  Ilmenite solid-solutions, (Ni1-xCox)TiO3 (0.05 < x < 0.8), were synthesized
at ambient atmosphere through solid-state reaction and were studied by energy
dispersive spectroscopy of X-rays, X-ray diffraction, and DC and AC
magnetometry. Temperature dependent DC magnetic measurements revealed two
transitions. The first took place at around 27 K and the second at 63 K. The
low-temperature phase was antiferromagnetic. The phase observed between 27 and
63 K is characteristic to the solid-solution and is not found in either of the
constituent members. A fit of the data to the Curie-Weiss law gave magnetic
moment values which were significantly larger than the values based on the
quenched orbital momentum assumption. Zero-field-cooled magnetization
measurements with weak magnetic field revealed unexpected negative
magnetization at low temperatures. Below 63 K the DC magnetization exhibited
time dependent behavior. Frequency and magnetic field dependent AC
magnetization is also addressed.
