Magnetic resonance study of co-modified (Co,N)-TiO₂ nanocomposites

Abstract

Abstract. Three nCo,N-TiO 2 nanocomposites (where cobalt concentration index n = 1, 5 and 10 wt %) were prepared and investigated by magnetic resonance spectroscopy at room temperature. Ferromagnetic resonance (FMR) lines of magnetic cobalt agglomerated nanoparticle were dominant in all registered spectra. The relaxation processes and magnetic anisotropy of the investigated spin system essentially depended on the concentration of cobalt ions. It is suggested that the samples contained two magnetic types of sublattices forming a strongly correlated spin system. It is suggested that the existence of strongly correlated magnetic system has an essential infl uence of the photocatalytic properties of the studied nanocomposites.

Colored Sparks

“…The emission of atomic erbium is located in the blue region with strong lines around 400 and 415 nm . Absorption bands of pink Er 2 O 3 are located at 383, 408, 455, 490, 525, 545 and 657 nm . The emission bands of hot Er 2 O 3 resemble these absorption bands quite exactly .…”

Temperature study of magnetic resonance spectra of co-modified (Co,N)-TiO2nanocomposites

“…Subsequently, the materials were calcined for 4 h at 800°C in an NH 3 flow. According to the XRD measurements, the (nCo,N)-TiO 2 photocatalysts consisted of two phases: rutile TiO 2 and ternary oxide, namely CoTiO 3 [27]. A small amount of metallic Co residues was also observed [27].…”

“…According to the XRD measurements, the (nCo,N)-TiO 2 photocatalysts consisted of two phases: rutile TiO 2 and ternary oxide, namely CoTiO 3 [27]. A small amount of metallic Co residues was also observed [27]. The three investigated samples have been designated as 1Co,NTiO 2 , 5Co,N-TiO 2 and 10Co,N-TiO 2 .…”

“…They obtained a strong EPR signal, which is normally the result of high spin Co 2+ ions on TiO 2 surface. Magnetic resonance study at RT of three (nCo,N)-TiO 2 (n = 1, 5, 10 wt.% of Co) nanopowder samples was also carried out in our group: Guskos et al [27] found that the observed spectrum arises from two types of strongly correlated spin systems, thus, the spectrum should be treated as FMR spectrum. In one spin system the magnetic anisotropy has not varied with Co concentration, in the other system the anisotropy has decreased with Co concentration.…”

FMR study of samples obtained by nitriding and nitrides reduction of nanocrystalline iron

“…It was determined that the magnetocrystalline anisotropy is the main contributor to the observed anisotropy, the shape anisotropy being of secondary importance. Magnetic nanoparticle agglomerates of iron and iron carbide located in a non-magnetic matrix have been already intensively studied by using FMR method [17][18][19][20][21][22][23][24].…”