Mg_(3)Y_(2)Ge_(3)O_(12)∶Pr^(3+)材料的多色发光及余辉性能

采用高温固相法制备了一种具有颜色变化的长余辉发光材料Mg_(3)Y_(2)Ge_(3)O_(12)∶Pr^(3+)。通过X射线衍射、激发发射光谱、余辉衰减及热释光曲线等,对样品的结构、发光及余辉性能进行了系统分析。在283 nm激发下,发射光谱在485 nm和609 nm处表现出两个较强的尖峰发射,分别归属于Pr^(3+)离子的^(3)P_(2)→^(3)H_(4)及^(3)P_(0)→3H6能级跃迁。通过对Pr^(3+)离子浓度的调控,有效改变了绿光和红光的相对发射强度,从而实现了发光颜色的多色化。此外,在激发光源停止后该材料同样具有多色的余辉发射,对于最佳样品(Mg_(3)Y_(2)Ge_(3)O_(12)∶0.015Pr^(3+))的余辉时间可达1200 s以上。之后,我们通过热释光曲线具体研究了陷阱的分布及余辉的充放能过程。结果表明,Mg_(3)Y_(2)Ge_(3)O_(12)∶0.015Pr^(3+)材料中浅陷阱的浓度相对较低从而导致室温下的余辉性能较弱。由于材料在高温区域具有超宽带陷阱分布,因此,我们进一步探究了其在高温下的多色长余辉性能。在本工作中,我们成功制备了一种单一离子激活的发光及余辉颜色可调的长余辉发光材料,考虑到其在室温以及高温条件下都具有发光及余辉颜色变化的特点,该材料在高温预警标识以及防伪领域有着潜在的应用价值。

Self-assembled S-scheme In_(2.77)S_(4)/K^(+)-doped g-C_(3)N_(4)photocatalyst with selective O_(2) reduction pathway for efficient H_(2)O_(2) production using water and air

The development of an efficient artificial H_(2)O_(2) photosynthesis system is a challenging work using H_(2)O and O_(2) as starting materials.Herein,3D In_(2.77)S_(4) nanoflower precursor was in-situ deposited on K^(+)-doped g-C_(3)N_(4)(KCN)nanosheets using a solvothermal method,then In_(2.77)S_(4)/KCN(IS/KCN)het-erojunction with an intimate interface was obtained after a calcination process.The investigation shows that the photocatalytic H_(2)O_(2) production rate of 50IS/KCN can reach up to 1.36 mmol g^(-1)h^(-1)without any sacrificial reagents under visible light irradiation,which is 9.2 times and 4.1 times higher than that of KCN and In_(2.77)S_(4)/respectively.The enhanced activity of the above composite can be mainly attributed to the S-scheme charge transfer route between KCN and In_(2.77)S_(4) according to density functional theory calculations,electron paramagnetic resonance and free radical capture tests,leading to an expanded light response range and rapid charge separation at their interface,as well as preserving the active electrons and holes for H_(2)O_(2) production.Besides,the unique 3D nanostructure and surface hydrophobicity of IS/KCN facilitate the diffusion and transportation of O_(2) around the active centers,the energy barriers of O_(2) protonation and H_(2)O_(2) desorption steps are ef-fectively reduced over the composite.In addition,this system also exhibits excellent light harvesting ability and stability.This work provides a potential strategy to explore a sustainable H_(2)O_(2) photo-synthesis pathway through the design of heterojunctions with intimate interfaces and desired reac-tion thermodynamics and kinetics.

First-Principles Investigation of Charge Transfer Mechanism of B-Doped 3C-SiC Semiconductor Material

This study delves into the charge transfer mechanism of boron (B)-doped 3C-SiC through first-principles investigations. We explore the effects of B doping on the electronic properties of 3C-SiC, focusing on a 12.5% impurity concentration. Our comprehensive analysis encompasses structural properties, electronic band structures, and charge density distributions. The optimized lattice constant and band gap energy of 3C-SiC were found to be 4.373 Å and 1.36 eV respectively, which is in agreement with previous research (Bui, 2012;Muchiri et al., 2018). Our results show that B doping narrows the band gap, enhances electrical conductivity, and influences charge transfer interactions. The charge density analysis reveals substantial interactions between B dopants and surrounding carbon atoms. This work not only enhances our understanding of the material’s electronic properties, but also highlights the importance of charge density analysis for characterizing charge transfer mechanisms and their implications in the 3C-SiC semiconductors.

Pr^(3+)掺杂碱土混合氟化物激光晶体的生长与发光性能研究

采用多孔坩埚温度梯度法生长了0.6%Pr∶Ca_(x)Sr_(1-x)F_(2)(x=0,0.3,0.5,0.7,1.0)和0.6%Pr,5%R∶Ca_(0.5)Sr_(0.5)F_(2)(R=Y,Lu,Gd)系列碱土氟化物激光晶体,对其晶体结构、吸收和可见波段的荧光光谱及荧光衰减寿命进行了系统研究。通过吸收截面、发射截面、荧光寿命、荧光半峰全宽等光谱参数分析发现,0.6%Pr,5%Y∶Ca_(0.5)Sr_(0.5)F_(2)混晶与其他掺杂混晶相比,具有最佳的光谱效果,443 nm处吸收截面和640 nm处红光发射截面分别为1.63×10^(-20)和3.39×10^(-20)cm^(2),相应荧光半峰全宽和荧光寿命分别为4.50 nm和42.8μs,光谱参数与0.6%Pr∶Ca_(x)Sr_(1-x)F_(2)(x=0,0.3,0.5,0.7,1.0)混晶相比有显著的提升。结果表明,0.6%Pr,5%Y∶Ca_(0.5)Sr_(0.5)F_(2)晶体具有极大的潜力作为新型Pr^(3+)掺杂宽带激光材料的增益介质。

Fabrication of Gd_(2)O_(3)-doped CeO_(2)thin films through DC reactive sputtering and their application in solid oxide fuel cells

Physical vapor deposition(PVD)can be used to produce high-quality Gd_(2)O_(3)-doped CeO2(GDC)films.Among various PVD methods,reactive sputtering provides unique benefits,such as high deposition rates and easy upscaling for industrial applications.GDC thin films were successfully fabricated through reactive sputtering using a Gd_(0.2)Ce_(0.8)(at%)metallic target,and their application in solid oxide fuel cells,such as buffer layers between yttria-stabilized zirconia(YSZ)/La0.6Sr0.4Co0.2Fe0.8O_(3−δ)and as sublayers in the steel/coating system,was evaluated.First,the direct current(DC)reactive-sputtering behavior of the GdCe metallic target was determined.Then,the GDC films were deposited on NiO-YSZ/YSZ half-cells to investigate the influence of oxygen flow rate on the quality of annealed GDC films.The results demonstrated that reactive sputtering can be used to prepare thin and dense GDC buffer layers without high-temperature sintering.Furthermore,the cells with a sputtered GDC buffer layer showed better electrochemical performance than those with a screen-printed GDC buffer layer.In addition,the insertion of a GDC sublayer between the SUS441 interconnects and the Mn-Co spinel coatings contributed to the reduction of the oxidation rate for SUS441 at operating temperatures,according to the area-specific resistance tests.

颜色可调CsLa(WO_(4))_(2):Pr^(3+)荧光粉的光致发光和温度传感特性

利用高温固相法制备了一系列不同Pr^(3+)掺杂浓度的CsLa(WO_(4))_(2)荧光粉,测试了X射线衍射(XRD)、漫反射光谱、激发光谱、发射光谱与荧光衰减曲线,讨论了光致发光光谱与浓度、温度的联系,并基于荧光强度比(FIR)技术计算得出温度传感相关参数。CsLa(WO_(4))2∶Pr^(3+)主要呈现源自3P_(0)和1D_(2)能级的发射,对应的最佳掺杂浓度分别为0.03和0.01,经证实电偶极‐电偶极相互作用导致了浓度猝灭。3P_(0)与1D_(2)能级的发射随温度变化趋势不同,这主要归因于Pr^(3+)‐W^(6+)的价间电荷迁移(IVCT)、交叉弛豫(CR)和多声子弛豫(MPR)等过程的综合作用。由于上述发射表现出不同的浓度和温度依赖特性,实现了颜色可调谐发光。基于3P_(1)→3H_(5)/3P_(0)→3H4热耦合能级对和1D_(2)→3H_(4)/3P_(0)→3H_(4)非热耦合能级对的FIR,计算得到相对灵敏度分别为586.01/T^(2)K^(-1)和1071.78/T^(2)K^(-1),表明该材料在温度传感领域具有潜在应用价值。

红光拓宽型植物照明用荧光粉La_(2)MgTiO_(6)∶Pr^(3+),Mn^(4+)的合成和发光性质探究

采用高温固相法合成了La_(2)MgTiO_(6)∶Mn^(4+)、La_(2)MgTiO_(6)∶Pr^(3+)、La_(2)MgTiO_(6)∶Pr^(3+),Mn^(4+)单掺杂和双掺杂荧光粉,并通过X射线衍射、扫描电镜、荧光光谱等测试方法对荧光粉的物相结构、形貌和发光特性进行了表征及分析。结果表明:成功合成了La_(2)MgTiO_(6)∶Mn^(4+)、La_(2)MgTiO_(6)∶Pr^(3+)、La_(2)MgTiO_(6)∶Pr^(3+),Mn^(4+)荧光粉且均为纯相;样品的粒径为1~2μm;La_(2)MgTiO_(6)∶Mn^(4+)在650~750 nm的红光发射是来自Mn^(4+)的2 E 1→4 A 2跃迁,La_(2)MgTiO_(6)∶Pr^(3+)在红光区域600~660 nm具有强烈的发射,归属为Pr^(3+)的3 P 0→3 H 6和3 P 0→3 F 2跃迁。当Mn^(4+)与Pr^(3+)共同掺杂于La_(2)MgTiO_(6)时,来自Mn^(4+)、Pr^(3+)不同波段的红光发射使荧光粉的发射光谱与植物光敏色素P r与P fr吸收光谱的重叠程度大幅增加,表明Mn^(4+)、Pr^(3+)共掺有效拓宽了La_(2)MgTiO_(6)荧光粉的红光发射区域,更符合植物照明的需求,在LED植物照明领域具有更明显的潜在应用价值。

以CaTiO_(3):Pr^(3+)为发光功能元的红色长余辉有机柔性薄膜的制备及光学性能研究

采用CaTiO_(3):Pr^(3+)红色长余辉发光材料为发光功能元,以绿色环保型高分子材料聚乙烯醇PVA为基体,通过共混法,引入石墨烯和Ag纳米颗粒,制备了红色长余辉有机柔性薄膜,运用SEM(扫描电子显微镜)、XRD(X射线衍射)、PL(光致发光)等多种分析测试方法,对红色长余辉发光薄膜的结构及性能进行表征,同时,还研究了Ag纳米颗粒的引入对红色长余辉柔性薄膜材料发光性能的影响。研究结果表明,由于CaTiO_(3):Pr^(3+)和Ag之间的能量转移,Ag颗粒在减弱柔性薄膜的红色余辉的同时,延长了其荧光寿命。

Luminescence of Co-doped SrTiO_3:Pr^(3+)

The SrTiO3 ： Pr^3＋ material, co-doped with monovalent Li^＋ , divalent Mg^2＋ , and trivalent Al^3＋ was prepared by a new sol-gel method. The phase and crystallinity of the synthesized materials were investigated by powder X-ray diffraction（XRD） and scanning electron microcopy（SEM）. Among the co-doped ion, Al^3＋ incorporation caused the least lattice change and had the best crystallinity. Photoluminescence spectra were taken to investigate the luminescence characteristics. We observed a red luminescence change of SrTiO3 ： Pr^3＋ after being co-doped, and a best enhancement on the red luminescence with the trivalent Al^3＋ was observed. The present results indicated that the charge defect associated with Al^3＋ has led to charge compensation of Pr^＋ and also implied that the charge defects（usually the second dopant ions replacing the A or B sites in the lattice） which are closer to PrSr^＋ contribute more to the red luminescence enhancement.

Y_(2)SiO_(5):Pr^(3+)上转换纳米荧光粉对ZnO:Pr^(3+)光催化性能的影响

文章主要研究了Y_(2)SiO_(5):Pr^(3+)上转换纳米荧光粉对ZnO:Pr^(3+)的光催化性能的影响,通过XRD、FE-SEM、FL和UV-Vis对样品的物相、形貌、发光性能和光催化行性能进行了分析表征,实验结果表明:随着Y_(2)SiO_(5):Pr^(3+)上转换纳米荧光粉的加入量增加,ZnO:Pr^(3+)光催化效率逐渐提高,当加入0.2 g Y_(2)SiO_(5):Pr^(3+)时,光催化效率最高,在光照60 min后对亚甲基蓝的降解率达到了98.11%,相比未加入Y_(2)SiO_(5):Pr^(3+)时的光催化效率有显著提升。

Ca_(3)La_(2)(BO_(3))_(4):Pr^(3+)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Ca_(3)La_(1.96)(BO_(3))_(4):0.04Pr^(3+)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Pr^(3+)的^(1)D_(2)→^(3)H_(4)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Pr^(3+)的^(3)H_(4)→^(3)P_(2)、^(3)H_(4)→^(3)P_(1)、^(3)H_(4)→^(3)P_(0)吸收跃迁。Ca_(3)La_(1.96)(BO_(3))_(4):0.04Pr^(3+)荧光粉是一种可被紫外光和可见光激发的新型红光荧光粉。

Preparation and Spectroscopic Properties of Pr^(3＋)-doped Transparent Glass-ceramic Containing LiYF_4 Nanocrystals

Pr^（3＋）-doped transparent oxyfluoride glass-ceramic containing tetragonal LiYF_4 nanocrystals has been synthesized by melting-quenching method and subsequent thermal treatment and spectroscopic properties of Pr^（3＋） ions were investigated. The crystalline phase and microstructure of the LiYF_4 nanocrystals were studied by X-ray diffraction（XRD） and transmission electron microscopy（TEM）, respectively. Compared with those of Pr^（3＋）-doped glass（Pr^（3＋）：PG）, the sharp absorption and emission bands of Pr^（3＋）-doped glass-ceramic（Pr^（3＋）：GC） reveal parts of Pr^（3＋） ions are incorporated into LiYF_4 nanocrystals. The peak absorption cross-section at 443 nm（~3H_4 → ~3P_2） adds to 110% and the full width at half maximum（FWHM） for the band around 443 nm reduces from 22 to 14 nm after crystallization. The fluorescence lifetime of the ~3P_0 multiplet of Pr^（3＋） ions increases from 5.35 to 11.14 μs after crystallization. The results indicate that this glass-ceramic is promising to be a visible laser material.

P^(5+)共掺杂对Lu_(2)SiO_(5):Pr^(3+)纳米颗粒紫外区长余辉发光性能的影响

用溶胶-凝胶法合成Lu_(2)SiO_(5):Pr^(3+)纳米紫外长余辉发光材料,并研究P^(5+)共掺杂对该材料长余辉发光性能的影响。结果表明,P^(5+)的少量加入对Lu_(2)SiO_(5):Pr^(3+)样品的光致发光性能几乎没有影响,Lu_(2)SiO_(5):Pr^(3+)的发光主要由270 nm处的UVC发光和320 nm处的UVB发光组成,位于270 nm的峰由5d^(1)-^(3)H_(4)跃迁引起,位于320 nm的峰由5d1-3H5跃迁引起。P^(5+)的加入可以很好增强Lu_(2)SiO_(5):Pr^(3+)样品的紫外长余辉发光性能,当P^(5+)的掺杂浓度达到4%时,Lu_(2)SiO_(5):Pr^(3+)的紫外长余辉性能达到最佳。热释发光的结果证明,P^(5+)的加入可以提高样品中陷阱的浓度,从而实现样品的长余辉发光性能的提升。

Ca_(2)MnO_(4)-layered perovskite modified by NaNO_(3)for chemical-looping oxidative dehydrogenation of ethane to ethylene

Chemical-looping oxidative dehydrogenation(CL-ODH)is a process designed for the conversion of alkanes into olefins through cyclic redox reactions,eliminating the need for gaseous O_(2).In this work,we investigated the use of Ca_(2)MnO_(4)-layered perovskites modified with NaNO_(3) dopants,serving as redox catalysts(also known as oxygen carriers),for the CL-ODH of ethane within a temperature range of 700-780℃.Our findings revealed that the incorporation of NaNO_(3) as a modifier significantly-nhanced the selectivity for-thylene generation from Ca_(2)MnO_(4).At 750℃and a gas hourly space velocity of 1300 h^(-1),we achieved an-thane conversion up to 68.17%,accompanied by a corresponding-thylene yield of 57.39%.X-ray photoelectron spectroscopy analysis unveiled that the doping NaNO_(3) onto Ca_(2)MnO_(4) not only played a role in reducing the oxidation state of Mn ions but also increased the lattice oxygen content of the redox catalyst.Furthermore,formation of NaNO_(3) shell on the surface of Ca_(2)MnO_(4) led to a reduction in the concentration of manganese sites and modulated the oxygen-releasing behavior in a step-wise manner.This modulation contributed significantly to the enhanced selectivity for ethylene of the NaNO_(3)-doped Ca_(2)MnO_(4) catalyst.These findings provide compelling evidence for the potential of Ca_(2)MnO_(4)-layered perovskites as promising redox catalysts in the context of CL-ODH reactions.

Mechanisms of Fluorescence Quenching of Pr^(3+)-Doped PbWO_4 Crystal

Fluorescence decay curves of the ^3P0 and ^1D2 manifolds in Pr^3＋ doped PbWO4 crystal were measured at room temperature and fluorescence lifetimes of both manifolds were estimated. Combining with the radiative lifetimes of the manifolds calculated on the basis of the modified J-O theory, the main mechanisms for the fluorescence quenching of the manifolds were analyzed. The multi-phonon relaxation and the cross-relaxation energy transfer are the major reasons for the fluorescence quenching of the ^3P0 and ^1D2 manifolds, respectively. The Inokuti-Hirayama model was used to analyze the fluorescence decay curve of the ^1D2 manifold and the cross-relaxation of dlpole-dipole interaction was confirmed. Consequently, the ^3p0 manifold is more favorable as an upper laser level than the ^1D2 manifold.

Temperature-Dependent Emission of Pr^(3+)-Doped LaB_3O_6 under Vacuum Ultraviolet Excitation

The vacuum ultraviolet （VUV） luminescent properties of Pr^3＋ -activated LaB3O6 were investigated with highenergetic synchrotron radiation from 20 to 300 K. In the emission spectra, the parity-forbidden 4f^2→4f^2 and parity-allowed 4f5d→4f^2 transitions were observed simultaneously. In addition, it was also observed that the intensity of 4f5d→4f^2 emission bands increased relative to the intensity of 4f^2→4f^2 emissions with increasing temperature. The thermal equilibrium model of energy levels was employed with respect to the lowest 4f5d state and ^1S0 state of LaB3O6：Pr^3＋ , as a result of which the fitted curve had a good agreement with the experiment values, which clarified the physical nature of temperature-dependent emission characteristics of Pr^3＋ in LaB3O6.

纳米晶ZrO_2∶Pr^(3+)与ZrO_2∶Pr^(3+),Sm^(3+)发光研究

采用化学共沉淀法制备了纳米晶ZrO2∶Pr3+粉体,所制备的纳米晶ZrO2∶Pr3+粉体中Pr3+的强室温特征发射的两个主发射带为1D2—3H4和3P0—3H4跃迁。不同热处理温度下纳米晶ZrO2∶Pr3+晶体结构不同,因此它们的发光不同;ZrO2基质向Pr3+有能量传递,在高温煅烧得到的单斜相配位场中能量传递较好。荧光强度与Pr3+浓度的关系研究表明:3P0和1D2能级有不同的猝灭规律,由于[1D2,3H4]→[1G4,3F4]的交叉弛豫,使得1D2—3H4跃迁的猝灭浓度很低,在我们的实验中,掺0.1 mol%Pr3+时1D2—3H4跃迁发射最强,掺2 mol%Pr3+时3P0—3H4跃迁发射最强。文章制备的纳米晶ZrO2∶Pr3+,Sm3+中Sm3+的4G5/2—6H7/2跃迁荧光峰因Pr3+加入而增强,这除了两种离子某些能级相近产生荧光发射的叠加效应外,还存在Pr3+→Sm3+的能量传递。

Ca_(1-x)Zn_xTiO_3∶Pr^(3+),R^+(R^+=Li^+,Na^+,K^+,Rb^+,Cs^+,Ag^+)的合成和发光性质

采用X射线衍射、荧光光谱和热释发光研究了Ca1 -xZnxTiO3∶Pr3+ ,R+ 的物相组成和发光性质。Pr3+ 取代Ca2 + 形成PrCa·正电性缺陷发光中心。激发光谱是峰值位于 3 3 0nm附近的宽带谱 ,发射光谱是峰值在 613nm半宽度为 2 0nm的带谱 ,对应Pr3+ 的1 D2 -3H4 跃迁发射。发光强度和余辉随基质组分Zn/Ca摩尔比和合成温度而变化。Zn2 + 的最佳含量在 10 %～ 2 0 %。X射线衍射研究表明掺入适量的Zn2 + 物相组成为CaTiO3,Ca2 Zn4 Ti1 5O36 和Zn2 TiO4 。热释发光曲线表明掺入Zn2 + 离子后体系中形成了新的缺陷ZnTi″ ,且ZnTi″的缺陷陷阱深度大于RCa′。

补偿离子掺杂与烧成温度对SrTiO_3∶0.002Pr^(3+)材料的红色发光特性的影响

采用高温固相反应法合成SrTiO3∶Pr3+系发光材料,利用荧光光谱、XRD等分析手段,研究了工艺参数,如不同价态K、Ca和A l离子掺杂,以及1 050~1 300℃不同烧成温度对SrTiO3∶Pr3+体系发光性能的影响,以获得具有较好综合发光性能的SrTiO3∶Pr3+系发光材料。选择不同价态补偿离子掺杂是为了研究电荷补偿作用机制对该类材料发光性能的作用。结果表明:随着烧成温度的升高,磷光体发光强度先增加后减弱,在1 150℃烧成的材料其发光强度最大。无补偿掺杂与K、Ca或A l离子掺杂的所有样品均发出源于Pr3+的1D2→3H4跃迁的610 nm红色光。在不同价态补偿离子掺杂样品中,以掺A l的SrTiO3∶Pr3+体系发光强度最好;其发光强度比无补偿离子掺杂SrTiO3∶Pr3+材料的发光强度提高10倍左右。另一方面,与A l离子具有类似的引入阴离子电荷缺陷的K离子掺杂材料的发光强度则基本没有变化,其发光强度与没有电荷补偿作用的无掺杂及Ca离子掺杂SrTiO3∶Pr3+材料相似。上述实验结果可从电荷缺陷及微观固溶结构两方面的联合作用机制进行解释。在引入电荷缺陷的掺杂体系中,只有在发光离子PrS+r最近邻的Ti格位引入的电荷缺陷才能有效地起电荷补偿作用,达到增强发光强度的作用。研究结果给出了合理的制备工艺条件,并且提供了一种可有效提高发光强度的补偿离子掺杂的选择依据。

水热法制备CaTiO_3∶Pr^(3+)微纳米荧光粉及其发光性能

采用水热法制备了微纳米CaTiO3∶Pr3+荧光粉,采用XRD、SEM和荧光光谱仪对荧光粉的结构、形貌及发光性能进行分析。结果表明,所制得的CaTiO3∶Pr3+荧光粉物相纯正无杂质,结晶度好;有较宽激发带,激发峰值为323nm,发射主峰位于613 nm处,呈锐线状,属红色发光。比较水解抑制剂的种类和NaOH溶液的浓度对制备CaTiO3∶Pr3+荧光粉的作用,发现选用HNO3作为水解抑制剂,NaOH溶液的浓度为1 mol/L时制备的CaTiO3∶Pr3+荧光粉结晶程度最高,晶粒尺寸均匀,粒度约为500 nm,发光性能最佳。