Gd^(3+)掺杂调控BiFeO_(3)-BaTiO_(3)高温无铅压电陶瓷的结构与性能

用于监测航空发动机、重型燃气轮机等重大技术装备高温部件振动状态的压电加速度传感器,需要一种高居里温度压电陶瓷作为敏感元件,而电子元器件的无铅化是环境保护的迫切要求。采用传统的固相反应法制备一种Gd/Mn共掺杂的BF-BT((0.67BiFeO_(3)-0.33Ba_(1-x)Gd_(x)TiO_(3))+0.5%(质量分数)MnO_(2),x=0~0.02)高温无铅压电陶瓷,并研究Gd^(3+)掺杂浓度(x)对BF-BT陶瓷的相组成、微观结构、压电性能、介电弛豫行为及交流阻抗特征的影响。结果表明:所有样品均为单一钙钛矿结构,三方相(R)和四方相(T)共存,且T相含量随x增加而增加;适量的Gd^(3+)(x<0.02)固溶进入钙钛矿点阵之中能够促进BF-BT陶瓷晶粒的生长。掺杂Gd^(3+)的样品表现出增强的弛豫相变行为,相变温度(T_m)随x的增加而减小,而介电弛豫程度(ΔT_(relax))随x的增加而增大。采用R-CPE等效电路模型对BF-BT陶瓷的高温复阻抗谱(Cole-Cole图)进行拟合分析,发现样品在高温下的交流阻抗主要来自晶界的贡献。并且随着Gd^(3+)掺杂浓度的提高,样品的介电弛豫激活能不断增大,证实Gd^(3+)取代Ba^(2+)减少了晶格中氧空位浓度的施主掺杂效应。综合来看,x=0.01的样品具有最优的电学性能:T_(C)=425℃,d_(33)=126 pC/N,k_(p)=25.9%,tanδ=0.059,有望作为一种合适的高温压电材料被应用。

Defect engineering on BiFeO_(3) through Na and V codoping for aqueous Na-ion capacitors

Sodium with low cost and high abundance is considered as a substitute element of lithium for batteries and supercapacitors,which need the appropriate host materials to accommodate the relatively large Na^(+) ions.Compared to Li^(+) storage,Na^(+) storage makes higher demands on the structural optimization of perovskite bismuth ferrite(BiFeO_(3)).We propose a novel strategy of defect engineering on BiFeO_(3) through Na and V codoping for high-efficiency Na^(+) storage,to reveal the roles of oxygen vacancies and V ions played in the enhanced electrochemical energy storage performances of Na-ion capacitors.The formation of the oxygen vacancies in the Na and V codoped BiFeO_(3)(denoted as NV-BFO),is promoted by Na doping and suppressed by V doping,which can be demonstrated by XPS and EPR spectra.By the first-principles calculations,the oxygen vacancies and V ions in NV-BFO are confirmed to substantially lower the Na^(+)migration energy barriers through the space and electric field effects,to effectively promote the Na^(+) transport in the crystals.Electrochemical kinetic analysis of the NV-BFO//NV-BFO capacitors indicates the dominant capacitive-controlled capacity,which depends on fast Na^(+) deintercalation-intercalation process in the NV-BFO electrode.The NV-BFO//NV-BFO capacitors open up a new avenue for developing highperformance Na-ion capacitors.

O-doping strategy enabling enhanced chemical/electrochemical stability of Li_(3)InCl_(6) for superior solid-state battery performance

Solid-state electrolytes with high oxidation stability are crucial for achieving high power density allsolid-state lithium batteries.Halide electrolytes are promising candidates due to their outstanding compatibility with cathode materials and high Li^(+)conductivity.However,the electrochemical stability of chloride electrolytes is still limited,leaving them unsuitable for ultrahigh voltage operation.Besides,chemical compatibility issue between sulfide and halide electrolytes affects the electrochemical performance of all-solid-state batteries.Herein,Li-ion conductor Li_(3+x)InCl_(6-x)O_(x) is designed to address these challenges.Li_(3.25)InCl_(5.75)O_(0.25)shows a Li-ion conductivity of 0.90 mS cm^(-1)at room temperature,a high onset oxidation voltage of 3.84 V,fewer by-products at ultrahigh operation voltage,and good chemical compatibility with Li_(5.5)PS_(4.5)Cl_(1.5).The Li_(3.25)InCl_(5.75)O_(0.25)@LiNi_(0.7)Co_(0.1)Mn_(0.2)O_(2)-Li_(3.25)InCl_(5.75)O_(0.25)-VGCF/Li_(3.25)InCl_(5.75)O_(0.25)/Li_(5.5)PS_(4.5)Cl_(1.5)/Li-In battery delivers good electrochemical performances at high operating voltage.This work provides a simple,economical,and effective strategy for designing high-voltage all-solid-state electrolytes.

Enhancing potassium-ion storage of Bi_(2)S_(3) through external–internal dual synergism: Ti_(3)C_(2)T_(x) compositing and Cu^(2+) doping

Potassium-ion batteries(PIBs)offer a cost-effective and resource-abundant solution for large-scale energy storage.However,the progress of PIBs is impeded by the lack of high-capacity,long-life,and fast-kinetics anode electrode materials.Here,we propose a dual synergic optimization strategy to enhance the K^(+)storage stability and reaction kinetics of Bi_(2)S_(3) through two-dimensional compositing and cation doping.Externally,Bi_(2)S_(3) nanoparticles are loaded onto the surface of three-dimensional interconnected Ti_(3)C_(2)T_(x) nanosheets to stabilize the electrode structure.Internally,Cu^(2+)doping acts as active sites to accelerate K^(+)storage kinetics.Various theoretical simulations and ex situ techniques are used to elucidate the external–internal dual synergism.During discharge,Ti_(3)C_(2)T_(x) and Cu^(2+)collaboratively facilitate K+intercalation.Subsequently,Cu^(2+)doping primarily promotes the fracture of Bi2S3 bonds,facilitating a conversion reaction.Throughout cycling,the Ti_(3)C_(2)T_(x) composite structure and Cu^(2+)doping sustain functionality.The resulting Cu^(2+)-doped Bi2S3 anchored on Ti_(3)C_(2)T_(x)(C-BT)shows excellent rate capability(600 mAh g^(-1) at 0.1 A g^(–1);105 mAh g^(-1) at 5.0 A g^(-1))and cycling performance(91 mAh g^(-1) at 5.0 A g^(-1) after 1000 cycles)in half cells and a high energy density(179 Wh kg–1)in full cells.

Synthesis and Luminescence Properties of(Y, Gd)(P, V)O_4:Eu^(3+), Bi^(3+) Red Nano-phosphors with Enhanced Photoluminescence by Bi^(3+), Gd^(3+) Doping

A series of(Y_(1-y), Gdy)_(0.95-x)(P_y, V_(1-y))O_4 :0.05Eu^(3+), xBi^(3+)+phosphors have been successfully prepared by a subsection method. The crystal structure, surface morphology and luminescence properties were investigated. It was found that the sintered samples crystallized in a tetragonal crystal system with space group I_(41)/amd(a = b = 0.7119 nm, c = 0.6290 nm). The products presented rod-like morphology with length of 100-150 nm and width of 50-100 nm. A maximum peak at 619 nm(~5D_0 →~7F_2) was observed in emission spectrum of the phosphors. It was also found that co-doping of Bi^(3+)+, P5+and Gd^(3+)ions into YVO_4:Eu^(3+)can not only made the right edge of the excitation band shift to the long-wavelength region, but also increased the emission intensity at 619 nm sharply and decreased the lifetime of fluorescence decay. These results may expand the application scope of the phosphors.

Gd^(3+)/Ce^(3+)对Tb^(3+)掺杂氟氧化物玻璃发光敏化作用的影响

本文采用高温熔融法制备了Gd/Tb、Gd/Ce、Gd/Ce/Tb掺杂的SiO_(2)-B_(2)O_(3)-BaF_(2)组分氟氧化物玻璃,通过测试X射线衍射光谱确定了其物相,通过测试其不同波段激发下的荧光光谱研究了不同Gd_(2)O_(3)掺量下Tb^(3+)的发光性能,并确定了Gd_(2)O_(3)更精确的最佳掺量范围。此外,文中通过改变气氛制备了Gd/Ce/Tb共掺杂氟氧化物玻璃,对比研究了Gd^(3+)和Ce^(3+)对Tb^(3+)的敏化作用。结果表明,本文所制备的氟氧化物玻璃都呈稳定的玻璃态;Gd^(3+)和Ce^(3+)对Tb^(3+)的发光都具有敏化作用,且Gd_(2)O_(3)掺量为7%(摩尔分数,下同)时敏化效果相较于其他掺量最为显著,超出7%则造成猝灭;Ce_(2)O_(3)掺入玻璃后以Ce^(3+)和Ce^(4+)两种价态共存,在还原气氛下掺入相较于空气气氛下掺入更容易保持Ce^(3+)状态,而且Ce^(3+)对Tb^(3+)的发光具有敏化作用,Ce^(4+)会抑制Tb^(3+)的发光。

Effects of Doping Trace Sm^(3+) and Gd^(3+) on Luminescent Character of Y_2O_2S∶Eu^(3+)

After trace Sm^3＋ ions and Gd^3＋ ions doping, the emission intensity of red phosphors Y2O2S： Eu^3 ＋ was enhanced and the voltage character （relation between emission intensity and excitation voltage） was improved while the other properties of physics and chemistry were not changed. The origins of enhancement and improvement are discussed. Probably the distortion and the defect of crystals are decreased by the substitution of Gd^3＋ for Y^3＋ instead of Eu^3＋ for Y^3＋ , and thus the Eu^3＋ crystal field is improved, and radiationless process and energy loss resulted from crystal defect are weakened, which leads to increased luminescence intensity and voltage character improvement. The overlapping fluorescent spectra of Y2O2S： Sm^3＋ emission and Y2O2S：Eu^3＋ excitation as well as Eu^3 ＋ excitation spectra transitions spectra lead to energy transfer from Sm^3 ＋ sensitization of Sm^3＋ ions fectively. containing Sm^3＋ excitation the possibility of resonance ions to Eu^3＋ ions, and the to Eu^3＋ ions is achieved effectively.

Gd^(3+)掺杂TiO_2纳米粉体的晶粒尺寸、表面特性和光催化活性

利用酸催化的溶胶-凝胶法制备了纯的和不同Gd3+掺杂量的TiO2纳米粉体,并用XRD、BET、XPS、SPS等技术对样品进行了表征.研究了Gd3+掺杂量和焙烧温度对样品光催化降解亚甲基蓝的活性、相结构、晶粒尺寸和表面织构特性的影响,并结合表面光电特性和表面组成等探讨了Gd3+掺杂对纳米TiO2的光催化活性的影响机制.结果表明:与纯TiO2相比,适量掺杂Gd3+可以显著提高其光催化活性.当Gd3+掺杂量为0·5%(质量),焙烧温度为500℃时,TiO2复合纳米粉体的光催化活性最佳,其锐钛矿含量为100%,平均晶粒粒径为15·55nm,比表面积为12·81m2·g-1.Gd3+掺杂强烈地抑制TiO2由锐钛矿相向金红石相的转变,减小晶粒尺寸,提高光响应阈值,这三方面均有利于提高光催化活性.XPS分析表明,Gd3+掺杂导致TiO2纳米粉体的表面羟基含量降低.

九配位Sm^(3+),Eu^(3+)和Gd^(3+)与EDTA配合物的合成及结构研究

详细报道了Sm3+,Eu3+和Gd3+分别与乙二胺四乙酸(EDTA)配体形成配合物的合成及结构测定。通过单晶X-射线衍射仪和元素分析的测定,确定了这些配合物的结构都是以Sm3+,Eu3+和Gd3+为中心的九配位单帽四方反棱柱体结构,组成分别为Na[Sm(EDTA)(H2O)3]·5H2O,Na[Eu(EDTA)(H2O)3]·4H2O和Na[Gd(EDTA)(H2O)3]·5H2O。

BaMgF_4中Gd^(3+)的光谱以及Gd^(3+)和Tb^(3+)离子之间的能量传递

本文在室温下研究了BaMgF_4氟化物中Gd^(3+)和Tb^(3+)离子的荧光光谱以及它们之间的能量传递。在BaMgF_4中Gd^(3+)可以直接将激发能传递给Tb^(3+)离子:在Tb^(3+)(4f^75d)-Gd^(3+)(4f)-Tb^(3+)(4f^8)能量输运过程中,Gd^(3+)离子可起中间体作用。

PT-28在硝酸体系中萃取Y^(3+)和Gd^(3+)的性能研究

探讨了PT-28在硝酸体系中对Y3+和Gd3+的萃取行为,发现其萃取机理不同,温度的影响和萃取反应方程式有显著差异,找到了利用温度和酸度可以分离Y3+和Gd3+的条件。

多孔二氧化硅中Gd^(3+)→Eu^(3+)的能量传递

通过水热反应法,获得了单掺和双掺Eu3+,Gd3+的多孔二氧化硅组装体,研究了掺杂体系的光谱特性,观察到Gd3+→Eu3+的能量传递。分析了能量传递过程,探讨了在多孔二氧化硅中Gd3+→Eu3+的能量传递的机理,其机理主要为电偶极鄄电偶极相互作用。

稀土Gd^(3+)的掺杂对Sr_2CeO_4∶Eu中Eu^(3+)发光的影响

采用共沉淀方法,合成了Gd3+和Eu3+共掺杂的Sr2CeO4荧光体.当Eu3+浓度较小(掺杂浓度为2%)时,Gd3+离子对Sr2CeO4的蓝带发射及附着在其上面的Eu3+的特征跃迁起猝灭作用;而当Eu3+的浓度较高(掺杂浓度为8%)时,Gd3+离子对Sr2CeO4的蓝带发射及附着在其上面的Eu3+的特征跃迁起敏化作用,尤其是当Gd3+离子的掺杂浓度为3%时,Eu3+的5D0-7F2跃迁发射(615nm)增强为原来的132%.

Gd^(3+)、Sm^(3+)共激活La_2O_2S:Eu^(3+)的发光特性

利用高温固相反应法合成了La2O2S:Eu3+及La2O2S:Eu3+、Sm3+、Gd3+荧光粉,并对其进行了表征。X射线衍射测试结果表明,合成样品为La2O2S纯物相,激光粒度分析测得荧光粉的平均粒径为18μm。光谱测试表明,Sm3+、Gd3+的掺入能有效增强Eu3+的627nm发射强度,所合成的(La0.945Gd0.01Sm0.005Eu0.03)2O2S荧光粉是一种具有应用前景的红色光致发光材料。

Effect of Mn-doping on performance of Li_3V_2(PO_4)_3/C cathode material for lithium ion batteries

Li3V2-2/3xMnx（PO4）3（0≤x≤0.12） powders were synthesized by sol-gel method. The effect of Mn2＋-doping on the structure and electrochemical performances of Li3V2（PO4）3/C was characterized by XRD, SEM, XPS, galvanostatic charge /discharge and electrochemical impedance spectroscopy（EIS）. The XRD study shows that a small amount of Mn2＋-doped does not alter the structure of Li3V2（PO4）3/C materials, and all Mn2＋-doped samples are of pure single phase with a monoclinic structure （space group P21/n）. The XPS analysis indicates that valences state of V and Mn are ＋3 and ＋2 in Li3V1.94Mn0.09（PO4）3/C, respectively, and the citric acid in raw materials was decomposed into carbon during calcination, and residual carbon exists in Li3V1.94Mn0.09（PO4）/C. The results of electrochemical measurements show that Mn2＋-doping can improve the cyclic stability and rate performance of these cathode materials. The Li3V1.94Mn0.09（PO4）3/C cathode material shows the best cyclic stability and rate performance. For example, at the discharge current density of 40 mA/g, after 100 cycles, the discharge capacity of Li3V1.94Mn0.09（PO4）3/C declines from initial 158.8 mA·h/g to 120.5 mA·h/g with a capacity retention of 75.9%; however, that of the Mn-undoed sample declines from 164.2 mA·h/g to 72.6 mA·h/g with a capacity retention of 44.2%. When the discharge current is increased up to 1C, the intial discharge capacity of Li3V1.94Mn0.09（PO4）3/C still reaches 146.4 mA·h/g, and the discharge capacity maintains at 107.5 mA·h/g after 100 cycles. The EIS measurement indicates that Mn2＋-doping with a appropriate amount of Mn2＋ decreases the charge transfer resistance, which is favorable for the insertion/extraction of Li＋.

GdB_3O_6中Gd^(3+)的级联发射特性

报道了Gd3 + 离子在GdB3 O6基质中的光子级联发射特性。用HitachiM85 0荧光分光光度计测定了Gd3 + 6GJ能态的位置和Gd3 + 离子的光子级联发射光谱 ,Gd3 + 离子的第一个光子发射为6GJ→6PJ(～ 6 0 0nm)和6GJ→6IJ(～ 780nm) ,第二个光子的发射为6PJ→8S7/ 2 (～ 310nm)。由于6D9/ 2 与6I11/ 2 间能级差 (～ 2 90 0cm-1)和6I7/ 2 与6PJ间能级差 (～ 390 0cm-1)较小 ,多声子弛豫的几率明显超过辐射跃迁几率。因此 ,当用8S7/ 2 →6GJ(2 0 2nm)的紫外光激发时 ,只能观察到6PJ→8S7/ 2 (～ 310nm)、6GJ→6PJ(～ 6 0 0nm)和6GJ→6IJ(～ 780nm)的发射跃迁 ,未能观察到6IJ→8S7/ 2 (～ 2 75nm)和6DJ→8S7/ 2 (～ 2 5 0nm)

Gd^(3+)掺杂TiO_2纳米复合材料的可见光响应性能

采用溶胶-凝胶技术,在钛酸四丁酯(TBOT)的水解过程中,加入硝酸钆(Gd(NO3)3),得到具有可见光响应活性的Gd3+/TiO2复合材料。应用TEM、XRD、TG-DTA和UV-Vis等手段对纳米TiO2复合材料进行了表征。当Gd3+的掺杂量为0.5%时,Gd3+/TiO2复合材料在550 nm附近产生宽强吸收带。Gd3+进入TiO2晶格中,形成了新的掺杂能级(Eg=1.27 eV)。适量Gd3+掺杂的纳米TiO2复合材料的光催化性能优于纯TiO2粉体材料。

白光LED用红色荧光粉Ca0.7Sr0.18-0.15xMoO4:Eu^3+0.08:Gd^3+x水热合成与发光性能研究

采用水热合成法以Gd^3+掺杂,Eu^3+为激活剂和谷氨酸(Glu)为辅助配位剂制备了荧光粉前驱体,并在800℃高温下焙烧得到了同一体系多种红色荧光粉:CaSrMoO4:Eu^3+:Gd^3+。采用X射线衍射谱(XRD)、扫描电子显微镜(SEM)、X射线能谱(EDS)和X射线光电子能谱(XPS)等多手段,并系统的分析了红色荧光粉的结构、形貌和组成,并且通过荧光光谱(PL)测试了样品的发光性能和荧光寿命,在此结果上进行了色坐标(CIE)分析。结果表明,制备的红色荧光粉的尺寸随着Gd^3+的引入实现与Eu^3+之间的能量交换,掺杂Gd^3+离子对晶质晶体结构影响不大,且晶体为四方正八面体晶系结构,粒度分布均匀且粒径较小,约在1.0~1.3μm之间。在395 nm的紫外光有效激发,与紫外光LED和芯片相匹配,其荧光寿命为460.67 ms。色坐标测试结果接近标准红色色坐标,并且符合我国彩电荧光粉的标准要求,接近美国NTSC标准值,有望商品化。

微波辐射稀土复合固体超强酸SO_4^(2-)/ZrO_2/Gd^(3+)催化合成环己酮乙二醇缩酮

以环己酮和乙二醇为原料,稀土复合固体超强酸SO_4^(2-)/ZrO_2/Gd^(3+)为催化剂,在微波辐射和无溶剂下,合成环己酮乙二醇缩酮。探讨了酮醇物质的量比、催化剂用量、微波功率和辐射时间对产品收率的影响。结果表明,环己酮乙二醇缩酮的最佳合成条件为:n(环己酮):n(乙二醇)=1:3.0,催化剂用量为反应物总质量的1.50%,微波功率为425W,辐射时间为10min。在此条件下,缩酮收率可达90.4%,说明稀土复合固体超强酸SO_4^(2-)/ZrO_2/Gd^(3+)是一种合成环己酮乙二醇缩酮的优良催化剂。

稀土固体超强酸Gd^(3+)-SO_4^(2-)/ZrO_2催化剂的制备及表征

研究以氨水、氧氯化锆和氧化钆为原料,用沉淀法制得锆的氢氧化物,经陈化、过滤、烘干、浸渍后高温焙烧,制备出Gd3+-SO42-/ZrO2稀土固体超强酸.用Hammett指示剂法测定其酸强度,用FT-IR对其进行表征.