Surface atomic and chemical structure of relaxor Sr0.63Ba0.37Nb2O6(001)

J. L. Wang (1) , B. Vilquin (2) , B. Gautier (3) , G. Dezanneau (4, 5) , N. Barrett (1)

1 SPEC - UMR3680 - Service de physique de l'état condensé
2 INL - H&N - INL - Hétéroepitaxie et Nanostructures
3 INSA Lyon - Institut National des Sciences Appliquées de Lyon
4 SPMS - Laboratoire Structures, Propriétés et Modélisation des solides
5 Ecole Centrale Paris

The surface atomic and chemical structures of a Sr0.63Ba0.37Nb2O6(001) single crystal are studied using the low-energy electron diffraction (LEED) and X-ray photoelectron spectroscopy. Sharp, well-defined LEED patterns are observed, consisting of the superposition of two surface reconstructions, (5 × 5)R26.6° and (5 2 × 2)R45°, probably due to long-range ordering of the alkaline earth metal vacancies in A1 or A2 sites. The Sr/Ba stoichiometry is determined by high-resolution X-ray photoelectron spectroscopy. The Sr 3d core level has 2 components corresponding to the 12- and 15-fold coordinated A1 and A2 sites. The Ba 3d core level has only one component, consistent with the A2 site occupancy. The long-range order of the cation vacancies implies that it is rather the Sr/Ba occupancy of the A2 sites which is responsible for the local random fields at the origin of the relaxor behavior.

Domains: Physics [physics]

J. L. Wang, B. Vilquin, B. Gautier, G. Dezanneau, N. Barrett. Surface atomic and chemical structure of relaxor Sr0.63Ba0.37Nb2O6(001). Applied Physics Letters, 2015, 106, pp.242901. ⟨10.1063/1.4922773⟩. ⟨hal-01489339v2⟩