Phase Relations in the NiFe2O4–NiCr2O4–CuCr2O4System

The phase relations in the NiFe₂O₄–NiCr₂O₄–CuCr₂O₄system were investigated experimentally and theoretically. X-ray diffraction data were used to construct the phase diagram of the system and elucidate the structural mechanisms of the transitions from the cubic spinel structure to the tetragonal (I42d, c/a< 1 and I4₁/amd, c/a> 1) and orthorhombic (Fdd2) structures.     

Synthesis of ZnFe2O4–Zn2ZrO4Solid Solutions

Low-temperature plasma synthesis was used to prepare solid solutions ( and ) in the ZnFe₂O₄–Zn₂ZrO₄pseudobinary system. The Zn_{2 – x} Zr_{1 – x} Fe_2x O₄solid solutions were found to have a tetragonal spinel structure (a= 8.607–8.740 Å, c= 8.798–9.120 Å) in the composition range x= 0–0.55 and a cubic spinel structure (a= 8.447–8.539 Å) at x= 0.75–1.0. The tetragonal lattice distortion is attributed to a pseudo-Jahn–Teller effect. The electrical conductivity of the solid solutions shows semiconducting behavior and rises by a few orders of magnitude with increasing Fe³⁺content.     

Electrical conduction and dielectric behaviour of the oxidic spinel Li0.5+0.5xCr0.3TixFe2.2−1.5XO4

The electrical conductivity of polycrystalline lithium-chromium ferrites substituted successively with Ti⁴⁺ was studied as a function of composition and temperature. The resistivity increased with composition and all the samples exhibited a change in slope in the resistivity-temperature curve. Two different regions with a large variation in activation energies were found. The dielectric constant and loss factor for different compositions were measured in the frequency range of 10kHz to 10 MHz. The dielectric permittivity showed a dispersion with frequency for all the samples. Peaks were observed for the samples with 0.4 x 0.8. The possible mechanisms involved are discussed.     

Synthesis of Double Uranyl Phthalates of the M4[(UO2)4(μ3-O)2(C6H4C2O4)4] ⋅ nH2O Type with M = NH4, K, and Cs. Crystal Structure of K4[(UO2)4O2(C6H4C2O4)4] ⋅ 3H2O

Double U(VI) phthalates with NH ₄ ⁺ , K⁺, and Cs⁺ ions in the outer sphere were synthesized. The X-ray phase analysis shows that their structures are similar. Single crystals were prepared and the structure of K₄[(UO₂)₄(μ₃-O)₂(C₆H₄C₂O₄)₄] ? 3H₂O was solved. In the [(UO₂)₄O₂(C₆H₄C₂O₄)₄]^4? anions forming the main structural motif, each bridging oxygen atom μ₃-O combines one pentagonal and two hexagonal bipyramids, which, in turn, are combined in centrosymmetrical tetramers. The phthalate ions have coordination capacity equal to 3; each ligand coordinates U(1) in the bidentate fashion via one carboxy group and U(2) in the bidentate fashion to form a planar seven-membered chelate ring.     

Intercalation of nitrogenous substances into HUO2PO4·4H2O

The laminar compound HUO₂PO₄·4H₂O (HUP) interacts with piperidine, hydrazine, pyridine, pyrazine and (dimethylamino-methyl)ferrocene to produce intercalation reactions. The intercalate materials exhibit a layered structure derived from the starting solid. The only observed structural modifications were dimensional changes in the crystal c axes.The amount of adsorbate taken up by the HUP is related to the size and geometry of the guest molecule and its basicity. The guest-host reactions are of the acid-base type as shown by i.r. spectra.     

CuCr2–xSbxS4 and Cu1–ySbyCr2S4 solid solutions

CuCr_2–ySb_xS₄ and Cu_1–ySb_yCr₂S₄ solid solutions with the spinel structure were synthesized, and their magnetic and electrical properties were studied. The limits of solid solutions in these systems were found to bex = 0.5 andy = 0.22. Models of the cation distributions in the solid solutions are proposed. The CuCr_2-xSb_xS₄ solid solutions with 0.10 <x < 0.15 are magnetic semiconductors with high ferromagnetic ordering temperatures.     

球形NH4FePO4·H2O的制备

以柠檬酸铵作络合剂通过控制结晶法制备了的球形NH4FePO4·H2O,用扫描电镜观察了颗粒的形貌和分布.通过研究加料方式、反应温度、滴加速度、搅拌速度、反应物浓度等对颗粒形态的影响,得到了制备球形NH4FePO4·H2O的最佳工艺条件.     

Cu_2ZnSnS_4薄膜的研究进展

Cu2ZnSnS4(CZTS)薄膜太阳能电池具有低成本、高效率、安全无毒等优点,是最具发展前景的太阳能电池之一,近几年来开始受到广泛关注。简要介绍了国内外几种制备Cu2ZnSnS4薄膜的方法,包括蒸发法、溅射法、脉冲激光沉积法、电化学沉积法、喷涂热解法、Sol-gel法、丝网印刷法,并阐述了这几种方法的优点及存在的问题,展望了今后CZTS薄膜的研究方向,认为通过溶剂热或热注入法制备出CZTS纳米晶体后,再通过丝网印刷法或旋涂等法制成CZTS薄膜能降低生产成本,在电池的工业化生产中具有很广阔的应用前景。     

ZnCo2O4及ZnCo2O4/rGO复合材料的制备与电化学性能

采用一步水热法制备尖晶石型钴酸锌(ZnCo_2O_4)及钴酸锌/石墨烯(ZnCo_2O_4/rGO)复合材料,通过XRD,SEM和RST5000电化学工作站对材料的组分、表面形貌及电化学性能进行表征。通过改变水热温度,制备出具有辐射状花簇团结构、褶皱片层结构和表面光滑的球体结构的ZnCo_2O_4电极材料。结果表明:加入石墨烯后,ZnCo_2O_4呈规则的多边形结构,附着在石墨烯片上,两者的协同作用可有效改善电极材料的电化学性能;钴酸锌与氧化石墨烯的质量比为6∶1时得到的ZnCo_2O_4/rGO复合材料的比电容为205F/g,比纯ZnCo_2O_4的比电容提升了约114%。     

纳米LiMn_2O_4的研究进展

尖晶石型LiMn_2O_4具有环境友好、安全性高、锰资源丰富、价格低廉、无毒等优点,被认为是锂离子电池最有发展前途的正极材料之一,但是在充放电循环过程中LiMn_2O_4遭受到严重的容量损失。基于此,研究了纳米化后的LiMn_2O_4对电化学性能的影响,并简要介绍了一些其他改性方法。     

NiMn2O4纳米粉体的制备

用溶胶－凝胶法（ｓｏｌ－ｇｅｌ）合成ＮｉＭｎ２Ｏ４纳米级粉体，利用差热分析（ＤＴＡ），热失重（ＴＧ），Ｘ射线衍射（ＸＲＤ），透射电子显微镜（ＴＥＭ）等广阔博征合成过程及纳米粉体的结构，研究结果表明，ＮｉＭｎ２Ｏ４纳米粉体相合成温度比传统固相反应方法合成温度低大约３００℃，粉体的形状呈多面体形。     

SiH4／C2H4体系激光合成SiC超细粉

本文报道了ＳｉＨ４／Ｃ２Ｈ４体系激光合成ＳｉＣ超细粉研究及对合成的ＳｉＣ超细粉进行的ＴＥＭ（ＴＥＤ）、ＸＲＤ、ＦＴＩＲ、ＸＰＳ及Ｒａｍａｎ散射等测试分析。在部分样品中发现了ＳｉＣ空心颗粒，讨论了ＳｉＣ超细粉的成核成长规律，得出了一些有价值的新结果：ＳｉＣ超细粉的合成由Ｓｉ成核生长和碳化组成；反应温度较高时，为获得接近化学计量化的ＳｉＣ超细粉，要求有较高的源气Ｃ／Ｓｉ比，并且高的Ｃ／Ｓｉ比有利于降低     

Ca3(VO4)2–LaVO4 Cation Conductors

Experimental data are presented on the electrical conductivity, ionic transference numbers, and phase transitions of Ca_{3 – x} La_2x/3(VO₄)₂ (0 x 1) vanadates, which are shown to be Ca ionic conductors. The highest Ca ion conductivity is found in Ca₂La_2/3(VO₄)₂ (palmierite structure) at low temperatures and in "-Ca₃(VO₄)₂ (whitlockite-like structure) at high temperatures. The mechanisms of Ca²⁺ transport are discussed.     

Mixed-Cation Molybdate Complex of Neptunium(V), Li2Na[NpO2(MoO4)2]·4H2O

Radiochemistry - A new mixed-cation complex Li2Na[NpO2(MoO4)2]·4H2O with NpO2+ : MoO42– = 1 : 2 has been synthesized and structurally characterized. The coordination environment of Np(V)...     

Li_2O-Al_2O_3-WO_3三元系中Al_2(WO_4)_3-Li_2WO_4和Al_2(WO_4)_3-Li_2O截面的相平衡研究

本文用 X 射线衍射和差热分析等方法研究了 Li_2O-Al_2O_3-WO_3三元系中 Al_2(WO_4)_3-Li_2WO_4和 Al_2(WO_4)_3-Li_2O 截面相平衡关系。在 Al_2(WO_4)_3-Li_2WO_4赝二元系中生成一新化合物 Al_2(WO_4)_3·Li_2WO_4,该化合物在883±3℃由包晶反应生成。它与 Li_2WO_4形成共晶体系,共晶温度为680±3℃,共晶点组成为90mol%Li_2WO_4。在 Al_2(WO_4)_3-Li_2O 截面中由包晶反应形成一新化合物 Al_2(WO_4)_3·4Li_2O,其包晶反应温度为720±3℃。在这一截面中,在组份45mol%Li_2O 处存在一化合物,该化合物确定为 Al_2(WO_4)_3·Li_2WO_4。Al_2(WO_4)3·4Li_2O 与 Al_2(WO_4)_3·Li_2WO_4形成共晶体系,其共晶温度为682±3℃,共晶点组成约为70mol%Li_2O。     

粉末锻钢12Cr2Ni4A和18Cr2Ni4WA的冲击韧性研究

分析讨论了影响粉末锻钢冲击韧性的因素和近年来为改进粉末锻钢冲击韧性和国内外的进展。为进一步提高粉末锻钢的冲击韧性，进行了降低粉末锻钢的氧含量和热处理试验。发现长时间扩散退火可显著提高粉末锻件的冲击韧性。     

锂离子电池正极材料LiFePO_4在LiBC_2O_4F_2基电解液中的电化学性能

采用循环伏安、交流阻抗和充放电测试等研究了使用LiBC_2O_4F_2基电解液的LiFePO_4/Li电池(LiBC_2O_4 F_2电池)和使用LiPF_6基电解液的LiFePO_4/Li电池(LiPF_6电池)的电化学性能.结果表明,常温下LiBC_2O_4 F_2电池和LiPF_6电池的循环伏安曲线都只有1对对应于Fe~(2+)/Fe~(3+)的氧化还原峰,但是高温下LiPF_6电池的氧化还原峰分裂为多个氧化还原峰,而LiBC_2O_4F_2电池的氧化还原峰却与常温下类似,说明LiBC_2O_4F_2电池在高温下工作能保持较好的稳定性.常温下LiBC_2O_4F_2电池的初始放电容量比LiPF_6电池低,但其具有较高的容量保持率,而且在高温下具有比LiPF_6电池更高的放电容量和更优良的循环性能,如经过50次循环后,LiBC_2O_4F_2电池的容量保持率为92.5%,而LiPF_6电池的容量保持率为78.4%.交流阻抗图谱也表明,使用LiBC_2O_4F_2电池在高温下电池的界面电荷传输反应阻抗比室温下有所下降,说明其具有良好的高倍率性能和高温循环性能.     

Cu-Sn-P-ZnCr2S4(CdCr2S4)纳米复合镀层的性质和组成研究

为了获得耐蚀性能优异的复合化学镀层,利用中性化学复合镀技术,在A3碳钢片表面制备了金黄色光亮致密的Cu-Sn-P-ZnCr2S4和Cu-Sn-P-CdCr2S4纳米复合化学镀层.用扫描电子显微镜(SEM)观察了镀层外貌;以称重法测定厚度;通过5%NaCl溶液、1%H2S气体加速腐蚀试验、抗粘性试验及室温氧化试验等多种手段测定了其性能;用X射线光电子谱(XPS)及俄歇电子能谱(AES)测定了其价态及组成.结果表明:Cu-Sn-P-ZnCr2S4(CdCr2S4)纳米复合材料镀层的性能优于Cu-Sn-P合金镀层,复合镀层Cu-Sn-P-ZnCr2S4中,各原子百分数(%)约为: Cu 68.00,Sn 3.50,P 6.90,Zn 2.10,Cr 4.20, S 8.40,C 6.80;Cu-Sn-P-CdCr2S4中:Cu 69.00,Sn 3.30,P 5.90,Cd 2.4,Cr 4.8, S 9.60,C 4.80.Cu-Sn-P-ZnCr2S4占镀层的93.10%,Cu-Sn-P-CdCr2S4占镀层的95.00%.所得镀层耐蚀性好,耐盐水及室温氧化性能均优于Q235钢片和相近厚度的Cu-Sn-P合金镀层.     

Rapid synthesis of stoichiometric lithium niobate powders with Li2SO4–Na2SO4 flux

Well-dispersed lithium niobate powders with an ideal stoichiometry were rapidly prepared at 650 °C by a molten salt method, with Li₂CO₃ and Nb₂O₅ as raw materials. The dwelling time was 5 min. Li₂SO₄–Na₂SO₄ was used as flux in the present work, which can lead to stoichiometric lithium niobate powders due to its very fast chemical reactions during the whole process. IR spectral characteristics strongly support the stoichiometric composition of our present powder samples.