Bi3+对纳米MnO2水热合成的影响研究

在中性和酸性条件下，以MnO2作为锰源，通过水热合成了纳米MnO2，通过XRD和TEM对产物进行的观察表明，在酸性条件下，向溶液中添加一定量的Bi^3 ，产物的晶型由α型向γ型转化，产物形貌由针状、丝状向颗粒状转变。     

Bi-doped La1.5Sr0.5Ni0.5Mn0.5O4+δ as an efficient air electrode material for SOEC

Bi-doped La_1.5-xBi_xSr_0.5Ni_0.5Mn_0.5O_4+δ (LBSNM-x, x = 0, 0.05, 0.1, 0.15) was investigated as a potential air electrode for solid oxide electrolysis cell (SOEC). The effect of Bi doping on the structure, electrical conductivity, chemical compatibility with GDC electrolyte, electrochemical performance and thermal expansion coefficients (TECs) were investigated. XRD characterization results show that the solid solution content of Bi is less than or equal to 0.1. XPS characterization results indicate that Bi doping increases the oxygen vacancy content of LBSNM-x air electrode and thus greatly benefits its oxygen evolution reaction. Among the Bi-doped samples, LBSNM-0.1 electrode has the best electrochemical performance with its lowest Rp (polarization resistance) of 0.28 Ω cm² at 800 °C based on LBSNM-0.1/GDC half-cell. LBSNM-0.1 single cell with 70%CO₂ + 30%CO fuel gas feed on the fuel electrode has achieved current density of 811 mA cm⁻² at 800 °C and 1.4 V, a 62.2% increase relative to that of LSNM single cell. In addition, LBSNM-0.1 single cell exhibits excellent stability at 800 °C and 1.3 V with 70%CO₂ + 30%CO feed gas on the fuel electrode. These results prove that Bi-doped LBSNM-0.1 is an efficient air electrode for SOEC.     

水热法制备纳米铋掺杂氧化锌的影响因素研究

以氯化锌、硝酸铋为主要原料,氢氧化钠为沉淀剂,采用水热法制备了纳米铋掺杂氧化锌粉体。研究了pH值对产物成分的影响,分析了水热时间和水热温度对产物形貌的影响。结果表明pH为9,水热温度为240℃,水热时间为25 h时可以得到微观形貌良好的纳米铋掺杂氧化锌粉体。     

Mechanism of fast hydrogen generation from pure water using Al–SnCl2 and bi-doped Al–SnCl2 composites

The mechanism of fast hydrogen generation from pure water using selectively activated Al–SnCl₂ composites was elucidated with the help of experimental data using combined XRD, SEM, EDX, DSC and calorimetric techniques. It is found that H₂ is produced from two different but simultaneous routes specific to the Al–SnCl₂ composite stoichiometry achieved after ball milling the precursor that readily yields, besides the excess of Al, Sn and AlCl₃. Hydrogen is simultaneously produced from the reaction of the so-formed Al–Sn alloy with water, and from the reaction of the in situ generated AlCl₃ with water, yielding HCl (protons) that further again react with Al, both reactions significantly increasing the hydrogen production rate. The effect of Bi on the hydrogen conversion yield on the Al–SnCl₂ composite was also investigated. The electrochemical activity of Al is further enhanced by doping Bi into Al–SnCl₂ composite. Meanwhile, DFT (density functional theory) calculations show that Bi micro domains present onto the Al (111) crystallite faces of the composite significantly reduce the adsorption energy of the OH groups while, Mg- or Cr-doped Al–SnCl₂ composites increase this adsorption energy. The Mulliken charge analysis indicates that Bi leads to less electron transport between Al and O atoms (weaker interaction) than pristine Al (111) surface. Bi therefore contributes to inhibit the formation of the hydroxyls on the Al metal surface, thereby allowing the clean metal to continuously react with water.     

掺铋纳米TiO_2制备及可见光催化降解有机污染物

采用在酸性条件下超声沉淀的方法低温制备了Bi掺杂TiO_2纳米粉体,采用X射线光电子能谱(XPS)、X射线衍射(XRD)和透射电镜(TEM)对催化剂进行了初步表征,发现其禁带宽度变窄,主要为锐钛矿(82.7%)和金红石(17.3%)混晶,纳米尺寸为25.8nm。以酸性桃红(SRB)和无色小分子2,4-二氯苯酚(2,4-dichlorophenol,2,4-DCP)作为探针反应,在可见光照射下(λ420nm)测定了SRB降解过程中总有机碳(1OC)的变化,发现SRB的TOC去除率为61.6%。跟踪测定光催化反应体系中氧化物种,表明光催化涉及羟基自由基(·OH)过程,所制备的催化剂在可见光下具有较高的催化氧化活性。     

掺铋钇铁石榴石磁光陶瓷的热压烧结及其性能研究

钇铁石榴石(Y₃Fe₅O₁₂, YIG)材料因其优异的磁性能和磁光性能在微波通信、激光技术和光纤通讯等领域具有重要应用。离子掺杂是提高YIG材料磁光性能的有效途径之一, 本研究选择离子半径适配的Bi³⁺掺杂改性YIG陶瓷以提高材料的磁光性能。本工作采用固相法热压烧结制备Bi_xY_3-xFe₅O₁₂ (x=0、0.3、0.6、0.9)陶瓷, 并研究Bi³⁺掺杂对YIG陶瓷材料相结构、微观形貌、红外透过性、磁性能以及磁光性能的影响。结果表明: 陶瓷样品均呈石榴石立方相结构; 显微结构致密, Bi³⁺掺杂后晶粒尺寸不同程度增大; 样品红外透过率良好, 随Bi³⁺掺杂量增大而降低; 陶瓷样品的法拉第旋转角随Bi³⁺掺杂量增加呈线性变化, Bi³⁺掺杂量每增加1% (原子分数), 在波长1064 nm和1550 nm处变化量分别约为-49.0 (°)/cm和-30.2 (°)/cm。Bi_0.6Y_2.4Fe₅O₁₂陶瓷样品在1064 nm和1550 nm波长下法拉第旋转角分别达到-703.3 (°)/cm和-461.5 (°)/cm, 绝对值远高于未掺杂YIG陶瓷的277.6 (°)/cm和172.0 (°)/cm。由此可见, 掺杂适量Bi³⁺可以显著增强YIG陶瓷材料的磁光性能。     

Electroluminescence and lasing properties of highly Bi-doped PbTe epitaxial layers grown by temperature difference method under controlled vapor pressure

Electroluminescence (EL) from PbTe pn homojunctions with a highly Bi-doped n-type emission layer with a concentration of N_Bi > 10¹⁹ cm⁻³, grown by the temperature difference method (TDM) under controlled-Te vapor pressure has shown a positive shift of the peak-photon energy, which coincides with the model that Bi atoms act as both donors and acceptors, and they make the nearest lattice-site or very close donor-acceptor (DA) pairs. Broad-contact pn junctions with highly Bi-doped layers easily cause laser emission compared to the difficulty in the lasing operation of undoped pn junctions, which suggests that the nearest lattice-site Bi-Bi DA pairs act as strong radiative centers in PbTe.     

Observation of broadband infrared luminescence in a novel Bi-doped P2O5-B2O3-Al2O3 glass

A novel Bi-doped P₂O₅-B₂O₃-Al₂O₃ glass was investigated, and strong broadband NIR (near infrared) luminescence was observed when the sample was excited by 445 nm, 532 nm, 808 nm and 980 nm lasers, respectively. The max FWHM with 312 nm, the lifetime with 580 μs and the σ_emτ product with 5.3 × 10^− 24 cm² s were obtained which indicates that this glass is a promising material for broadband optical amplifier and tunable laser. The effect of the introduction of B₂O₃ on the glass structure and Bi-ions illuminant mechanism were discussed and analyzed. It is suggested that the introduction of B₂O₃ makes the glass structure closer, and the broadband NIR emission derives from Bi⁰:²D_3/2 → ⁴S_3/2 and Bi⁺:³P₁ → ³P₀ transitions.     

电沉积法制备掺铋金属锌及其性能表征

以铜片为基体,分别在酸性或碱性镀液中电沉积得到掺铋的金属锌电极。采用X射线衍射(XRD)、电感耦合等离子光谱(ICP)和扫描电子显微镜(SEM)等测试手段对制备的材料进行了表征。结果表明,在碱性镀液中添加Bi离子并不能从根本上改变金属锌疏松的树枝状沉积形态,随着镀液中Bi含量的增加,沉积层中的金属铋含量几乎不发生变化;而在酸性镀液中添加Bi离子后,金属锌由致密的树枝状沉积改变为颗粒状沉积,且随着镀液中Bi含量的增加,金属铋在锌沉积层中的含量线性增加。后者能够在一定程度上提高二次锌负极在1 mol·L-1ZnSO4溶液中的放电容量并改善其循环性能,这可能得益于金属锌结晶形态的改变。     

Properties of Bi-doped PbTe epitaxial layers and pn junction diodes grown by TDM-CVP

Effects of Bi-doping in PbTe liquid-phase epitaxial layers grown by the TDM-CVP have been investigated. For Bi concentration in the solution, x_Bi, lower than 0.2 at.%, Hall mobility is low. In contrast, for x_Bi>0.2 at.%, Hall mobility is high, while carrier concentration is in the range 10¹⁷ cm⁻³. However, ICP emission analysis shows that, for x_Bi=1.0 at.%, Bi concentration in epitaxial layer is N_Bi=2.3–2.7×10¹⁹ cm⁻³.These results indicate that Bi behaves not only as a donor but also as an acceptor; the nearest neighbor or very near DA pairs are formed. Carrier concentration for Bi-doped layers takes a minimum value at a Te vapor pressure of 2.2×10⁻⁵ Torr for growth temperature 470°C, which is coincident with that of the undoped PbTe. And broad contact pn junctions with highly Bi-doped layers easily cause laser emission compared to undoped junctions. The result suggests that the nearest lattice site Bi–Bi DA pairs behave as strong radiative centers in PbTe.