Growth of CaxBa1−xNb2O6 thin films on MgO(1 0 0) by pulsed laser deposition

Thin films of ferroelectric calcium barium niobate, CaxBa1−xNb2O6, are deposited on MgO(1 0 0) substrates by pulsed laser deposition. The microstructure of the films is investigated by means of conventional and high-resolution transmission electron microscopy. The observation of plan-view and cross-sectional samples shows that the films are polycrystalline. The grains orient with their c-axis parallel to the normal of the film surface. Two sets of preferential in-plane crystallographic relationships are determined as 〈1 1 0〉CBN//〈4 1 0〉MgO and 〈1 0 0〉CBN//〈3 1 0〉MgO. Chemical reactions occur at the interface between the film and the MgO substrate, leading to the formation of two phases, corundum-type Mg4Nb2O9 and pseudobrookite-type Mg5Nb4O15.