Chemical synthesis and L12 ordering of CrPt3 nanoparticles

Cr–Pt nanoparticles of different compositions around the ferrimagnetic Pt3Cr have been synthesized with the thermolytic method and proper adjustment of the Pt(acac)2 and Cr(acac)2 mole ratios. The as prepared particles have a size of (5.5±1.0) nm but after heat-treatment at 850 °C for 2 h an inhomogeneous microstructure consisting of clustered nanoparticles with variable sizes 5–50 nm is obtained. Chemical ordering to the L12 phase up to S=0.83 has been achieved for the nanoparticles with optimized stoichiometry while moderate coercivity values up to 380 Oe are achieved.

► Thermolytic chemical synthesis of Cr–Pt nanoparticles.
► Only partial chemical ordering to the L12 phase and moderate coercivity obtained.
► Sluggish kinetics require high heat-treatment temperatures exceeding size-dependent ordered phase critical temperature.