铋掺杂钒酸钇的合成及发光性能研究

采用高温固相法合成钒基荧光材料YVO4:Bi3+,其最佳掺杂浓度是1.5％,最宜煅烧温度为1000℃.用XRD,SEM以及荧光光谱等手段对所合成的荧光粉进行了表征,结果表明,样品在近紫外光254 nm激发下,产生位于300 ～ 750 nm的宽带发射峰.其中,铋离子浓度为1.5％时,样品的荧光发射主峰543 nm.     

三维网状Dy3+:YVO4/TiO2复合纤维的制备及光催化产氢性能

以电纺TiO₂纳米纤维为基质, 柠檬酸为软模板, 采用一步水热法制备了具有三维立体网状结构的稀土Dy ³⁺掺杂YVO₄/TiO₂复合纤维. 通过X射线衍射、 扫描电子显微镜、 X射线光电子能谱、 N₂吸附-脱附、 紫外-可见漫反射光谱及荧光光谱等手段对材料的组成、 表面形貌和性能进行表征, 以光分解水产氢实验考察其光催化活性. 结果表明, Dy ³⁺∶YVO₄纳米枝与TiO₂纳米纤维相互交联构筑的纳米纤维网具有大比表面积, 可提供更多活性位点, 改善了多相光催化反应的传递过程; 稀土Dy ³⁺掺杂的YVO₄与TiO₂复合形成异质结相互促进, 在拓宽光谱响应范围、 提高太阳光利用率的同时使光生电子-空穴对得到较好分离, 从而提高了样品的光催化活性. 模拟太阳光照射下, Dy ³⁺∶YVO₄/TiO₂复合纤维光催化产氢速率达到8.63 mmol· h ^-1·g ^-1, 是纯TiO₂纳米纤维的10倍.     

Er3+:YVO4中Er3+的光谱参数计算

根据掺杂Er3+(0.5%)的YVO4样品的吸收光谱,用Jubb-Ofelt理论拟合出唯象强度参最Ωλ,并由此计算了激发能级的振子强度、自发辐射跃迁速率、荧光分支比和积分发射截面等光谱参量.并根据这些光学参量,分析了Er3+:YVO4晶体的应用价值.其中,特别是4I13/2→4I15/2, 2H11/2→4I15/2, 4S3/2→4I15/2和4F9/2→4I15/2等几个强发光能级具有较大的振子强度(大于10-6)和积分发射截面(大于10-18cm),分别分析了它们的应用前景,因此非常值得关注.并且,本文结果和Capobianco等所报道的Er3+(2.5 mol%):YVO4晶体强度参量结果很相近.而且,通过比较掺Er3+钒酸钇晶体和掺Er3+其他晶体的光学性能,可以看出钒酸钇晶体作为激光晶体的优点.最后,还根据Er3+在晶体中的对称性,利用群论讨论了Er3+在YVO4晶场中各能级的劈裂情况.     

High power, long pulse duration, single-frequency Nd:YVO4 master-oscillator power-amplifier

An efficient single-frequency Nd:YVO₄ master-oscillator power-amplifier is described. Gated pulses from a CW diode-pumped ring laser were amplified by three Nd:YVO₄ amplifiers. Pulses of 1mJ energy; 2 kW peak power and 1 μs duration were obtained at a repetition frequency of 10 kHz. Analogue shaping of the input pulses was used to control the output pulse shape and thus extend the useful range of pulse widths from the 100 ns to the μs regime. A simple mathematical expression was used to model the results which provided reasonable agreement with the experimental work. This system offers a promising pump source for a quasi-CW singly-resonant optical parametric oscillators.     

The Study on the Interaction between Tm~(3 ) and Tb~(3 ) Rare Earth Ions in YVO_4 Crystal

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｔｈｅｌａｓｉｎｇｐｅｒｆｏｒｍａｎｃｅｓｏｆｒａｒｅ ｅａｒｔｈｉｏｎＴｍ3 ｄｏｐｅｄｌａｓｅｒｃｒｙｓｔａｌｓａｔ～ 2 .3 μｍａｎｄ～1 .9μｍｗａｖｅｌｅｎｇｔｈ ,ｃｏｒｒｅｓｐｏｎｄｉｎｇｔｏ3Ｈ4→3Ｈ5 ａｎｄ3Ｆ4→ 3Ｈ6 ｔｒａｎｓｉｔｉｏｎｓｗｅｒｅｓｔｕｄｉｅｄｂｙＪ .Ａ .Ｃａｉｒｄ[1] ａｎｄＬ .Ｆ .Ｊｏｈｎｓｏｎ[2 ] .ＲｅｃｅｎｔｌｙＦ .Ｓ .Ｅｒｍｅｎｅｕｘ[3] ｓｕｇｇｅｓｔｅｄｔｈｅｌａｓｉｎｇｐｏｓｓｉｂｉｌｉｔｉｅｓｏｆＴｍ3 ｄｏｐｅｄｌａｓｅｒｃ…     

YVO4双折射晶体生长及完整性分析

在较低氧分压的保护气氛中用提拉法(CZ法)生长YVO4晶体,采用自行设计的气压计,精密调节炉内的氧、氮比例,有效防止了晶体生长中的过度缺氧,生长出33mm×31mm(等径)YVO4晶体.设计了生长YVO4晶体最佳工艺条件:转速5～10r/min,拉速:2～6mm/h,生长周期:24h,液面上8mm温度梯度2.875℃/mm.用偏光显微镜对YVO4晶体的裂纹、散射颗粒、包裹物、偏心生长等缺陷进行观察,认为它们的成因主要是生长速率过快,生长环境中湿度大及晶体中存在分解和挥发性物质等.     

Simultaneous Q-switching and Frequency-doubling by a Single KTP Crystal in a Diode-pumped Nd: YVO4 Laser

The interrelation between the phase matching condition for second harmonic generation (SHG) and the electro-optic Q-switching in KTP was numerically analyzed. A diode-pumped Q-switched Nd: YVO4/KTP green laser was reported, where the KTP crystal was simultaneously used as both an electrooptic Q-switcher and a frequency-doubling crystal in type Ⅱ phase matching.Compared with the conventional frequency-doubling and Q-switching configuration, low loss and high efficiency characteristics were realized by using a single KTP crystal. The Q-switched green laser pulse with a peak power of 762 W and a pulse width of 12 ns was obtained with 1 W pump power.     

微型Nd：YVO4激光器在碘分子调制转移光谱中的应用

以半导体激光器抽运微型Nd:YVO4倍频激光器为光源获得碘分子在532nm处的光外差调制转移光谱信号,并对获取最佳稳频信号的实验条件进行了讨论。     

Influence of Y3+, Bi3+ content on photoluminescence of YVO4:Dy3+ phosphor induced by ultraviolet excitation

YxVO4:0.01Dy3+ and Y0.99-xVO4:0.01Dy3+,xBi3+ phosphors were synthesized by chemical coprecipitation method.Their crystal structure,micromorphology and photoluminescence (PL) properties were investigated by X-ray diffraction (XRD),scan electron microscopy (SEM) and spectrofluorometer.YxVO4:0.01Dy3+ and Y0.99-xVO4:0.01Dy3+,xBi3+ phosphors have a broad excitation band from about 250 to 350 nm including a strongest peak at about 310 nm.Under its excitation,the emission spectra exhibits two sharp peaks,one of which centered at about 483 nm for 4 F9/2→6 H15/2 transition of Dy3+ and the other at about 574nm due to the 4F9/2→6H13/2 transition of Dy3+.For YxVO4:0.01Dy3+ (x=0.94,0.97,0.99,1.01,1.03)phosphor,with increasing value of x,the body color of phosphor changes from yellow to white and the strongest peak in the excitation spectra shifts a little to shorter wavelength.It is detrimental to luminous intensity when Y3+ content deviates stoichiometric ratio.For Y0.99-xVO4:0.01Dy3+,xBi3+ (x=0.01,0.05,0.1,0.15,0.2,0.25) phosphor,the samples have extraneous bismuth vanadium oxide phase except for the major tetragonal zircon structure when x≥0.20.With increasing value of x,the band edge in the excitation spectra shifts to longer wavelength,the excitation intensity and luminous intensity increase early and decrease late.When the value of x is 0.01,the intensities increase evidently.In addition,the influence of Y3+ or Bi3+ on the color temperature of emission and micromorphology of YVO4:Dy3+ is slight.     

The temperature‐sensitive luminescence of (Y,Gd)VO4:Bi3+,Eu3+ and its application for stealth anti‐counterfeiting

Anti‐counterfeiting technologies are desired to protect products far away from the violation of dummy, fake and shoddy goods. The phosphor of (Y,Gd)VO₄:Bi³⁺,Eu³⁺ was synthesized for the application of this purpose. Its photoluminescence was investigated by exciting with different wavelengths at variant temperatures. Wide emission color ranged from green through yellow to orange was tuned up by tailor‐ing Bi³⁺ and Eu³⁺ concentrations. The temperature dependent luminescence and wavelength selective excitation of (Y,Gd)VO₄:Bi³⁺,Eu³⁺ were observed, which provide different encryptions in anti‐counterfeiting. To verify the feasibility in application, two anti‐counterfeiting patterns were fabricated practically and excellent performance was obtained. Moreover, the physical mechanisms for the different phenomena of luminescence were elucidated from excitation spectra combining with the configuration coordinate model. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)