Microstructural, Magnetic, Magnetocaloric, and Electrical Properties of Ni0.4Mg0.3Cu0.3Fe2O4 Ferrite Prepared Using Sol–Gel Method

Microstructural analysis, magnetic properties, magnetocaloric effect, and critical behaviors of Ni0.6Cd0.2Cu0.2Fe2O4 ferrites prepared using the sol–gel method under different sintering temperatures

“…The tting curves gave n values of 0.626 and 0.601 for S1000 and S1200, respectively. These values were in good agreement with those obtained from eqn (14) and (15). This suggested that the critical exponents obtained for the studied samples were reliable.…”

“…Furthermore, the ÀDS max M and RCP values were comparable to those found at the same applied magnetic eld in some other ferrite systems that are considered potential candidates for magnetic refrigeration. 9,11,14 3.4. Critical behavior 3.4.1.…”

“…where b and g are the critical exponents. By multiplying the Widom relation by b, we can write bd ¼ (b + g), and consequently eqn (14) can be rewritten as:…”

“…From eqn (14): n ¼ 622 for sample sintered at 1000 C n ¼ 0:596 for samples sintered at 1200 C From eqn (15): n ¼ 0:620 for sample sintered at 1000 C n ¼ 0:594 for sample sintered at 1200 C…”

“…In recent years, large MCEs have been found in other materials, such as perovskite manganites ABO 3 (ref. [4][5][6][7][8] and spinel ferrites AFe 2 O 4 , [9][10][11][12][13][14] which have attracted increasing attention in MR research. The main advantages of these materials over Gd and GdSiGe alloys 15 are low coercive forces, nonactive chemical properties (no oxidation), low costs, and high electric resistance (minimum Eddy current loss).…”