Heterostructured dysprosium vanadate – ZnO for photo-electrocatalytic and self-cleaning applications

In this article, we report fabrication of 5 wt% of Dy as DyVO₄ supported ZnO by template-free hydrothermal-thermal decomposition method and its photocatalytic activity towards degradation of azo dyes Rhodamine-B (Rh-B) and Trypan Blue (TB) in solar light, Electrocatalytic activity in methanol oxidation and Self-cleaning properties. The as prepared DyVO₄-ZnO was characterized by surface analytical and spectroscopic techniques. The results suggested that Dysprosium vanadate doping on ZnO has increased its photocatalytic efficiency with high reusability. DyVO₄-ZnO exhibits higher electrocatalytic activity than prepared ZnO for methanol electrooxidation in alkaline medium, revealing its promising potential as the anode in direct methanol fuel cells. Hydrophobicity of ZnO increases by doping of DyVO_4.     

Carbon Free and Noble Metal Free Ni2Mo6S8 Electrocatalyst for Selective Electrosynthesis of H2O2

Electrocatalytic two-electron reduction of oxygen is a promising method for producing sustainable H₂O₂ but lacks low-cost and selective electrocatalysts. Here, the Chevrel phase chalcogenide Ni₂Mo₆S₈ is presented as a novel active motif for reducing oxygen to H₂O₂ in an aqueous electrolyte. Although it has a low surface area, the Ni₂Mo₆S₈ catalyst exhibits exceptional activity for H₂O₂ synthesis with >90% H₂O₂ molar selectivity across a wide potential range. Chemical titration verified successful generation of H₂O₂ and confirmed rates as high as 90 mmol H₂O₂ g_cat⁻¹ h⁻¹. The outstanding activities are attributed to the ligand and ensemble effects of Ni that promote H₂O dissociation and proton-coupled reduction of O₂ to HOO*, and the spatial effect of the Chevrel phase structure that isolates Ni active sites to inhibit O O cleavage. The synergy of these effects delivers fast and selective production of H₂O₂ with high turn-over frequencies of ≈30 s⁻¹. In addition, the Ni₂Mo₆S₈ catalyst has a stable crystal structure that is resistive for oxidation and delivers good catalyst stability for continuous H₂O₂ production. The described Ni-Mo₆S₈ active motif can unlock new opportunities for designing Earth-abundant electrocatalysts to tune oxygen reduction for practical H₂O₂ production.     

沉积物孔隙水的拉曼光谱探测及荧光时间演化特性

为了研究孔隙水取样后的荧光时间演化特性,对柱状沉积物榨取得到的孔隙水样品进行了光谱采集。拉曼光谱分析表明,沉积物中的SO42-浓度随深度变大而逐渐减小,这说明沉积物孔隙水中的SO42-参与了沉积物中硫酸盐还原而被消耗;同一深度的孔隙水样品随着暴露时间的不同,采集到的拉曼光谱的荧光背景也有所差别。荧光光谱分析表明,随着孔隙水暴露时间的延长,在300~350 nm处的荧光峰的强度逐渐变大,并对荧光的形成机制进行了初步分析。     

新型稀土6063铝材热加工性能研究

采用高温拉伸、高温压缩试验方法,对新型稀土6063铝合金半连续铸造锭坯材进行热变形加工性能研究。通过拉伸变形抗力、伸长率、压缩变形量、冲击速度的测量比较,以及两类试验试样的形貌、形态观察对比,确定新型稀土6063铝合金半连续铸造锭坯材最佳热挤压加工温度区间为450~480℃;实施大变形、高速挤压与在线连续淬火工艺,最佳热挤压温度区间应控制在430~480℃。     

同时含有稀土元素La Ce Pr Nd的材料的电子探针定量分析方法

研制了稀土六硼化物单晶LaB_6、CeB_6、PrB_6和NdB_6电子探针分析标样。根据X-射线峰位表和实测的特征X-射线谱,考察分析了La、Ce、Pr和Nd元素谱线之间的干扰情况,发现分析谱线PrLα_1受到L_αLβ_1线严重的干扰。以混合稀土金属为试样,采用扣除谱线重叠强度的背底非对称测量等方法对L_n、Ce、Pr和Nd进行了电子探针定量分析,其结果与荧光X-射线光谱分析结果符合较好。     

锡铅稀土钎料合金高温蠕变性能试验研究

文中对比分析了Ｓｎ６０Ｐｂ４０和Ｓｎ－Ｐｂ－０．０５Ｒｅ两种钎料合金在多轴应力状态下的蠕变断裂规律,初步探讨了主控两种钎料复合金为断裂的力学因素,并从金属学角度初步探讨了两种钎料合金的蠕变断裂方式,着重分析了混合稀土对锡铅秆料合金蠕变性能的影响。     

Reversible Disorder in a Room Temperature Ferromagnet

Random magnetic fields, varying from site to site in a magnetic material, are a form of disorder that can determine the local architecture and stability of the magnetic state. In a ferromagnet, the application of an external magnetic field can amplify the effects of the internal random fields and, in principle, harden a magnetic domain, without changing temperature and only for as long as the external field is present. Here, the rare‐earth compound Nd₂Fe₁₄B, formed with a granular morphology of random‐packed, elongated grains, is an experimental realization of the Random Field Ising Model in a room temperature ferromagnet. The application of magnetic fields transverse to the easy axis tunes the coupling between the structural disorder and the magnetic pinning properties. This material both illuminates the intricacies of tunable disorder and serves as a guidepost along the way to developing increased‐density magnetic storage media.     

Transport and interface states in high-κ LaSiOx dielectric

The paper presents the results of capacitance-voltage, conductance-frequency and current-voltage characterization in the wide temperature range (140-300 K) as well as results of low temperature (5-20 K) thermally stimulated currents (TSC) measurements of metal-oxide-semiconductor (MOS) structures with a high-κ LaSiO_x dielectric deposited on p- and n-type Si(1 0 0) substrate. Interface states (D_it) distribution determined by several techniques show consistent result and demonstrates the adequacy of techniques used. Typical maxima of interface states density were found as 4.6 × 10¹¹ eV⁻¹cm⁻² at 0.2 eV and 7.9 × 10¹¹ eV⁻¹cm⁻² at 0.77 eV from the silicon valence band. The result of admittance spectroscopy showed the presence of local states in bandgap with activation energy E_a = 0.38 eV from silicon conductance band, which is in accord with interface states profile acquired by conductance method. Low-temperature TSC spectra show the presence of shallow traps at the interface with activation energies ranging from 15 to 32 meV. The charge carrier transport through the dielectric film was found to occur via Poole-Frenkel mechanism at forward bias.     

稀土元素对铂的室温强度和电阻率之影响

添加微量稀土元素使纯Pt的再结晶温度提高200～300℃,硬度和抗拉强度增高2～3倍。含重稀土铂合金的强度一般高于轻稀土铂合金。Eu和Yb与Pt组成的合金的强度很高。微量稀土元素使铂的电阻率增加很少,当含量增加到1wt%时,电阻率明显升高,而硬度和抗拉强度反而降低。     

掺杂Sc和Sb的Mg2Si基热电材料的电性能研究

采用机械合金化-电场激活压力辅助合成(MA-FAPAS)技术,快速合成Sc,Sb掺杂的Mg2Si基热电材料,并对其进行电性能的测试与分析。结果表明:掺杂摩尔分数为0.47%Sb的Mg2Si试样在测试温度范围内,电导率和Seebeck系数均优于未掺杂试样,其平均电功率因子约为后者的2.2～2.3倍;电导率比采用熔融-热压法制备的同类试样有所提高;在低温阶段,掺杂摩尔分数为0.43%Sc的Mg2Si试样Seebeck系数约为307 K,达未掺杂试样的2.03倍;电功率因子在温度低于550 K时高于未掺杂试样,最大值与Sb掺杂试样相当。