Morphology and stability in a half-metallic ferromagnetic CrO2 compound of nanoparticles synthesized via a polymer precursor

Nanoparticles of stable CrO2 of a half-metallic ferromagnet are synthesized with a novel chemical method involving a Cr4+-polymer composite precursor. A single phase CrO2 of D4h14:P42/mnm tetragonal crystal structure (lattice parameters a=0.4250 and c=0.3190 nm) lies after firing the precursor at 350 deg. C for 1 h in air. Microstructure reveals single domain CrO2 particles of thin platelets (aspect ratio ∼1) of average 50 nm diameter and 35 nm thickness. In air, unless heating at temperatures above 500 deg. C, no due CrO2->Cr2O3 phase transformation encounters. The results are presented in terms of X-ray diffraction and thermal or thermogravimetric analysis of precursor and derived CrO2 powder