透明SiO2-Al2O3-CaO-CaF2 微晶玻璃中Tb3+的发光性能研究

通过对1.0 mol;Tb2O3掺杂45SiO2-20Al2O3-10CaO-25CaF2玻璃进行热处理制备出透明微晶玻璃,经XRD分析微晶玻璃内析出了大小约为27 nm 的CaF2颗粒.并分别在紫外和X射线激发下研究了Tb3+在基质玻璃和透明微晶玻璃中的发光行为.结果表明:微晶玻璃中CaF2纳米晶颗粒的析出有利于提高Tb3+的发光性能,紫外激发时,Tb3+的545 nm特征发光强度增强了4倍;而X射线激发时,Tb3+的545 nm特征发光强度增加了3.5倍.     

Eu3+掺杂ZnAl2O4/SiO2微晶玻璃制备与发光性能

采用溶胶-凝胶法制备Eu3+掺杂的Zn Al2O4/Si O2(ZAS)块状透明微晶玻璃发光材料。利用X射线衍射(XRD),透射电子显微镜(TEM)和荧光光谱(PL)等测试手段,系统研究了不同Eu3+掺杂浓度对ZAS发光性能的影响以及不同热处理温度对ZAS∶Eu3+发光性能的影响。结果表明,ZAS∶Eu3+在611 nm处具有强烈的红光发射峰,发射强度随着Eu3+掺杂浓度的增加,出现浓度淬灭效应,当掺杂量为20mol%时,发光强度最大;随着热处理温度的升高,存在高温淬灭效应,当热处理温度为900℃时,材料发光强度最优。CIE色度图分析表明,ZAS∶0.20Eu3+是一种潜在、优良的红光显示微晶玻璃材料。     

高热膨胀Na2O-MgO-Al2O3-SiO2微晶玻璃的制备及性能研究

采用传统熔体冷却法制备了Na2O-MgO-Al2 O3-SiO2玻璃并采用整体析晶工艺制备了微晶玻璃.利用DSC、XRD、SEM等测试手段研究了微晶玻璃的析晶行为和显微结构,探讨了热处理制度对该体系微晶玻璃热膨胀系数、密度、抗弯强度、显微硬度等性能的影响.研究结果表明,当晶化温度为800℃时该体系微晶玻璃主晶相为颗粒状霞石晶体(NaAlSiO4);当晶化温度达到900℃时玻璃中开始析出镁橄榄石(Mg2SiO4)晶体;延长保温时间可显著促进析晶但对晶体种类没有影响.析晶后微晶玻璃的密度、热膨胀系数、抗弯强度和显微硬度值显著增加,其最高热膨胀系数可达14.1×10-6℃-1.所制备的微晶玻璃具有很好的机械性能,当热处理温度为1000℃时,其抗弯强度和显微硬度分别达160 MPa和7.8 GPa.     

Er3+/Ni2+共掺双相微晶玻璃的结构与发光性能研究

采用熔融法制备了Er3+/Ni2+共掺含GdF3与Ga2O3双晶化相透明微晶玻璃.X射线粉末衍射(XRD)和透射电子显微(TEM)分析表明,平均粒径为34 nm的六方相GdF3和9 nm的立方相Ga2O3晶粒在玻璃基体中均匀分布.吸收与荧光光谱结果显示,EF3+位于GdF3纳米晶,Ni2+选择性地进入Ga2O3纳米晶.受益于此,在976 nm激光激发下,透明微晶玻璃具有覆盖1050 ～ 1600 nm波段的宽近红外发射带,由位于1210 nm的Ni2+∶3T2(F)→3A2(F)跃迁转变和位于1530 nm的Er3+∶4I13/2→4I15/2跃迁转变组成.     

Er3+/Yb3+共掺铌硅酸盐透明玻璃陶瓷的制备及表征

采用熔融晶化法制备了主晶相为CaNb2O6的Er3+/Yb3+共掺透明铌硅酸盐玻璃陶瓷,利用DSC、XRD、SEM、UV-Vis-NIR和荧光光谱仪分别对样品的热处理制度、析出的晶相、微观形貌、光透过率和发光性能进行了测试和表征.研究表明:该体系玻璃最佳晶化温度为800℃,最佳热处理时间为2h;制得的玻璃陶瓷在可见光区的透过率可达70;;并讨论了不同Er3 +/Yb3+掺杂浓度对玻璃陶瓷样品发光性能的影响,发现当yb3+/Er3+掺杂浓度比为10∶1时发光强度为最大.     

Na2 O-B2O3-SiO2-CaO-P2O5-F生物微晶玻璃制备与性能研究

采用烧结法,选用Na2O-B2O3-SiO2为基础玻璃(NBS),按照氟磷灰石组成配比添加CaO,P2O5,CaF2三种组分,制备Na2O-B2O3-SiO2-CaO-P2O5-CaF2生物微晶玻璃.利用差热分析、X射线衍射分析及扫描电镜等测试手段对微晶玻璃物相、微观结构进行了测试和分析,并采用模拟体液对样品的生物活性进行了验证.结果表明:随着热处理温度升高,样品的晶化程度逐步提高,当热处理温度在750℃时,可以获得主晶相为氟磷灰石,晶粒尺寸在100 nm左右、其晶化率≥80;的微晶玻璃样品,通过模拟体液浸泡实验证明了样品具有一定的生物活性.     

SiO2@Gd2O3∶Tb3+核壳微球的可控合成及发光性能研究

采用简便的尿素辅助沉淀法将Gd2O3∶Tb3+成功包覆在二氧化硅微球表面合成了尺寸均匀的球形SiO2@Gd2O3∶Tb3核壳发光材料,解决了稀土发光材料普遍存在的形貌可控性差和颗粒尺寸不均一等问题.利用XRD、SEM、红外光谱和荧光光谱等表征测试了样品的形貌、结构和发光性能.SEM照片和尺寸分布图显示,SiO2@Gd2O3∶Tb3+粒子呈现均匀球形形貌,分散性良好,粒径约(608 +18) nm.XRD图谱分析表明,600℃煅烧后,壳层Gd(OH)3CO3完全转变为立方相Gd2O3,结晶性良好,无杂相生成.同时,结合红外光谱推测了SiO2@Gd2O3∶Tb3核壳微球的形成机理,并得出Gd2O3∶Tb3+壳层主要以Si-O-Gd键形式连接在二氧化硅微球表面.在240 nm紫外光激发下,SiO2@Gd2O3∶Tb3核壳微球呈现绿光发射,其中,位于540 nm处的主峰归属于Tb3+的5D4→7F5能级跃迁.不同Tb3掺杂浓度下的发射光谱表明,当Tb3+掺杂浓度为4mol;时,SiO2@Gd2O3∶Tb3+核壳微球的发射强度达到最大值,寿命为1.55 ms,色坐标位于绿色区域,展现了良好的绿光发光性能.     

煅烧温度对络合溶胶-凝胶法制备ZnGa2O4微晶形貌及光催化性能的影响

采用EDTA络合溶胶-凝胶法制备了尖晶石结构的ZnGa2O4微晶.通过XRD、SEM等分析方法对ZnGa2O4微晶进行了测试和表征.研究了不同煅烧温度对其物相组成、显微结构及光催化性能的影响.结果表明,以乙酸锌和氧化镓为反应原料,以乙二胺四乙酸为络合剂,在650～800℃能合成单一物相的ZnGa2O4微晶.在700℃时可以成功制备八面体形的ZnGa2O4微晶,在800℃时可以合成棒状的ZnGa2O4微晶;随着温度从650～800℃逐渐升高,其对罗丹明B的光催化降解性能逐渐提高.     

Tb3+-Eu3+共掺杂2ZnO·2.2B2O3·3H2O的制备和发光性能

采用水热法合成了Tb3+和Eu3+共掺的2ZnO.2.2B2O3.3H2O红色荧光粉。通过固定Eu3+的掺杂浓度为3%(物质的量比:Eu∶Zn=3%),改变Tb3+的掺杂浓度(2%～15%),研究Tb3+掺杂浓度对红色荧光粉晶相结构和光学性能的影响。用X射线衍射和荧光光谱仪对样品的结构和发光性能进行表征,结果表明:随着Tb3+掺杂浓度的升高,样品由晶态向无定形的玻璃态转变;Eu3+的发光强度也逐渐增强;Tb3+与Eu3+之间存在能量传递的过程,且当采用不同的激发波长(220 nm和393 nm)激发时,其能量传递的过程也不一样。     

烧结法制备高炉渣CMAS系统微晶玻璃的研究

利用高炉渣及其它辅助原料制备基础玻璃,采用一步烧结法制备主晶相为辉石的CaO-MgO-Al2O3-SiO2(CMAS)微晶玻璃.综合运用DSC,XRD以及场发射扫描电子显微镜等测试手段,分析热处理制度对高炉渣CMAS微晶玻璃的析晶行为及性能的影响.结果表明:随着热处理温度上升,微晶玻璃的主晶相均为辉石,次晶相均为长石,晶相析出量增加,微晶玻璃的体积密度及抗折强度均呈现先增后减趋势.随着热处理时间增加,微晶玻璃的体积密度及抗折强度均呈现下降趋势.当热处理温度为1020 ℃,晶化时间30 min时,样品的机械性能最好,体积密度为2.690 g·cm-3,抗折强度为67.00 MPa.     

Time-resolved fluorescence measurements on Dy3+ and Sm3+ doped glasses

Various fluoride, phosphate and borosilicate glasses with known properties and global structure have been doped with Dy³⁺ (4f⁹) and Sm³⁺ (4f⁵) between 10¹⁸ and 10²¹ cm^?3 and their time resolved fluorescence in the visible range in combination with characteristic physical properties were studied. Different fit procedures were carried out. Although both ions differ in their intrinsic fluorescence lifetime, with 1.5 ms for Dy³⁺ and 6.5 ms for Sm³⁺, their dependence on glass matrix is remarkable similar. Fluoroaluminate glasses with varying phosphate content between 0 and 20 mol% (FPx), a pure phosphate glass (P100), and two borosilicate glasses with low (DURAN^®-like) and high optical basicity (NBS1) were used for investigations. A strongly ionic surrounding by fluorine ligands, as in fluoroaluminate glass samples, provides the longest fluorescence lifetime. It decreases with increasing phosphate content by increasing oxygen surrounding and with increasing RE³⁺ doping. Large differences were detected in the two borosilicate glasses depending on their optical basicity mainly due to differences in the Na₂O/B₂O₃ ratio. Duran-like samples with low Na₂O content have shown phase separation with higher doping concentration. The RE³⁺ ions are accumulated in the borate-rich droplets. Surprisingly only very low concentration-quenching effects were observed. In the opposite of NBS1 samples with high Na₂O content this generated extremely high quenching effect.     

Energy transfer in Eu3+-Yb3+ and Tb3+-Yb3+ system in glasses

The behavior of the phonon-assisted energy transfer between trivalent rare-earth ions in glasses was investigated. The ions Eu³⁺ and Tb³⁺ as energy donors and Yb³⁺ as acceptor were selected. The energy gap between the levels of the donor and acceptor was estimated on the basis of the energy diagram of each ion determined from absorption and emission spectra. The probability for the transfers of (Eu, ⁵D₀-⁷F₆): (Yb, ${}^2\text{F}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{-}{}^2\text{F}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$) and (Tb, ⁵D₄-⁷F₀): (Yb, ${}^2\text{F}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{-}{}^2\text{F}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$) in silicate, borosilicate, phosphate and germanate glasses was measured in the temperature range of liquid-nitrogen temperature - 650K. The probability of transfer was the smallest in phosphate glass and B₂O₃ had the effect of increasing it. In germanate glass the dependence of the probability of the energy gap was relatively weak. These results were correlated to the difference in the phonon energy and the strength of the electron-lattice coupling in each glass.     

Energy transfer between Tm3+ and Er3+ in borate and phosphate glasses

A study of the energy transfer process between thulium and erbium is presented. From our measurements of fluorescence emissions and decay times the energy transfer efficiencies and probabilities were calculated. In this work the energy transfer which occurs between the upper levels in the UV and VIS regions of the two ions was especially studied. In the Tm-Er system, a mutual migration of energy occurs. The energy transfer from thulium to erbium is a multichannel process in which the energy is transferred from all the metastable levels of thulium to the matching energy levels of erbium. In addition, backtransfer of energy from erbium to thulium occurs by crossrelaxation of respective erbium transitions. The efficiency of energy transfer from thulium to erbium is independent of the levels between which the transfer occurs, but is dependent on the matrix. It is concluded that the energy is transferred via the phonons of the host glass.     

Gd3+/Eu3+掺杂羟基磷灰石的自燃烧法制备与性能研究

以尿素为燃料,采用自燃烧法制备Gd3 +/Eu3+掺杂羟基磷灰石(HAp∶ Gd-Eu),并用X射线衍射仪、扫描电子显微镜、荧光分光光度计和振动磁强计等对所得样品进行表征.结果表明,自燃烧法获得的产物由不规则形貌和长条状的颗粒组成,平均粒径为216.2 nm.HAp∶ Gd-Eu在紫外光(255 nm)和可见光(464 nm)激发下,具有较强的红光发射.Gd3掺杂摩尔分数X(Gd3+)为5;,Eu3+掺杂摩尔分数X(Eu3+)为2;时,Gd3+敏化Eu3+发光,HAp∶Gd-Eu发光强度最大.增大X(Gd3+)为10;,由于浓度淬灭,Eu3+发光强度减小.HAp∶ Gd-Eu发光强度随引燃温度升高,逐渐增大.HAp∶ Gd-Eu具有一定的磁响应性.     

Visible up-conversion photoluminescence from IR diode-pumped SiO2–TiO2 nano-composite films heavily doped with Er3+–Yb3+ and Nd3+–Yb3+

Efficient infrared-to-visible conversion is reported in thin film nano-composites, with composition 90% SiO₂–10% TiO₂, fabricated by a spin-coating sol–gel route and co-doped with Er³⁺ Yb³⁺ and with Nd³⁺:Yb³⁺ ions. The conversion process is observed under 808 nm laser diode excitation and results in the generation of green (526 and 550 nm) and red (650 nm) emissions: from the former, and blue (478 nm) and green (513 and 580 nm) emissions from the latter. The main mechanism that allows for up-conversion is ascribed to energy transfer among Er³⁺ and Yb³⁺ ions in their excited states. Up-conversion efficiency for red emission predominates in samples doped with Er³⁺:Yb³. The results illustrate the large potential of this class of materials for photonic applications in optoelectronics devices.     

Tb3+,Yb3+共掺杂LuBO3荧光粉的下转换发光

利用水热法成功合成了近红外量子剪裁荧光粉LuBO3∶15;Tb3+,x; Yb3+(x=0,1,2,4,8,12).通过X射线衍射(XRD)、光致发光谱(PL)、激发谱(PLE)和荧光寿命测试了合成物质的物相结构与发光性质.在286 nm(Tb3+∶7 F6→5D)紫外光激发下,观察到了Tb3∶5D4→7Fj(J=6,5,4,3)可见波段特征发射光和Yb3+:2F5/2→2F7/2的近红外光.研究了Yb3+浓度与激发发射光谱和荧光寿命之间的关系,表明Tb3+和Yb3+之间存在能量传递.当Tb3和Yb3+掺杂摩尔浓度分别为15;和2;时,近红外发射最强.计算得知,其最大下转换量子效率为160.74;.     

铒镱双掺的钒酸钇和铌酸锂晶体中的铒离子的上转换发光

利用J-O理论,计算了在铒、镱双掺的钒酸钇和铌酸锂晶体中的铒离子在室温下的晶场唯象参数Ωλ(λ=2,4,6)及辐射跃迁几率、无辐射跃迁几率和共振跃迁几率.考虑到铒、镱间的能量转移,写出了在这些晶体中的铒离子的速率方程.速率方程的解表明,在铒、镱双掺的钒酸钇晶体中的铒离子的550 nm的上转换发光,比它在铒、镱双掺的铌酸锂晶体中更为有效.这一理论结果与我们的实验观察结果一致.     

Na+,Dy3+,Eu3+掺杂YAG荧光粉的光学性能

本文用高温固相法制备了Na+,Dy3+,Eu3+掺杂YAG系列荧光粉.通过改变掺杂的Dy3+浓度、激发波长、掺杂Na+,研究其对发光的影响.X射线衍射结果显示,硼酸、Na+、Dy3+、Eu3+掺入基本不影响YAG的立方晶相,且随Na+、Dy3+、Eu3+浓度增加,样品衍射峰位置向小角度偏移.用λem=590 nm监测D...     

Upconversion luminescence in Ho3+/Yb3+- and Tb3+/Yb3+-codoped fluorogermanate glass and glass ceramic

Energy-transfer excited upconversion luminescence in Ho³⁺/Yb³⁺- and Tb³⁺/Yb³⁺-codoped PbGeO₃–PbF₂–CdF₂ glass and glass–ceramic under infrared excitation is investigated. In Ho³⁺/Yb³⁺-codoped samples, green (545 nm), red (652 nm), and near-infrared (754 nm) upconversion emission corresponding to the ⁵S₂(⁵F₄) → ⁵I₈, ⁵F₅ → ⁵I₈, and ⁵S₂(⁵F₄) → ⁵I₇ transitions, respectively, was observed. Blue (490 nm) emission assigned to the ⁵F_2,3 → ⁵I₈ transition was also detected. In the Tb³⁺/Yb³⁺-codoped system, bright UV–visible emission around 384, 415, 438, 473–490, 545, 587, and 623 nm, identified as due to the ⁵D₃(⁵G₆) → ⁷F_J(J = 6, 5, 4) and ⁵D₄ → ⁷F_J(J = 6, 5, 4, 3) transitions, was measured. The comparison of the upconversion process in glass ceramic and its glassy precursor revealed that the former samples present much higher upconversion efficiencies. The dependence of the upconversion emission upon pump power, and doping contents was also examined. The results indicated that successive energy-transfer between ytterbium and holmium ions and cooperative energy-transfer between ytterbium and terbium ions followed by excited-state absorption are the dominant upconversion excitation mechanisms herein involved. The viability of using the samples for three-dimensional solid-state color displays is also discussed.     

Optical properties of Er3+-singly doped and Er3+/Yb3+-codoped novel oxyfluoride glasses

Novel oxyfluoride glasses SiO₂–Al₂O₃–Na₂O–ZnF₂ doped with Er³⁺ and Er³⁺/Yb³⁺ were fabricated. The optical properties of the synthesized glasses were experimentally and theoretically investigated in detail. The experimental and calculated oscillator strengths of Er³⁺ were determined by measurement of the absorption spectrum of Er³⁺-singly doped glass. According to the Judd–Ofelt theory, the experimental intensity parameters were calculated, from which the radiative transition probabilities, fluorescence branching ratios and radiative lifetimes were obtained. The fluorescence lifetime and quantum efficiency for the near-infrared emission of Er³⁺-singly doped glass were determined to be 3.0 ms, and 42%, respectively. Visible upconversion luminescence was observed under 980 nm diode laser excitation. The dependence of the upconversion emission intensity upon the excitation power was examined, and the upconversion mechanisms are discussed.