Simultaneous segregation of lanthanum to surfaces and grain boundaries in MgAl2O4 nanocrystals
Simultaneous segregation of lanthanum to surfaces and grain boundaries in MgAl2O4 nanocrystals
复制标题
DOI：
10.1016/j.apsusc.2020.147145
复制
发表时间：
2020-11-01
影响因子：
6.7
通讯作者：
Castro, Ricardo H. R.
中科院分区：
文献类型：
--
作者：
Muche, Dereck N. F.;da Silva, Andre L.;Castro, Ricardo H. R.
界面的热化学稳定化可以改善纳米氧化物在严重热应力下的应用性能。这是通过使用易于界面偏析的掺杂剂（离子添加剂）来实现的，从而导致局部能量降低并降低粗化驱动力。在这里，我们实验证明自发偏析镧（La）的MgAl_2O_4纳米晶体的界面。偏析被证明是依赖于界面类型，即表面与晶界（固-固界面），具有不同的能量效应。通过使用量热协议，我们证明的表面能的MgAl 2 O 4降低通过添加La，与掺杂剂的微晶尺寸依赖的效果。晶界能没有表现出类似的尺寸依赖性，这可能与掺杂剂的界面的早期饱和有关。
The thermochemical stabilization of interfaces can improve properties of nanocrystalline oxides for applications under severe thermal stresses. This is achieved by using dopants (ionic additives) prone to interfacial segregation, causing local energy decrease and reducing coarsening driving forces. Here, we experimentally demon strate the spontaneous segregation of lanthanum (La) to the interfaces of MgAl2O4 nanocrystals. The segregation is shown to be dependent on interface-type, i.e. surfaces versus grain boundaries (solid-solid interfaces), with distinct energetic effects. By using calorimetric protocols, we demonstrate the surface energy of MgAl2O4 is lowered by the addition of La, with the effect of the dopant being crystallite size-dependent. Grain boundary energies did not show similar size dependency, which can be related to an early saturation of the interface by the dopant.