Yb掺杂Ca_(1-x)R_xF_(2+x)(R=La,Gd)激光晶体的结构与光谱性能参数的研究

采用坩埚下降法生长了两个系列晶体3at%Yb:Ca_(1-x)R_xF_(2+x)(R=La,Gd;x=0,0.01,0.03,0.06,0.09),测试了晶体的XRD、拉曼光谱、吸收光谱、荧光光谱、荧光寿命。系统地研究了调剂离子La~(3+)、Gd~(3+)对Yb:CaF_2晶体晶格常数、拉曼光谱和光谱性能的影响规律,分析讨论了Yb~(3+)离子的结构与光谱性能之间的关系。研究结果表明,随着La~(3+)、Gd~(3+)掺杂浓度增加,晶体的晶格常数和拉曼半高宽都逐渐增大,这说明晶体膨胀和晶格振动模式种类增多。在3at%Yb:Ca_(1-x)La_xF_(2+x)晶体中,当调剂离子La~(3+)掺杂浓度为6at%时,具有最大吸收截面0.71×10-20 cm~2,荧光强度也最大;而在3at%Yb:Ca_(1-x)Gd_xF_(2+x)晶体中,当调剂离子Gd~(3+)掺杂浓度为3at%时,荧光强度最大,Gd~(3+)掺杂浓度为6at%时,具有最大吸收截面0.64×10~(-20) cm~2。共掺晶体相比于单掺3at%Yb:CaF_2晶体有更好的光谱参数。综上可知,通过调节La~(3+)、Gd~(3+)离子浓度,可以改变Yb~(3+)离子的结构,优化晶体的光谱性能。     

0.6%Pr,x%La:CaF2的发光性能研究和Judd-Ofelt分析(英文)

氟化钙(CaF₂)是一种良好的激光材料基质,具有较宽的透过范围(0.125～10μm)、良好的导热性(9.71W/(m·K))和低非线性效应系数。在Pr:CaF₂晶体中,[Pr³⁺-Pr³⁺]团簇导致Pr³⁺离子在较低浓度下出现荧光猝灭现象。在CaF₂中共掺入La³⁺离子有可能打破[Pr³⁺-Pr³⁺]团簇。本研究通过温度梯度法(Temperature Gradient Technique, TGT),成功地生长了一系列共掺入不同浓度La³⁺离子的Pr:CaF₂晶体。在室温下采用X射线粉末衍射、吸收光谱、荧光光谱和荧光衰减寿命对Pr,La:CaF₂晶体进行表征。Pr:CaF₂晶体共掺入La³⁺离子后仍具有立方晶体结构。³P₀→^3<...     

Cr,Yb:YAG晶体的光谱性质

采用提拉法生长了原子分数为10％的Yb和不同掺杂浓度Cr的Cr,Yb:YAG激光晶体.测试了室温下晶体的吸收光谱、荧光光谱和荧光寿命.随着晶体中Cr离子掺杂浓度的增加,晶体在1.03μm处的吸收系数增大、荧光强度和荧光寿命下降,同时Yb³⁺→Cr⁴⁺能量转移效率增加、量子效率降低.确定了Cr,Yb:YAG晶体中Cr的最佳浓度值.     

不同掺杂对Ba3Y(BO3)3晶体的生长和相变的影响

结合X射线粉末衍射和差示扫描量热法,系统研究了不同格位上的掺杂对Ba₃Y(BO₃)₃晶体的生长和相变的影响. 研究发现,相同掺杂浓度10at%时,掺Nd³⁺的α-Ba₃Y(BO₃)₃晶体的相变温度（1099.6℃）比掺Yb³⁺的晶体的相变温度（1145.3℃）低;且随着掺Nd³⁺浓度的降低,晶体的相变温度升高,晶体在降温过程中更容易发生相变. 在晶体中掺入Sr²⁺离子,可以有效提高Yb³⁺∶α-Ba₃Y(BO₃)₃晶体的稳定性. 随着Sr²⁺掺入浓度的增加,晶体的熔点升高,相变温度降低. 当Sr²⁺掺杂浓度为16at%时,晶体的相变峰消失;当Sr²⁺掺杂浓度分别为5at%、10at%时,晶体仍然发生相变.     

Eu2+和Dy3+掺杂浓度对Sr2MgSi2O7材料的荧光和长余辉性能的影响

采用高温固相法制备得到Sr₂MgSi₂O₇: Eu²⁺和Sr₂MgSi₂O₇: Eu²⁺, Dy³⁺发光粉, 并详细研究了Eu²⁺和Dy³⁺的掺杂浓度对Sr₂MgSi₂O₇材料的荧光和长余辉性能的影响。所有样品都在470 nm附近呈现较宽的发光峰, 这可归因于Eu²⁺离子的4f⁶5d→4f⁷电子能级跃迁。当Eu²⁺掺杂浓度超过淬灭浓度, 其浓度淬灭效应导致发光粉的荧光强度下降和余辉时间减短。同时, 发射峰的峰位随Eu²⁺浓度的增加而发生红移, 这主要由于晶体场分裂能和斯托克斯位移变化造成的, 而电子云扩大效应变化所产生的影响相对较弱。Dy³⁺离子会抑制荧光, 但有助于延长余辉时间。当其掺杂浓度超过10mol%时, Eu²⁺\Dy³⁺离子通过隧道复合机制发生浓度淬灭, 从而使材料的长余辉寿命减少。     

Nd3+:Lu2O3放电等离子烧结及光学性能

Lu₂O₃是具有高热导率而成为极具潜力的高功率激光介质材料。实验以商用氧化物粉体为原料, LiF为烧结助剂, 采用放电等离子烧结法制备了不同Nd³⁺掺杂浓度(C_Nd=0, 1at%, 3at%和5at%) Lu₂O₃透明陶瓷, 并研究了Nd³⁺掺杂浓度对Lu₂O₃陶瓷的物相、烧结性能、微观结构及光学性能的影响。结果表明：在高Nd³⁺浓度(5at%)掺杂后烧结样品仍为纯Lu₂O₃相;Nd³⁺掺杂对Lu₂O₃陶瓷烧结性能及微观形貌的影响有限;所有样品最终均表现出高致密性(99.5%以上)和优异的透光性能, 其中3at% Nd³⁺:Lu₂O₃的透过率最高, 在1064和2000 nm处的透过率分别为82.7和83.2%。Nd³⁺:Lu₂O₃透明陶瓷的最强发射峰位于1076和1080 nm;且随着Nd³⁺掺杂浓度的增加, 荧光强度降低, 寿命变短, 发生浓度淬灭。     

MF2(M=Mg,Ca,Zn,Sr,Ba)对掺Yb3+磷酸盐玻璃性质的影响

熔制了60P₂O₅·6Al₂O₃·(33-x)BaO·xBaF₂·1Yb₂O₃(x=0,3,6,9)和60P₂O₅·6Al₂O₃·27BaO·6MF₂·1Yb₂O₃(M=Mg、Ca、Sr、Zn、Ba)(分子分数)玻璃,测试了其折射率、密度、转变温度、析晶温度、熔点温度、红外光谱和紫外吸收光谱,讨论了二价氟化物MF₂(M=Mg、Ca、Sr、Zn、Ba)对磷酸盐玻璃热稳定性及内部结构的影响,测试了Yb³⁺离子的吸收光谱、荧光光谱、荧光寿命,计算了光谱参数,讨论了MF₂对Yb³⁺磷酸盐玻璃光谱性质的影响,结果表明二价金属氟化物是作为网络外体进入到磷酸盐玻璃结构中,并没有改变磷酸盐玻璃内部的[PO₄]链状结构,二价金属氟化物还有助于提高Yb³⁺离子的受激发射截面,和自发辐射几率,荧光半高宽。     

Ce3+掺杂Li2O-MgO-Al2O3-SiO2玻璃的结构与荧光猝灭现象

采用熔融淬冷法制备了不同浓度Ce³⁺离子掺杂的20Li₂O-5MgO-20Al₂O₃-55SiO₂玻璃闪烁材料。采用X射线衍射(XRD)、高分辨透射电镜(HRTEM)技术、密度检测等方法研究了玻璃的微观结构随Ce³⁺离子掺杂浓度的变化规律, 采用荧光分光技术检测了玻璃的紫外光致激发光谱(PLE)、发射光谱(PE)。研究结果表明: 在不对称的晶体场作用下, Ce³⁺离子5d能级被劈裂为5个组分; 随着玻璃基质内Ce³⁺离子掺杂浓度增大, 玻璃的非晶化程度加深; 5d能级的劈裂宽度随之增大, 由此导致激发带向低能量端展宽、发射光谱明显红移; Ce³⁺离子的荧光发射强度随Ce³⁺离子掺杂浓度先升高、后降低, 浓度猝灭过程成为其荧光发射效率降低的主要原因。     

Ce掺杂SrMgF4超结构多晶体的吸收/光致发光光谱

稀土(RE)离子掺杂的钙钛矿型氟化物是可调谐光学材料的候选材料。本工作通过沉淀法合成了SrMgF₄: xCe (x = 0, 0.007, 0.013和0.035)粉末。X射线衍射(XRD)分析表明所获得的荧光粉具有单斜超结构, 价态分析证实存在Ce³⁺/Ce⁴⁺混合价, 在紫外光区通过不同波长的激发光观察到两个荧光带B和C。当Ce³⁺多面体的对称性从高对称变为低对称时, 源于单斜超结构的晶体场导致能级发生强烈的改变。     

新型双钙钛矿Ca2GdSbO6:Sm3+橙红色荧光粉的制备及其发光性能

用高温固相法合成一种新型系列橙红色荧光粉Ca₂Gd_1-xSbO₆:x Sm³⁺(x=0、0.01、0.02、0.03、0.04、0.05、0.06),使用X射线衍射(XRD)、扫描电子显微镜(SEM)、光致发光(PL)光谱、高温荧光光谱和荧光衰减寿命等手段表征其物相结构、晶体结构、化学纯度和光学性质,研究了材料的发光性能。结果表明,这种荧光粉基于Sm³⁺在597 nm处的⁴G_5/2→⁶H_7/2跃迁,引入Sm³⁺作为发光中心在407 nm激发下可发出波长为597 nm的橙红光。随着Sm³⁺离子浓度的提高Ca₂GdSbO₆:Sm³⁺荧光粉的发光强度先提高后降低。根据Dexter理论,其浓度猝灭是电偶极-电偶极相互作用主导的,Sm³⁺离子的最佳掺杂浓度为x=0.03。...     

Optical properties and laser performance of neodymium doped fluoroapatites SrxCa5−x(PO4)3F (x = 0, 1, 2, 3, 4, and 5)

Nd doped fluoroapatites Sr_xCa_5−x(PO₄)₃F(S_xC_5−xPF, X = 0, 1, 2, 3, 4, and 5) single crystals have been grown by the Czochralski technique. Their polarized absorption and emission spectra have been recorded at room temperature and used to calculate the absorption and stimulated emission cross sections. Broadening of the absorption and emission bands is observed for Nd³⁺ in the solid solutions SPF-CPF compared to Nd³⁺ in CPF or SPF. 1% Nd:S_xC_5−xPF, X = 0, 2, 3, 4, and 5, laser rods have been tested in a cavity longitudinally pumped by a 1 W AlGaAs laser diode and compared to Nd:YAG and Nd:YVO₄ rods. All fluoroapatites exhibit very good laser performance with low thresholds and high slope efficiencies, higher than in the case of YAG and equal to the YVO₄ samples. The dependance of the laser output power versus the diode temperature has also been measured for all materials. The laser output was found to be as sensitive to the diode temperature fluctuations for fluoroapatites as for YAG.     

Yb to Er energy transfer and rate-equations formalism in the eye safe laser material Yb:Er:Ca2Al2SiO7

Rate equations formalism is used to predict the population ratio of the Er^{3+ 4}I_13/2 levels involved in the 1.55 μm laser transition in the Yb:Er:CAS laser materials. An effective Yb → Er energy transfer, favourable to the Er³⁺ 1.55 μm laser emission, is demonstrated in this laser host. Indeed, the Yb → Er transfer and the Er → Yb back transfer rates are calculated to be 6 x 10⁻¹⁶ and 0.45 x 10⁻¹⁶ cm³ s⁻¹, respectively. Attempts of codoping the system with Nd³⁺, Eu³⁺ and Ce³⁺ have been realised in order to increase the population of the Er^{3+ 4}I_13/2 laser emitting level. Best results are obtained with Ce³⁺ ion since in the sample containing 6 x 10²⁰ Ce³⁺/cm³, the Er^{3+ 4}I_11/2 level lifetime is divided by a factor of 3 while the Er^{3+ 4}I_13/2 fluorescence lifetime remains unaffected. On the contrary, codoping with Nd³⁺ or Eu³⁺ ions simultaneously decreases the Er^{3+ 4}I_11/2 and ⁴I_13/2 kinetics parameters. The role of the other parameters such as Yb/Er concentrations ratios is also discussed.     

Effects of growth conditions on the domain structure and dielectric properties of (1 − x)Pb(Sc1/2Nb1/2)O3–xPbTiO3 single crystals

The studies of the (1 − x)Pb(Sc_1/2Nb_1/2)O₃–xPbTiO₃ (PSN–PT) single crystals reveal that the chemical and physical properties of the materials are affected by the growth conditions. By the measurements of the dielectric constant as a function of temperature upon cooling, it is found that crystals grown from the same charged stoichiometric composition (x = 0.425), but under different flux environments (i.e. the composition of flux and the flux to PSN–PT ratios are varied), show anomalies (i.e. phase transitions) at different temperatures. This phenomenon is attributed to the complex local chemical structure of the PSN–PT solid solution single crystals with B-site random occupancy of three different cations (Sc³⁺, Nb⁵⁺ and Ti⁴⁺). The dielectric and domain structure of the PSN–PT crystals with composition near the morphotropic phase boundary (MPB) are investigated, showing much more complex situations compared with Pb(Sc_1/2Nb_1/2)O₃.     

Crystal growth and spectral properties of pure and Co-doped Mg3B2O6 crystal

Novel pure and cobalt-doped magnesium borate crystals (Mg₃B₂O₆) have been grown successfully by the Czochralski technique for the first time. Crystal growth, X-ray powder diffraction (XRD) analysis, absorption spectrum, fluorescence spectrum as well as fluorescence decay curve of Co²⁺:Mg₃B₂O₆ (MBO) were described. From the absorption peaks for the octahedral Co²⁺ ions, the crystal-field parameter Dq and the Racah parameter B were estimated to be 943.3 cm⁻¹ and 821.6 cm⁻¹, respectively. The fluorescence lifetime of the transition ⁴T₁(⁴P) → ⁴T₂ centered at 717 nm was measured to be 9.68 ms.     

Temperature dependent luminescence in (Eu, Dy) doped tellurite glass

This short paper reports both the photoluminescence and the lifetime measurements of a prominent emission transition (⁵D₀→⁷F₂) of Eu³⁺ both in the presence and absence of the codopant rare earth ion (Dy³⁺) in an optical glass of the composition (79−x)TeO₂+6AlF₃+15LiF+xLn₂O₃ as a function of temperature down to 10 K.     

Spectroscopic analysis and the effects of color centers on the laser performance of Nd: CaZn2Y2Ge3O12

Spectroscopic and EPR investigations of Nd³⁺-doped CaZn₂Y₂Ge₃O₁₂ (CAZGAR) have been performed. The absorption, fluorescence, excitation spectra and fluorescence lifetime have been measured at room temperature. The Judd-Ofelt theory has been applied to the measured optical absorption intensities to predict the radiative decay rates, branching ratios, and peak stimulated emission cross section from the metastable ⁴F_3/2 state to the ⁴I_9/2 manifold. The fluorescence lifetime of the ⁴F_3/2 level of Nd³⁺ at low concentration in this host was measured to be 285 ± 10 μs, which is longer than that for Nd³⁺: YAG. Color centers located at zinc octahedral sites have been produced in these crystals by ultraviolet irradiation and have been detected by EPR techniques. The effects of the color centers on the potential laser characteristics of this materials are discussed.     

Preparation and optical properties of sol–gel derived Er-doped Al2O3–Ta2O5 films

Thin films of the system xAl₂O₃–(100 − x)Ta₂O₅–1Er₂O₃ were prepared by a sol–gel method and a dip-coating technique. The influences of the composition and the crystallization of the films on Er³⁺ optical properties were investigated. Results of X-ray diffraction indicated that the crystallization temperature of Ta₂O₅ increased from 800 to 1000 °C with increased values of x. In crystallized films, the intensities of the visible fluorescence and upconversion fluorescence tend to decrease with an increase in x values, due to the high phonon energy of Al₂O₃; the strongest fluorescence is observed in a crystallized film for x = 4 heat treated at 1000 °C. In amorphous films obtained by heat treatment at relatively low temperatures the Er³⁺ fluorescence could not be observed because strong fluorescence from organic residues remaining in the films thoroughly covered the Er³⁺ fluorescence. On the other hand, the Er³⁺ upconversion fluorescence in the amorphous films was observed to be stronger than that in the crystallized films. The strongest upconversion fluorescence is observed in an amorphous film for x = 75 heat treated at 800 °C.     

Evaluation of the capabilities of several ions to sensitize Nd in the laser material LNA (La0.9Nd0.1MgAl11O19)

In the hexaaluminate laser material La_0.9Nd_0.1MgAl₁₁O₁₉ also known as LMA:Nd the Nd³⁺ fluorescence can be enhanced by codoping the matrix with rare-earth (REⁿ⁺) or transition metal (TM^m+) ions. A large number of potential donor ions D (D = Mn²⁺, Dy³⁺, Tb³⁺, Eu²⁺, Eu³⁺ and Ti³⁺) are studied in the hexaaluminate host. The D→Nd³⁺ energy transfer, t he, luminescent efficiency as well as the back-transfer strongly depend on the overlap of the D emission and Nd³⁺ absorption, the concentration of the two ions and their localization in the crystal host. In this paper the optical properties — absorption and emission — of the D and Nd³⁺ ions as well as the D→Nd³⁺ interactions are considered using a Forster-Dexter's approach, to compare the capabilities of the different donors in the Nd³⁺-doped hexaaluminate host. The C_DNd and R₀ parameters are estimated in each case, and the results discussed in terms of the localization of the donor ions, their absorption and emission as well as their lifetime properties.     

紫外光激发Ce3+掺YVO4蓝光发射性能研究

利用提拉法生长了YVO₄和掺2.0at% CeO₂(或Ce₂(CO₃)₃)的YVO₄: Ce³⁺晶体。样品的XRD测试表明Ce³⁺代替Y³⁺进入晶格, Ce³⁺的加入并没有影响YVO₄的晶格结构。XPS测试显示YVO₄: Ce³⁺晶体中Ce离子3d分裂为882.0、885.8、902.9、908.0和915.9 eV等5个峰, 峰位表明样品中铈离子是以Ce³⁺和Ce⁴⁺两种价态形式存在。YVO₄和YVO₄: Ce³⁺激发谱都呈现出260~360 nm宽带激发, 此激发带源于基质中VO₄^3-离子团的配体O到V的电荷迁移吸收。使用325 nm的紫外线激发时, 两种样品均可发出以440 nm 为中心的宽带蓝光,其中YVO₄发射峰应归属于VO₄^3-离子团中³T₂→¹A₁和³T₁→¹A₁跃迁; 而YVO₄: Ce³⁺的蓝光发射则来源于Ce³⁺的5d→4f 的跃迁。分析可知YVO₄: Ce³⁺中VO₄^3-的π轨道和Ce³⁺的电子波函数能有效地重叠, 使得VO₄^3-和Ce³⁺可通过交换作用有效地向Ce³⁺传递能量, 可大幅提高Ce³⁺的蓝光发射强度。实验结果显示YVO₄: Ce³⁺可作为UV-LED管芯激发的白光发光二极管用高亮度蓝色发光材料。     

Sc3+和Ru4+联合取代BZN基陶瓷结构与介电性能的研究

采用传统的固相反应法制备致密的Bi_1.4Sc_0.1ZnNb_1.5-xRu_xO₇陶瓷样品, 研究Sc³⁺, Ru⁴⁺共同替代对Bi₂O₃-ZnO-Nb₂O₅陶瓷的相结构、晶体化学特性和介电性能的影响。结果表明: 当掺杂量x≤0.055 mol时, 样品保持单一的立方焦绿石结构。当掺杂量x=0.055 mol时, X射线衍射峰强度变弱, 峰形变宽。随着掺杂量的增加(0≤x≤0.04 mol), 陶瓷样品的晶格常数a和A位离子与第7个氧O′平均键长R_(A-O')逐渐减小, 结晶化学参数键价和AV(O')[A₄]增大, AV(O)[A₂B₂]减小, 48f(O)偏移量ξ增加。室温下样品的介电常数随着掺杂量的增加而减小, 介电损耗逐渐增加, 介电松弛特征减弱。低温下样品呈现明显的弛豫现象, 峰值温度T_m随着掺杂量的增加向高温方向移动。利用修正的Curie-Weiss(C-W)公式对样品ε_r-T曲线进行最小二乘法拟合, 得出样品的弛豫度γ由R0样品的1.57减小到R40样品的1.33。