Magnetic and optical investigations on LaFeO3 powders with different particle sizes and corresponding ceramics

Abstract

The optical and magnetic properties of nano-LaFeO 3 powders prepared by a starch assisted soft-chemistry synthesis and corresponding ceramics have been investigated. Magnetic measurements on LaFeO 3 powders with crystallite sizes of 37−166 nm show pronounced magnetization hysteresis loops. Measurements at 300 K reveal that the coercivity (H c) of 19−32 kOe depends on the crystallite size, whereas the low remanence values (M r) of roughly 0.2 emu/g and the maximal magnetization (M max) at 90 kOe of 1.05−0.85 emu/g are only slightly changing. Investigations at 10 K reveal a loop shift (exchange bias) up to 12 kOe in the negative direction depending on the crystallite size. Ceramic bodies, sintered at ≥ 1300 °C possess a considerably reduced hysteresis loop. H c is decreased up to 3.0 kOe, whereas M r 2 and M max are slightly increasing. None of the samples reaches saturation at 90 kOe indicating an anti-ferromagnetic ordering of the spins. The optical band gaps of the LaFeO 3 samples were determined by means of diffuse reflectance spectra. For all LaFeO 3 powders similar band gaps of 2.65 eV were observed. However, ceramics with grain-size significantly larger than 250 nm show smaller band gap values up to 2.12 eV.

Synthesis, Characterization and Catalytic Properties of Perovskite LaFeO3Nanoparticles

“…The result is tabulated in Table. 2. This value is closed to the value reported in the literature [26][27][28].…”

“…The band gap energy of LaFeO 3 nanoparticles was calculated from diffuse reflectance spectra by performing a Kubelka-Munk analysis using the following equation: F(R) = (1-R) 2 /2R [26], with R as the diffuse reflectance. According to this function the band gap energy can be obtained by plotting the F(R) 2 vs. the energy in electron volts.…”

The organic residue and synthesis of LaFeO3 by combustion of citrate and nitrate precursors

“…Therefore, one can expect surface absorbed organic species as a result of added organic precursors. Although, LaFeO 3 has been investigated for the dependence of phase formation, structural and physical properties on the particle size and surface area [17,26,32,33]. However, up to the best of our knowledge no article reports the detailed investigations regarding the thermal stability of the organic residue and its effects on the physical properties.…”

Improvement of Catalytic Performance over LaMnO3/Nanographene Platelets Composites

“…The crystal size and lattice parameters of all samples are tabulated in Table 1. The lattice parameter obtained by Rietveld refinement method using MAUD program and crystal size <D> of the samples calculated using the Scherrer's formula [20]. The BET method was also examined to obtain the specific surface area of all samples.…”