Synthesis and Magnetic Properties of $CuCr_{1.65}Se_4$ Nanoparticles

$CuCr_{1.65}Se_{4}$ nanoparticles crystallize in the monoclinic $Cr_{2}Se_{3}$-type structure of the space group I2/m. The average crystallite size basing on the line broadening is less than 10 nm. With decrease of the size of grains a change from ferromagnetic to ferrimagnetic order, a lack of the magnetization saturation and a strong spin-orbit coupling visible in the large value of the Landé factor $g_{χ}$ = 2.72 are observed. The change in magnetic order is caused by the change of the crystalline symmetry from the cubic phase to monoclinic one.