Simultaneous segregation of lanthanum to surfaces and grain boundaries in MgAl2O4 nanocrystals

Author(s)

Muche, Dereck N. F. ^{[1, 2]} ; da Silva, Andre L. ^[3] ; Nakajima, Kimiko ^[1] ; Gouvea, Douglas ^[3] ; Castro, Ricardo H. R. ^[1]

Affiliation

^[1] Univ Calif Davis, Dept Mat Sci & Engn, One Shields Ave, Davis, CA 95616 - USA

^[2] Fed Univ Sao Carlos UFSCar, Dept Mat Engn DEMa, Rod Washington Luis, Km 235, BR-13565905 Sao Carlos, SP - Brazil

^[3] Univ Sao Paulo, Polytech Sch, Dept Met & Mat Engn, BR-05508030 Sao Paulo - Brazil

• Document type: Journal article
• Source: Applied Surface Science; v. 529, NOV 1 2020.
• Web of Science Citations: 0

Abstract

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. (AU)

• FAPESP's process: 15/50443-1 - Interfaces in ceramic processing
• Grantee: Douglas Gouvêa
• Support Opportunities: Regular Research Grants
• FAPESP's process: 13/23209-2 - Ions segregation onto oxide nanopowders surfaces and the influence on the colloidal processing
• Grantee: Douglas Gouvêa
• Support Opportunities: Regular Research Grants