Fabrication, characterization and photocatalytic activity of Gd-doped titania nanoparticles with mesostructure

Gd³⁺-doped mesoporous TiO₂ (m-TiO₂) nanoparticles were synthesized via hydrothermal process by using cetyltrimethylammonium bromide (CTAB) as surfactant-directing agent and pore-forming agent. The resulting products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), diffuse reflection spectra (DRS), and linear sweep voltammetry (LSV) etc. Experimental results indicate that different Gd³⁺-doping levels make great impact on the photocatalytic activity of the obtained m-TiO₂ nanoparticles and the 3.5 at.% Gd³⁺-doped m-TiO₂ nanoparticles calcined at 300 °C exhibit the optimal photoactivity on the degradation of Rhodamine B (RB), which is as nearly two times as that of the commercial photocatalyst P25. The mesoporosity, anatase wall as well as the cooperativity of ‘lattice Gd³⁺’ and ‘free Gd³⁺’ in the m-TiO₂ nanoparticles can be used to explain the observed high photoactivity of the doped m-TiO₂ nanoparticles.     

Gd掺杂BiFeO3薄膜的溶胶-凝胶法制备和电性能研究

利用溶胶-凝胶工艺在ITO/玻璃衬底上制备了Bi1-xGdxFeO3(x=0.00、0.05、0.10和0.15)薄膜.研究了Gd掺杂对薄膜的结构、形貌、漏电流性能和介电性能的影响.结果显示,未掺Gd和Gd掺杂为5％的样品为菱方结构,当Gd掺杂量达到10％和15％时,样品变为四方结构.掺10％Gd的薄膜样品表面光滑、平整,晶粒大小均匀.Gd的掺入大大降低了BiFeO3(BFO)薄膜的漏电流,其中掺Gd量为10％和15％的薄膜的漏电流几乎为零.在整个测试频率范围内,掺10％Gd的样品的介电常数较大且能保持恒定,同时其介电损耗最小.     

The gadolinium effect on crystallization behavior and luminescence of β-NaYF4:Yb,Er phase

Single phase β-NaY_0.8-xGd_xYb_0.18Er_0.02F₄ nanoparticles with different concentrations of gadolinium ions were prepared via PVP-assisted solvothermal treating at 200°C (PVP- polyvinylpyrrolidone). With the increase in Gd³⁺ concentration, size of the nanoparticles decreased. The up-converting spectra recorded upon 980 nm irradiation showed the green (510-560 nm) and red (640-690 nm) emissions, due to ²H_11/2, ⁴S_3/2 → ⁴I_15/2 and ⁴F_9/2 → ⁴I_15/2 transitions, respectively. The strongest up-conversion luminescence was detected in 15 mol% Gd³⁺-doped nanoparticles obtained after 20 hours of solvothermal treating. With the rise of Gd³⁺ content up-conversion emission decreased due to increased defect concentration in the NaYF₄ matrix. Fourier transform infrared spectroscopy proved in situ generation of hydrophilic nanoparticles as a result of PVP ligands retention at the particle surface.     

Gd掺杂强化(Cu56Zr44)1–xGdx合金非晶形成能力及摩擦学性能

目的 通过稀土元素掺杂Cu-Zr非晶合金,开发远离典型共晶型合金Cu-Zr共晶点的新型非晶合金,探索性能优异的生物质燃油新能源汽车新型活塞材料.方法 采用单辊旋淬法制备了(Cu56Zr44)1–xGdx(x=0,0.01,0.05,0.09)试样,通过X射线衍射仪和扫描电子显微镜对试样的物相结构和形貌进行分析,通过量热分析仪和纳米压痕仪对试样的热力学性能以及力学性能进行研究,在乙醇汽油稀释机油润滑下检测试样的摩擦学性能.结果 通过单辊旋淬法制备的(Cu56Zr44)1–xGdx试样为完全非晶组织,当锆(Gd)掺杂量从1％(原子数分数)增至9％时,(Cu56Zr44)1–xGdx非晶试样的约化玻璃转变温度Trg从0.668降至0.653,纳米硬度从8.73 GPa降至7.18 GPa,但均优于0％Gd非晶试样的0.644和6.82 GPa.在相同摩擦实验条件下,当Gd掺杂量从1％增加到9％时,(Cu56Zr44)1–xGdx非晶试样的摩擦因数和磨损率分别从0.068和1.07×10–5 mm3/(N·m)降低到0.076和1.42×10–5 mm3/(N·m),但是都优于0％Gd非晶试样的0.082和1.62×10–5 mm3/(N·m),更是远低于ZL109铝合金的0.095和75.47×10–5 mm3/(N·m).结论 Gd掺杂能有效地增强体系的非晶形成能力(GFA,Glass forming ability)和力学性能,极大地改善体系的摩擦学性能,且在掺杂1％Gd时,性能达到最佳.(Cu56Zr44)1–xGdx非晶合金的减摩抗磨性能也远优于活塞常用材料ZL109铝合金.