Elsevier

Materials Research Bulletin

Volume 66, June 2015, Pages 249-253
Materials Research Bulletin

Structural and magnetic properties of La1−xCexFe1−xCrxO3 orthoferrite prepared by co-precipitation method

https://doi.org/10.1016/j.materresbull.2015.02.038Get rights and content

Highlights

  • The composition of La1−xCexFe1−x CrxO3 was prepared by co-precipitation method.

  • X-ray diffraction showed orthorhombic structure with space group Pnma.

  • With increasing Ce and Cr content, a decrease of the unit cell volume.

  • Enhancement in the coercivity (Hc) with increasing Ce and Cr content.

  • Reduction of Ms and Mr up to x = 0.15 and increases with further increases of x.

Abstract

Nanocrystalline orthoferrites with the composition of La1−xCexFe1−x CrxO3 where (x = 0, 0.1, 0.15 and 0.2) were prepared by co-precipitation method. The structural and magnetic properties of the La1−xCexFe1−xCrxO3 system have been investigated. X-ray diffraction showed the formation of orthorhombic structure with space group Pnma for different compositions. With increasing Ce and Cr content, lattice parameters a and c were found to decrease while b increases, resulting in a decrease of the unit cell volume. The crystallite size was calculated from XRD data and compared with that obtained from TEM micrographs. Vibrating sample magnetometer measurements reveal an enhancement in the coercivity (Hc) with increasing Ce and Cr content and reduction of saturation magnetization (Ms) and remnant magnetization (Mr) up to x = 0.15 and increases with further increases of x. The magnetic susceptibility measurements vs. temperature showed canted-antiferromagnetic (AFM) in which the Neel temperature is increasing with Ce and Cr content.

Graphical abstract

TEM micrographs of La1−xCexFe1−xCrxO3 for x = 0.0.

  1. Download : Download full-size image

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)

  • V.V. Kharton et al.

    J. Membr. Sci.

    (1999)
  • D. Kuscer et al.

    J. Power Sources

    (1996)
  • E. Traversa et al.

    Sens. Actuators B

    (1995)
  • Z. Zhu et al.

    Mater. Res. Bull.

    (2013)
  • S.E. Dann et al.

    J. Solid State Chem.

    (1994)
  • W.C. Koehler et al.

    J. Phys. Chem. Solids

    (1957)
  • H. Taguchi et al.

    Mater. Res. Bull.

    (2005)
  • M.S. Seehra et al.

    Solid State Commun.

    (2003)
  • K. Kobayashi et al.

    J. Alloys Compd.

    (1995)
  • K. Haneda et al.

    Solid State Commun.

    (1977)
  • S.T. Shen et al.

    Ind. Eng. Chem. Res.

    (1998)
  • V.V. Kharton et al.

    J. Solid State Electrochem.

    (1999)
  • H. Sakakima et al.

    IEEE Trans. Magn.

    (1999)
  • Cited by (0)

    View full text