Controlled phase evolution and the occurrence of single domain CoFe2O4 nanoparticles synthesized by PVA assisted sol-gel method

Microwave spin resonance investigation on the effect of the post-processing annealing of CoFe2O4 nanoparticles

“…The M–H loops revealed the transition from the single domain to the multi-domain nature with the increase in the annealing temperature from 700 to 900 °C, which led to an increase in the coercivity of sample ‘c’ and a decrease in the coercivity of sample ‘d’. 21 The saturation magnetization ( M s ) increased significantly from 37.7 emu g −1 to 71.4 emu g −1 ( Table 3 ) with the increase in annealing temperature from 300 to 900 °C, showing the enhancement of ferromagnetism at a higher annealing temperature. The increase in the M s value for larger particle size was found at a higher annealing temperature, showing the dependence of M s on the particle size.…”

“…The absorption band ν 1 is caused by the stretching vibrations of the tetrahedral metal (Fe 3+ )–oxygen bond, and the absorption band ν 2 is caused by the octahedral metal (Fe 3+ /Co 2+ )–oxygen vibrations in octahedral sites. 21 …”

“…The increase in coercivity from sample ‘a’ to sample ‘c’ ( Table 3 ) could be attributed to the increase in the magnetic anisotropy for sample ‘c’. 21,22 The magnetic anisotropy and coercivity decreased on increasing the annealing temperature to 900 °C, due to the formation of the multi-domain region within the particles of sample ‘d’. 1,28 The variation in the saturation magnetization and coercivity with particle size could also be explained on the basis of the magnetic domain structure, super-exchange interaction, particle diameter, magneto-crystalline anisotropy and shape anisotropy.…”

Silk Fibroin Based Magnetic Nanocomposites for Actuator Applications

“…To understand the magnetic behavior of the CFO/SF nanocomposites, all samples were measured in a vibrating sample magnetometer (VSM) at room temperature in a temperature range from 20 to 175 °C (Figure ). The used nanoparticles with a size distribution around 50 nm, are larger than the critical size of 27–28 nm for single domain particles, so the magnetic behavior of the nanocomposites is expected to be dominated by a multi‐domain magnetic behavior. Figure a shows the hysteresis loops of neat CFO and CFO/SF nanocomposites, whereas Figure b shows the most important parameters obtained from the hysteresis loops.…”

Effect of apple cider vinegar agent on the microstructure, phase evolution, and magnetic properties of CoFe2O4 magnetic nanoparticles

“…Among magnetic nanoparticles (MNPs), the iron oxides and ferrites have attracted the most attention of numerous researchers duo to their wide range of applications in biomedicine, cancer treatment, and etc . CoFe 2 O 4 (CFO) with a cubic inverse spinel structure contains Co 2+ ions distributed at octahedral sites (B) and Fe 3+ ions placed at tetrahedral sites (A) and octahedral sites (B) .…”