New opportunities of variation in the particle sizes and properties of chromium dioxide

Synthesis of single-domain chromium dioxide nanoparticles with high coercivity

“…That result was likely due to the composition of surface magnetic layer based on the Cr 1-x Fe x O 2 solid solution, its high magnetic crystallographic anisotropy preventing magnetization reversal of the particles and uniting the polycrystalline and potentially multidomain particle into a single-domain one. The comparison of the data on change of Н С of CrO 2 particles with their thickness [10], similar results of the γ-Fe 2 O 3 powder studies [11], and the above-mentioned results permit a conclusion that the single-domain CrO 2 particles were magnetically switched primarily incoherent/fanning model. The presence of iron atoms turned the magnetic reversal mechanism to the coherent one, allowing preparation of the powders with Н С over 900 Oe.…”

“…The hysteresis squareness loop was simultaneously decreased from 0.46 to 0.43; in other words, despite the higher thickness the particles were single-domain. Iron-free CrO 2 particles with the similar SSA (17-13 m 2 /g) were not single-domain [10] and showed the hysteresis loop with lower squareness. That result was likely due to the composition of surface magnetic layer based on the Cr 1-x Fe x O 2 solid solution, its high magnetic crystallographic anisotropy preventing magnetization reversal of the particles and uniting the polycrystalline and potentially multidomain particle into a single-domain one.…”

“…Basing on the obtained data on Н С as a function of the anisotropic particles thickness [10], the experimentally determined Н С can be considered as a sum of the purely dimensional part and the contribution from modification with iron. It was found that the second part was the highest (347 Oe) at z = 75, being of 324-316 Oe at higher z.…”

“…Chromium dioxide nanoparticles were prepared via hydrothermal route at 330°С from CrO 3 , tin dioxide, and metatelluric acid in stainless steel autoclave as described elsewhere [1,10,12,13]. The product was removed from the ampule, ground with a knife mill, washed with distilled water, and dried in an oven.…”

Investigation into chromium dioxide nanopowders obtained under hydrothermal conditions in the presence of molybdenum and antimony modifiers

“…Chromium dioxide (CrO 2 ) is one such compound, a magnetic material with a rutiletype structure. The key peculiarities of chromium(IV) oxide are ferromagnetism, half-metallic conductivity, and a giant magnetic resistance [1].…”