Single crystal synthesis of higher-order sulfohalogenides in the temperature gradient: Bi19S27Br3, Bi2Cu3S4Br,Pb1−xBi2+xCu4−xS5I2

The present paper reports on the single crystal synthesis of three sulfohalogenides (ternary, quaternary, and quinary) in the temperature gradient and focuses primarily on the thermochemical aspects of the synthesis.     

Synthesis of Tyr-Pro-Phe-Val-Glu-L-[3,4-3H]Pro-Ile,Tyr-D-Ala-Phe-Gly-Tyr-L-[3,4-3H]Pro-Ser-NH2, and Tyr-D-Ala-Phe-Gly-Tyr-D-[3,4-3H]Pro-Ser-NH2, Labeled Analogs of Human β-Casomorphin and Dermorphin

Analogs of human -casomorphin and dermorphin, unsaturated in the proline unit, were prepared. Procedures were developed for tritium labeling of these peptides. It was advantageous to introduce the label before deprotection, since in this case the reaction can be performed in an aprotic solvent. Tritiation before deprotection ensured 5-6 times higher molar radioactivity of the products.     

Optoelectronic operation in ferroic [NH2(C2H5)2]2CuxCo1−xCl4 nanocomposites

The complex studies of optically induced piezooptics and second harmonic generation (SHG) are performed for the [NH₂(C₂H₅)₂]₂Cu_xCo_1?xCl₄ nanocomposites in a form of films and bulks. The corresponding nanoparticles (NP) were embedded into different polymer matrices with content of NP varying from 1 % up to 9 % in weight units. The changes of the photoinduced optical SHG were caused by simultaneous illumination of two bicolour coherent laser beams and simultaneously applied dc-electric field at different temperatures, above glass transition temperature. The fundamental 1,064 nm Nd: YAG laser duration was equal to 12 ns. A comparison of the same features with the analogous crystals doped with Fe²⁺ was carried out. The samples doped by Fe³⁺ ions have shown substantially less photo induced SHG up to one order. The time kinetics of the photoinduced changes after the switching off the external laser fields was studied. Temperature dependences of the piezooptics and the SHG near the incommensurate phase existence were explored.     

[（C6H5）2NH2]3[PWl2PO40]·4H2O的合成与表征

以12-钨磷酸和二苯胺为原料合成了一种电荷转移盐。通过元素分析确定其组成为[（C6H5）2NH2]3[PW12O40]·4H2O，各元素的质量分数分别为（括号内为理论值）C 12．91％（13．08％），H 1．304％（1．344％），N 1．793％（1．793％），采用红外光谱、紫外．可见分光光度法、X射线粉末衍射等测试技术对该化合物进行了分析表征。结果表明：所合成的新型电荷转移化合物的杂多阴离子保持Keggin结构特征。     

Crystal structure of (Ba1−x Lax) [Mg(1 + x)/3Nb(2−x)/3]O3 ceramics

The crystal structure of (Ba_1–x La _x )[Mg_{(1 + x)/3}Nb_(2–x)/3]O₃ (BLMN) ceramics with 0 x 1 was investigated using X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). When the La content, x, was above 0.1, the 1:2 ordered hexagonal structure found in Ba(Mg_1/3Nb_2/3)O₃ (BMN) was transformed into the 1:1 ordered cubic structure. The 1:1 ordered cubic structure was maintained up to x = 0.7. When x exceeded 0.7, however, BLMN exhibited a 1:1 ordered monoclinic structure, rather than a 1:1 ordered cubic structure. La(Mg_2/3Nb_1/3)O₃ (LMN) has a 1:1 ordered monoclinic P2₁/n structure with a = 5.6004 Å, b = 5.6414 Å, c = 7.9346 Å, and = 89.9819°. The monoclinic LMN has the in-phase and the anti-phase tilt of oxygen octahedra. The anti-parallel shift of A-site cations was also found in LMN.     

Thermal Conductivity, Thermal Expansion, and Microhardness of CaLa2S4–La2S3 Solid Solutions

The thermal conductivity, thermal expansion, and microhardness of CaLa₂S₄–La₂S₃ solid solutions were measured. The increase in thermal expansion in going from La₂S₃ to CaLa₂S₄ was shown to correlate with the variation in bond strength. The thermal conductivity and microhardness were found to vary nonmonotonically, which was interpreted in terms of the defect structure of the solid solutions. The estimated thermal shock resistance of the solid solutions passes through a maximum around 70 mol % La₂S₃.     

Hydrothermal Crystallization in the Systems LiOH–MO2–GeO2–H2O (M = Ti, Sn) at 500°C and 0.1 GPa: Li2Ti[5]Ge[4]O5 and Li2Ge[6]Ge2 [4]O6 Phase Relations

Crystallization in the LiH–Ti₂–Ge₂–H₂O and LiOH–SnO₂–GeO₂–H₂O hydrothermal systems was studied at 500°C and 0.1 GPa. The phases crystallizing in the Ti system are Li₂Ti^[5]Ge^[4]O₅, Li₂Ge^[6]Ge₂ ^[4]O₆(OH)₂, Li₃HGe₄ ^[6]Ge₃ ^[4]O₁₆ · 4H₂O, and Li₂Ge^[4]O₃ (Ge in four- or sixfold oxygen coordination, and Ti in fivefold oxygen coordination). Over a wide range of TiO₂ : GeO₂ molar ratios (6 : 1 to 1 : 1), the dominant phase is Li₂Ge^[6]Ge₂ ^[4]O₆(OH)₂. At higher GeO₂ contents (TiO₂ : GeO₂ = 1 : 2 to 1 : 6), both Li₂Ti^[5]Ge^[4]O₅ and Li₂Ge^[6]Ge₂ ^[4]O₆(OH)₂ crystallize. The crystallization fields of Ge-containing phases at TiO₂ : GeO₂ = 1 : 2 to 1 : 6 are (in order of increasing LiOH concentration) GeO₂ (rutile structure), Li₂Ti^[5]Ge^[4]O₅ + Li₂Ge^[6]Ge₂ ^[4]O₆(OH)₂, and Li₂Ti^[5]Ge^[4]O₅ + Li₂Ge^[6]Ge₂ ^[4]O₆(OH)₂ + Li₂Ge^[4]₃ + Li₃HGe₄ ^[6]Ge₃ ^[4]O₁₆ · 4H₂O. The phases crystallizing in the Sn system are Li₂Ge^[6]Ge₂ ^[4]O₆(OH)₂, Li₃HGe₄ ^[6]Ge₃ ^[4]O₁₆ · 4H₂O, and Li₂Ge^[4]O₃. Tin is present in the form of SnO₂ only. The structures of Li₂Ti^[5]Ge^[4]O₅ and Li₂Ge^[6]Ge₂ ^[4]O₆(OH)₂ are characterized by the simplest type of matrix assembly: direct packing of substructural precursor units and their two-dimensional growth in various crystallographic directions.     

Normal and Anomalous Pseudogap of Superconducting Y0.9−x Pr x Ca0.1Ba2[Cu1−y Zn y ]3O7−δ

Electrical resistivity measurements on the superconducting oxides of the compositions Y_0.9−x Pr _x Ca_0.1Ba₂[Cu_1−y Zn _y ]₃O_7−δ (0≤x≤0.20 and 0.0≤y≤0.10) sintered in oxygen atmosphere were carried out to obtain the normal and anomalous pseudogaps in underdoped and overdoped samples. It is observed that pseudogap temperature T ^* decreases with increasing doping level p in the underdoped case. For the overdoped sample with y=0.06, T ^* shows no p dependence.      

[Mn(en)3]2·Sn2Se4Te2的结构和光吸收性能

按照K2Se:K2Te2:MnCl2@4H2O:SnCl2 2H2O:Se:乙二胺(en)＝3.8:1:2:2:6:270的摩尔比配料,采用溶剂热法使原料混合物在180℃反应7 d,得到黑色块状晶体[Mn(en)3]2@Sn2Se4Te2.属于三斜晶系,空间群为P-1,晶胞参数a＝0.91428(7)nm,b＝1.02781(7)nm,c＝1.15745(8)nm,α＝94.632(2)°,β＝100.944(2)°,γ＝115.918(1)°,V＝0.94382(12)nm3,Z＝1.晶体由[Mn(en)3]2+和(Sn2Se4Te2)4-堆积而成.具有Zintl结构的特征半导体[Mn(en)3]2@Sn2Se4Te2的光学能隙(Eg)为2.2 eV.当温度低于190℃时,[Mn(en)3]2@Sn2Se4Te2晶体是稳定的.详细讨论了这类化合物的组成对晶体结构和光吸收性能的影响.     

Diamagnetic and Electrical Properties of Si x Mo2S3−x (x=0.1, 0.2, 0.33, 0.5) and A0.1Mo2S3−x (A=C, B, and Ru)

Mo₂S₃ doped with Si, C, B, and Ru, is identified to bear the same crystalline structure P2₁/m as that of Mo₂S₃ through XRD analysis. Diamagnetic transitions with χ _m ～10^?4 emu/g?Oe at temperature ranging from 2 K to 6 K were observed in the doped samples of Si _x Mo₂S_3?x (x=0.1, 0.2, 0.33, 0.5). And both of the x=0.2 and 0.5 samples were found to have double diamagnetic transitions with higher T _c at the same temperature of 6.01 K, while Si _x Mo₂S_3?x of x=0.33 displayed an extra ferromagnetic-like response at 63 K. The corresponding transition in resistivity of Si _x Mo₂S_3?x with x=0.1 was noticed to show a mild drop with less than 10 % of its original transition values as measured down to 2 K. But a superconducting-like magnetic field dependence on the phase transition of resistivity was also noted. Its diamagnetic signals were greatly reduced when the applied magnetic fields were raised to 10³ Oes. In the doped samples of A_0.1Mo₂S_2.9 (A=C, B, and Ru), the phase transition in resistivity at 4.08 K, 4.62 K, and 4.35 K, respectively, exhibited similar fashion as that in the case of Si_0.1Mo₂S_2.9.     

Comparison of Li+ conductivity in Li3−xNb1−xMxO4 (M = W,Mo) with that in Li3−2xNixNbO4

The performance at 300 °C of Li_2.9Nb_0.9M_0.lO₄, M = W or Mo, as a solid electrolyte is compared to that reported in 2004 by McLaren et al. for Li_2.9Ni_0.05NbO₄. The Li⁺ conductivity and activation energy were found to be nearly identical for M = W. Ni in the Li array does not impede Li⁺ mobility more than aliovalent substitution for Nb, and W(VI) is not reduced before Nb(V). Substitution of Nb(V) by Mo(VI) was not as advantageous.     

Macroscopic magnetic properties in TlBa2Ca3Cu4O−δ−δ−δ single crystals

The four-CuO₂-layer TlBa2Ca₃Cu₄O_11– compound has a high superconducting transition temperature of 128 K and strong interlayer coupling. We have performed magnetic experiments on single crystals of TlBa₂Ca₃Cu₄O_11–, which include hysteresis loop, irreversibility line and time relaxation measurements. From these measurements, we observed the large critical current density, high irreversibility line and strongly temperature dependent flux creep rate in the TlBa₂Ca₃Cu₄O_11-gd single crystals.     

Morphology,structural, optical,magnetic, and photocatalytic properties of Co1−xZnxFe2−yCeyO4 NPs

Journal of Materials Science: Materials in Electronics - In the current study, we looked into the effects of simultaneous trivalent Ce and divalent Zn doping on the optical, magnetic, and...     

A comparison of as-fatigue and re-consolidation residual properties for notched quasi-isotropic [0/45/90/−45]2S and cross-ply [0/90]4S AS4/PEEK composite laminates

A comparison of the as-fatigued and re-consolidated properties have been made between notched quasi-isotropic [0/45/90/−45]_2S and cross-ply [0/90]_4S AS4/PEEK laminates. For the former, the ±45° plies tend to constrain longitudinal damage development so that damage growth primarily occurred in the transverse direction, causing more widespread damage. This led to prominent mechanical properties degradation, shorter fatigue lives and lower residual strengths. For cross-ply laminates, quick and extensive longitudinal crack tangential to the hole and the corresponding 90° fiber shear off brought about effective stress concentration alleviation. This discouraged further damage development. Hence, their fatigue lives exceeded one million cycles even at high cyclic stress levels and their residual strengths were significantly higher than their virgin strength. On the other hand, the re-consolidation process removed most of the defects that alleviated the stress concentration and thus decreased the strengths. Detailed study of the residual strength changes and damage development history revealed that the residual as-fatigued and re-consolidated strengths were governed by the competition between local structural decay and its resulting stress concentration alleviation.     

[Li,La]TiO_3包覆锂离子电池用正极材料LiMn_2O_4的电化学性能研究

采用溶胶-凝胶法在锰酸锂(LiMn_2O_4)正极材料表面包覆一层[Li,La]TiO_3(LLTO),通过XRD、SEM、EDS等对LLTO包覆LiMn_2O_4材料的晶体结构、形貌及组成元素进行表征分析,并对其电化学性能进行了研究。结果表明:改性后的尖晶石LiMn_2O_4无杂相出现,循环性能稳定;在1C电流倍率条件下循环200次后,1.5%LLTO包覆的LiMn_2O_4材料在所有改性样品中循环性能最佳,其比容量为106.1mAh/g,高于空白LiMn_2O_4的92.7mAh/g,容量保持率高达90.8%,高于空白LiMn_2O_4的74.1%。     

Synthesis and characterization of a new organic sulphate, [2,3-(CH3)2C6H3NH3]HSO4·H2O

Crystals of a new hybrid compound C₈H₁₂N⁺, HSO₄^?·H₂O were synthesized in aqueous solution and characterized by X-ray diffraction and IR absorption spectroscopy. This compound crystallizes in the orthorhombic non-centrosymmetrical space group P2₁2₁2₁ and an unit cell with a = 5.74(2) Å, b = 9.17(2) Å, c = 21.34(4) Å, V = 1124(6) Å³, and Z = 4. Its crystal structure is a packing of alternated inorganic and organic layers parallel to (a,b) planes. The different components are connected by a bi-dimensional network of strong OH…O and NH…O hydrogen bonds. Then, in order to detect phase transitions and watch changes in the conductivity behaviour, investigations by DTA–TG and differential scanning calorimetry (DSC) and electrical conductivity measurements were carried out.     

Complexes with substituted 2,5-dihydroxy-p-benzoquinones: The inclusion compounds [Y(H2O)3]2 (C6Cl2O4)3·6.6H2O and [Y(H2O)3]2 (C6Br2O4)3·6H2O

Single crystal of [Y(H₂O)₃]₂ (C₆Br₂O₄)₃·6H₂O and [Y(H₂O)₃]₂ (C₆Cl₂O₄)₃·6.6H₂O were grown in aqueous silicagel. The compounds are in principle isostructural. In Y chloranilate one additional water site is occupied as verified by X-ray single crystal structure analysis. Y³⁺ is nine-coordinated by three water molecules and six oxygen atoms of the bischelating (C₆X₂O₄)²⁻ ions (XCl, Br). The coordination polyhedron is an only slightly distorted tri-capped trigonal prism. The connection of Y³⁺ with the dianions leads to infinite, corrugated layers. The layer stacking yields cage-like cavities in which water molecules are accomodated. Hydrogen bonds interlink adjacent layers. Further hydrogen bonds involve the entrapped water molecules. DSC measurements indicated a complicated dehydration process which caused right at the start destruction of the single crystals.     

In Search of Chiral Molecular Superconductors: κ-[(S,S)-DM-BEDT-TTF]2ClO4 Revisited

The relationship between chirality and superconductivity is an intriguing question. The two enantiomeric crystalline radical cation salts κ-[(S,S)-DM-BEDT-TTF]₂ClO₄ and κ-[(R,R)-DM-BEDT-TTF]₂ClO₄, showing κ-type arrangement of the organic layers, are investigated in search for superconducting chiral molecular materials following a 1992 report indicating the occurrence of a superconducting transition in the former compound. While the initial interpretation is presently challenged through in-depth temperature and pressure dependent single crystal resistivity measurements combined with band structure calculations, the two chiral conductors show metal like behavior with room temperature conductivities of 10–30 S cm⁻¹ at ambient pressure and stabilization of the metallic state down to the lowest temperatures under moderate pressures. Moreover, their structural and theoretical investigations reveal an original feature, namely the existence of two different κ layers with 1D and 2D electronic dimensionality, respectively, as a consequence of an interlayer charge transfer. The resistivity drop observed for one sample below 1 K and insensitive to magnetic field, possibly results from mixing in-plane and out-of-plane contributions to the measured resistance and suggests current induced charge order melting. This feature contradicts the occurrence of superconductivity in these chiral molecular conductors and leaves open the discovery of the first chiral molecular superconductors.