Mossbauer spectra and magnetic properties of ferrites-chromites CuFe$_{2-x}$Cr$_x$O$_4$

The results of our Mossbauer investigations of ferrite Zno.4Feo.6fNio.6Cr1.4lO4 and compositions of the system CuFe$_{2-x}$Cr$_x$O$_4$ ($x=0.2$, $1.0$, $1.4$) confirmed the assumption that in ferrites of this system, the frustration degree in an A sublattice increases with the growth of the substitution parameter x, as a result of which the spontaneous magnetization relationship $x\ge1.0$ of the N type becomes anomalous.