Magnetic and optical investigations on LaFeO3 powders with different particle sizes and corresponding ceramics. Solid State Ionics, Elsevier, 2013, 249-250, pp.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 onLaFeO 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.