Novel combustion synthesis of La3+-substituted MnFe2O4

Synthesis and functional properties of the Ni1−xMnxFe2O4 ferrites

“…Similar dielectric properties were often reported for other spinel ferrites [16][17][18][19]34] and are determined by the Maxwell-Wagner interfacial polarization phenomena [35][36][37], which are dominant at low frequencies. The polarization is the results of electron exchange between the ferrous and ferric ions Fe 2+ ↔ Fe 3+ + e − , which gives rise to local electron displacements in the direction of the applied external field.…”

“…This can be associated with an increase in the hopping frequency of the charge carriers between Fe 2+ and Fe 3+ in the octahedral sites, as suggested in Refs. [16][17][18][19]33,34]. The frequency-dependent conductivity results at room temperature presents an almost zero conduction at low frequency (up to 10 kHz) for the compositions with x = 0.17, 0.34 with a large increasing for the frequency range 10 5 -10 6 Hz, for all compositions.…”

Enhancing the electro catalytic activity of manganese ferrite through cerium substitution for oxygen evolution in KOH solutions

“…A similar behaviour of lattice parameter with La 3+ substitution is observed by L. J. Berchmans et al in a similar ferrite system. 18 Fig. 2 shows the chemical composition of Pt/MnFe 2 O 4 electrodes (sintering at 1200 C, in the presence of air for 2 hours) estimated by energy-dispersive X-ray (EDX) analysis, which revealed that the catalysts contained only Mn, Fe and O atoms in a ratio of 1 : 2 : 4.…”

“…Due to the bimetallic nature of spinels, the conductivity of ferrites can be tuned by substituting with a foreign metal, using different preparation conditions or using heat treatment. [16][17][18] Previous studies of MnFe 2 O 4 employed several synthesis methods, mostly to examine structural, electrical conductivity, magnetization and OER properties. 19,20 Recently, Shouheng Sun and his co-works found that similar ferrite system exhibits the ORR activity in alkaline solution, comparable to that of Pt.…”

“…We prepared manganese ferrite and ceriumsubstituted manganese ferrites by a combustion method. 18 Electro catalytic analysis showed that Ce 0.2 MnFe 1.8 O 4 is a promising catalyst for OER in alkaline solutions.…”