Effect of the Cation Distribution and Microstructure on the Magnetic Behavior of the CoMn₂O₄ Oxide

Abstract

The sizes of CoMnO nanoparticles can easily be tuned, from 40 to 8 nm, depending on the temperature of decomposition of the single-source molecular precursor {[Co(bpy)][Mn(CO)]·HO}. The structural features of the CoMnO spinel are also affected by the heat treatment temperature, showing a pronounced expansion of unit cell parameters as a consequence of thermally induced cation redistribution between tetrahedral and octahedral sites. Moreover, the magnetic behavior of CoMnO was successfully tailored as well; depending on the heat treatment, it is possible to switch between the superparamagnetic and ferrimagnetic ordering and to tailor the magnetic transition temperatures, i.e., the boundaries between the hard and soft magnetic behavior.

Template and sol‐gel routed CoMn 2 O 4 nanofibers for supercapacitor applications

“…For the zero value of x , it is considered as normal spinel, whereas for it is considered as inverse spinel. When x has the values between 0 and 1, it is called mixed spinel 28 . In addition, it is known that the supercapacitive performance of the electrode material varies with the morphology, dimension, grain size, porous structure, pore size distribution, aspect ratio, and chemical composition of electrode materials.…”

Single‐step preparation of rutile‐type CrNbO4 and CrTaO4 oxides from oxalate precursors–characterization and properties

“…[1][2][3][4][5][6] In the search for suitable oxide semiconductor materials as photocatalysts, several tantalates and niobates have shown promising photochemical and photocatalytic activities. 14 Full control over particles dimensions and morphology is also prerequisite for the photocatalytic applications of oxide materials; large surface area, promoting substrate adsorption at the surface and increasing the number of active sites, is considered to be an imperative. [11][12][13] It is well known that structural features, crystallinity, particle size, morphology and surface area affects materials properties, in general.…”

“…14 Full control over particles dimensions and morphology is also prerequisite for the photocatalytic applications of oxide materials; large surface area, promoting substrate adsorption at the surface and increasing the number of active sites, is considered to be an imperative. 14,[22][23][24][25][26][27][28][29][30] Rutile (TiO 2 ) is a prototypical photocatalyst used for splitting water into hydrogen and oxygen, and decomposition of organic pollutants. Thus, it is still challenging to attain both high crystallinity and high surface area in the same synthesis.…”

“…Recently it was shown that for spinel systems (ie, CoMn 2 O 4 ) temperature of preparation affects also the cation redistribution, resulting in tuneable magnetic properties. 14 Full control over particles dimensions and morphology is also prerequisite for the photocatalytic applications of oxide materials; large surface area, promoting substrate adsorption at the surface and increasing the number of active sites, is considered to be an imperative. However, in general, synthesis approaches for obtaining highly crystalline materials utilize high temperature treatments, which can often lead to the increase in particle size and consequently the decrease the surface area.…”

“…21 There are several reports where heterometallic oxalate complexes have been successfully used for the preparation of mixedmetal oxides. 14,[22][23][24][25][26][27][28][29][30] Rutile (TiO 2 ) is a prototypical photocatalyst used for splitting water into hydrogen and oxygen, and decomposition of organic pollutants. [2][3][4] Several metal oxides of MO 2 , MM′O 4 , and MM′ 2 O 6 stoichiometries adopt similar rutiletype structure.…”