Synthesis and characterization of indium oxide-hematite magnetic ceramic solid solution

Abstract

Indium oxide-doped hematite xIn 2 O 3 * (1 − x)α-Fe 2 O 3 (molar concentration x = 0.1-0.7) solid solutions were synthesized using mechanochemical activation by ball milling. XRD patterns yield the dependence of lattice parameters and grain size as function of milling time. After 12 h of milling, the completion of In 3+ substitution of Fe 3+ in hematite lattice occurs for x = 0.1. For x = 0.3, 0.5 and 0.7, the substitutions between In 3+ and Fe 3+ into hematite and respectively, In 2 O 3 lattices occur simultaneously. The lattice parameters of α-Fe 2 O 3 (a and c) and In 2 O 3 (a) vary with milling time. For x = 0.1, Mössbauer spectra were fitted with one, two, or three sextets versus milling time, corresponding to gradual substitution of In 3+ for Fe 3+ in hematite lattice. For x = 0.3, Mössbauer spectra after milling were fitted with three sextets and two quadrupole-split doublets, representing In 3+ substitution of Fe 3+ in hematite lattice and Fe 3+ substitution of In 3+ in two different sites of In 2 O 3 lattice. For x = 0.5 and 0.7, Mössbauer spectra fitting required two sextets and one quadrupole-split doublet, representing coexistence of In 3+ substitution of Fe 3+ in hematite lattice and Fe 3+ substitution of In 3+ in indium oxide lattice. The recoilless fraction studied versus milling time for each molar concentration exhibited low values, consistent with the occurrence of nanoparticles in the system. SEM/EDS measurements revealed that the mechanochemical activation by ball milling produced xIn 2 O 3 * (1 − x)α-Fe 2 O 3 solid solution system with a wide range of particle size distribution, from nanometer to micrometer, but with a uniform distribution of Fe, In, and O elements.

Structural, thermal, 57Fe and 151Eu Mössbauer studies of Eu2O3–Fe2O3 ceramic nanostructures

“…Recently, the authors have performed several studies on mechanochemical activation of various mixed-oxide systems such as xIn 2 O 3 Á (1À x)α-Fe 2 O 3 [7,8], La 2 O 3 À α-Fe 2 O 3 [9], xTiO 2 Á (1À x)α-Fe 2 O 3 [10], xZrO 2 Á (1À x)α-Fe 2 O 3 [11], xCeO 2 Á (1À x)α-Fe 2 O 3 [12], vanadium oxides and niobium oxides doped hematite [13,14]. In the case of the In 2 O 3 À α-Fe 2 O 3 system with the lowest molar concentration of In 2 O 3 (x=0.1), indium-doped hematite was formed after 12 h of high-energy ball milling [7,8]. Simultaneous substitutions of In 3 þ and Fe 3 þ into hematite and In 2 O 3 lattices were reported for 0.3rxr0.7.…”

Mössbauer Study of Graphite-Containing Iron Oxide Nanoparticles

“…[13] Recently, the authors have performed several studies on mechanochemical activation of various oxide systems with hematite. [14][15][16][17][18][19][20][21][22] Our results ranged from demonstrating the formation of a single phase perovskite for La 2 O 3 [16] to the occurrence of multiple phases for Li 2 O [22] and providing evidence for the effect of metallic species valence on the properties of the nanostructures formed for NbO, NbO 2 , and Nb 2 O 5 ball milled with hematite. [20] Indeed, mechanochemical activation by high-energy ball-milling technique is a well-established method for the synthesis of nanostructured materials in which non-equilibrium phases, extended solid solutions or complex structures can be formed at moderate temperatures.…”