Multicolour tunable luminescence of thermal-stable Ce3+/Tb3+/Eu3+-triactivated Ca3Gd(GaO)3(BO3)4 phosphors via Ce3+ → Tb3+ → Eu3+ energy transfer for near-UV WLEDs applications

A series of single-component blue, green and red phosphors have been fabricated based on the Ca₃Gd(GaO)₃(BO₃)₄ host through doping of the Ce³⁺/Tb³⁺/Eu³⁺ ions, and their crystal structure and photoluminescence properties have been discussed in detail. A terbium bridge model via Ce³⁺ → Tb³⁺ → Eu³⁺ energy transfer has been studied. The emission colours of the phosphors can be tuned from blue (0.1661, 0.0686) to green (0.3263, 0.4791) and eventually to red (0.5284, 0.4040) under a single 344 nm UV excitation as the result of the Ce³⁺ → Tb³⁺ → Eu³⁺ energy transfer. The energy transfer mechanisms of Ce³⁺ → Tb³⁺ and Tb³⁺ → Eu³⁺ were found to be dipole-dipole interactions. Importantly, Ca₃Gd(GaO)₃(BO₃)_4:Ce³⁺,Tb³⁺,Eu³⁺ phosphors had high internal quantum efficiency. Moreover, the study on the temperature-dependent emission spectra revealed that the Ca₃Gd(GaO)₃(BO₃)_4:Ce³⁺,Tb³⁺,Eu³⁺ phosphors possessed good thermal stability. The above results indicate that the phosphors can be applied into white light-emitting diodes as single-component multi-colour phosphors.     

Li2SrSiO4:Eu2+,Tb3+中Eu2+和Tb3+的发光特性和能量传递

用高温固相法在N2/H2=95/5(v/v)还原气氛下合成了Li2SrSiO4:Eu2+,Tb3+荧光粉发光材料,通过荧光光谱研究其发光特性,并从理论上探讨了Eu2+与Tb3+之间的能量转移类型。结果表明:该发光材料主发射峰值550nm,与Eu2+在4f7-4f65d1产生跃迁有关;通过掺杂,共存于Li2SrSiO4基质中的Tb3+通过电多级相互作用将能量传递给Eu2+;在500~650nm范围内对Eu2+具有很强的敏化作用,使其在主发射峰550nm的发射强度显著增强;当名义化学组成为Li2Sr0.995SiO4:0.005Eu2+,0.010Tb3+时,发光强度为最佳。     

Tb3+掺杂的Y2（C2O4）3-SiO2的结构和性质研究

利用溶胶-凝胶法和沉淀法相结合的方法以及高温焙烧法,制备了以Y2(C2O4)3-SiO2为基质掺杂稀土离子Tb3+掺杂的无机发光材料。TG-DTA、IR和荧光光谱研究了材料的结构和发光性质。TG-DTA谱图表明,400℃时材料中的水、乙醇及其它挥发性组分已除净,草酸钇开始分解。IR光谱显示,Si-O-Si、O-Si-O是发光材料的主要结构,并不随退火温度的升高而变化。激发光谱和发射光谱表明,在613nm监测波长下,测得最佳激发波长为273nm;最适pH为pH=4时;最佳退火温度为200℃。     

Sr0.5Zr2(PO4)3陶瓷的力学性能研究

用共沉淀法和低分子有机溶剂分散获得SZP粉体,经干压成型和烧结得到SZP陶瓷.研究了其力学性能与烧结温度烧结时间和添加剂用量的关系.最佳工艺条件为添加MgO6wt%,1300℃或ZnO3wt%,1200℃均烧结1.5小时,SZP陶瓷的抗压强度分别可达244.0MPa和226.2MPa.     

KCaM（PO4）2:Dy3+（M=La,Y,Lu）荧光粉的制备与发光性质

采用传统高温固相法制备了KCaM(PO4)2:Dy3+(M=La,Y,Lu)荧光粉。X射线衍射表明,KCaM(PO4)2:Dy3+(M=La,Y,Lu)荧光粉属于六方晶系,P6222空间点群;随着金属阳离子M离子半径的增大,衍射峰向小角度方向移动。低温下的KCaM(PO4)2:Dy3+(M=La,Y,Lu)荧光光谱表明:同一基质中Dy3+在不同波长光激发下,发射峰发生了改变。金属阳离子M在晶体中存在2种格位(发光中心),在不同金属阳离子M的基质中,用相同光激发时,发射光谱明显不同。金属阳离子M的改变引起周围晶体场的改变,从而改变2种格位在不同基质中所占有的比例。因此,可以把Dy3+作为探针来研究晶体结构的变化。     

Single-phase silicocarnotite synthesis in the subsystem Ca3(PO4)2–Ca2SiO4

In the last years, the addition of silicon to hydroxyapatite and tricalcium-phosphate materials is being widely studied, due to the well-known influence of silicon on bone formation. Silicocarnotite (Ca₅(PO₄)₂SiO₄) presents a structure type carnotite, very close to hydroxyapatite, with a wide range of Ca²⁺, SiO₄⁴⁻ and PO₄³⁻ solid solutions. These characteristics make silicocarnotite attractive as potential biomaterial.     

A2B2O7(A=Ln3+,B=Zr4+,Hf4+Ti4+Ce4+)型透明陶瓷研究进展

A₂B₂O₇型化合物具有高熔点、高密度和高折射率等特点,在照明材料、航空材料、医疗成像、磁光材料等领域具有潜在应用价值。随着陶瓷制备工艺的进步,透明陶瓷的光学、力学和热学等性能不断提升使A₂B₂O₇型透明陶瓷受到越来越多研究者的关注,本文介绍了一些A₂B₂O₇型透明陶瓷的制备工艺、性能参数和其潜在的应用价值。     

掺杂RE3+对CaAl2O4:Eu2+,Nd3+发光性能的影响

以燃烧法合成了CaAl2O4∶Eu2+,Nd3+,RE3+紫色长余辉发光材料。实验结果表明,掺杂辅助激活剂Pr3+和Ce3+对CaAl2O4∶Eu2+,Nd3+磷光体发光性能有明显影响。掺杂Pr3+的CaAl2O4∶Eu2+,Nd3+样品的发射峰蓝移;掺杂Ce3+的CaAl2O4∶Eu2+,Nd3+样品的发射峰红移。Pr3+或Ce3+掺杂,可以提高CaAl2O4∶Eu2+,Nd3+磷光体的初始亮度,Pr3+或Ce3+在其中起到增加陷阱密度,提高发光亮度的作用。     

Ba3Y1.9(BO3)4:0.1Sm3+荧光粉的制备及光谱性质的研究

采用高温固相法合成了Ba₃Y_1.9(BO₃)₄:0.1Sm³⁺橙色荧光粉,对其发光性质进行了研究。样品的X射线衍射(XRD)图谱表明制得的样品为纯相。样品的激发光谱由位于200～275 nm之间的宽峰和位于300～500 nm之间的一系列锐峰组成,其中宽峰归因于O^2-→Sm³⁺电荷迁移带跃迁,而锐峰则归因于Sm³⁺的f-f跃迁吸收。在紫外光、近紫外光和可见光激发下,Ba₃Y_1.9(BO₃)₄:0.1Sm³⁺在566 nm、602 nm和651 nm处有强发射峰,分别归因于Sm³⁺的⁴G_5/2→⁶H_J/2(J=5,7,9)特征发射。通过CIE色度图可知样品发光位于橙色区。研究结果表明Ba_3...     

低热固相反应法合成掺Eu3+的双磷酸盐KZnLa（PO4）2及其光致发光性能研究

在表面活性剂PEG-400的存在下,于室温下研磨ZnSO4.7H2O,La(NO3)2和K3PO4.3H2O的混合物,使其进行固态反应。研磨结束后,将反应混合物在60℃下保温4 h。用去离子水洗去混合物中的可溶性无机盐,在100℃下烘干,即得纳米晶KZnLa(PO4)2的前驱体。煅烧前驱体得到纳米晶KZnLa(PO4)2。前驱体和它的煅烧产物通过热重和微分热分析,傅立叶变换红外光谱和X-射线粉末衍射表征。结果表明,前驱体仅是结晶度低的化合物;前驱体在高于700℃下煅烧2 h,得到具有高结晶度的纳米晶KZnLa(PO4)2。以相同方法合成了KZnLa0.94Eu0.06(PO4)2,在900℃下煅烧2 h,得到的KZnLa0.94Eu0.06(PO4)2在紫外线照射下是一种发射红光的荧光粉。     

LiTi2（PO4）3表面包覆LiNi0.05Mn1.95O4及其性质

采用湿化学法在LiNi0.05Mn1.95O4表面包覆锂离子导体LiTi2(PO4)3。采用X射线衍射、扫描电子显微镜、恒电流充放电、电位阶跃、交流阻抗技术对合成产物进行物相、形貌和电化学分析。结果表明:LiTi2(PO4)3包覆LiNi0.05Mn1.95O4与未包覆LiNi0.05Mn1.95O4具有相似的X射线衍射结果,LiNi0.05Mn1.95O4包覆LiTi2(PO4)3前后的锂离子扩散系数变化不大,但包覆LiTi2(PO4)3后的LiNi0.05Mn1.95O4颗粒边界和轮廓变得模糊。LiTi2(PO4)3包覆LiNi0.05Mn1.95O4的比容量略低于未包覆LiNi0.05Mn1.95O4,且随着LiTi2(PO4)3包覆量的增加而减小,但包覆LiTi2(PO4)3后的LiNi0.05Mn1.95O4循环性能得到了大幅提高。     

Yb3+/Tm3+∶KLa（MoO4）2激光晶体的生长与光谱特性研究

采用顶部籽晶提拉法生长出了Yb3+/Tm3+∶KLa(MoO4)2双掺杂激光晶体,单晶体尺寸达到15 mm×27mm。测试并分析了室温下的吸收光谱,计算出了各跃迁能级对应的吸收截面。利用J-O理论计算出了Yb3+/Tm3+∶KLa(MoO4)2中Tm3+掺杂离子的J-O强度参数。     

白光LED用蓝色荧光粉Sr10（PO4）6Cl2:Eu2+合成及其光谱特性

本文采用传统的高温固相法合成白光LED用Sr10(PO4)6Cl2:Eu2+蓝色荧光粉,利用X-射线粉末衍射和荧光光谱进行表征。实验结果表明,在紫外近紫外区(200～400 nm)激发下荧光粉发射光谱主峰位于447 nm。当灼烧温度为1000℃,Eu2+掺杂浓度为0.12,SrCl2.6H2O添加量过量20%,发光强度最高。与商业近紫外LED芯片发射相匹配,是一种优秀的近紫外白光LED用的蓝色荧光粉。     

Observation of efficient Er3+:4I11/2→4I13/2 transition in highly Er3+ doped germanosilicate glass

Highly rare earth（RE）ions doped glass laser materials can produce efficient single frequency mid-infrared laser. In this work, a series germanosilicate glasses with various high erbium-doping concentration (up to 4?mol%) and without concentration quenching are fabricated. Spectroscopic properties and energy transfer (ET) mechanism of efficient Er³⁺:⁴I_11/2 →⁴I_13/2 transition have been investigated in detail upon a conventional 980?nm Laser Diode. The dense structure of silicate glass can be dissolved effectively by the introduction of GeO_2, which was analyzed by Raman spectra, so that the compatibility and luminous intensity of RE ions were improved. The high predicted spontaneous transition probability (A_rad =?37.65?s^?1) based on the Judd-Ofelt theory and large calculated emission cross section (8.8?×?10^?21 cm²) are obtained. The above results indicate that these glasses are promising to be the single frequency mid-infrared laser material.     

AlF3-CsH5(PO4)2中温质子导体电解质的制备及性能

提出了一种磷酸五氢铯(CsH₅(PO₄)₂)与氟化铝(AlF₃)形成P-OH…F氢键的方法,同步提高了固体质子导体CsH₅(PO₄)₂的热机械稳定性和导电率。结果表明,AlF₃-CsH₅(PO₄)₂复合电解质即使在250℃的高温下也能保持坚固的固态,这比纯CsH₅(PO₄)₂的熔化温度提高了100℃。同时,在AlF₃-CsH₅(PO₄)₂复合电解质中,由于P-OH…F氢键的协同作用和CsH₅(PO₄)₂固有的质子导电性能,使得AlF₃-CsH₅(PO₄)_2<...     

橙红色荧光粉K2Bi1–xZr(PO4)3:xSm3+的电子结构与荧光性能(英文)

采用常规固相反应合成了无水钾镁矾基荧光粉材料钐(+3)激活磷酸锆铋钾,并用X射线衍射、紫外–可见漫反射光谱、密度泛函理论计算(DFT)和光致发光谱等方法进行了研究。DFT计算表明,磷酸锆铋钾是一种具有间接带隙的绝缘体,带宽为4.26 eV,适合作为荧光主体材料。该荧光粉可被340～425 nm范围内近紫外光有效地激发,发射出一系列钐(+3)的特征发射峰。主要包括562、600、647 nm附近3个发射带,分别对应于钐(+3)离子4G5/2→6HJ (J=5/2, 7/2, 9/2)的能级跃迁。通过改变x值制备了不同钐(+3)浓度的样品,并比较了其发射强度,得出钐(+3)的最佳掺杂浓度为10%(摩尔分数)。因此,钐(+3)激活磷酸锆铋钾材料可作为橙红色荧光粉在照明和显示领域具有一定的应用价值。     

焙烧条件对Na3V2(PO4)3/C的制备及储锌性能影响

采用喷雾干燥法合成了Na₃V₂(PO₄)₃(NVP)前驱体,然后经过高温煅烧得到水系锌离子电池正极复合材料Na₃V₂(PO₄)₃/C(NVP/C),考察了煅烧温度和煅烧时间对NVP/C性能的影响。通过XRD、SEM和BET对样品结构和形貌进行了表征,通过循环伏安和充放电测试了样品的电化学性能。结果表明,不同煅烧温度和煅烧时间制备样品均为纯相的NVP/C,且并没有改变NVP/C的晶体结构;煅烧温度过高或煅烧时间过长会导致晶粒尺寸增大,性能迅速衰减。NVP/C制备最佳条件为煅烧温度700℃、煅烧时间8 h,在该条件下所制备的NVP/C(记为NVP/C-700-8)形貌更为规整,结晶性良好,具有较小的阻抗以及更好的离子扩散能力,进而表现出最佳的电化学性能。在0.1 A/g电流密度下表现出最佳的放电比容量(122.4 mA·h/g)。在1.0 A/g电流密度下经过200圈循环后放电比容量仍高达103.9 mA·h/g。     

Ca3La2(BO3)4:Pr3+荧光粉的制备及其发光性质的研究

通过高温固相法合成了Ca₃La_1.96(BO₃)₄:0.04Pr³⁺荧光粉。通过X射线衍射(XRD)确定了样品的晶体结构,通过激发光谱和发射光谱对样品发光性能进行了研究。X射线衍射测试结果表明,样品已经成相。光谱测试结果表明,在449 nm、473 nm和485 nm光的激发下,样品的发射谱峰位于607 nm附近,这归因于Pr³⁺的¹D₂→³H₄跃迁。监测607 nm时,样品的激发谱由位于320～400 nm的宽激发带和分别位于449 nm、473 nm和485 nm处的窄激发峰组成。位于449 nm、473 nm和485 nm处的激发峰分别归因于Pr³⁺的³H₄→³P₂、³H₄→³P_1...     

Structural-microstructural characterization and optical properties of Eu3+,Tb3+-codoped LaPO4·nH2O and LaPO4 nanorods hydrothermally synthesized with microwaves

Rhabdophane-type Eu³⁺,Tb³⁺-codoped LaPO₄·nH₂O single-crystal nanorods with the compositions La_0.99999-xEu_xTb_0.00001PO₄·nH₂O (x?=?0–0.03), La_0.99999-yTb_yEu_0.00001PO₄·n′H₂O (y?=?0–0.010), and La_0.99999-zTb_zEu_0.000007PO₄·n′′H₂O (z?=?0–0.012) were hydrothermally synthesized with microwaves. It is shown that the Eu³⁺,Tb³⁺ codoping does not affect the thermal stability of these nanorods, which is due to the formation of substitutional solid solutions with both Eu³⁺ and Tb³⁺ replacing La³⁺ in the crystal lattice. Moreover, it is also shown that monazite-type Eu³⁺,Tb³⁺-codoped LaPO₄ single-crystal nanorods can be obtained by calcining their rhabdophane-type Eu³⁺,Tb³⁺-codoped LaPO₄·(n,n′ or n′′)H₂O counterparts at moderate temperature in air, and that they are thermally stable. It is also observed that, for the same Eu³⁺,Tb³⁺-codoping content, the monazite-type Eu³⁺,Tb³⁺-codoped LaPO₄ nanorods exhibit higher photoluminescent efficiency than the rhabdophane-type Eu³⁺,Tb³⁺-codoped LaPO₄· (n,n′ or n′′)H₂O nanorods. Moreover, it is found that the highest photoluminescence emission corresponds to the monazite-type La_0.96999Eu_0.02Tb_0.00001PO₄ nanorods for the La_0.99999-xEu_xTb_0.00001PO₄ system. However, for those compositions energy transfer from Tb³⁺ to Eu³⁺ does not occur. In addition, for an efficient energy transfer to occur, a content of at least 1?mol% Tb³⁺ is needed in all the studied materials.     

Tuning of Bi3+-related excitation and emission positions through crystal field modulation in the perovskite-structured La2(Znx, Mg1-x)TiO6 (0 ≤ x ≤ 1):Bi3+ solid solution for white LEDs

In the past year, emission-tunable crystals based on the rare-earth (RE) ions as luminescent center have been frequently reported for use in UV and blue converted white LEDs, but so far tuning the non-RE Bi³⁺ related emissions through the crystal field modulation is still not discovered in the perovskite crystals. In this work, we design and report a type of Bi³⁺ doped La₂(Zn_x,Mg_1-x)TiO₆ (0 ≤ x ≤ 1) perovskite solid solutions, which enable showing the tunable Bi³⁺ excitation and emission positions. The XRD results show that gradual substitution of smaller Mg²⁺ ions with larger Zn²⁺ ions can lead to the blue-shifting of X-ray diffraction (XRD) position, revealing the expansion of cell lattice. Together with structural analysis, our refined XRD and time-resolved spectral results reveal that there is only one type of La site available for Bi³⁺ substitution. With this regular crystal lattice change, the crystal field strength around Bi³⁺ ions is found to vary regularly, allowing to realization of the excitation and emission spectral tuning, i.e., the Bi³⁺ excitation and emission positions as the Mg ions are replaced by the Zn ions can tune from 348?nm to 392?nm and from 405?nm to 433?nm, respectively. This Bi³⁺ spectral tuning peak after calculated by the dielectric chemical bond theory features a linear relationship with the crystal field strength and, thus, is ascribed to the crystal field modulation. On basis of the La₂(Zn_0.4,Mg_0.6)TiO₆ blue, SrGa₂S₄:Eu²⁺ green and Y₂O₃:Eu³⁺ red phosphors, a UV converted warm white LED device with desirable color rendering index (CRI) of 78, correlated color temperature (CCT) of 3650 K and good luminous efficacy of 118.13?lm/W, is fabricated. This work provides new insights into using the crystal-field modulation to discover more Bi³⁺ emission-tunable crystals for white LEDs in the future.