Annealing Temperature Effect on Physical Properties of Lanthanum Substituted Cobalt Ferrite Nanoparticles using Co-precipitation Technique
Ramadona Rahmawati (a*), Nurdiyantoro Putra Prasetya (b), Suharno (c), Utari (d), Yofentina Iriani (e), and Budi Purnama (f)

a) Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Sebelas Maret, Jl. Ir. Sutami 36A Kentingan, Surakarta 57126, Indonesia
*ramadonarahmawatii[at]gmail.com

Abstract

Lanthanum-substituted cobalt ferrite nanoparticles have been prepared by co-precipitation technique. After were annealed at 200 &#8304-C, 300 &#8304-C, and 400 &#8304-C for 5 hours, the samples were structurally characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Magnetic properties were measured at room temperature conditions using a vibrating sample magnetometer (VSM). The effect of annealing treatment on the structural and magnetic properties of nanoparticles was investigated. XRD results showed that the obtained nanoparticles sample indicates a single phase of FCC inverse spinel conforming to ICDD No 22-1086. The crystallite size calculation at the strongest peaks shows an increase in the increase of annealing temperature. At temperature annealing of 200 &#8304-C, the crystallite size of 18.99 nm is obtained. Then the crystallite size increased to 19.90 nm and 23.21 nm for annealing temperatures at 300 &#8304-C and 400 &#8304-C, respectively. The FTIR results showed absorption band at the tetrahedral site (v1 = 589.28 - 571.92 cm-1) and the octahedral site (v2 = 471.62 - 493.80 cm-1). The absorption band that appears indicates the lanthanum ion has succeeded in replacing Fe3+ cations in the original structure of the cobalt ferrite. The VSM results show that the coercive field magnitude decreases from 700 Oe to 550 Oe as the annealing temperature increases. This result is consistent with the anisotropy constant which decreased from 7.53 x 104 erg/cm3 to 5.50 x 104 erg/cm3. Magnetic property studies have also shown a dominant dependence on crystallite size due to surface anisotropy effects.

Keywords: annealing- cobalt ferrite- co-precipitation- lanthanum- nanoparticles

Topic: Magnetic materials