Zhongmin WANG
,
Huaiying ZHOU
,
R.P.ZOU
,
Zhengfei GU
材料科学技术（英）
Mg1.95RE0.05Ni (RE=La, Ce, Pr, Nd, Y), REMgNi4 (RE=La, Ce, Pr, Nd) and REMg2Ni9(RE=Pr, Nd) compounds were prepared by ball-milling of mixed powder of Mg, Ni, RENi (or RE) followed by sintering in pure Ar. XRD analysis showed that Mg1.95RE0.05Ni compounds are all single-phase with a crystal structure same as Mg2Ni. The lattice constants (a, c, c/a) were calculated. It was suggested that rare earth substitution leads to a slight increase in the values of a and c compared with Mg2Ni. Electrode properties of these compounds were evaluated by means of a simulated battery test. The effectiveness in improving the discharge capacity resulted from the addition of RE increased in the following order: Mg1.95Pr0.05Ni>Mg1.95Nd0.05Ni>Mg1.95Ce0.05Ni>Mg1.95La0.05Ni>Mg1.95Y0.05Ni. For REMgNi4 compounds, a slight increase in the discharge capacity was observed in the following order: NdMgNi4>PrMgNi4>La- MgNi4>CeMgNi4. The maximum discharge capacity of NdMgNi4 compound was about 200 mAh/g. The discharge capacities of both NdMg2Ni9 and PrMg2Ni9 compounds were less than 100 mAh/g.
关键词:
Mg-Ni-RE compounds
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Huarui XU
,
Huaiying ZHOU
,
Aibing YU
材料科学技术（英）
The synthesis of nanosized, homogeneous Ba(Ti0.8Zr0.2)O3 (BTZ) powders from cheap raw materials BaCl2, TiCl4, and ZrOCl2 can be achieved by a simple precipitation process operated at a temperature less than 100℃. Characterization via scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis confirms that the as-prepared powder is ~100 nm with a narrow size distribution. It is also well dispersed because the particle size from SEM observation is almost the same as from BET calculation. Characterization via powder X-ray diffraction (XRD) confirms that the phase of the as-precipitated powder is not the simple mixture of BaTiO3 and BaZrO3 phases but is clearly crystallized as monophasic Ba(Ti0.8Zr0.2)O3 (BTZ) and no other phases have been detected, although the initial concentration ratio of [BaCl2]/[TiCl4+ZrOCl2] varies from 1.0 to 2.0. The dielectric behavior of as-prepared BTZ powder is then investigated and it is found that the change in the dielectric constant during the tested temperature does not exceed 30% and with very low dissipation factor. So, the as-prepared BTZ powder is suitable for MLCC.
关键词:
BTZ
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