Structural and magnetic properties of La1−xCexFe1−xCrxO3 orthoferrite prepared by co-precipitation method
Graphical abstract
TEM micrographs of La1−xCexFe1−xCrxO3 for x = 0.0.
Introduction
The compounds of RFeO3 (R = rare earth) are important magnetic oxides which represent a promise as catalysts [1] for gas separators [2], [3] cathodes in solid oxide fuel cells [4], sensor materials [5], magneto-optic materials [6] and as spin valves [7]. RFeO3 belong to a relevant class of weak ferromagnetic materials with interesting magnetic and magneto-optical properties [6], [7]. In a series of rare-earth orthoferrite compounds, there are three allowed spin configurations. All the spin configurations consist of variations of a canted antiferromagnetic alignment of Fe3+ magnetic moments. The first spin configuration is called G4(Fz) configuration where the net magnetic moment aligns along the c-axis [8], [9]. The net magnetic moment aligning along the a-axis is the second configuration G2(Fx). The last spin configuration G1(0) has been proposed for the Dy orthoferrite which has a fully antiferromagnetic state [10]. At low temperature, several of the rare-earth orthoferrites exhibit a further spin order which is related to the rare-earth ions themselves and the ordered Fe3+ lattices will reorientate. Lanthanum orthoferrite (LaFeO3) is well known canted antiferromagnetic material with high value of Néel temperature (TN ∼740 °C) [11], [12]. Actually, it crystallizes in an orthorhombically distorted perovskite oxide with a space group Pnma. The lattice parameters are a = 5.557 Å, b = 5.565 Å and c = 7.854 Å [13], [14]. The aim of this work is to understand the nature of magnetic interactions in structures of La1−xCexFe1−xCrxO3 prepared by co-precipitation method.
Section snippets
Experimental
A series on nanocrystalline ferrites with composition La1−xCexFe1−xCrxO3 (x = 0, 0.1, 0.15 and 0.2) were synthesized by co-precipitation method using stoichiometric amounts of lanthanum(III) chloride heptahydrate (LaCl3·7H2O), cerium(III) chloride (CeCl3), chromium(III) chloride hexahydrate (CrCl3·6H2O) and iron(III) chloride hexahydrate (FeCl3·6H2O) as starting raw materials. The solutions of the desired concentrations were prepared in double distilled water and heated under constant stirring.
Structure and morphology
X-ray diffraction patterns of powder samples La1−xCexFe1−xCrxO3 (x = 0, 0.1, 0.15 and 0.2) prepared by co-precipitation method are shown in Fig. 1. All reflections observed were indexed based on the orthorhombic unit cell of space group Pnma). The peaks were observed, indicating that all the samples have single phase with small intensity of a secondary phase appeared as Fe2O3 with orthorhombic structure (card no. 89-7047). The lattice cell parameters a, b, c and unit cell volume of the samples
Conclusions
- -
Series of compounds of La1−xCexFe1−xCrxO3 where (x = 0, 0.1, 0.15 and 0.2) were prepared by co-precipitation method.
- -
X-ray diffraction showed the formation of single phase orthorhombic structure with space group Pnma at x = 0, 0.10 and crystallite size 34.5 to 39.4 nm. With increasing Ce and Cr content, lattice parameters a and c were found to decrease while b increases. This lead to a decrease of the unit cell volume.
- -
Vibrating sample magnetometer measurements revealed an enhancement in the
References (27)
- et al.
J. Membr. Sci.
(1999) - et al.
J. Power Sources
(1996) - et al.
Sens. Actuators B
(1995) - et al.
Mater. Res. Bull.
(2013) - et al.
J. Solid State Chem.
(1994) - et al.
J. Phys. Chem. Solids
(1957) - et al.
Mater. Res. Bull.
(2005) - et al.
Solid State Commun.
(2003) - et al.
J. Alloys Compd.
(1995) - et al.
Solid State Commun.
(1977)