  Single phase nickel-cobalt-titanate thin films with a formula A1+2xTi1-xO3,
where A is Ni2+,Co2+ and -0.25<x<1, were grown by pulsed laser deposition on
sapphire substrates. There is a large window in which both Ni/Co ratio and x
can be chosen independently. In the prototype ilmenite and corundum structures
one third of the octahedra are vacant. The reported structure is obtained by
filling vacant (x>0) or emptying filled (x<0) octahedra. When x = 1 all
octahedra are filled. Two factors controlling the magnetism and crystal
distortion are identified. First is a direct overlap between the adjacent
cation d-orbitals resulting in a bond formation and magnetic interactions
between the cations. This is most clearly revealed as a crystal distortion in
the x approximately 0 compositions with approximately equal amounts of Ni and
Co: the distortion of the x approximately 0 compound is a function of Ni/Co
ratio. The second factor is x, which controls the cation shift towards a vacant
octahedron. The displacement decreases and the symmetry increases with
decreasing Ti content as was revealed by x-ray diffraction and Raman
spectroscopy. When all octahedra are filled the cations prefer octahedron
center positions. Also the number density of cations has increased by a factor
of 50 percent when compared to the ilmenite structure. The number density
ratios of Ni/Co cations between x=1 and x=0 compounds is 3. The Raman and x-ray
diffraction data collected on samples with x = 1 or close to 1 are interpreted
in terms of P63/mmc space group.
