Yihang Dong,Zhaoyang Liu,Lipeng Pang,Ye Han,Shuyu Yao,Xiangnan Wang
{(Y 2 O 3 ) 0·08 (ZrO 2 ) 0.92 } 1- x (CeO 2 ) x (0 ≤ x ≤ 0.6) is synthesized by co-precipitation method. Thermal analysis, phase structure, lattice constant , micro-morphology, elements distribution, density, open porosity and electrical conductivity are measured by TG, DSC , XRD , GSAS, SEM , EDS, Archimedes method and EIS respectively, and the influence of CeO 2 content on the above properties are investigated. TG-DSC results show that the weight loss of the sample is mainly due to the decomposition of the initial powder, forming a solid solution above ~600 °C. XRD results show that {(Y 2 O 3 ) 0·08 (ZrO 2 ) 0.92 } 1- x (CeO 2 ) x (0 ≤ x ≤ 0.6) is a cubic solid solution, and the lattice parameters and volume increase with the increase of CeO 2 content. SEM results show that YZC is a dense sintered body. Density and open porosity of YZC sample are ~4.5 g cm −3 and ~0.12, respectively. The electrical conductivity results show that the conductivity of {(Y 2 O 3 ) 0·08 (ZrO 2 ) 0.92 } 1- x (CeO 2 ) x (0 ≤ x ≤ 0.2) is equivalent, and then the conductivity decreases due to defect association with the increase of CeO 2 content.
Fe 3+ and Zn 2+ ions were doped into the lattice of CeO 2 via the hydrothermal method . The microstructure and spectra features were analyzed systemically. XRD results show that the solid solubility of Fe 3+ and Zn 2+ ions in Ce 1– x (Fe 0.5 Zn 0.5 ) x O 2 can be identified as x = 0.16. The cell volumes are decreased by increasing the doped content. The TEM graphs prove that the grain size of the sample is about 10 nm, and the EDS result indicates that the doped contents are in accordance with that of the theory concentrations. Meanwhile, the doping also causes the increasing concentrations of the defects and oxygen vacancies which are supported by the XPS , Raman, UV and PL characterizations. The samples exhibit better catalytic activities for improving the hydrogen storage properties and the electrochemical kinetics of the ball milled Mg 2 Ni based composites. Further, the catalysis effects are improved by increasing the doped contents, which can be ascribed to the increasing contents of the oxygen vacancies, defects, the special electron transition states and the nature of the doped ions in CeO 2 -based solid solutions.
The Cu 2+ and Zn 2+ co-doped CeO 2 -based solid solutions were synthesized via hydrothermal method . The microstructure and the spectra features of the solid solutions were characterized systematically. The XRD results showed that the dopants were incorporated into the CeO 2 lattice to form Ce 1-x Cu 0.5x Zn 0.5x O 2 solid solutions when x was lower than 0.14. The cell parameters and the crystalline size decreased linearly, and the lattice strain gradually increased with increasing the doping level. The TEM patterns showed that the particle size in the solid solution was lower than 10 nm which is in accordance with the XRD results. The ICP analysis indicated that the real doped content in the solid solution was close to the nominal proportion. XPS proved that the Ce 3+ component was increased by doping. The Raman and PL spectra indicated that the lattice distortion and the oxygen vacancies also increased following the same trend. At the same time, the synergistic effects of two ions co-doped solid solutions were studied by comparing them with that of single ions doped samples. The catalysis effects of Cu 2+ and Zn 2+ co-doped CeO 2 -based solid solutions on the hydrogen storage electrochemical and kinetic properties of Mg 2 Ni alloys were detected. The electrochemistry properties of the Mg 2 Ni-Ni-5 wt% Ce 1-x Cu 0.5x Zn 0.5x O 2 composites indicated that the doped catalysts could provide better optimizations to improve the maximum discharge capacities and the discharge potentials. On the other hand, the charge transfer abilities on the surface and diffusion rate of H atoms in the bulk of alloys also got improved. The DSC measurements showed that the hydrogen desorption activation of the hydrogenated composites with Ce 0.88 Cu 0.06 Zn 0.06 O 2 solid solutions decreased to 77.03 kJ mol −1 , while that of the composites with pure CeO 2 was 97.62 kJ mol −1 . The catalysis effect was enhanced by the doped content increase that means that the catalysis mechanism had close links to the oxygen vacancy concentration and the lattice defects in the solid solutions. On the other hand, the doped Cu 2+ and Zn 2+ ions could also play an important role in the catalytic process.
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