  We investigate the temperature evolution of the structural parameters of
potential ferrotoroidic LiFeSi2O6 compound across structural and magnetic phase
transitions. The structural transition (TS)is around 220K and the paramagnetic
to antiferromagnetic transition (TN) is around 18K. The lattice parameters
exhibit unusual temperature dependence and based on its behaviour, the exper-
imental results can be divided into 3 regions.In region I (300K to 240K), the
cell parameters are mainly governed by mere thermal effect. As the compound
enters region II (below 240K to 50K), the lattice parameters show non linear
behaviour. In this region, the exchange pathways that lead to the magnetic
interactions within and between the Fe-Fe chains do not show significant
response.The region III (below 50K) is dominated by the magnetic contribution
where we observe setting up of intra and inter-chain magnetic interaction. This
behaviour is unlike other low dimensional com- pounds like Ca3Co2O6, Sr3NiRhO6,
MnTiO3 etc. thereby suggesting the magnetism in LiFeSi2O6 is of three
dimensional nature. The present results will be helpful in understanding the
evolution of the spin rings that give rise to net toroidal moment and hence its
multiferroic behaviour.
