Background:

The nanocrystalline structure of La_1-xCa_xFeO₃ was prepared by a sol–gel method involving an auto-combustion process. The incorporation of rare-earths in LaFeO₃ induces strain in magnetic properties, especially in terms of the following parameters: replacement amount, oxygen partial pressure, and calcination temperature.

Methods:

To determine the effects of the amount of Ca²⁺ ion doping agent and the calcination temperature on the microstructure, particle morphology, and magnetic properties of LaFeO₃ crystal, we performed the following respective analytical methods: X-ray powder diffraction, Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy, and vibrating sample magnetometer tests.

Results:

The orthorhombic structure of LaFeO₃ perovskite did not change even when it was doped with Ca²⁺ ions, and its space group continued to be Pnma (No.62). FT-IR spectra confirmed that the main band appearing at 568 cm⁻¹ is due to the antisymmetric stretching vibration of Fe–O–Fe bonds in FeO₆. The introduction of Ca inhibits the growth of grains but the morphology of particles is improved. With an increasing concentration of Ca²⁺ ions, magnetic behavior of the samples also witnessed an increasing trend in a proportionate manner. With an increase in calcination temperature, the enclosed area of the magnetic hysteresis curve of the sample reduced remarkably.

Conclusions:

The growth of nanoparticles can be restrained with an increase of Ca content that is used as doping agent. The magnetic behavior of La_1-xCa_xFeO₃ tilts towards G-type antiferromagnetism; the magnetic orientation is achieved from the super exchange interaction of Fe³⁺ ions with oxygen ions.