Crystal and Magnetic Structure of the System Li 0.5+0.5 x Fe 2.5−1.5 x Ti x O 4 ( x =0.16, 0.44, and 0.72)

The influence of thermal treatment on the structure of lithium titanium ferrite spinels of general formula Li 0.5+0.5x Fe 2.5−1.5x Ti x O 4 ( x =0.16, 0.44, and 0.72) has been studied by X‐ray and neutron diffraction and analysed by the Rietveld method. The results allow us to conclude the presence of an ordered phase (space group P 4 3 32) at room temperature for the sample with x =0.16; this phase does not appear for the remaining compositions. The magnetic properties evidence a ferrimagnetic ordering in the structures when a random cation distribution (space group Fd 3  m ) is obtained. An exhaustive study carried out by neutron diffraction measurements on these samples shows a different behaviour when the titanium content is increased, concluding that the lower substituted phase ( x= 0.16) exhibits a Néel's collinear ferrimagnetic structure, with the higher substituted structures being noncollinear ( x =0.44 and 0.72).