(Ce, La)yFe1.0Co3.0Sb12热电化合物的固相反应合成及性能研究

研究了以Co，Sb，Fe及稀土Ce，La为起始原料，采用固相反应-放电等离子烧结(SPS)技术合成二元稀土填充式Skutterudite化合物(Ce，La)yFexCo4-xSb12(x=1．0，y=0—0．3)，并对化合物的热电性能进行了研究。实验结果表明：在y=0—0．3组成范围内，采用固相反应-SPS法在900-1000K温度范围内合成了(Ce，La)yFexCo4-xSb12化合物，并伴有极少量的Sb相。(Ce，La)，FexCo4-xSb12化合物呈现P型传导，化合物的晶格常数和Seebeck系数随Ce，La复合填充分数y的增加而增加，电导率和热导率由于Ce，La的复合填充大幅度降低，并且随着填充分数的增加进一步降低。当Ce，La复合填充分数为0．3时热导率达到最小值。在773K，富Co组成Ce0.1La0．2FeCo3Sb12化合物的最大无量纲热电性能指数ZTmax达0．46。     

填充式skutterudite化合物(Ce或Y)yFexCo4-x-Sb12的固相反应合成及填充原子Ce或Y对晶格热导率的影响

研究了以Sb, Co, Fe, 及Ce和Y的氯化物为起始原料, 用固相反应法合成填充式skutterudite化合物(Ce或Y)yFexCo4-xSb12的可能性和合成条件, 在 850～1 123 K温度及x = 0～1.0, y = 0～0.15组成范围内, 用固相反应法合成了单相的(Ce或Y)yFexCo4-xSb12化合物. Rietveld结构解析结果证明了固相反应法所得到的化合物(Ce或Y)yFexCo4?xSb12具有填充式skutterudite结构. (Ce或 Y)yFexCo4-xSb12化合物的Rietveld结构解析所得到的Ce或Y的填充分数与化学分析所得到的组成一致. 化合物的晶格常数随着在Co原子位置Fe置换量的增加及在skutterudite结构中的Sb二十面体空位上Ce的填充而明显增大. (Ce或 Y)yFexCo4-xSb12化合物的晶格热导率随着Ce 或Y原子在空位上的填充及在Co原子位置Fe的置换而大幅度下降.     

NdxCoSb1化合物的快速合成及其热电性能研究

采用机械合金化和放电等离子烧结(MA-SIS)技术成功合成了NdxCo4Sb12化合物热电材料。借助于先进的结构和性能表征手段，系统研究了NdxCo4Sb12化合物成相和热电性能。实验结果表明，NdxCo4Sb12化合物中稀土Nd的最佳添加量为x=1．0。Nd1.00Co4Sb12化合物具有较高的热电性能，其中在400℃时具有最大ZT，值0．265。     

NdxCo4Sb12化合物的快速合成及其热电性能研究

采用机械合金化和放电等离子烧结(MA-SPS)技术成功合成了NdxCo4Sb12化合物热电材料. 借助于先进的结构和性能表征手段, 系统研究了NdxCo4Sb12化合物成相和热电性能. 实验结果表明, NdxCo4Sb12化合物中稀土Nd的最佳添加量为x=1.0. Nd1.0Co4Sb12化合物具有较高的热电性能, 其中在400 ℃时具有最大ZT值0.265.     

巡游电子系化合物La0.8Ce0.2(Fe1-xCox)11.4Si1.6的磁热效应

对制备的化合物La0.8Ce0.2(Fe1-xCox)11.4Si1.6(x=0.02,0.04,0.06)的相组成、巡游电子变磁转变(IEMT)特性和磁热效应(MCE)进行了研究。粉末X射线衍射结果表明,经1373 K真空退火处理7 d后,化合物La0.8Ce0.2(Fe1-xCox)11.4Si1.6(x=0.02,0.04,0.06)均为单相立方NaZn13型晶体结构。随着Co含量由x=0.02增加到x=0.06,样品的居里温度TC由207 K上升到277 K。在0~1.5 T磁场变化下,x=0.02,0.04,0.06时样品的最大磁熵变|ΔSM(T)|分别为40.17,12.60和7.65 J.kg-1.K-1,可见该化合物有巨大的磁熵变,而且随Co含量的增加最大磁熵变迅速减小。该化合物的巨大磁熵变来源于TC处的一级相变,以及在TC以上由磁场诱导IEMT,但由于Co原子对Fe原子的替代能够抑制变磁转变的发生,因此该系化合物最大磁熵变随Co含量的增加迅速减小。     

Solid state reaction synthesis of filled skutterudite compounds (Ce or Y)yFexCo4-xSb12 and the effect of filling atoms Ce or Y on lattice thermal conductivity

The synthesis of filled skutterudite compounds (Ce or Y)_y(Fe)_x(Co)_(4x)(Sb)_(12), through a solidstate reaction using chloride of Ce or Y,high purity powder of Co, Fe, and Sb as starting materials,was investigated. (Ce or Y)_y(Fe)_x(Co)_(4x)(Sb)_(12) (x=0--1.0, y=0--0.15) compounds were obtained at850--1 123 K. The results of Rietveld analysis demonstrate that (Ce or Y)_y(Fe)_x(Co)_(4x)(Sb)_12synthesized by a solid state reaction possesses a filled skutterudite structure. The filling fraction ofCe or Y obtained by Rietveld analysis agrees well with the composition obtained by chemicalanalysis. The lattice constant of (Ce)_y(Fe)_x(Co)_(4x)(Sb)_(12) increases with increasing substitution of Fe at Cosites, and with an increasing Ce filling fraction in the Sb-dodecahedron voids. The lattice thermalconductivity of (Ce or Y)_y(Fe)_x(Co)_(4x)(Sb)_(12) decreases significantly with an increasing Ce or Y fillingfraction in the voids and with substitution of Fe at Co sites.     

Sm2Fe17N3晶体的价电子结构分析和结合能、最强键能计算

由EET理论直接建立了Sm2Fe17N3晶体的价电子结构,同时计算并筛选了晶体的结合能和最强键能,分别为EC^0=14716.8±13.7kJ·mol^-1和Eα=110.1311 kJ·mol^-1。分析计算结果表明:Sm2Fe17N3晶体内共价电子数主要分布在12对由Fe(c1),Fe(c2)和Fe(c3)参与形成的最强键能的键上,由这3种Fe晶位原子形成的共价键键距普遍小于0.3 nm,共价键较强对晶体结合能作主要贡献;并且其结合能相比Sm2Fe17晶体的小得多,解释了Sm2Fe17合金在低温和非真空状态条件下易氧化而经过渗氮后得到的Sm2Fe17N3则表现出常温下结构稳定、化学性能好的特性;计算出N原子参与形成的成键原子对的理论键能值普遍在1 kJ·mol^-1左右,反映出Sm2Fe17N3化合物内在渗氮特性,分析了制备钐铁氮永磁材料过程中Sm2Fe17合金较低温渗氮难、渗氮不稳定和渗氮不均匀的缺陷。     

金属间化合物Y(Fe_(1-x)Co_x)_(11.3)Nb_(0.7)的磁性能机制研究

通过X射线衍射和磁性测量方法研究了金属间化合物Y(Fe1 -xCox) 1 1 .3 Nb0 .7(x =0 ,0 0 5 ,0 10 ,0 2 0 )的结构与磁性能。粉末样品的X射线衍射和热磁曲线测量表明 ,所有Y(Fe1 -xCox) 1 1 .3Nb0 .7(x =0 ,0 0 5 ,0 10 ,0 2 0 )化合物具有ThMn1 2 型结构 ,具有良好的单相性。Co替代Fe引起居里温度显著提高和晶格常数的单调减小 ,室温下的饱和磁化强度Ms 随Co含量的增加在x =0 1～ 0 2之间呈现极大值 ,各向异性场Ba 随x的增加 ,先增加而后减小     

金属间化合物Y（Fe1—xCox）11.3Nb0.7的磁性能机制研究

通过X射线衍射和磁笥测量方法研究了金属间化合物Y（Fe1-xCox)11.3Nb0.7（x=0,0.05,0.10,0.20）的结构与磁性能。粉末样品的X射线衍射和热磁曲线测量表明,所有Y（Fe1-xCox)11.3Nb0.7（x=0,0.05,0.10,0.20）化合物具有ThMn12型结构,具有良好的单相性,Co替代Fe引起居里温度显著提高和晶格常数的单调减小,室温下的饱和磁化强度M。随Co含量的增加在x=0.1-0.2之间呈现极大值,各向异性场Ba随x的增加,先增加而后减小。     

La0.6Pr0.05Fe11.5-xCoxSi1.5合金的磁性和磁热效应

使用电弧炉熔炼法制备La0.6Pr0.05Fe11.5-xCoxSi1.5(x=0,0.1,0.2,0.3,0.4,0.5和0.6)系列合金.XRD分析与SEM成分分析表明该系列合金中除含有少量富镧相(P4/nmm)和α-Fe相外.均由NaZh13型立方结构单相组成.品格常数随着Co含量的增加基本保持不变.磁性测量表明该系列合金的Tc随着Co含母的增加旱线性增加,当x=0.6时,Tc达264 K.合金的升、降温磁化曲线随着Co含量的增加逐渐重合,即表明该系列合金的热滞随着Co含量的增加而减小;利用Maxwell方程计算得出在x=0时,合金在△B=1.5 T的外磁场下-△Sm达到38.4 J·kg-1·K-1.这种磁熵变来源于外磁场引起的一级相变,随着Co含量的增加-△Sm线性减小,这是由于Co含量的增加使合金的磁相变出现由一级相变向二级相变转变.     

Large thermal conductivity reduction induced by La/O vacancies in the thermoelectric LaCoO3 system

A series of compact La/O-vacant La(1-x)CoO(3-y) compounds were prepared by a cold high-pressure procedure, and their thermoelectric (TE) properties were investigated. Compared with the ion-substituted hole-type LaCoO(3) systems (e.g., La(1-x)Sr(x)CoO(3)), the thermal conduction of La(1-x)CoO(3-y) is noticeably reduced by the La/O vacancies, whereas the electric transport is less influenced, which results in an efficient ZT enhancement. We demonstrate that the large thermal conductivity reduction originates from the strong point-defect scattering, and La(1-x)CoO(3-y) can be rationalized as a partially filled solid solution: La(1-x)?(x)CoO(3-y)?(y), where ? denotes a vacancy. Such intrinsic thermal conductivity suppression provides an effective pathway for the design of better TE materials.     

Nanostructured Bi(2-x)Cu(x)S3 bulk materials with enhanced thermoelectric performance

Nanostructured Bi(2-x)Cu(x)S(3) (x = 0, 0.002, 0.005, 0.007, 0.01, 0.03) thermoelectric polycrystals were fabricated by combining mechanical alloying (MA) and spark plasma sintering (SPS) methods. The effect of Cu content on the microstructure and thermoelectric property of Bi(2-x)Cu(x)S(3) bulk samples was investigated. It was found that the subtle tailoring of Cu content could reduce both the electrical resistivity and the thermal conductivity at the same time, and consequently enhancing the thermoelectric property. A low electrical resistivity of 1.34 × 10(-4)Ω m(-1) and a low thermal conductivity of 0.52 W m(-1) K(-1) were obtained for the Bi(1.995)Cu(0.005)S(3) sample at 573 K. The low thermal conductivity is supposed to be due to the nanoscopic Cu-rich regions embedded in the host matrix. A peak ZT value of 0.34 at 573 K was achieved for the Bi(1.995)Cu(0.005)S(3) composition, which is the highest value in the Bi(2)S(3) system reported so far.     

Glass foam from window panes and bottle glass wastes

Glass foams are building materials that now compete with classic insulating polymeric and fiber materials for thermal enveloping. The low flammability, high chemical durability and thermal stability are distinct advantages over polymeric materials. The present paper proposes the possibility of producing glass foam using two types of recycled glass wastes (window panes and bottle glass) together with plaster wastes from used ceramic casting molds as foaming agent. Optical microscopy, measurements of apparent porosity and density, hydrolytic and chemical stability, as well as thermal conductivity were used in order to characterize the obtained glass foams as insulator materials for the building industry. The apparent porosity of glass foams ranges between 20.19–54.54% when using window glass wastes, and 18.77–51.75% with bottle glass wastes. Thermal conductivity was less than 0.25 W mK-1 for all the studied glasses. The obtained results confirm that there exists an alternative method for producing glass foams, for example, from glass wastes and used ceramic plaster molds, which are utilized as foaming agents with good chemical stability and insulating properties.     

高色纯度高热稳定性红色荧光粉Sr3La2Ge3O12:Sm^3+的合成及其性能

通过高温固相法合成了一系列Sr3La2-xGe3O12:xSm^3+(0≤x≤0.04)红色荧光粉,并对样品的形貌、元素组成、晶体结构、发光性能及热稳定性进行了探究。结果表明:样品Sr3La2Ge3O12:xSm^3+为较宽尺寸分布的颗粒,且结构中仅含有Sr、La、Ge、O、Sm等元素。样品Sr3La1.97Ge3O12:0.03Sm^3+的Rietveld结构精修图与实测XRD图完全吻合,具有六方晶系结构。漫反射测试结果显示基质Sr3La2Ge3O12的带宽为5.54 eV,属于宽带隙材料。在404 nm激发下,样品Sr3La2-xGe3O12:xSm^3+(0≤x≤0.04)的最大发射峰位于601nm处,属于Sm^3+的6H5/2→4L13/2能级跃迁。此外,样品Sr3La1.97Ge3O12:0.03Sm^3+的发光性能最佳,其CIE色坐标为(0.5321,0.4601),色纯度高达94.2%,在298-473 K范围内具有较好的热稳定性,测试温度达到423 K时发射强度仍为室温时的81.6%。     

Solid state reaction synthesis of filled skutterudite compounds (Ce or Y)yFexCo4-xSb12 and the effect of filling atoms Ce or Y on lattice thermal conductivity

The synthesis of filled skutterudite compounds (Ce or Y)yFexCo₄-xSb12, through a solid state reaction using chloride of Ce or Y, high purity powder of Co, Fe, and Sb as starting materials, was investigated. (Ce or Y)yFexCo₄-xSb12 (x = 0 1.0,y = 0 0.15) compounds were obtained at 850 1 123 K. The results of Rietveld analysis demonstrate that (Ce or Y)yFexCo₄-xSb12 synthesized by a solid state reaction possesses a filled skutterudite structure. The filling fraction of Ce or Y obtained by Rietveld analysis agrees well with the composition obtained by chemical analysis. The lattice constant of CeyFexCo₄-xSb12 increases with increasing substitution of Fe at Co sites, and with an increasing Ce filling fraction in the Sb-dodecahedron voids. The lattice thermal conductivity of (Ce or Y)yFexCo₄-xSb12 decreases significantly with an increasing Ce or Y filling fraction in the voids and with substitution of Fe at Co sites.     

Robust self-supported anode by integrating Sb_2S_3 nanoparticles with S,N-codoped graphene to enhance K-storage performance

Developing high-performance anode materials for potassium-ion batteries is significantly urgent. We here demonstrate Sb_2S_3 nanoparticles(~20 nm) homogeneously dispersed in porous S,N-codoped graphene framework(Sb_2S_3-SNG) as a self-supported anode material for potassium-ion batteries. The rational structure design of integrating Sb_2S_3 nanoparticles with S,N-codoped graphene contributes to high reactivity, strong affinity, good electric conductivity, and robust stability of the composite, enabling superior K-storage performance. Moreover, the self-supported architecture significantly decreases the inactive weight of the battery, resulting in a high energy density of a Sb_2S_3-SNG/KVPO_4 F-C full cell to ~166.3 W h kg~(-1).     

Ionic Conductivity of Solid Solutions and Composites Based on Sm2W3O12

Russian Journal of Electrochemistry - The conductivity of samples based on Sm2W3O12 obtained by using homogeneous (solid solutions Sm2 –xМxW3O12 – 0.5x, where М = Ca, Zn)...     

Cubic aluminum silicides RE8Ru12Al49Si9(Al(x)Si12-x) (RE = Pr, Sm) from liquid aluminum. Empty (Si,Al)12 cuboctahedral clusters and assignment of the Al/Si distribution with neutron diffraction.

Two new quaternary aluminum silicides, RE8Ru12Al49Si9(Al(x)Si12-x) (x approximately 4; RE = Pr, Sm), have been synthesized from Sm (or Sm2O3), Pr, Ru, and Si in molten aluminum between 800 and 1000 degrees C in sealed fused silica tubes. Both compounds form black shiny crystals that are stable in air and NaOH. The Nd analog is also stable. The compounds crystallize in a new structural type. The structure, determined by single-crystal X-ray diffraction, is cubic, space group Pm3m with Z = 1, and has lattice parameters of a = 11.510(1) A for Sm8Ru12Al49Si9(Al(x)Si12-x) and a = 11.553(2) A for Pr8Ru12Al49Si9(Al(x)Si12-x) (x approximately 4). The structure consists of octahedral units of AlSi6, at the cell center, Si2Ru4Al8 clusters, at each face center, SiAl8 cubes, at the middle of the cell edges, and unique (Al,Si)12 cuboctohedral clusters, at the cell corners. These different structural units are connected to each other either by shared atoms, Al-Al bonds, or Al-Ru bonds. The rare earth metal atoms fill the space between various structural units. The Al/Si distribution was verified by single-crystal neutron diffraction studies conducted on Pr8Ru12Al49Si9(Al(x)Si12-x). Sm8Ru12Al49Si9(Al(x)Si12-x) and Pr8Ru12Al49Si9(Al(x)Si12-x) show ferromagnetic ordering at Tc approximately 10 and approximately 20 K, respectively. A charge of 3+ can be assigned to the rare earth atoms while the Ru atoms are diamagnetic.     

Effect of La filling on thermoelectric properties of LaxCo3.6Ni0.4Sb12-filled skutterudite prepared by MA-HP method

Starting from elemental powder mixtures, single-phase La_xCo_3.6Ni_0.4Sb₁₂(x=0, 0.1, 0.4, 0.6)-filled skutterudites were synthesized via the route of mechanical alloying-hot pressing (MA-HP) in this paper. With increasing of La fraction, the lattice spacing of filled skutterudite phase increases and its variation follows the Vegard's law. The magnitude of the Seebeck coefficient and electrical resistivity show slight increases with increasing of La filling fraction; thermal conductivity of the filled skutterudite decreases and the resultant figure of merit increases with increase of La filling fraction. The as-HPed filled skutterudite has a composite nanocrystalline microstructure, which includes some coral-like clusters with relatively large spoke-like grains about 300 nm in length and a superfine equiaxial nanocrystalline matrix with an average grain size of about 50 nm. The coral-like cluster corresponds to the prime filled skutterudite formed directly by MA, while the filled skutterudite formed during hot pressing, which has the same nucleation condition and experiences less grain growth, develops equiaxially into the superfine nanocrystalline matrix.