  A possibility was assessed to modify physico-chemical properties of
ferronematic mixtures by introducing additional mesogenic and non-mesogenic
components. The mixture, consisting of RM734 and DIO at the 70:30 weight ratio
of the components, was doped with standard nematic 5CB and its chiral isomer
CB15. This allowed a substantial lowering of the ferronematic temperature
range, as well as induction of helical twisting in both nematic (N) and
ferronematic (NF) phases. The effects of 5CB and CB15 on the NF to N phase
transition were nearly identical, but the isotropic transition temperature
decreased more strongly upon addition of CB15. Optical transmission vs.
temperature measurements showed lower transmittance in the NF phase, probably
due to scattering on the domain boundaries. In the vicinity of the NF - N
transition, a noticeable range of anomalously low transmission was noted both
on heating and cooling, suggesting a complex character of molecular
reorientation features. In the chiral NF (N*F) system, helical twisting was
recorded using Grandjean-Cano wedge, with the helical pitch decreasing upon
cooling in both N* and N*F phases. In the cooling mode, transient undulations
emerged in the N*F phase. The complex picture of the ferronematic transition is
supported by POM images taken at different temperatures.
