Synthesis,Crystal Structure,and Optical Properties of (CH3NH3)2CoX4 (X = Cl,Br, I,Cl0.5Br0.5, Cl0.5I0.5, Br0.5I0.5)

The reaction of methylammonium halides and cobalt halides yielded the organic‐inorganic hybrid compounds of general formula (CH₃NH₃)₂CoX₄. By varying the different halides, we were able to synthesize the whole row from Cl to I as well as some mixed halides compounds and to determinate the crystal structures. (CH₃NH₃)₂CoX₄ (X = Cl, Br, Cl_0.5Br_0.5, Br_0.5I_0.5) crystallize isotypic to (CH₃NH₃)₂HgCl₄ in space group P2₁/c with Z = 4 [X = Cl: a = 7.6483(9), b = 12.6885(18), c = 10.8752(12) Å, β = 96.639(9)°; X = Cl_0.5Br_0.5: a = 7.8271(9), b = 12.9543(9), c = 11.1007(11) Å, β = 96.320(8)°; X = Br: a = 7.9782(2), b = 13.1673(2), c = 11.2602(2) Å, β = 96.3260(10)° and X = Br_0.5I_0.5: a = 8.2435(12), b = 13.645(2), c = 11.5856(18) Å, β = 95.54(2)°]. The mixed halides show a statistic distribution in both cases. In (CH₃NH₃)₂CoCl₂I₂ an ordered variant is realized representing a new structure type [C2/m, Z = 4, a = 18.808(4), b = 7.3604(7), c = 10.4109(17) Å, β = 120.364(13)°]. (CH₃NH₃)₂CoI₄ crystallizes again isotypic to the respective mercury compound [(CH₃NH₃)₂HgCl₄] [Pbca, Z = 8, a = 10.9265(5), b = 12.1552(5), c = 20.9588(9) Å]. All structures are build up by inorganic tetrahedral [CoX₄]^2– anions and organic (CH₃NH₄)⁺ cations. Additionally the Raman spectra as well as the optical reflectance spectra are discussed.     

Ultra-incompressible Ternary Diborides Re_（0.5）Ir_（0.5）B_2,Re_（0.5）Tc_（0.5）B_2,Os_（0.5）W_（0.5）B_2 and Os_（0.5）Ru_（0.5）B_2：Density Functional Calculation

In this paper, density functional computations have been applied to the structural, elastic and electronic properties of ternary transition metal diborides Re0.5Ir0.5B2, Re0.5Tc0.5B2, Os0.5W0.5B2 and Os0.5Ru0.5B2 in hexagonal (P63/mmc) and orthorhombic (Pmmn) structures with both local density approximation and generalized gradient approximation. LDA gives smaller lattice parameters and larger elastic moduli than GGA. Both results show that the hexagonal ones are more stable than orthorhombic ones except Os0.5Ru0.5B2. Moreover, the hexagonal structure has superior elastic property than orthorhombic one. Generally speaking, the calculated elastic moduli of Re0.5Ir0.5B2 and Os0.5Ru0.5B2 are smaller than those values of Re0.5Tc0.5B2 and Os0.5W0.5B2 within the same structure because of the filling of antibonding states. The relativistic effects result in weaker bonds of Tc-B (Ru-B) than those of Re-B (Os-B). All the diborides are ultra-incompressible. Re0.5Tc0.5B2 has the largest shear modulus and it is a promising superhard diboride like Os0.5W0.5B2. The elastic properties are in high correlation with the bond strength. The shear moduli are more sensitive than the bulk moduli to the bond strength.     

KTa_(0.5)Nb_(0.5)O_3电子结构的第一性原理研究

用全电势线性缀加平面波法 (FLAPW )计算了KTa0 .5Nb0 .5O3 铁电相和顺电相的态密度、能带结构 .通过对两相态密度的对比分析我们发现在铁电相 ,钽原子的d电子和氧原子的 2p电子以及铌原子d电子与氧原子的 2p电子之间存在强烈的轨道杂化 ,对能带的分析也得出同样的结论 .这种轨道杂化对KTa0 .5Nb0 .5O3 铁电性的稳定有着重要的意义 .钽原子在四方铁电体KTa1 xNbxO3 中的作用与在纯钽酸钾中的作用有明显的差别 .     

KTa_(0.5)Nb_(0.5)O_3电子结构的第一性原理研究

用全电势线性缀加平面波法（FLAPW）计算了KTa_(0.5)Nb_(0.5)O_3铁电相和 顺电相的态密度、能带结构。通过对两相态密度的对比分析我们发现在铁电相，钽 原子的d电子和氧原子的2p电子以及铌原子d电子与氧原子的2p电子之间存在强烈的 轨道杂化，对能带的分析也得出同样的结论。这种轨道杂化对KTa_(0.5)Nb_(0.5) O_3铁电性的稳定有着重要的意义。钽原子在四方铁电体KTa_(1-x)Nb_xO_3中的作 用与在纯钽酸钾中的作用有明显的差别。     

稀土取代的复合氧化物Eu_（0．5）RE_（0．5）Fe_（0．5）Mn_（0．

利用固相反应合成了稀土取代的复合氧化物Ｅｕ_（０．５）ＲＥ_（０．５）Ｆｅ_（０．５）Ｍｎ_（０．５）Ｏ_３（ＲＥ＝Ｌａ，Ｐｒ，Ｎｄ，Ｓｍ，Ｇｄ，Ｔｂ，Ｄｙ，Ｈｏ，Ｅｒ，Ｔｍ，Ｙｂ）．测量了这些化合物的ＸＲＤ和ＸＰＳ谱。在ＸＰＳ研究中发现，稀土取代而使稀土元素本身的结合能相对于其倍半氧化物中的有所降低；在取代的复合氧化物中，随着ＲＥ离子半径的减小，Ｆｅ、Ｍｎ的结合能随之增加。     

Sm（0.5）Sr（0.5）Co（0.4）M（0.6）O3（M=Co,Mn,Fe）作为IT-SOFCs阴极的结构与性能

通过X射线衍射(XRD)、热重、热膨胀、电导率以及交流阻抗等测试方法,研究了Sm0.5Sr0.5Co0.4M0.6O3(M=Co,Mn,Fe;分别简写为SSCC,SSCM,SSCF)作为中低温固体氧化物燃料电池(IT-SOFCs)阴极的结构与性能.研究表明,同相法合成的Sm0.5Sr0.5Co0.4M0.6O3均为正交钙钛矿型结构,材料的结构参数和性能都与M元素半径及M-O的键能有关.晶胞参数随着Co、Mn、Fe的顺序增大.材料的氧空位浓度、热膨胀系数、电导率、电极催化活性随着Co、Fe、Mn的顺序降低.同时由于SSCM较低的氧空位浓度,使得电极反应受到氧在电极内的扩散过程控制,具有较差的电极催化性能,而SSCC和SSCF较高的氧空位浓度,电极反应同时受到电极表面氧还原反应和氧离子在电极中的扩散过程混合控制.由于SSCF具有较高的氧扩散系数,使得700 ℃以上SSCF电极表面氧还原电阻(ASR)也低于SSCC的,因而出现了SSCF的总电极催化活性高于SSCC的现象.     

Li0.5-0.5xZnxFe2.5-0.5xO4纳米纤维的电纺制备及其结构和磁性能

以聚乙烯吡咯烷酮、硝酸锂、硝酸锌和硝酸铁为主要原料,通过静电纺丝技术结合后期的热处理制备了直径在50～100 nm的单相Li0.5-0.5xZnxFe2.5-0.5xO4（x=0.0,0.2,0.3,0.4,0.5,0.8）纳米纤维.利用热重-差热分析、X射线衍射、场发射扫描电子显微镜、透射电子显微镜和振动样品磁强计研...     

Magnetoelectric perovskite (Bi0.5Pb0.5)(Fe0.5Zr0.5)O3: Preparation,structural and magnetic properties

The perovskite (Bi_0.5Pb_0.5)(Fe_0.5Zr_0.5)O₃ was synthesized by solid-state reaction in an attempt to find magnetoelectric materials, in which ferroelectricity and ferromagnetism coexist. This complex perovskite has been studied by X-ray and neutron powder diffraction in combination with magnetic measurements. The compound crystallizes in the orthorhombic space group Pbam with a ～ √2a_p, b ～ 2√2a_p and c ～ 2a_p (with a_p ～ 4.057 Å). The field and temperature dependence of the magnetization combined with neutron diffraction data showed antiferromagnetic behavior with the Neel temperature, T_N ～ 450 K. Rietveld refinements of neutron powder diffraction data collected at different temperatures, between 10 and 700 K, have been carried out in order to extract information about the thermal evolution of the nuclear and magnetic structures. A distorted orthorhombic perovskite structure was found within the whole temperature interval. The Bi/Pb and Fe/Zr ions were found to be partially ordered over the perovskite A-site and disordered over the B-site. The neutron diffraction patterns of the (Bi_0.5Pb_0.5)(Fe_0.5Zr_0.5)O₃ sample showed evidence of a long-range magnetic ordering below T_N with a propagation vector k = (0,0,0) and an antiferromagnetic arrangement of the magnetic moments of the Fe³⁺ cations in the B-site. This is consistent with an A_y-type magnetic structure. The factors governing the structural and magnetic properties of (1 ? x)BiFeO₃–xPbZrO₃ solid solutions are discussed and compared with those of pure BiFeO₃ and PbZrO₃. A solid solution strategy for developing magnetoelectric properties in BiFeO₃-based compounds is described, with the aim of realizing both a spontaneous polarization and magnetization at room temperature.     

Synthesis,Structure and Photophysical Properties of a New Complex:Co_(0.5)Ni_(0.5)(C_2H_6N_2O)_6SO_4

A new complex,Co_(0.5)Ni_(0.5)(C_2H_6N_2O)_6SO_4(Ⅰ), was synthesized and its single crystal was obtained from aqueous solution by evaporating solvent slowly. Single-crystal X-ray analysis revealed that the complex belongs to trigonal system, space group R-3c, with a = b = 10.999(2) ?, c = 40.439(13) ?, V = 4237(2) ?~3, Z = 6, D_c = 1.410 g/cm~3, M_r = 599.41, μ = 0.785 mm~(-1), F(000) = 1893, the final R = 0.0330 and wR = 0.0926(I 2σ(I)). IR spectrum and compositional analyses(elemental analyzer and ICP) were used to characterize the composition of the product. TGA(Thermal Gravimetric Analysis) showed that complex Ⅰ remained stable until it is heated up to 200 ℃, indicating its good thermostability. The main transmission peak of complex Ⅰ in UV-Vis spectrum appeared at 290 nm, making it an eligible material for ultraviolet light filters(ULF).     

三乙酰基三苄基六氮杂异伍兹烷(TATBIW·0.5H2O)的合成及晶体结构

通过控制六苄基六氮杂异伍兹烷(HBIW)的氢解程度,成功制备了其氢解反应过程中一个重要的中间体三乙酰基三苄基六氮杂异伍兹烷(TATBIW),并对其单晶结构(TATBIW·0.5H2O)进行了测定,它属三斜晶系,空间群为P-1,a=0.9893(2)nm,b=1.2624(3)nm,c=1.3396(3)nm;V=1.5963(6)nm3,z=2,Dc=1.194 g·cm-3,该化合物的单晶数据未见文献报道.TATBIW的制备有助于我们进一步了解HBIW的氢解反应机理,提高氢解产品得率.     

La_(0.5)Na_(0.5)TiO_3纳米晶的制备及光致发光研究

以硬脂酸、硝酸镧、氢氧化钠和钛酸四丁酯为原料制备了La0 .5Na0 .5TiO3 纳米晶 ,粒度最小可达 1 4nm ,烧成温度为 50 0℃ ,低于传统固相反应的合成温度。光致发光研究表明 :用 392nm光作激发光 ,在室温下观察到了一个强的蓝光发射带 ,并且它的强度和半宽度随粒度发生明显变化。     

具有螺旋结构的新型硼磷酸盐化合物:(NH4)0.5(H3O)0.5Mg(H2O)2BP2O8

利用水热方法合成新型硼磷化合物:(NH4)0.5(H3O)0.5Mg(H2O)2BP2O8,单晶X射 线衍射分析证明化合物属六方晶系,空间群为P6522,a=0.94507(19)nm,c=1.5803(5) nm,γ=120°,V=1.2224(5)nm^3,Mr=279.06,Dc=2.258g/cm^3,Z=6,F(000)=834,μ =0.663mm^-1。结构中BO4,PO4基团形成∞^1{[BP2O8]^3-}的螺旋带与MgO6相连构 成八面体-四面体空间骨架,元素分析、IR光谱、热重差热分析和电荷平衡计算证 明晶体中含有NH4^+和质子。NH4^+占据螺旋带螺旋纹内,质子化的水分靠近螺旋带 通道的内侧,两者均起到平衡电荷和稳定骨架的作用。     

MgNi-x% TiNi0.5Mn0.5 (x＝10, 30, 50)贮氢合金的制备与电化学性能

用机械合金化法成功制备出MgNi和TiNi0.5Mn0.5合金, 并将不同质量的TiNi0.5Mn0.5与MgNi合金球磨复合10 h制备MgNi-x% TiNi0.5Mn0.5 (x＝10, 30, 50)合金. XRD结果表明球磨后几种合金均为非晶体, TiNi0.5Mn0.5均匀分散到MgNi合金主相中; 充放电结果表明MgNi-TiNi0.5Mn0.5复合合金的初始容量比纯MgNi合金(443.12 mAh/g)低, MgNi- 10% TiNi0.5Mn0.5首次放电容量是394.46 mAh/g, 但循环寿命有较大的改善, 50次循环后容量保持在232.57 mAh/g, 保持率达59%; 动电位扫描结果表明复合后合金电极抗腐蚀能力提高; 循环伏安法和电化学阻抗谱法研究结果表明: 复合后电极表面的电化学催化性能增强, H原子在合金电极内部的扩散阻抗减小.     

Phase separation and superconductivity in Fe(1+x)Te(0.5)Se(0.5)

Fe(1+x)Te(0.5)Se(0.5) is the archetypical iron-based superconductor. Here we show that the superconducting state is controlled by the stacking of its anti-PbO layers, such that homogeneous ordering hinders superconductivity and the highest volume fractions are observed in phase separated structures as evidenced by either a distribution of lattice parameters or microstrain.     

Synthesis, Crystal Structure, UV-vis and EPR Studies of（ NH3CH2CH2NH2 ） 2.5 [ Mo0.5^（V）W0.5^（VI）O2 （ OC6H4O ） 2]

Cis-dioxo-metal complex ( NH3CH2CH2NH2 ) 2.5 [ Mo0.5^(V)W0.5^(VI)O2 ( OC6H4O ) 2] 1 was obtained by the reaction of tetra-butyl ammonium hexamolybdotungstate with 1, 2-dihydroxybenzene in the mixed solvent of CH3OH, CH3CN and ethylenediamine,and characterized by X-ray diffraction, UV-vis and EPR analysis. Compared with its analogous complexes (NH3CH2CH2NH2)3[Mo^(V)O2(OC6H40)2] 2 and (NH3CH2CH2NH2)2[W^(VI)O2(OC6H4O)2] 3, the results show that tungsten(VI) is less active in redox than molybdenum (VI) and that the change of the valence induced by substitution of W(VI) for Mo(V) in EMO2(OC6H40)2]n- does not influence the coordination geometry of the complex anion in which the metal center exhibits distorted octahedral coordination with cis-dioxo catechol. The responses to EPR of complexes 1 and 2 are active but complex 3 is silent,and the UV-vis spectra exhibited by the three complexes are obvious different because of the different electronic configuration between the central Mo(V) and W(VI) ions in the complexes.It is noteworthy that complexes 1 and 2 have the similar EPR signal to flavoenzyme, suggesting that the three complexes have the same coordination geometry feature with the co-factor of flavoenzyme.     

Sm_(0.5)Sr_(0.5)CoO_3阴极氧还原动力学

利用极化、交流阻抗技术考察了担载于La0.9Sr0.1Ga0.8Mg0.2O3(LSGM)电解质上的Sm0.5Sr0.5CoO3-La0.8Sr0.2Ga0.8Mg0.15Co0.05O3(SSC-LSGMC5)复合阴极的氧还原反应动力学.在SSC-LSGMC5阴极氧还原反应的阻抗谱中可以观察到明显的两个半圆.高频环的电导与氧分压无关,低频环的电导正比于氧分压的0.5次方.并且低频环的氧分压级数随着反应温度的降低而减小,可能对应于吸附氧原子的扩散过程.SSC-LSGMC5极化曲线与经典的Butler-Volmer方程吻合.阴、阳极的电荷转移系数均为1左右,交换电流密度的氧分压级数为1/4,对应于电荷转移过程.实验结果显示SSC-LSGMC5上的氧还原反应机制随反应条件的不同而发生变化.