Mn1.2Fe0.8P0.48Six化合物的结构和磁热效应

对Mn1.2Fe0.8P0.48Si0.52和非化学计量比Mn1.2Fe0.8P0.48Si0.49化合物的物相与磁热效应(MCE)进行了研究。结果表明:两种化合物均为Fe2P型六角结构(空间群为P-62m),化合物中含有少量的(Fe,Mn)3Si第二相。当Si的含量x由0.52降到0.49时,化合物的居里温度由268K升到282K,而Si含量的变化对化合物的热滞没有明显的影响。Mn1.2Fe0.8P0.48Si0.52和Mn1.2Fe0.8P0.48Si0.49化合物在外磁场变化为0~1.5T下的最大磁熵变分别为11.7J/kg·K和9.0J/kg·K。低成本的原料、较大的磁熵变使得Mn1.2Fe0.8P0.48Six化合物成为一种理想的室温磁致冷材料。     

MnFe(P,Si)一级相变热磁发电材料的制备与磁性研究

通过机械合金化和固相烧结方法,制备一系列MnFe(P,Si)一级相变化合物,并测定其结构、磁热性能及部分热力学性能。研究结果表明:MnFe(P,Si)系列化合物呈Fe_2P型六角结构,空间群为P-62 m,其中部分化合物存在少量Fe_3Si或Fe_5Si_3第二相。MnFe_(0.9)P_(0.5)Si_(0.5)呈单相Fe_2P型六角结构,由铁磁态到顺磁态(升温)和顺磁态到铁磁态(降温)的转变分别出现在Ttw=330K,Ttc=318K,其热滞ΔThys=12K。升降温相变较快,均在10K以内完成,说明相变是一级相变。在0~1.5T的外磁场中最大等温磁熵变-ΔS_(max)=18.6J/(kg·K);其比热容最高为(升温)C_p=1 571J/(kg·K),(降温)C_p=1 447J/(kg·K)。由此推断,MnFe_(0.9)P_(0.5)Si_(0.5)化合物符合热磁发电工作需求,是一种具有良好磁热性能的热磁发电候选材料。     

Mn_(1.25)Fe_(0.65)P_(0.5)Si_(0.5-x)B_x系列化合物的结构及磁性

研究了Mn_(1.25)Fe_(0.65)P_(0.5)Si_(0.5-x)B_x(x=0,0.01,0.03,0.04,0.06,0.07)系列化合物的结构及磁性。结果表明,该系列化合物均为Fe2P型六角结构,空间群为P-62m;磁性测量表明该系列化合物都经历了一级相变,并且均存在热滞,但热滞都较小,当硼的原子分数为0.07时,热滞最大值为5K。居里温度随着硼含量的增加,呈现升高的趋势,当硼的原子分数为0.07时,居里温度为325K,而化合物的最大磁熵变呈现下降的规律,当硼的原子分数为0.07时,最大磁熵变为2J/(kg·K)。     

Co1.2Mn0.8B化合物的磁性能与磁热效应

采用球磨和固相烧结相结合的方法制备了Co_(1.2)Mn_(0.8)B化合物,并对其晶体结构、磁性能和磁热效应进行了研究。结果表明,Co_(1.2)Mn_(0.8)B化合物的物相为Co_2B单相结构,具有CuAl2型体心正方晶体结构,空间群为I14/mcm;在居里温度TC=175 K附近,化合物发生了铁磁(FM)-顺磁(PM)二级磁相转变,热滞为0.7 K;Co_(1.2)Mn_(0.8)B化合物在外磁场0～5 T变化下的最大磁熵变ΔSM为1.17 J·(kg·K)~(-1),其对应的温度不随外场的变化而变化。     

MnFeP_(0.63)Ge(0.12)Si_(0.25)B_x(x=0,0.01,0.02,0.03)化合物的磁热效应

对MnFeP_(0.63)Ge_(0.12)Si_(0.25)B_x(x=0,0.01,0.02,0.03,原子分数)化合物的结构和磁热效应(MCE)进行了研究.XRD分析结果表明:MnFeP_(0.63)Ge_(0.12)Si_(0.25)B_x(x=0,0.01,0.02,0.03)的主相均为Fe_2P型六角结构,空间群为P62m.随着B含量的增加晶格常数a增大c减小,晶胞体积基本保持不变.磁性测量表明:随着B含量由0增加到0.03时,Curie温度(T_C)从300 K升到347 K,热滞分别为20,17,11和6 K.0-1.5 T外磁场下最大磁熵变△S_M分别为14.83,11.41,11.26和11.8 J/(kg·K).     

Mn_(1.2)Fe_(0.8)P_(0.74)Ge_(0.26-x)Se_x化合物磁热性能研究

利用机械合金化(MA)结合放电等离子烧结(SPS)技术,成功制备了Mn1.2Fe0.8P0.74Ge0.26-xSex(x=0,0.005,0.01,0.015,0.02,0.03)化合物,并采用XRD,DSC,振动样品磁强计(VSM)和磁热效应直接测量仪等手段对其晶体结构、相变过程以及磁热性能进行了研究.结果表明:该系化合物均具有六方Fe2P结构.随着Se含量的增加,晶格常数a和c都发生了明显的变化,c/a先减小,然后保持不变,最后又增大;且c/a的值与化合物的Curie温度Tc成一定对应关系,c/a减小会升高Tc,反之则降低Tc.外加磁场和温度的变化都能引起化合物产生一级磁热相变,即顺磁相(PM)?铁磁相(FM).少量Se对Ge的置换(x≤0.015)能够提高材料的磁热性能,使该系化合物的Tc升高,转变温区?Tcoex变窄,绝热温变?Tad增大;而热滞?Thys和熵变?SDSC基本不变.当x=0.01时,化合物的磁热性能最好,与x=0化合物相比,Tc升高了5.6 K,?Tcoex降低了10.6%,?Tad增加了10%,当Se含量继续增加时,化合物的磁热性能有所下降.     

Mn1.3Fe0.7P0.45Si0.55化合物的热滞与磁热效应

用机械合金化方法制备出了Mn1.3Fe0.7P0.45Si0.55化合物。研究了Mn1.3Fe0.7P0.45Si0.55化合物的结构、磁性和磁热效应。结果表明,该化合物形成了Fe2P型六角结构,空间群为P62m,化合物中存在少量的(Mn,Fe)3Si相。在居里点附近,随着温度的提高化合物发生了由铁磁到顺磁的一级相变过程。化合物的Curie温度为315K,热滞为4K。在1.5T磁场变化下,化合物的最大等温磁熵变为10.3J/(kg.K)。低成本的原料、简单的制备工艺、合适的Curie温度、较小的热滞和较大的磁熵变,使得Mn1.3Fe0.7P0.45Si0.55化合物有希望成为一种可应用的新型室温磁制冷材料。     

Ti100-xNix(x=40～70)形状记忆合金的Ni含量-时效工艺-相变行为关系图及其应用

采用示差扫描量热仪(DSC)建立了Ti_100-xNi_x(x=40～70)形状记忆合金的Ni含量-时效工艺-DSC曲线关系图、Ni含量-时效工艺-相变类型关系图、Ni含量-时效工艺-相变温度关系图、Ni含量-时效工艺-相变热滞关系图、Ni含量-时效工艺-相变潜热关系图。利用这些图能解决两类问题：当TiNi形状记忆合金的Ni含量、时效温度和时效时间已知时，可预测该合金的DSC曲线、相变类型、相变温度、相变热滞和相变潜热；当期望TiNi形状记忆合金具有某个DSC曲线、相变类型、相变温度、相变热滞或相变潜热时，可设计该合金的Ni含量、时效温度和时效时间。     

磁制冷材料Ni-Mn-Ga合金的连续马氏体相变与奇异热膨胀特性

为深入解磁制冷材料Ni-Mn-Ga合金的热膨胀特性,利用SEM、XRD、DSC及PPMS系统分别对合金Ni_(54+x)Mn_(19-x)Ga_(27)(x=0.2,0.6,1.0)的组分、结构、相变及热膨胀特性进行实验测试。结果表明:随着Ni含量的增加,合金的马氏体相变温度逐渐增加。当x从0.2增至1.0时,合金正反马氏体相变峰温分别从274、282 K增至300、309 K,且存在7～10 K的热滞后。在升降温过程中,x为0.2和0.6的合金出现两个连续的马氏体相变、x=1.0的合金发生磁-结构耦合转变,相变温区分别为33.5 K、35.1 K、27.5 K。零场热应变曲线表明,合金具有各向同性的热膨胀特性。马氏体相与奥氏体相的热膨胀系数分别为5.02×10~(-6)～10.31×10~(-6 )K~(-1)和3.74×10~(-6)～7.72×10~(-6)K~(-1)之间。马氏体相变过程中合金出现正热膨胀行为和奇异的负热膨胀行为,最大的负热膨胀系数约为-139.84×10~(-6 )K~(-1)。结合实验数据,从微观的角度对Ni-Mn-Ga的负热膨胀效应进行初略讨论。     

Mn_(1.35)Fe_(0.65)P_(0.45)Si_(0.55)B_x合金的磁热效应

对Mn1.35Fe0.65P0.45Si0.55Bx(x=0,0.01,0.02,0.03,0.04)合金的结构和磁热效应(MCE)进行了研究。XRD分析结果表明:Mn1.35Fe0.65P0.45Si0.55Bx(x=0,0.01,0.02,0.03,0.04)的合金均为Fe2P型六角结构,空间群为P6-2 m,并随着B元素(原子分数)的增加,晶格常数a增大,c/a减小,晶胞体积V略有减小。磁性测量表明:随着B元素(原子分数)的增加,Curie温度(Tc)从228K升高到315K,热滞(ΔThys)变化不大。0~1.5T外磁场下最大磁熵变(-ΔSmax M)下降,分别为3.6,2.5,2.0,1.7,1.9J/(kg·K)。     

X-ray diffraction study of Ba0.985Na0.015Ti0.985Nb0.015O3, Ba0.6Na0.4Ti0.6Nb0.4O3 and Ba0.3Na0.7Ti0.3Nb0.7O3 compositions

The Ba_0.985Na_0.015Ti_0.985Nb_0.015O₃, Ba_0.6Na_0.4Ti_0.6Nb_0.4O₃ and Ba_0.3Na_0.7Ti_0.3Nb_0.7O₃ compositions of the (1 − x) BaTiO₃–xNaNbO₃ (BTNNx) system have been studied by X-ray diffraction and by measurements of dielectric properties. The specimens with composition BTNN (x = 0.015, 0.40 and 0.70) have been refined by the JANA program from X-ray powder diffraction data. Ceramic samples with composition (1 − x) BaTiO₃ + xNaNbO₃ (where x = 0.015, 0.40 and 0.70) were prepared by calcinations from appropriate mixture of BaCO₃, TiO₂, Na₂CO₃ and Nb₂O₅. The calcined powder was sintered at temperature range 1200–1400 °C. As the composition x increased from 0.015 (and 0.70), the ferroelectric ceramics (x = 0.015, FE) with tetragonal phase changed to the ferroelectric relaxors (RFE, x = 0.40). RFE ceramics showed a peculiar diffuse phase transition and dielectric relaxation at the low temperature (down to 180 K) due to a frustration between RFE and FE state. These ceramics present the classical ferroelectric character when 0 ≤ x < 0.075 and 0.55 < x ≤ 1 and relaxor character when 0.075 ≤ x ≤ 0.55.     

Magnetic, electrical and plastic properties of Fe76Nb2Si13B9, Fe75Ag1Nb2Si13B9 and Fe75Cu1Nb2Si13B9 amorphous alloys

Influence of 1 h annealing in vacuum on magnetic, electrical and plastic properties of Fe₇₆Nb₂Si₁₃B₉, Fe₇₅Ag₁Nb₂Si₁₃B₉ and Fe₇₅Cu₁Nb₂Si₁₃B₉ melt spun ribbons were carefully investigated. It was shown that in all cases soft magnetic properties can be significantly enhanced by applying 1-h annealing at characteristic temperatures T_op. This optimization annealing causes that permeability increases more than 15-times and magnetic losses (tangent of loss angle) achieves a minimum in relation to the as quenched state. Using structural examinations (X-ray and HRTEM) it was shown that for the Fe₇₅Cu₁Nb₂Si₁₃B₉ alloy the optimized microstructure corresponds to a nanocrystalline αFe(Si) phase whereas in other alloys to a relaxed amorphous phase free of iron nanograins. As a consequence of this fact the Fe₇₆Nb₂Si₁₃B₉ and Fe₇₅Ag₁Nb₂Si₁₃B₉ alloys show higher plasticity in comparison to the nanocrystalline Fe₇₅Cu₁Nb₂Si₁₃B₉ alloy. Temperatures of the first stage of crystallization, and related diffusion parameters were determined using measurements of resistivity versus temperature with different heating rates.     

Fe2+-Ni2+-NH3-NH4+-C2O42-H2O体系的沉淀配合平衡热力学

针对草酸盐配位共沉淀热分解还原法制备超细铁镍合金粉过程中Fe2+-Ni2+-NH3-NH4+-C2O42--H2O体系的溶液平衡建立热力学分析模型,并根据模型进行相关计算,揭示反应体系中各物质随pH值、氨及草酸浓度的变化关系。结果表明:溶液中的Fe主要以[Fe(C2O4)n]2 2n络合物形式存在,而铁氨络合物含量很低。当氨含量较低时,溶液中的Ni主要以[Ni(C2O4)n]2 2n存在;氨含量较高时,在酸性条件下,溶液中的Ni主要以[Ni(C2O4)n]2 2n存在,在碱性条件下,则主要以[Ni(NH3)n]2+存在。低pH值下,Ni的沉淀率较Fe的高,而高pH值下,Ni的沉淀率则较Fe的低。     

Thermodynamics and phase diagrams in the binary systems Na2O-SiO2, Na2O-GeO2, Na2O-B2O3, Li2O-B2O3, CaO-B2O3, SrO-B2O3, and BaO-B2O3

We applied our model to the enthalpy of mixing data of the binary systems Na₂O-SiO₂, Na₂O-GeO₂, Na₂O-B₂O₃, Li₂O-B₂O₃, CaO-B₂O₃, SrO-B₂O₃, and BaO-B₂O₃. The most stable composition in the liquid, that is where the enthalpy of mixing is most negative, is with a metal-oxygen ratio of 4 to 3, for monovalent metals (Na and Li) and 3 to 4 for divalent metals (Ba and Ca) in liquid silicates or borates. The same applies to the CaO-SiO₂, CaO-Al₂O₃, PbO-B₂O₃, PbO-SiO₂, ZnO-B₂O₃, and ZnO-SiO₂ systems. The oxygen to metal ratio, its constant value in various types of systems, reflects and describes the structure of the liquid. Using the analyzed enthalpies of mixing data and the available phase diagrams, we calculated the enthalpies of formation of the various binary compounds. The results are in excellent agreement with data in the literature that were obtained from direct solid-solid calorimetry.     

New Zr6CoAs2-type compounds: Y6CoBi2, Ho6CoBi2 and Tm6CoBi2

Results of a powder X-ray diffraction investigation of new ternary compounds are reported. The compounds Y₆CoBi₂ [a=0.8312(1) nm, c=0.4144(1) nm], Ho₆CoBi₂ [a=0.8246(2) nm, c=0.4095(1) nm], and Tm₆CoBi₂ [a=0.8155(2) nm, c=0.4066(1) nm] crystallize in the hexagonal Zr₆CoAs₂-type structure (space group P6b2m No. 189). The Zr₆CoAs₂-type structure is a superstructure of the Fe₂P-type structure.     

Zur Kenntnis von RbBa3Ca4Cu3V7O28

Single crystals of RbBa₃Ca₄Cu₃V₇O₂₈ were prepared above the melting point of the reaction mixture. It crystallizes with hexagonal symmetry, space group C_6V⁴-P6₃mc, a 11.1751, c 12.434 Å, Z = 2. RbBa₃Ca₄Cu₃V₇O₂₈ is the second member of a new structure type of the copper-oxovanadates. Ba²⁺ shows an unusual 12-fold coordination. The two calcium positions are coordinated by trigonal prisms and octahedra respectively. The copper coordination is characterized by a stretched square pyramid. The Cu²⁺ ions are outside the centre nearly in plane of the pyramids.

Zusammenfassung

Einkristalle von RbBa₃Ca₄Cu₃V₇O₂₈ wurden oberhalb des Schmelzpunktes der Reaktionsmischung erhalten. Die Verbindung kristallisiert hexagonal, Raumgruppe C_6V⁴-P6₃mc, a 11.1751, c 12.434 Å, Z = 2. RbBa₃Ca₄Cu₃V₇O₂₈ ist das zweite Beispiel für einen neuen Strukturtyp der Kupfer-Oxovanadate, mit 12-fach koordinierten Ba²⁺ -Ionen. Die zwei Calciumpositionen sind trigonal prismatisch bzw. oktaedrisch koordiniert. Die Koordination der Cu²⁺-Ionen ist durch eine gestreckte Pyramide charakterisiert. Cu²⁺ ist auβerhalb des Polyederzentrums nahezu in der quadratischen Fläche der Pyramide angeordnet.     

Al2O3-Sm2O3-CeO2电解质的性能（英文）

采用溶胶-凝胶法和低温燃烧技术制备Ce1-xSmxO2（x=0,0.1,0.2,0.3）和掺杂Sm和（2%-8%）Al2O3的二氧化铈;研究其合成、结构、致密化、导电性和热膨胀等性能,并利用XRD研究其结构和相组成。结果表明,于1300°C烧结球团,获得致密的陶瓷,于1250°C在Ce0.8Sm0.2O0.2中加入2%和4%的Al2O3以促进烧结。利用扫描电子显微镜观察烧结后球团的表面形貌,使用双探针交流阻抗谱研究总离子电导率。     

电弧喷涂制备Fe65Cr20Mo7B3.5SiMn1.5W3涂层

在Q235低碳钢板上利用电弧喷涂工艺进行喷涂,以制得Fe65Cr20Mo7B3.5SiMn1.5W3涂层。喷涂材料为自行配制的丝材,按照35%的填充率将配好的粉填充到U型不锈钢外皮中,经过多道拉拔、挤压工艺制成Φ2mm的粉芯丝材。采用X射线衍射仪、扫描电镜、能谱分析仪、透射电镜对涂层的物相和组织形貌及成分进行了表征;采用差示扫描量热仪、显微硬度仪等设备对涂层的热稳定性及显微硬度进行了检测和分析。试验结果表明:涂层组织形貌呈典型的层状组织结构,由变形良好的带状粒子相互搭接堆积而成。涂层含有50.63%的非晶相,同时含有纳米级的晶相。涂层组织均匀、结构致密、孔隙率低,并且涂层硬度高达1040.5HV0.3,属硬质涂层,具有良好的热稳定性。     

Synthesis and electrochemical properties of LiNi0.4Mn1.5Cr0.1O4 and Li4Ti5O12

Spinel compound LiNi_0.4Mn_1.5Cr_0.1O₄ (LNMCO) and Li₄Ti₅O₁₂ (LTO) were synthesized by the sol-gel method and the solid-state method, respectively. The particle sizes of the products LiNi_0.4Mn_1.5Cr_0.1O₄ and Li₄Ti₅O₁₂ were 0.5 to 2 um and 0.5 to 0.8 um, respectively. All samples exhibited excellent electrochemical properties. A LiNi_0.4Mn_1.5Cr_0.1O₄/Li₄Ti₅O₁₂ (LNMCO/LTO) cell was fabricated and was demonstrated to exhibit good electrochemical properties at the high current rate of 1 C. When the specific capacity was determined based on the mass of the LNMCO cathode, the LNMCO/LTO cell delivered 125 mAh g⁻¹ at 1 C and 77 mAh g⁻¹ at 5 C. The capacity retentions after 30 cycles were 94.4 % and 83.1 %, respectively.