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.

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.

Gd^(3+)取代及十二面体空位对石榴石铁氧体高功率低损耗特性的影响

采用传统陶瓷工艺制备足量和缺量Gd^(3+)取代的钇铁石榴石铁氧体,研究通过缺量Gd^(3+)取代在十二面体位(24c)引入空位对材料显微结构、饱和磁化强度、铁磁共振线宽、自旋波线宽、居里温度、电阻率等性能的影响。研究表明,24c空位可促进了烧结阶段的致密化过程和晶粒生长。通过适量引入24c空位,铁磁共振线宽从154 Oe减小到64 Oe,自旋波线宽从9.7 Oe提高到24.4 Oe。空位的存在还增强了16a位与24d位Fe^(3+)之间的超交换作用,提高了材料的居里温度。另外,空位对铁氧体材料电阻率影响不大,使其具备优异的介电性能。

Gd^(3+)和In^(3+)联合取代对石榴石铁氧体高功率低损耗特性的影响

采用传统陶瓷工艺制备Gd^(3+)和In^(3+)取代的钇铁石榴石铁氧体,研究Gd^(3+)和In^(3+)取代对材料显微结构、饱和磁化强度、铁磁共振线宽、自旋波线宽、电阻率等性能的影响。研究表明,Gd^(3+)取代24c位的Y^(3+),对样品显微结构、居里温度和电阻率无明显影响。随着Gd^(3+)取代量的增加,自旋波线宽从9.7 Oe提高到21.7 Oe。为了降低石榴石铁氧体损耗,采用适量的In^(3+)取代16a和24d位的Fe^(3+),铁磁共振线宽从198 Oe减小到95 Oe。此外,In^(3+)取代对石榴石铁氧体的电阻率、介电常数和介电损耗影响不大,使其保持良好的介电性能。

Gd^(3+)掺杂对白光LED用Y_(2.88)Al_(5)O_(12):Ce^(3+)荧光粉性能的影响

采用化学共沉淀法一次煅烧工艺制备了Y_(2.88-x)Gd_(x)Al_(5)O_(12):0.06Ce^(3+)(x=0~0.5)系列荧光粉,研究了Gd^(3+)掺杂对制备的荧光粉样品的晶体结构、发光性能和光色性能的影响。研究结果表明:Gd^(3+)掺杂没有改变样品晶体结构,晶胞参数先减小后增大;其激发光谱分布在320~520 nm,激发峰位于340 nm和450 nm处,可被蓝光InGaN芯片有效激发;在450 nm蓝光激发下,发射光谱强度先增大后减小,光谱峰位从533 nm红移到542 nm,色坐标点向白光坐标曲线移动。

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.

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。

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)

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。

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。

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.

Gd^(3+)对Ca_(0.8)Zn_(0.2)TiO_3:Pr^(3+)红色发光材料的敏化作用

采用溶胶-凝胶法在较低温度下合成了红色发光材料C a0.8Zn0.2T iO3:0.002P r3+,xG d3+。金属离子预先溶解含有柠檬酸的乙二醇溶液中。XRD表明在800℃灼烧2h形成了钛酸盐的晶体。荧光检测结果表明所合成样品的特征激发峰为330nm、特征发射峰为614nm,分别对应于O(2p)→T i(3d)带间跃迁和P r3+的1D2→3H4的特征发射。样品的发光强度随x的不同而不同,发光强度增强了29%—69%。当x=0.0005时,即nP r3+:nG d3+=4∶1时样品的红色发光强度最强,发光强度增强了69%。

HPMBP-P507-TBP三元协萃Gd^(3+)

本文研究1-苯基3-甲基4-苯甲酰吡唑啉酮-5HPMBP)、2-乙基己基膦酸2-乙基己基酯(P507)与磷酸三丁酯(TBP)的甲苯溶液,从高氯酸底液中萃取钆机理。实验发现Gd^(3+)有三元协萃效应。该体系属于螯合中性络合AAB类协萃体系。其一元、二元和三元萃取平衡常数分别为lgβ_1=-4.24(HPMBP),lgβ_1=-2.88(生成Gd(PMBP)_3(HBMBP));lgβ_(12)=-1.04(HPMBP-P507);lgβ_(13)=-0.316(HPMBP-TBP);lgβ_(13)=1.87(生成Gd(PMBP)_3·2TBP);lgβ_(123)=1.04(HPMBP-P507-TBP)。

壳-芯结构Gd^(3+)掺杂BaTiO_3/网状PPy吸波材料的性能研究

采用溶胶-凝胶法(sol-gel)制备了Gd3+掺杂钛酸钡纳米粉体,借助XRD、SEM及矢量网络分析仪等分析测试手段对试样晶相、颗粒粒径、表面形貌及吸波特性进行了研究。结果表明:煅烧温度为1 150℃可获得Gd3+掺杂钛酸钡,是顺电相与铁电相的混合相,Gd3+掺杂钛酸钡可产生间隙杂质能级及电偶极子畴壁共振和弛豫共振的改变,影响吸收特性;网状结构的PPy微观具有更大的离域空间,利于形成导电链和局部导电网络,提高导电率,促进电磁波损耗;Gd3+掺杂BaTO3/PPy复合材料,在5.25 GHz左右有最大回损-32 dB,小于-5 dB的频宽达到1.70 GHz。