A novel low-temperature preparation of several ferrimagnetic spinels and their magnetic and Mössbauer characterization

Abstract

Ultrafine subdomain particles of NiFe2O4, Ni0.5Zn0.5Fe2O4, and CoFe2O4 were prepared under mild hydrothermal conditions by precipitating from metal nitrates. Magnetic and Mössbauer effect measurements revealed the superparamagnetic nature of these ferrite particles. The crystallite sizes were in the range 5.0–20.0 nm with a very narrow particle size distribution. The magnetic properties and Mössbauer hyperfine parameters of these subdomain ferrite particles are somewhat different from those reported for multidomain bulk materials. The hydrothermal ferrite powders were found to sinter to almost theoretical density with little or no intergranular porosity.

Sonochemical Preparation of Nanosized Amorphous NiFe2O4 Particles

“…It is known that the magnetic properties, i.e., the saturation magnetization and the magnetic hyperfine field value, of nanoparticles are much smaller than those of the corresponding bulk materials. 29,30,[34][35][36] Pannaparayil et al have observed an hyperfine field value, H A ) 505 kOe, H B ) 513 kOe for the ultrafine nickel ferrite particles prepared by the hydrothermal process. 34 The BET surface areas of the amorphous, as well as the crystallized (heated), samples of NiFe 2 O 4 are given in Table 1.…”

“…29,30,[34][35][36] Pannaparayil et al have observed an hyperfine field value, H A ) 505 kOe, H B ) 513 kOe for the ultrafine nickel ferrite particles prepared by the hydrothermal process. 34 The BET surface areas of the amorphous, as well as the crystallized (heated), samples of NiFe 2 O 4 are given in Table 1. The surface areas of the amorphous and the crystallized (annealed) samples of NiFe 2 O 4 , 107 and 46 m 2 /g, respectively, corroborate the Mössbauer spectroscopic studies.…”

Structural and thermal studies of Ni0.25Mn0.75Fe2O4 composites by sol–gel combustion method

“…Ferrites are a group of technologically important materials under the category of spinel (AB 2 O 4 ) structures, which hold a very wide diversity of compositions and properties, lead to applications such as fabrication of magnetic, electronic and microwave devices [6]. Nickel ferrite is one of the most versatile magnetic materials, which finds many applications both in low and high frequency devices [7,8] heads for high speed digital tape, etc.…”

Synthesis and optical characterization of nanocrystalline NiFe2O4 structures

“…The preparation and characterization of nanosized structures have attracted increasing attention to researchers and scientists in the last decade. Among the nanostructured materials of different shapes and sizes, spinel ferrite nanoparticles have found considerable interest due to their technological promising applications in the microwave industries, for high speed digital tape or disk recording, the production of repulsive suspensions for use in levitated railway systems, ferrofluids, and magnetic refrigeration systems [4][5][6].…”