新型应力发光材料Ca_(5)Ga_(6)O_(14):Sm^(3+)制备及其性能

采用高温固相法成功制备出新型Ca_(5-x)Ga_(6)O_(14):xSm^(3+)应力发光材料。通过X射线衍射、扫描电镜、漫发射光谱、光致激发和发射光谱、荧光衰减曲线、应力发光光谱和热释光光谱等测试详细研究了Ca_(5-x)Ga_(6)O_(14):xSm^(3+)的晶体结构、表面形貌、光致发光和应力发光性能及其发光机理。在404 nm激发下,Ca_(5-x)Ga_(6)O_(14):xSm^(3+)呈现出4个发射峰,分别位于562,599,642,715 nm,对应Sm^(3+)的^(4)G_(5/2)→6Hj(j=5/2,7/2,9/2,11/2)的特征发射。随着Sm^(3+)离子掺杂浓度的增加,发光强度先增强后减弱,在x=0.07时获得最强发射,且衰减时间从1.92 ms缩短至1.30 ms。在滑动摩擦激发下可获得Ca_(5-x)Ga_(6)O_(14):xSm^(3+)的应力发光发射带,且应力发光强度与施加应力满足线性增长,表明该材料在应力传感领域具有潜在应用价值。

反常热猝灭Sr_(2)Ga_(2)SiO_(7)∶Sm^(3)+红色荧光粉的合成及发光性能

采用高温固相法合成了系列Sr_(2-x)Ga_(2)SiO_(7)∶xSm^(3)+红色荧光粉,通过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、荧光量子效率和荧光衰减寿命等一系列表征手段对合成荧光粉的物相及晶体结构、发光性能和热稳定性进行研究。一系列结果表明,在404 nm紫外光激发下,Sr_(2-x)Ga_(2)SiO_(7)∶xSm^(3)+荧光粉在598 nm处发出明亮的红色光。Sr_(2-x)Ga_(2)SiO_(7)∶xSm^(3)+荧光粉发光强度随Sm^(3)+离子浓度变化,在x=0.03时发生浓度猝灭,是由电偶极-电偶极相互作用导致的。随着温度逐渐上升,系列荧光粉表现出反常的热猝灭现象,在393 K时发光强度达到最大,强度为室温下的102.5%;在473 K时,发光强度仍可以保持室温下的101.3%。此外,最佳样品的荧光量子效率可达72.5%。研究表明,Sr_(2-x)Ga_(2)SiO_(7)∶xSm^(3)+红色荧光粉是一种具有高热稳定性、高量子效率可用于WLED的发光材料。

Ba_(3-x)B_(6)Si_(2)O_(16)∶xSm^(3+)发光材料的制备及其性能表征

采用高温固相法制备Ba_(3)B_(6)Si_(2)O_(16)∶Sm^(3+)系列发光材料的荧光粉样品,对其进行粉末X射线衍射、荧光光谱、固体紫外-可见漫反射等相关性能的研究与表征,探讨不同的Sm^(3+)离子浓度对Ba_(3-x)B_(6)Si_(2)O_(16)荧光粉发光性能的影响,并对其浓度猝灭机理进行讨论.实验表明,在405 nm近紫外光激发下,Ba_(3-x)B_(6)Si_(2)O_(16)∶xSm^(3+)系列发光材料能够同时发射出571 nm(黄光)和606 nm(橙光)荧光,分别对应于Sm^(3+)离子的4G_(5/2)→6H_(5/2)和4G_(5/2)→6H_(7/2)能级跃迁.当x=0.21时,Ba_(2.79)B_(6)Si_(2)O_(16)∶0.21Sm^(3+)荧光粉发光性能最强;继续增加掺杂Sm^(3+)离子的浓度,则出现浓度猝灭现象.其浓度猝灭机制可以通过相邻Sm^(3+)离子之间的相互作用来解释.所制备的Ba_(3)B_(6)Si_(2)O_(16)∶Sm^(3+)荧光粉可被近紫外光有效激发,在白光LED领域具有潜在的应用前景.

Sm^(3+)掺杂Ba_(0.85)Ca_(0.15)Ti_(0.90)Zr_(0.10)O_(3)无铅多功能铁电陶瓷的储能和光致发光性能

通过高温固相反应法制备了Ba_(0.85)Ca_(0.15)Ti_(0.90)Zr_(0.10)O_(3)∶xSm^(3+)(BCTZ∶xSm^(3+),x=0.0%、0.2%、0.4%、0.6%、0.8%、1.0%,物质的量分数)陶瓷,系统研究了其微观形貌、铁电性能、储能性能和光致发光性能。研究表明,Sm^(3+)掺入后,陶瓷平均晶粒大小明显下降,致密度显著提高。所有陶瓷均表现出典型的铁电性。BCTZ∶xSm^(3+)陶瓷放电储能密度得到了极大的提高,BCTZ∶1.0%Sm^(3+)陶瓷放电储能密度较纯BCTZ陶瓷可提高约49.0%。此外,在408 nm光的激发下,BCTZ∶xSm^(3+)陶瓷在596 nm左右表现出强烈的橙红色发光,且发光强度相对可调性可达449%。

KY(CO_(3))_(2):Sm^(3+)新型红光荧光粉的制备及其发光性能研究

为解决白光LED中因蓝光芯片激发黄色荧光粉而导致显色指数较低问题,采用水热法制备一种新型红光荧光粉KY(CO_(3))_(2):Sm^(3+)。通过X射线粉末衍射、光致发光光谱、色度坐标及荧光寿命等表征手段研究样品的物相结构及其发光性能。结果表明:掺入Sm^(3+)后,KY(CO_(3))_(2)的晶体结构并没有发生改变。随着Sm^(3+)掺杂量的增加,荧光粉的发光强度先增强后减弱,最佳掺杂浓度为10%。Dexter理论分析表明,Sm^(3+)的浓度猝灭归因于电偶极-电偶极相互作用机制。以596 nm作为监测波长,KY(CO_(3))_(2):Sm^(3+)荧光粉激发峰主要包含402 nm (6H_(5/2)→4F_(7/2))和474 nm (6H_(5/2)→4I_(13/2)) 2波长,表明该荧光粉可以被商用紫外LED芯片和蓝光LED芯片有效激发。改变Sm^(3+)掺杂比例,荧光粉色度坐标值基本保持不变,均位于标准红光区,因此KY(CO_(3))_(2):Sm^(3+)红光荧光粉有望作为白光LED用红光荧光粉。

Sm^(3+)掺杂Na_(5)Y(MoO_(4))_(4-y)(WO_(4))_(y)高热稳定性荧光粉的制备及发光性能研究

本文采用高温固相法合成了一系列Na_(5)Y_(1-x)(MoO_(4))_(4-y)(WO_(4))y∶xSm^(3+)(x=0~0.10,y=0~4)橙红色荧光粉。通过粉末衍射、透射电镜、常温/变温荧光发射谱、荧光激发谱、荧光动态衰减曲线和CIE色度坐标等光谱手段对荧光粉样品的光谱性能进行了研究。粉末衍射结果表明,合成的样品相位与Na_(5)Y(MoO_(4))_(4)的标准相一致,Sm^(3+)掺杂与引入(WO_(4))2-均未改变材料的相结构。在波长为406 nm光源的激发下,Na_(5)Y0.92(MoO_(4))3WO_(4)∶0.08Sm^(3+)荧光粉在643 nm附近橙红色荧光发射强度最高,继续增加Sm^(3+)的掺杂浓度,存在荧光猝灭现象,浓度猝灭的主要原因归为电偶极-电偶极相互作用。研究发现,Na_(5)Y(MoO_(4))_(4)基质中掺杂Sm^(3+)会引起电负性改变和晶格畸变,在Na_(5)Y_(1-x)(MoO_(4))_(4)∶xSm^(3+)中引入(WO_(4))2-阴离子基团,可以弥补因掺杂Sm^(3+)出现的缺陷,改善Na_(5)Y(MoO_(4))_(4)∶xSm^(3+)荧光粉的发光性能。在300~440 K,样品具有优异的热稳定性,荧光发射强度均超过室温时的96%;其CIE色度坐标均位于橙红光区域。以上结果表明新型Na_(5)Y_(1-x)(MoO_(4))_(4-y)(WO_(4))y∶xSm^(3+)橙红色荧光粉在WLED应用上有潜在价值。

Extending the solid solution range of sodium ferric pyrophosphate:Off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)as a novel cathode for sodium‐ion batteries

Iron‐based pyrophosphates are attractive cathodes for sodium‐ion batteries due to their large framework,cost‐effectiveness,and high energy density.However,the understanding of the crystal structure is scarce and only a limited candidates have been reported so far.In this work,we found for the first time that a continuous solid solution,Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2)(0≤α≤1,could be obtained by mutual substitution of cations at center‐symmetric Na3 and Na4 sites while keeping the crystal building blocks of anionic P_(2)O_(7) unchanged.In particular,a novel off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)is thus proposed,and its structure,energy storage mechanism,and electrochemical performance are extensively investigated to unveil the structure–function relationship.The as‐prepared off‐stoichiometric electrode delivers appealing performance with a reversible discharge capacity of 83 mAh g^(−1),a working voltage of 2.9 V(vs.Na^(+)/Na),the retention of 89.2%of the initial capacity after 500 cycles,and enhanced rate capability of 51 mAh g^(−1)at a current density of 1600 mA g^(−1).This research shows that sodium ferric pyrophosphate could form extended solid solution composition and promising phase is concealed in the range of Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2),offering more chances for exploration of new cathode materials for the construction of high‐performance SIBs.

固态照明用Li_(2)Gd_(4)(MoO_(4))_(7):Sm^(3+)橙红色荧光粉的结构和发光特性

白光LED具有广阔的应用前景与市场需求,而红色荧光粉对改善器件性能至关重要.本文采用高温固相法制备了一系列Li_(2)Gd_(4-x)Sm_(x)(MoO_(4))_(7)(x=0.01—0.13)荧光粉,利用X射线衍射、扫描电子显微镜、X射线光电子能谱和荧光光谱仪对样品进行了表征.在406 nm激发下,Li_(2)Gd_(4)(MoO_(4))_(7):Sm^(3+)荧光粉的发射峰分别位于563,598,645,706 nm处,这是由于Sm^(3+)的4f-4f跃迁引起的.当Sm^(3+)浓度为0.07时发光最强,浓度猝灭主要归因于电偶极-电偶极相互作用.随着Sm^(3+)浓度的增大,荧光寿命逐渐缩短.温度依赖性发射光谱研究发现,当温度为423 K时,Li_(2)Gd_(4)(MoO_(4))_(7):0.07Sm^(3+)的发射强度依然保持在298 K时的79%,显示了样品优良的热稳定性.CIE色度图确认了该荧光粉的发射位于橙红色区域.进一步利用最佳样品制作了白光LED,其CIE色坐标为(0.3788,0.3134),位于白光圈内.研究表明Li_(2)Gd_(4)(MoO_(4))_(7):Sm^(3+)荧光粉是一种很有前途的白光LED用橙红色荧光粉.

Insights on advanced g‐C_(3)N_(4)in energy storage:Applications,challenges,and future

Graphitic carbon nitride(g‐C_(3)N_(4))is a highly recognized two‐dimensional semiconductor material known for its exceptional chemical and physical stability,environmental friendliness,and pollution‐free advantages.These remarkable properties have sparked extensive research in the field of energy storage.This review paper presents the latest advances in the utilization of g‐C_(3)N_(4)in various energy storage technologies,including lithium‐ion batteries,lithium‐sulfur batteries,sodium‐ion batteries,potassium‐ion batteries,and supercapacitors.One of the key strengths of g‐C_(3)N_(4)lies in its simple preparation process along with the ease of optimizing its material structure.It possesses abundant amino and Lewis basic groups,as well as a high density of nitrogen,enabling efficient charge transfer and electrolyte solution penetration.Moreover,the graphite‐like layered structure and the presence of largeπbonds in g‐C_(3)N_(4)contribute to its versatility in preparing multifunctional materials with different dimensions,element and group doping,and conjugated systems.These characteristics open up possibilities for expanding its application in energy storage devices.This article comprehensively reviews the research progress on g‐C_(3)N_(4)in energy storage and highlights its potential for future applications in this field.By exploring the advantages and unique features of g‐C_(3)N_(4),this paper provides valuable insights into harnessing the full potential of this material for energy storage applications.

In situ luminescence measurements of GaN/Al_(2)O_(3) film under different energy proton irradiations

Ion beam-induced luminescence(IBIL) experiments were performed to investigate the in situ luminescence of GaN/Al_(2)O_(3) at varying ion energies,which allowed for the measurement of defects at different depths within the material.The energies of H^(+)were set to 500 keV,640 keV and 2 MeV,the Bragg peaks of which correspond to the GaN film,GaN/Al_(2)O_(3) heterojunction and Al_(2)O_(3) substrate,respectively.A photoluminescence measurement at 250 K was also performed for comparison,during which only near band edge(NBE) and yellow band luminescence in the GaN film were observed.The evolution of the luminescence of the NBE and yellow band in the GaN film was discussed,and both exhibited a decrease with the fluence of H^(+).Additionally,the luminescence of F centers,induced by oxygen vacancies,and Cr^(3+),resulting from the ^(2)E →^(4)A_(2) radiative transition in Al_(2)O_(3),were measured using 2 MeV H^(+).The luminescence intensity of F centers increases gradually with the fluence of H^(+).The luminescence evolution of Cr^(3+)is consistent with a yellow band center,attributed to its weak intensity,and it is situated within the emission band of the yellow band in the GaN film.Our results show that IBIL measurement can effectively detect the luminescence behavior of multilayer films by adjusting the ion energy.Luminescence measurement can be excited by various techniques,but IBIL can satisfy in situ luminescence measurement,and multilayer structural materials of tens of micrometers can be measured through IBIL by adjusting the energy of the inducing ions.The evolution of defects at different layers with ion fluence can be obtained.

Polypyride intercalation boosting the kinetics and stability of V_(3)O_(7)·H_(2)O cathodes for aqueous zinc-ion batteries

V_(3)O_(7)·H_(2)O(VO)is a high capacity cathode material in the field of aqueous zinc ion batteries(AZIBs),but it is limited by slow ion migration and low electrical conductivity.In this paper,polypyridine(PPyd)intercalated VO with nanoribbon structure was prepared by a simple in-situ pre-intercalation,which is noted VO-PPyd.The total density of states(TDOS)shows that after the pre-intercalation of PPyd,an intermediate energy level appears between the valence band and conduction band,which provides a step that can effectively reduce the band gap and enhance the electron conductivity.Furthermore,the density functional theory(DFT)results found that Zn^(2+)is more easily de-intercalated from the V-O skeleton,which proves that the embeddedness of PPyd improves the diffusion kinetics of Zn^(2+).Electrochemical studies have shown that VO-PPyd cathode materials exhibit excellent rate performance(high specific capacity of 465 and 192 mA h g^(-1)at 0.2 and 10 A g^(-1),respectively)and long-term cycling performance(92.7%capacity retention rate after 5300 cycles),due to their advantages in structure and composition.More importantly,the energy density of VO-PPyd//Zn at 581 and 5806 W kg^(-1)is 375 and 247 W h kg^(-1),respectively.VO-PPyd exhibits excellent electrochemical properties compared to previously reported vanadium based cathodes,which makes it highly competitive in the field of high-performance cathode materials of AZIBs.

Solid-state NMR study on sodium intercalation at low voltage window for Na_(3)V_(2)(PO_(4))_(3) as an anode

In-situ XRD,^(31)P NMR and ^(23)Na NMR were used to analyze the interaction behavior of Na_(3)V_(2)(PO_(4))_(3) at low voltage,and then a new intercalation model was proposed.During the transition from Na_(3)V_(2)(PO_(4))_(3) to Na_(4)V_(2)(PO_(4))_(3),Na ions insert into M1,M2 and M3 sites simultaneously.Afterwards,during the transition of Na_(4)V_(2)(PO_(4))_(3)to Na_(5)V_(2)(PO_(4))_(3),Na ions mainly insert into M3 site.

基于Sm^(3+)敏化的红色荧光粉Na_(5)Y(MoO_(4))_(4)∶Eu^(3+)发光性能研究

采用高温固相法制备了一系列新型Na_(5)Y_(1-x)(MoO_(4))_(4)∶x Eu^(3+)(x=0~0.14)和Na_(5)Y_(0.9)-y(MoO_(4))_(4)∶0.1Eu^(3+),y Sm^(3+)(y=0~0.08)红色荧光粉,并对Na_(5)Y_(1-x)(MoO_(4))_(4)∶x Eu^(3+)(x=0~0.14)和Na_(5)Y_(0.9)-y(MoO_(4))_(4)∶0.1Eu^(3+),y Sm^(3+)(y=0~0.08)的物相结构、发光性能、热稳定性、荧光寿命等性能进行了研究。结果表明,在单掺Eu^(3+)的条件下,Na_(5)Y_(1-x)(MoO_(4))_(4)∶x Eu^(3+)(x=0~0.14)荧光粉在395nm紫外光激发下,发射出峰值波长在615nm的强红光,其掺杂浓度为x=0.1,样品的发光强度最高。进一步探究Sm^(3+)对Eu^(3+)在Na_(5)Y_(1-x)(MoO_(4))_(4)∶x Eu^(3+)(x=0~0.14)中的敏化增强作用。通过研究该样品不同Sm^(3+)掺杂浓度下的荧光发射谱,发现Sm^(3+)敏化增强的最佳掺杂浓度为y=0.04;相较于单掺Eu^(3+)的样品,Sm^(3+)敏化后的样品其发光强度为原来的113.8%。Sm^(3+)敏化后的样品存在能量传递现象,能量传递机制为Eu^(3+)与Sm^(3+)之间的电偶极-电偶极相互作用。温度相关荧光发射谱实验结果表明Na_(5)Y_(0.86)(MoO_(4))_(4)∶0.1Eu^(3+),0.04Sm^(3+)具有较好的热稳定性,在437K时荧光发射强度约为室温时的70%左右,而Na_(5)Y_(0.9)(MoO_(4))_(4)∶0.1Eu^(3+)在437K时的荧光发射强度约为室温时的68%左右。因此,Sm^(3+)敏化的Eu^(3+)掺杂Na_(5)Y(MoO_(4))_(4)荧光粉在白光LED领域中具有较大的应用可能性。

Robust Cross-Linked Na_(3)V_(2)(PO_(4))_(2)F_(3) Full Sodium-Ion Batteries

Sodium-ion batteries(SIBs)have rapidly risen to the forefront of energy storage systems as a promising supplementary for Lithium-ion batteries(LIBs).Na_(3)V_(2)(PO_(4))_(2)F_(3)(NVPF)as a common cathode of SIBs,features the merits of high operating voltage,small volume change and favorable specific energy density.However,it suffers from poor cycling stability and rate performance induced by its low intrinsic conductivity.Herein,we propose an ingenious strategy targeting superior SIBs through cross-linked NVPF with multi-dimensional nanocarbon frameworks composed of amorphous carbon and carbon nanotubes(NVPF@C@CNTs).This rational design ensures favorable particle size for shortened sodium ion transmission pathway as well as improved electronic transfer network,thus leading to enhanced charge transfer kinetics and superior cycling stability.Benefited from this unique structure,significantly improved electrochemical properties are obtained,including high specific capacity(126.9 mAh g^(-1)at 1 C,1 C=128 mA g^(-1))and remarkably improved long-term cycling stability with 93.9%capacity retention after 1000 cycles at 20 C.The energy density of 286.8 Wh kg^(-1)can be reached for full cells with hard carbon as anode(NVPF@C@CNTs//HC).Additionally,the electrochemical performance of the full cell at high temperature is also investigated(95.3 mAh g^(-1)after 100 cycles at 1 C at 50℃).Such nanoscale dual-carbon networks engineering and thorough discussion of ion diffusion kinetics might make contributions to accelerating the process of phosphate cathodes in SIBs for large-scale energy storages.

碱金属掺杂对高温固相法制备的CaMoO_(4):Sm^(3+)荧光粉发光性质的影响

在无机发光材料领域里,值得注意的是具有稳定化学及物理性质的优良材料钼酸钙。本次研究使用高温固相法制备一系列单一基质Ca MoO_(4)掺杂Sm^(3+)的白光荧光粉,并使用XRD测试其物相结构,用激发和发射光谱测试发光性能。最终研究发现钼酸钙(CaMoO_(4))中Sm^(3+)掺杂浓度为0.020时,荧光粉发光性能最强。当进一步掺杂碱金属作电荷补偿剂时,CaMoO_(4):0.020Sm^(3+)的发光强度最优异,其中掺杂K^(+)的荧光粉样品具有最大的发光强度,表明这种荧光粉在发光二极管照明方面具有深远而广阔的发展前景。

Interfacial built-in electric field and crosslinking pathways enabling WS_(2)/Ti_(3)C_(2)T_(x) heterojunction with robust sodium storage at low temperature

Developing efficient energy storage for sodium-ion batteries(SIBs)by creating high-performance heterojunctions and understanding their interfacial interaction at the atomic/molecular level holds promise but is also challenging.Besides,sluggish reaction kinetics at low temperatures restrict the operation of SIBs in cold climates.Herein,cross-linking nanoarchitectonics of WS_(2)/Ti_(3)C_(2)T_(x) heterojunction,featuring built-in electric field(BIEF),have been developed,employing as a model to reveal the positive effect of heterojunction design and BIEF for modifying the reaction kinetics and electrochemical activity.Particularly,the theoretical analysis manifests the discrepancy in work functions leads to the electronic flow from the electron-rich Ti_(3)C_(2)T_(x) to layered WS_(2),spontaneously forming the BIEF and“ion reservoir”at the heterogeneous interface.Besides,the generation of cross-linking pathways further promotes the transportation of electrons/ions,which guarantees rapid diffusion kinetics and excellent structure coupling.Consequently,superior sodium storage performance is obtained for the WS_(2)/Ti_(3)C_(2)T_(x) heterojunction,with only 0.2%decay per cycle at 5.0 A g^(-1)(25℃)up to 1000 cycles and a high capacity of 293.5 mA h g^(-1)(0.1A g^(-1)after 100 cycles)even at-20℃.Importantly,the spontaneously formed BIEF,accompanied by“ion reservoir”,in heterojunction provides deep understandings of the correlation between structure fabricated and performance obtained.

基于Mg^(2+)电荷补偿的红色荧光粉Sr_(2)Ga_(2)GeO_(7):0.02 Sm^(3+)的可控光学调谐

为进一步改善红光荧光粉Sr_(2)Ga_(2)GeO_(7):0.02Sm^(3+)(SGGOS)的光谱性能和白光应用特性,以Mg^(2+)为电荷补偿离子对样品进行光学调谐,并通过高温固相法合成了一系列红光荧光粉Sr_(2)Ga_(2)GeO_(7):0.02Sm^(3+),x Mg^(2+)(0≤x≤0.12)。研究结果表明,Mg^(2+)可以成功引入样品SGGOS中并取代Ga^(3+),样品的晶粒尺寸约为1~10μm。荧光测试结果表明,Mg^(2+)可以增强激活离子Sm^(3+)的电荷传输效率,进而显著提升样品的荧光发射(PL)强度。此外,当Mg^(2+)的掺杂量为0.08时,样品Sr_(2)Ga_(2)GeO_(7):0.02Sm^(3+),0.08 Mg^(2+)(SGGOSM)的荧光发射强度最大。与参比样品SGGOS相比,荧光粉SGGOSM的光学带隙(E_(g))变大、色纯度提升、热稳定性增强,进而有效改善其在白光器件中的电致发光性能。基于SGGOSM为红光组分的白光器件(WLED)的显色指数(R_(a))高达90.5,色温(CCT)低至3563 K,与实验预期吻合,实现了Sm^(3+)掺杂红光荧光粉Sr_(2)Ga_(2)GeO_(7):0.02Sm^(3+)的有效光谱调控,为高R_(a)、低CCT类白光器件的研究提供了一定的实验和理论依据。

新型红色荧光粉Sr_(3)CaNb_(2)O_(9):Sm^(3+),Eu^(3+)的发光特性和能量传递分析

利用高温固相反应法制备一系列单基质荧光粉Sr_(3)CaNb_(2)O_(9):xSm^(3+),yEu^(3+)(x=0.04~0.09,y=0.03~0.15),并对样品的物相形貌、发光性能、能量传递机制和CIE色坐标进行分析。研究表明,Sr_(3)CaNb_(2)O_(9):xSm^(3+)荧光粉在激发波长为407 nm时的浓度淬灭点为x=0.07。在Sr_(3)CaNb_(2)O_(9):0.07Sm^(3+),yEu^(3+)荧光粉中,随着Eu^(3+)掺杂浓度的增加,Sm^(3+)的发光强度降低而Eu^(3+)发光强度却先增加后降低,Eu^(3+)的浓度淬灭点为y=0.09。Sm^(3+)→Eu^(3+)的能量传递以电偶极-电偶极相互作用为主,能量传递效率达到76.6%。色坐标图表明Eu^(3+)离子的加入可使色坐标从橙红色区域向纯红色区域移动。此外,样品还具有较高的色纯度和较低的色温。结果表明,Sr_(3)CaNb_(2)O_(9)∶Sm^(3+),Eu^(3+)荧光粉有望成为白光LED发出红光物质的候选材料。

GdPO_(4):Sm^(3+)荧光粉的焙烧温度和掺杂浓度的优化及发光和磁性能

以GdPO_(4)为基质,Sm^(3+)为激活剂,采用水热法合成了纳米荧光粉前驱体,分别在800、900、1000、1100和1200℃下焙烧,得到一系列GdPO_(4):Sm^(3+)荧光粉。首先探究了GdPO_(4):Sm^(3+)的最佳焙烧温度;其次研究了Sm^(3+)掺杂浓度对GdPO_(4):Sm^(3+)荧光性能的影响;最后研究了GdPO_(4):2%Sm^(3+)的高温荧光性能和磁性能。使用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、磁强计和荧光分光光度计(FL)对荧光粉的晶体结构、形貌、发光和磁性能进行了表征。结果表明:荧光粉的晶体结构由前驱体六方晶系GdPO_(4)·H_(2)O:Sm^(3+)变为单斜晶系的GdPO_(4):Sm^(3+),形貌由纳米棒变为无规则块体。当焙烧温度为1000℃,Sm^(3+)掺杂浓度为2%时,荧光粉的发光强度和荧光寿命达到最大值。GdPO_(4):2%Sm^(3+)中Sm^(3+)之间能量传递类型为电偶极-电偶极相互作用,能量传递的临界距离为1.646~1.884 nm。最佳样品Gd PO_(4):2%Sm^(3+)有优异的热稳定性,热猝灭活化能为-0.157 eV,且具有良好的顺磁性,质量磁化率为1.22×10^(-4)emu·g^(-1)·Oe^(-1)。

Sm^(3+)掺杂0.96Na_(0.5)Bi_(0.5)TiO_(3)-0.04CaTiO_(3)陶瓷的制备及光致发光性能研究

采用固相烧结法制备了一系列Sm^(3+)掺杂0.96Na_(0.5)Bi_(0.5)TiO_(3)-0.04CaTiO_(3)(NBT-0.04CT∶xSm^(3+),0.002≤x≤0.020)无铅陶瓷。通过X射线衍射仪表征样品的物相结构,所有样品均呈现单一钙钛矿结构。用荧光光谱仪测量样品的发光性能,样品在479 nm处激发峰最强,可与白光LED合成中使用的蓝色LED芯片相匹配。发射主峰位于597 nm(^(4)G_(5/2)→^(6)H_(7/9)),呈现强橙红色发光。NBT-0.04CT∶0.010Sm^(3+)陶瓷在Sm^(3+)掺杂NBT-0.04CT陶瓷中的发光性能最佳,且在278~473 K陶瓷样品的发光性能呈现良好的热稳定性。结果表明,NBT-0.04CT∶xSm^(3+)陶瓷在白光LED中具有广阔的应用前景。