The effect of grain size on electrical transport and magnetic properties of La0.9Te0.1MnO3

Abstract

The effect of grain size on structural, magnetic and transport properties in were dissolved in diluted nitric acid in which an excess of citric acid and ethylene glycol was added to make a metal complex. After all the reactants had completely dissolved, the solution was mixed and heated on a hot plate resulting in the formation of a gel. The gel was dried at 250 °C, and then preheated to 600 °C to remove the remaining organic and to decompose the nitrates of the gel. The resulting powder was pressed into pellets, each of which was sintered at a different temperature (T s = 800 °C, 900 °C and 1000 °C) in air. In order to obtain a polycrystalline reference pattern, The crystal structures were examined by x-ray diffractometer using Cu 4 α K radiation at room temperature. The magnetic measurements were carried out with a Quantum Design superconducting quantum interference device (SQUID) MPMS system (2 ≤T≤400 K, 0 ≤ H ≤5 T). Both zero-field-cooling (ZFC) and field-cooling (FC) data were recorded. The resistance was measured by the standard four-probe method from 25 to 300 K. ACKNOWLEDGMENTS

Synthesis, structural and ferromagnetic properties of La1−x K x MnO3 (0·0 ≤ x ≤ 0·25) phases by solution combustion method

“…However, in the present study, all the samples show a broad metal insulator transition and we attribute this to the nano crystalline nature of the grains and weak grain boundary contact. The effect of grain size on magnetic, transport and structural properties of manganites have been extensively studied by many investigators (Mahendiran et al 1996;Hueso et al 1998;Wang et al 2001;Yang et al 2004). These studies suggest that particle size, the doping level in the lanthanum site as well as oxygen content play an important role in the transport properties of these classes of oxides.…”

Tuning of Curie Temperature and Magnetocaloric Effect via Annealing Condition Change in La 0.8 K 0.2MnO 3 Manganites

“…In addition, the change of lattice parameters, especially the variation of Mn-O bond length with increasing T a , need to be considered. The exchange integral between the neighboring orbits of Mn ions is decreased by the increase of Mn-O band length, which would result in a reduction of the magnetization [24]. Consequently, the variation of μ eff and M S may be attributed to the competition of the mentioned effects.…”

Enhanced low-field magnetoresistence in the absence of Mn content in polycrystalline La0.67Ca0.33MnO3

“…This also decreases T C dramatically. For the samples sintered at 1 100 and 900 ℃, the enhanced small grain size effect, including the enhancement of tunneling barrier effects and the loss of long-range order in the ferromagnetic state with the decrease of grain size [15,16] , strongly affects their magnetic and electrical transport properties.…”

“…16). With the increase of x, the intrinsic MR effect is weakened and the extrinsic MR effect is enhanced for all the samples sintered at different temperatures.…”