Uniform colloidal spheres for (Y1-xGdx)2O3 (x=0-1):: Formation mechanism, compositional impacts, and physicochemical properties of the oxides
Uniform colloidal spheres for (Y1-xGdx)2O3 (x=0-1):: Formation mechanism, compositional impacts, and physicochemical properties of the oxides
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DOI：
10.1021/cm7033257
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发表时间：
2008-03-25
影响因子：
8.6
通讯作者：
Ishigaki, Takamasa
中科院分区：
文献类型：
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作者：
Li, Ji-Guang;Li, Xiaodong;Ishigaki, Takamasa
(Y(1-x)Gd(X))(2)O(3)(x=0-1)均匀球体在荧光粉、光学陶瓷制造和组合合成中具有重要的应用价值。在这项工作中，我们通过均相沉淀法合成的前驱体热分解制备了这种粒子。详细地研究了前驱体球体的生长动力学和成分演化，首次发现：(1)Y和Gd发生差异成核，导致Y/Gd混合体系的每个前驱体粒子内存在浓度梯度(从颗粒表面到核心，Gd较多，Y较少)；(2)胶体球的平均粒径与成核密度成反比，并受Gd含量的显著影响；(3)胶体球的生长是扩散控制的，遵循三次根定律。(4)干燥的前驱体球体在1000℃时直接转化为立方结构的(Y(1-x)Gd(X))(2)O(3)(x=0-1)氧化物，同时基本保持其形貌。随着Gd加入量的增加，氧化物的晶格参数呈线性增加，禁带宽度由Y(2)O(3)的5.57 eV降至Gd(2)O(3)的5.20 eV。这项工作的发现可能对其他混合材料体系具有广泛的影响。
Uniform spheres of (Y(1-x)Gd(x))(2)O(3) (x = 0-1) are valuable for applications in phosphors, in optical ceramics fabrication, and in combinatorial synthesis. We made in this work such particles by thermal decomposition of precursors synthesized via homogeneous precipitation. Growth kinetics and composition evolution of the precursor spheres were investigated in detail, and it was identified for the first time that (1) differential nucleation occurs with regard to Y and Gd, and as a result concentration gradients exist within each precursor particle of the mixed Y/Gd system (more Gd and less Y from particle surface to the core), (2) average particle size of the colloidal sphere is inversely proportional to nucleation density and is significantly affected by the Gd content, (3) growth of the colloidal spheres is diffusion controlled and follows the cubic-root law, and (4) the dried precursor spheres directly convert to cubic-structured (Y(1-x)Gd(x))(2)O(3) (x = 0-1) oxides at 1000 degrees C while largely retaining their morphologies. The resultant oxides exhibit linearly increased lattice parameters and linearly decreased bandgaps (from 5.57 eV for Y(2)O(3) to 5.20 eV for Gd(2)O(3)) with increased Gd addition. The findings of this work may have wide implications to other mixed materials systems.