SrAl12O19 thin films by chemical solution deposition and their use as buffer layers for oriented growth of hexagonal ferrites

•Two procedures developed for preparation of oriented SrAl12O19 thin films on Al2O3.•(1) by high temperature topotactic reaction of thin SrO film with substrate•(2) by nucleation and growth in amorphous SrAl12O19 film on Al2O3•Used as a chemical buffer and structural template for growth of hexagonal ferrites•Hexagon-on-hexagon epitaxy (001)subst ||(001)film and [100]subst ||[110]film

Thin films of SrAl12O19 were prepared on α-Al2O3(0001) substrates through the chemical solution deposition method and thermal treatment. Two types of precursor systems were used: stoichiometric mixture of strontium methoxyethoxide with aluminium iso-butoxide, and strontium methoxyethoxide topotactically reacting with Al2O3 substrate. Two distinctly different film-substrate orientation relationships were observed. In the latter case the orientation can described as perfect hexagon-on-hexagon epitaxy with 112−0SrAl12O19 || 101−0Al2O3 and (0001)Al2O3 || (0001)SrAl12O19. This relationship has 1.17% lattice misfit in the substrate plane. In the former case SrAl12O19 grains are rotated about the substrate normal and form more orientation variants that can be explained by the coincident-site lattice model for grain boundaries. We demonstrated that both types of SrAl12O19 films can be used as a chemical buffer and structural template layer for the growth of oriented hexagonal ferrite thin films. In both types of films the (BaSr)Fe12O19 phase cope the in-plane orientation of their respective templates.