La2O3与Sb2O3掺杂钛酸锶钡陶瓷的介电性能及相变（英文）

采用固相法制备La2O3与Sb2O3掺杂的钛酸锶钡陶瓷,研究其介电性能及相变特性。通过X射线衍射法分析体系微观结构并利用扫描电镜观察其表面微观形貌。(La,Sb)共掺杂的钛酸锶钡陶瓷具有典型的钙钛矿结构,且随着Sb2O3掺杂量的增多其平均粒径显著减小。La3+离子以及Sb3+离子均占据钙钛矿晶格的A位。La2O3与Sb2O3添加量的改变显著影响钛酸锶钡基陶瓷的介电常数以及介电损耗。La2O3改性的钛酸锶钡陶瓷其四方?立方相变为二级相变,且居里温度随着La2O3掺杂量的增多向低温方向移动。(La,Sb)共掺杂的钛酸锶钡陶瓷则体现为弥散相变,随着Sb2O3含量的增大而偏离居里-外斯定律越显著。由于Sb3+离子对晶格原位离子的取代使得(La,Sb)共掺杂的钛酸锶钡陶瓷的介电常数最大值下的温度亦随着Sb2O3含量的增大而降低。     

Zn1+xSb二元体系的相形成和热电性能

在Zn?Sb二元相图固相线以下使Zn和Sb粉末反应并随炉冷却,合成一系列Zn1+xSb(x=0,0.05,0.1,0.15,0.25,0.3)材料,分析Zn–Sb相图中心区域的相形成和热电性能.在此过程中,非化学计量比的混合粉末结晶形成ZnSb和 β-Zn4Sb3相的组合.然后,将材料研磨并热压成致密的ZnSb/β-Z...     

Study of structure and magnetic properties of the perovskite Tb0.5Sr0.5CoO3

The perovskite compound Tb_0.5Sr_0.5CoO₃ has been prepared and studied for the first time. We report here the structural and magnetic properties of the compound using the DC magnetization and powder neutron diffraction techniques. The compound is found to be orthorhombic with Pbnm space group. The magnetic ground state of the system is ferromagnetic with T_c = 120 K. The ordered magnetic moment is found to be 1.57 (4) μ_B/Co ion at 12 K along the crystallographic b-axis. The observed effective paramagnetic moment μ_eff = 2.54 μ_B/f.u. The role of ionic size effect on the magnetic and transport properties of the compound through the variation of CoOCo bond angles is highlighted.     

Sb掺杂量对ATO纳米颗粒结构及激光吸收性能的影响(英文)

以SnCl4·5H2O和SbCl3为原料,采用共沉淀法制备不同Sb掺杂量的氧化锡锑(ATO)纳米粉末。分别采用XRD、FESEM、紫外可见分光光度计和激光器对晶体结构、形貌、激光反射率进行表征,研究Sb掺杂量对ATO纳米颗粒的结构、晶粒尺寸和激光反射性能的影响。结果表明:共沉淀法制备的ATO纳米颗粒为四方相金红石结构,粒径大小约为几十纳米;随着Sb掺杂量的增加,ATO的晶粒尺寸减小,晶胞体积则逐渐增大;与未掺杂的SnO2粉末相比,Sb掺杂后的ATO粉末在1.06μm激光波长处的反射率明显低于未掺杂的SnO2的反射率;随着Sb掺杂量的增加,反射率值呈先减小后增大的趋势,在Sb掺杂量为20%时,ATO粉末在1.06μm激光波长处的反射率低于0.02%,激光隐身性能最佳。     

耐酸非贵金属Ti／MO2阳极SnO2＋Sb2O4中间层研究

采用热分解法制备了非贵金属Sn02＋Sb204中间层Ti基MO2活性层电极，利用SEM，XRD和XPS方法对中间层进行了表征。测定了Ti／SnO2＋Sb2Od／MnO2和Ti／SnO2＋Sb2O4／PbO2电极在硫酸溶液中的析氧极化曲线，二者起始析氧过电位均比贵金属小；考察了在高电流密度（4A／cm^2）下的加速寿命，二者依次分别达到18h和86h。实验表明，SnO2＋Sb2O4是一种具有良好导电性和结合力的耐酸Ti基MO2电极中间层材料。     

Semiconducting of nanocrystalline tin oxide and its influence factors

1 INTRODUCTIONSnO2has non-stoichiometric structure and itsconductivity critically originates from oxygen va-cancies initself ,but the content of oxygen vacan-cies in materials is usually difficult to control .Doped SnO2with Sb, Mo and Fis often availablefor applications to various areas such as displays ,electrochromic windows , gas sensors , catalysts ,rechargeable Li batteries and optical electronic de-vices[1 7].Specially Sb is the best dopant ,becauseSnO2is of the preferable conduc…     

部分填充Skutterudite化合物La_yCo_(4-x)Fe_xSb_(12)与未填充Skutterudite化合物Co_(4-x)Fe_xSb_(12)的制备及热电性能(英文)

采用机械合金化-热压成形-退火工艺制备了部分填充Skutterudite化合物LayCo4-xFexSb12（x≤1,y≤1）,对比研究了填充化合物LayCo3.5Fe0.5Sb12与未填充化合物Co3.5Fe0.5Sb12的热电性能。结果表明,稀土元素La的填充使热导率显著下降,但同时也降低了功率因子,导致材料热电优值上升不大。因此,要提高材料热电优值,还须优化材料电性能。     

富锑铅锑熔体电阻率及黏度的异常变化(英文)

通过测量PbSb合金熔体的电阻率及黏度,探讨熔体中Peierls畸变的演变。Pb30Sb70、Pb20Sb80和Pb10Sb90在降温过程中具有非线性电阻率温度关系。在663°C下,实验与计算的等温电阻率成分关系的变化趋势不同,也暗示了富Sb熔体中Peierls畸变的存在。Pb20Sb80与Pb30Sb70熔体的异常的黏度温度关系证实了异常结构转变的存在,这种异常转变被认为是具有Peierls畸变的大尺寸Sb团簇的形成。在过冷液态Pb20Sb80中,由于提高了熔体与晶态固体的结构相似性并降低了液固界面能,含有Peierls变的Sb团簇在凝固过程中提供优先的形核位;抛物线的电阻率温度关系及极小的电阻率系数被认为是由这些Sb团簇尺寸的快速增加而导致的。     

Magnetic and transport properties of YbRhIn and YbPdIn

Electrical resistivity, magnetization and specific heat have been measured on a single crystal of YbRhIn and polycrystals of LuRhIn and YbPdIn. It is confirmed that YbPdIn is a metal with a divalent Yb ion. For YbRhIn, the electrical resistivity increases with logarithmic temperature dependence with decreasing temperature and saturates at a constant value below 20 K, while that of the nonmagnetic reference LuRhIn shows typical metallic behavior. The magnetic susceptibility of YbRhIn indicates that the Yb ion is in the trivalent state. The irreversibility of the magnetization curves which is observed in the high pulsed magnetic field below 1.5 K suggests an increase of relaxation time in the magnetic system. The specific heat increases rapidly below 4 K with decreasing temperature down to 0.9 K and moves toward higher temperatures on application of a magnetic field. These facts suggest that some magnetic transition to either ferromagnetic or spin-glass state occurs at low temperature.     

Crystal structure and magnetic properties of the new ternary actinide compounds AnPd5Al2 (An = U, Np)

We report the crystal structure and magnetic properties of new ternary actinide compounds UPd₅Al₂ and NpPd₅Al₂. Both compounds crystallize in the body-centered tetragonal ZrNi₂Al₅-type tetragonal structure (I 4/mmm). Although the magnetic susceptibility of both compounds follows the Curie–Weiss behavior at high temperature, no magnetic phase transition was observed. UPd₅Al₂ has a nonmagnetic ground state where the magnetic susceptibility saturates at low temperature, while NpPd₅Al₂ superconducts below 4.9 K as reported recently.     

Piezoelectric and dielectric properties of Lix（K0.46Na0.54） 1-xNb0.86Ta0.1 Sb0.04O3 lead-free ceramics

Lead-free piezoelectric ceramics Lix（K0.46Na0.54）1-xNb0.86Ta0.1Sb0.0403 （with x ranging from 0 to 0.1） were synthesized by conventional solid state sintering method. The effect of cationic substitution of Li for K and Na in the A sites of perovskite lattice on the structure, phase transition behavior and electrical properties were investigated. Morphotropic phase boundaries（MPB） between orthorhombic and tetragonal phase are found in the composition range of 0.06≤x≤0.08. Analogous to Pb（Zr, Ti）O3, the dielectric and piezoelectric properties are enhanced for the composition near the morphotropic phase boundary. The Li0.06（K0.46Na0.54）0.94- Nb0.86Ta0.1Sb0.04O3 ceramics show excellent electrical properties, that is, piezoelectric constant d33=215 pC/N, planar electromechanical coupling factor kp=41%, dielectric constant ε33^T /ε0=1 303, and dielectric loss tan δ=2.45%. The results indicate that Lix（K0.46Na0.54）1 -xNb0.86Ta0.1Sb0.0403 ceramic is a promising lead-free piezoelectric material.     

Mysterious ground states in the organic conductor α-(BEDT-TTF)2KHg(SCN)4 mixed SDW and CDW?

We present magnetoresistance measurements in static fields up to 30T on the organic conductor α-(BEDT-TTF)₂KHg(SCN)₄ . The current and field direction dependence of the magnetoresistance with respect to the crystallographic axis are described, suggesting a topological change of the Fermi surface. The change results from the phase transition from the normal metal to the mysterious ground state. We discuss a possible ground state of mixed charge-density and spin-density waves from the viewpoint of the orbital and Pauli couplings of the external field to the band electrons.     

-NMRC-NMR study on α-(BEDT-TTF)2MHg(SCN)4

The low temperature electronic states of the organic conductors, α-(BEDT-TTF)₂MHg(SCN)₄ [M = K, Rb], have been studied by -NMR¹³C-NMR with the use of ¹³C labeled samples. We observed anomalies in the nuclear spin-lattice relaxatin rate, T₁, and shift of the NMR line below 8 K for the K salt and below 12 K for the Rb salt. These indicate some phase transition. However, absence of critical fluctuation near the transition temperature and absense of splitting or broadening of the NMR line is against the static magnetic ordering as found in usual SDW systems such as the TMTSF compounds. The present results imply that the electronic density of states decreases to a half below the transition.     

Magnetic and neutron diffraction studies on potassium uranate KUO3

The magnetic properties of KUO₃ with the cubic perovskite structure have been studied. It shows an antiferromagnetic-type of transition at ca. 17 K in the magnetic susceptibility vs. temperature curve. Magnetic hysteresis is observed at 4.5 K, but not observed at 20 K. Neutron diffraction measurements have been performed on the powdered KUO₃ below and above the transition temperature. The neutron diffraction pattern measured at 10 K shows no appreciable difference from that measured at 50 K. A small ordered magnetic moment of U⁵⁺ ion will make it very difficult to observe magnetic diffractions, even if a magnetic ordering occurs. If the magnetic spin alignment occurs in a small domain, no magnetic diffraction will be found in the neutron experiments. On the other hand, the magnetic phenomena of KUO₃ have been analyzed on the basis of an octahedral crystal field model.     

Sensing properties of sprayed antimony doped tin oxide thin films: Solution molarity

Transparent conductive thin films of nanocrystalline Sb:SnO₂ have been deposited onto preheated glass substrates by using spray pyrolysis technique. The effect of the solution molarity on structural, morphological, optoelectronic properties of Sb:SnO₂ films has been investigated. XRD study reveals that films are polycrystalline with tetragonal crystal structure having average crystallite size about 20 nm. The compact and homogeneous grains are seen in FESEM images. The BEs of Sn 3d_5/2 for all samples show the Sn⁴⁺ bonding state for SnO₂. The BEs of Sb 3d_5/2 are in the range of 530.6-530.9 eV, indicating that all antimony detected is in a pentavalent state (Sb⁵⁺). Transparency of films in the visible region decreases with increase in precursor concentration. Photoluminescence study shows the strong violet and weak orange emission. The sensing properties of the Sb:SnO₂ films for acetone, ethanol and LPG with operating temperature and gas concentration have been investigated.     

Physiological characteristics of Ficus tikoua under antimony stress

A greenhouse culture experiment was used to evaluate the effects of antimony (Sb) stress on Ficus tikoua (F. tikoua). The results showed that the growth of F. tikoua leaves was significantly inhibited when Sb concentration was higher than 30 μmol/L, and no significantly inhibitory effect of Sb on the roots and stems of F. tikoua was found in all the treatments, implying that leaves were more sensitive to Sb toxicity than roots and stems. Antimony concentration in the roots was higher than that in the stems and leaves. To reduce reactive oxygen species (ROS) level in the F. tikoua, the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) increased with Sb treatments, but the SOD and CAT were more early active than POD. Although the decrease of chlorophyll content with high Sb treatments (450 μmol/L) was observed at the end of the experiments, the positive impact on chlorophyll content was observed with all the Sb treatments at the early period. No significant difference of the maximum quantum efficiency of PSII and quantum yield of PSII electron transport values with different Sb treatments was observed at the end of this experiment, suggesting that the photosynthesis was not inhibited with Sb concentration below 450 μmol/L. The results implied a certain tolerance to Sb stress for F. tikoua. This meets the essential condition for utilization in Sb contamination environments.     

The antimony-niobium (Sb-Nb) system

A constitutional diagram was established for the Nb-Sb system in the region with more than 30 at. % Sb and below 1450 °C. Investigation of the phase relations was based on differential thermal analysis (DTA), light optical microscopy, electron probe microanalysis, and X-ray diffraction experiments on argon arc melted bulk alloys, which were annealed at 600 °C in vacuum-sealed silica capsules up to 1400 h. Differential thermal analysis runs (5 to 20 K/min, T _max=1450 °C) were performed on alloys vacuum sealed in Ta crucibles with an inner lining of W. In contrast to earlier claims for the existence of five binary phases, Nb₃Sb, Nb₃Sb₂, NbSb, Nb₅Sb₄ (or Nb₄Sb₃), and NbSb₂, the authors observed only three binary compounds: Nb₃Sb, Nb₅Sb₄, and NbSb₂. These compounds are essentially line compounds at their stoichiometric composition and without a significant homogeneity region at 600 °C. All compounds are formed by peritectic reactions: L+(Nb)↔Nb₃Sb (1750±25 °C, (L℞55 at.% Sb), L+Nb₃Sb↔Nb₅Sb₄ (1320±10 °C, L℞71 at.% Sb), and L+Nb₅Sb₄↔NbSb₂ (1180±10 °C, L℞88 at.% Sb). The system is characterized by a depleted eutectic reaction L↔(Sb)+NbSb₂ at 618±8 °C and L℞99 at.% Sb.     

Electronic absorption and vibrational IR and Raman studies of binary phosphate β-K4Ce2P4O15

The binary phosphate K₄Ce₂P₄O₁₅ was prepared in the polycrystalline state in the solid state reaction of cerium oxide and potassium phosphate KPO₃. The phosphate fragment of this compound appears in the form of two PO₄³⁻ and one P₂O₇⁴⁻ anions occupying the sites of low symmetry. Electronic absorption, emission as well as infrared and Raman spectroscopic methods have been applied to characterise the properties and structure of the compound studied. Its electronic spectra agree with the Ce³⁺ ion spectroscopic characteristics. The ²F_5/2→²F_7/2 transition appears in the typical for this ion region: about 2000 cm⁻¹. The multiplet structure of the spectrum suggests the existence of at least two crystallographic different sites of this ion in the unit cell. The absorption bands in the range 25000–45000 cm⁻¹ have been assigned to the 4f¹→5d¹ transitions of the cerium ion and CT transition of the phosphate ligands. The vibrational spectra were discussed on the basis of correlation diagrams and factor group analysis.

The radiation-less mechanism of the return from the excited state to the ground state via CT states in the system studied is proposed.     

The effect of some alloying elements on the corrosion resistance of lead-antimony alloys—I. Cadmium

The role played by Cd in lowering the corrosion rate of PbSb alloys has been investigated. It has been shown that 0·1%Cd reduces the steady state corrosion rate of PbSb by ca. 50%. This effect is discussed with respect to results obtained from galvanostatic experiments and from microscopic examination and microprobe analysis. Cd is effective through modification of the nucleation rate in the pores of the originally formed PbSO₄ film.