On the pseudo-binary systems RexM1−xO2 (M=V,Mo, W)

Phase analysis studies on the $\text{Re}{}_{\mathrm{<mtext>x</mtext>}}\text{M}{}_{\mathrm{<mtext>1?</mtext><mtext>x</mtext>}}\text{O}{}_2$ systems ($\text{M}\text{=}\text{V, Mo, W}$) performed by means of X-ray powder photographs of samples prepared 1000K – 1225K have established the existence of the following phases:

$\text{ReO}{}_2\text{?}\text{VO}{}_2\text{:}\text{REo}{}_2\text{(orh) for 1>}{}_{\mathrm{<mtext>x</mtext>}}\text{>0.94 and}\text{VO}{}_2\text{(mon and tetr) for 0<}{}_{\mathrm{<mtext>x</mtext>}}\text{<0.5}$

$\text{ReO}{}_2\text{?}\text{MoO}{}_2\text{:}\text{ReO}{}_2\text{(orh) for 1>}{}_{\mathrm{<mtext>x</mtext>}}\text{>0.70. No. homogenity range of}\text{MoO}{}_2\text{.}$

$\text{ReO}{}_2\text{?}\text{WO}{}_2\text{: No mutual solubility nor anyintermediary phases}$

Metal-metal distances in the orthorhombic rhenium dioxide phases, derived from powder photographs, show slight changes with the $\text{x}$ value.     

GaxIn1 ? xBiyAszSb1 ? y ? z/InSb and InBiyAszSb1 ? y ? z/InSb heterostructures grown in a temperature gradient

Heterophase equilibria in the Ga _x In_{1 − x} Bi _y As _z Sb_{1 − y − z} -InSb and InBi _y As _z Sb_{1 − y − z} -InSb systems have been analyzed within the simple solution approximation. Ga _x In_{1 − x} Bi _y As _z Sb_{1 − y − z} /InSb and InBi _y As _z Sb_{1 − y − z} /InSb heterostructures have been grown in a temperature gradient, and their composition and structural perfection have been assessed.     

Magnetization Processes of (La0.7Pb0.3MnO3)1?x(SiO2)x Composites

The ceramic composites, (La_0.7Pb_0.3MnO₃)_1−x (SiO₂) _x , with diluted magnetic properties are prepared using solid-sate sintering route. Magnetization processes of (La_0.7Pb_0.3MnO₃)_1−x (SiO₂) _x composites are explored in this study. Ferromagnetism is gradually attenuated due to the magnetic dilution induced by the increase of SiO₂ content. Clearly, irreversible behavior is observed in the zero-field cooling and the field cooling (ZFC–FC) curves at a low field of 100 Oe. Saturation magnetization decreases as x increases while ferromagnetic transition temperature remains around 346 K for all composites. All the composites exhibit ferromagnetic hysteresis behavior which can be modeled by the law of the approach to saturation in the form M=M _S(1−a/H). The term a/H expresses the deviation of magnetization from saturation. The smaller factor a for La_0.7Pb_0.3MnO₃-rich samples results in sharper square curve which should be associated with the long-range spin order of ferromagnetic coupling.     

欧盟G/TBT/N/EU/75通报分析

日前,欧盟发布G/TBT/N/EU/75通报,通报了计算机和计算机服务器的ErP指令实施条例草案,规定了计算机和计算机服务器产品的最低能源效率和信息要求,拟批准日期是2013年5月。该实施条例是ErP框架指令(2009/125/EC)下关于计算机产品的具体生态设计要求,该条例要求一旦正式生效,不符合要求的产品将不允许在欧盟市场销售。     

Superconductivity of YBa2?xNdxCu3Oy Solid Solution

The solubility of Nd at the Ba sites and the superconductivity of YBa_2–x Nd _x Cu₃O _y were investigated by X-ray powder diffraction and measurements of the electrical resistance and ac susceptibility. The single Re123 phase was obtained for x0.30. The onset transition temperature is insensitive to the Nd content x in the region of x0.40. All are higher than 95 K. The zero resistance transition temperatures , however, exhibits two-step variation with the increase of x. For x0.25, are all above 92 K. The highest of 94 K was obtained for x=0.25. For x0.3 drops sharply to about 84 K. Finally falls to 30 K and is below 10 K for x=0.5. The two-step variation of T _c might be an indication of the existence of two trap levels for holes.     

Relation of Structure and Superconductivity in Self-compensated Y1?xCaxBa2Cu3?xAlxOz System

The co-doped compounds of Y_1−x Ca _x Ba₂Cu_3−x Al _x O _z , with x from 0.1 to 0.4, were synthesized through a solid-state reaction method. Structural and superconducting properties have been investigated by X-ray diffraction, Rietveld refinement, and DC magnetization measurement. The lattice constant a decreases while b increases with the addition of x. The difference between a and b diminishes gradually. Careful study of the crystalline structure shows that the critical temperature (T _c ) changes monotonically with some local structural parameters, such as the difference between Ba and Cu(2) atoms’ Z coordinates, the bond length of Cu(2)–O(4), and the bond angle of Cu(2)–O(2)–Cu(2), which are all closely related to the interaction between the perovskite block and the rock salt block in the unit cell. The results indicated that the influence of the crystalline structure on superconductivity is important and independent of the carrier concentration.     

Characterizations of InzGa1?z As1?x?yN xSbyP-i-N structures grown on GaAs by molecular beam epitaxy

The GaAs-based double-heterojunction P-i-N structures using In_zGa_1–zAs_1–x–yN_xSb_y as the i-layer is investigated for the first time using solid source molecular beam epitaxy. High quality coherent bulk InGaAsN_3.45%Sb (0.5 m) with a lattice-mismatch of 2.6 × 10^–3 can be achieved due to the surfactant properties of antimony, while the bulk InGaAsN_2% at 0.5 m with 1.06× 10^–3 mismatch is fully relaxed. Rapid thermal annealing (RTA) resulted in 25 meV low temperature (LT) photoluminescence (PL) full-width half-maximums (FWHM) for the bulk InGaAsNSb layers. InGaAsNSb experiences 30% less blueshifting with subjected under the same annealing conditions as InGaAsN with similar N content. Room temperature (RT) absorption measurements are in the range of 0.9–1.4 eV. The absorption edge of 1.41 m is achieved for sample D4.     

The Effects of Substitution of Sn for Cu in Bi1.75Pb0.25Sr2CaCu2.3?xSnxSnxOy

The influence of Sn doping on superconductivity in the Bi-based 2212 phase is studied in this paper. For the samples R–T relations and magnetic hysteresis loops were measured. X-ray powder diffraction analysis was also performed. For Bi_1.75Pb_0.25Sr₂CaCu_2.3–x Sn _x O _y , the experimental results show that by adding the proper amount of Sn the superconductivity of the samples can be improved. As x = 0.15, the critical temperature T _c, the critical current density J _c, and the magnetic pinning force density F reach a maximum. At T = 11 K, the critical state parameters H _c1, H _c2, , , and are calculated and compared with the results reported by other researchers. The experimental results also show that the Sn doping is able to speed up the growth of the 2223 phase. In brief, Sn doping is an effective way of improving the superconductivity in Bi-based superconductors.     

Electrical properties of Zn2(TiaSnb)1 ? xZrxO4 solid solutions

The electrical conductivity, band gap, dielectric permittivity, and molar polarizability of Zn₂(Ti _a Sn _b )_{1 − x} Zr _x O₄ solid solutions have been determined. All of the synthesized samples are dielectrics with semiconducting behavior of conductivity. The phase diagram of the Zn₂TiO₄-Zn₂SnO₄-Zn₂ZrO₄ system is presented.     

Study of the Crystal Structures of New Buffer Materials Bi1?xYxO1.5

Bismuth based oxides, formed by bismuth oxide doped with the yttrium or lanthanum element, have been widely studied for their high ionic conductivities and other applicable properties. Recently, they were used as buffer layers for film superconductors and have shown a promising future. But the detailed information of their structures and properties has not been fully understood. In this work, the series samples of Bi_1−x Y _x O_1.5 (x=0.2, 0.3, 0.4, and 0.5, respectively) were prepared. The crystalline structures of them were determined by X-ray powder diffraction and the data were analyzed by Rietveld refinement method. Two phases, face centered cubic (FCC) and rhombohedral structures, were observed. When annealed at 1,000 °C, the samples are FCC structure. But for Bi_0.8Y_0.2O_1.5, annealed at 650 °C, the sample shows a rhombohedral structure. The change of the structures of the samples were studied and discussed.     

Neutron structural investigations of Y1?xCaxBa2Cu3?yCoyO7±δ

The results of a systematic powder neutron study on Y_1–x CaxBa₂Cu_3–y Co _y O_7± for A (x=y=0), B (x=0;y=0.2), C (x= 0;y=0.4), D (x=y=0.2), and E (x=y=0.4) are investigated with a view to understanding the relation between the structural parameters and superconductivity. Rietveld refinements of the structures show that: (a) Co substitutes at the chain Cu(1) sites only, except for sample E, where the presence of a minor amount of Co at the planar Cu(2) site cannot be ruled out; (b) Co substitution reduced thec-parameter, which is reduced even further upon substitution of Ca at the Y-sites; (c) the occupancy factors of the chain O(1) site indicate an average coordination of 4.8 and 5.1 for Co for samples B and C, but only 4 for D and E; (d) Cu/Co(1) atoms for B and C display large thermal parameters, suggesting a displacement from their ideal centrosymmetric location; (e) the apical Cu(1)-O(4) bond lengthens upon substitution of Co in samples B and C but undergoes shortening upon substitution of Ca in the case of samples D and E. The apical Cu(2)-O(4) bond, on the other hand, shows just the opposite trend; (f) samples D and E show a reduction in the separation of CuO₂ layers and their oxygen content; and (e) the bond valence of the Cu(2) ion shows the lowest value of 2.127 for the nonsuperconducting sample C.     

Li0.5La0.5TiO3包覆LiNil/3Co1/3Mnl/3O2材料的研究

以Li0.5La0.5TiO3为包覆物,制备了固体电解质包覆的LiNil/3Co1/3Mnl/3O2正极材料。采用XRD、SEM对材料进行了表征:XRD显示未包覆的材料具有α-NaFeO2层状结构,粒径在200～300nm之间,包覆后材料粒径略有增大,包覆层具有ABO3型固体电解质结构。包覆层的致密程度及材料的循环稳定性与热处理温度有关。包覆后400℃热处理得到的材料首次放电比容量为185mAh/g,较未包覆材料容量有所提高,50次循环后其容量仍能达到156.5mAh/g,表明包覆物Li0.5La0.5TiO3对LiNil/3Co1/3Mnl/3O2具有保护作用。     

Electrical properties and microstructure of CdxHg1 ? x ? yCrySe crystals

Crystals of the Cd _x Hg_{1 − x − y} Cr _y Se (x = 0.4, y = 0.1) quaternary solid solution have been grown by the Bridgman method, and their microstructure and electrical properties have been studied. The crystals are shown to contain various types of inclusions in the form of filaments and triangles.     

The Effect of Silver Substitution in Bi1.7Pb0.3Sr2Ca2?xAgxCu3Oy

The effect of Ag substitution on the properties of high-temperature superconductor Bi_1.7Pb_0.3Sr₂Ca_2−x Ag _x Cu₃O _y system have been investigated. The electrical and structural properties of the samples, prepared by the conventional solid-state reaction method, have been characterized by X-ray diffraction (XRD), electrical resistance and scanning electron microscopy (SEM) studies. XRD analysis reveals a multiphase structure of the samples, whereas SEM micrographs indicate some morphological changes induced by silver addition. It was found that an increase of the amount of Ag₂O addition leads to an enhancement of the critical temperature and the percentage of Bi-2223 phase in the phase mixture.     

New Thorium-Doped YBa2(1 ? x)SrxThxCu3O7 ? δ High-Tc Superconductors

Thorium-doped YBa_{2(1 – x)}Sr _x Th _x Cu₃O_{7 –} high-T _c ceramic superconductors (with x = 0.1, 0.15, 0.2, and 0.3) have been carefully prepared by the usual ceramic procedure and sintering technique, with intermediate grindings and annealing under a stream of compressed-air atmosphere. The structural parameters of the prepared samples are calculated and interpreted using X-ray diffraction analysis. The electrical properties are also carefully investigated in the present work using the four-probe technique. Results obtained were compared, explained, interpreted, and discussed in detail; meanwhile, the major goal of the present work and promising deductions are attained at.     

Electronic Properties and Superconductivity of Electron-Doped La1?x/2Pr1?x/2CexCuO4

La_1−x/2Pr_1−x/2Ce _x CuO _y (LPCCO) samples with doping level up to 20% have been synthesized and their electronic and superconductive properties are studied. X-ray diffraction revealed that the LPCCO system is a pure phase system with a T’214 structure. Magnetic and resistive measurements show that the system is superconducting at 0.08≤x<0.20 with T _cmax=25 K at x=0.12. An anti-ferromagnetism transition was also observed in under-doped PLCCO (x=0.05) with the window width of the anti-ferromagnetism phase being significantly narrower than that NCCO and PCCO systems. The behavior of the Ce doping is compared with Sr doping in this system, and the mechanism is discussed.     

Microwave properties of the systems Ba1?xSrx(Zn1/3Ta2/3)0.94T{i}0.06 O3 and Ba(Zn1/3Nb2/3)1?xZrxO3

By means of a solid-phase synthesis two types of microwave dielectric materials are obtained as follows: Ba_1–xSr_x(Zn_1/3Ta_2/3)_0.94Ti_0.06O₃, where x = 0.20, 0.25, 0.30, 0.35 and 0.40 at sintering temperature T_S = 1350, 1400 and 1450 C; Ba(Zn_1/3Nb_2/3)_1–xZr_xO₃, where x = 0.04, 0.06, 0.08 and 0.10 at T_S = 1300, 1350, and 1400 C. The microwave characteristics of the materials are investigated at f = 10 GHz. The composition Ba(Zn_1/3Nb_2/3)_1–xZr_xO₃ demonstrates _r = 38, Q = 6100 and _f = +15 ppm C^–1 and the composition Ba_0.80Sr_0.20- (Zn_1/3Ta_2/3)_0.94Ti_0.06O₃ has _r = 42, Q = 8200 and _f = –13 ppm C^–1. The composition Ba_0.75Sr_0.25(Zn_1/3Ta_2/3)_0.94Ti_0.06O₃ has _r = 40, Q = 6500 and low _f = –13 C^–1 ppm. This composition could be used successfully for realisation of dielectric microwave resonators for the satellite television.