Synthesis, characterization and surface modification of ZnCrFeO4 nanoparticles

► Novel two stage process produced optimal size and quality ZnCrFeO4 nanocrystals. ► We examined quality by electron and atomic force microscopy and X-ray diffraction. ► Average nanoparticle size of the, order of 10 nm, was determined by five methods. ► Relaxivity studies indicate possible use as negative contrast agent for MRI. ► Cell culture work shows that the nanocrystals have possible biomedical applications.