引：12，自引：8，他引：4
本文综述了新型压电晶体La3Ga5SiO14的最新研究进展,详细讨论了该晶体的生长问题,简单介绍了该晶体的性能及其在SAW和BAW方面的应用,分析了该晶体在压电应用方面的优势. 相似文献
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铁电薄膜的工作电场加载频率及基底失配应变可影响微观畴结构形态和材料宏观铁电性能。本文利用相场模拟方法分别研究了在-0.1%、-0.7%的失配应变下,0.1~100 kHz频率范围内BaTiO3纳米单晶薄膜的铁电性能变化规律。研究发现,随着外加电场频率的增大,薄膜电滞回线由四方形向椭圆形转变,标准蝶形曲线向腰果形曲线发生改变。在50 kHz以下的低频段,矫顽场随频率增加而快速升高,但剩余极化强度变化幅度不大;而在50 kHz以上的高频段,矫顽场随频率增加略有升高,剩余极化强度则呈下降趋势。在低频段下铁电性能的频率依赖性受失配应变的影响较大,而在高频段下则对失配应变不敏感。同时发现,压缩失配应变可导致剩余极化及矫顽场显著升高,而拉伸应变的效果相反。分析表明,BaTiO3纳米单晶薄膜铁电性能的频率依赖性源自内部微结构演化速度与外电场施加速率的相互竞争。本研究可为铁电功能薄膜材料的实验设计提供理论基础,为其在高频电子器件中的应用提供有力支撑。 相似文献
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Igor A. Schelokov Dmitry V. Roshchupkin Dmitry V. Irzhak Remi Tucoulou 《Journal of Applied Crystallography》2004,37(1):52-61
The dynamical theory was used to model X‐ray diffraction by the YZ‐cut of an LiNbO3 crystal modulated by surface acoustic waves (SAWs). It includes both the calculation of the crystal lattice deformation, induced by a surface wave of Rayleigh type, and the simulation of X‐ray wavefields in the crystal based on Takagi–Taupin equations. A detailed discussion is included on the effect of peak splitting occurring at high acoustic amplitudes. The developed theory entirely describes this effect and proves to be a powerful tool for understanding X‐ray diffractometry and topography measurements by SAW‐modulated crystals. 相似文献
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沉积温度对磁控溅射生长SrRuO_3薄膜结构和性能的影响 总被引：1，自引：1，他引：0
采用射频磁控溅射法在(001)SrTiO_3基片上制备了SrRuO_3薄膜,采用X射线衍射(XRD)、原子力显微镜(AFM)、四探针测试仪等分析方法系统研究了沉积温度对SrRuO_3薄膜结构、表面形貌及输运性质的影响.实验结果表明:当生长温度低于550 ℃时,SrRuO_3薄膜为多晶结构;当温度在550～650 ℃范围内变化时,SrRuO_3薄膜可以在SrTiO_3基片上外延生长,薄膜的最低电阻率约为0.5 mΩ·cm. 相似文献
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In:Zn:LiNbO3 crystals doped with different indium concentrations were grown by Czochralski technique. The optical damage threshold value and ultraviolet‐visible absorption spectra of the In:Zn:LiNbO3 crystals were measured. The In:Zn:LiNbO3 crystals were made into optical waveguide substrates using hexanedioic acid as proton exchange agent. The optical damage resistant ability of those optical waveguide substrates was investigated by the m‐line method. The optical damage threshold values of In(2mol.%):Zn(3mol.%):LiNbO3 crystal and optical waveguide substrate are two orders of magnitude higher than those of pure LiNbO3. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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T. Tsukada K. Kakinoki M. Hozawa N. Imaishi K. Shimamura T. Fukuda 《Journal of Crystal Growth》1997,180(3-4):543-550
A global analysis of heat transfer was carried out in an inductively heated Czochralski (CZ) furnace which was actually used to grow LiNbO3 single crystals, and then the temperature profiles obtained were used to calculate the three-dimensional thermal stress field in the crystal. By comparing the numerical results with the experimental ones, it was found that controlling the thermal environment in the CZ furnace so that the thermal stresses at the crystal surface might not exceed a certain value is important to realize the cracking free growth operation. In this study, this was accomplished through some modifications in the furnace design such as insertion of an after-heater into the furnace. These findings were verified by additional numerical simulations and crystal growth experiments for some growth conditions. 相似文献