Subdomain zinc ferrite particles: Synthesis and characterization

Abstract

Ultrafine and nearly spherical particles of zinc ferrite were synthesized under mild hydrothermal conditions by precipitating from metal nitrates. These particles exhibited antiferromagnetic ordering below 13 K. Mossbauer spectroscopic measurements revealed the subdomain superparamagnetic nature of the particles having a narrow particle size distribution. The hydrothermal ferrite powders were found to sinter to almost theoretical density with little or no intragranular porosity.

Effect of mechanical milling on the structural, magnetic and dielectric properties of coprecipitated ultrafine zinc ferrite

“…Nanoparticles have been generating extensive interest in recent years among researchers worldwide owing to their interesting physical and chemical properties with respect to their coarser sized cousins in the bulk [1][2][3][4][5]. Nanoparticles of many ferrites have been successfully obtained by numerous chemical routes, such as reverse micelle synthesis, coprecipitation, thermal decomposition, solgel and aerogel process [1][2][3][4][5][6][7][8][9][10][11][12]. High-energy ball milling (HEBM) is being extensively employed as an alternate route to obtain novel materials through solid state reactions [5,6,[13][14][15][16][17][18][19][20][21].…”

“…Ferrites and materials derived from ferrites find extensive application in devices like transformers, TV yokes, loud speakers and in a horde of other devices. They are also one of the largely used material medium for audio/video applications and computer memories [6,12]. They have the general formula {(M) d (Fe) 1Àd }[(M) 1Àd (Fe) 1+d ]O 4 .…”

“…In the coarser regime, the magnetic and structural properties of these ferrites are determined by a variety of factors like madelung energy, cationic size, charge and site preference energy. For example cation like Ni 2+ and Zn 2+ have exclusive octahedral and tetrahedral site preferences, respectively [2][3][4][5]7,8,10,12,24]. So in a typical Nickel ferrite, Nickel occupies only the octahedral (B) sites and this results in an inverse spinel while in zinc ferrite, zinc occupies tetrahedral (A) sites exclusively and results in a normal spinel.…”

Synthesis and Magnetic Characterization of Zinc Ferrite Nanoparticles with Different Environments: Powder, Colloidal Solution, and Zinc Ferrite−Silica Core−Shell Nanoparticles

“…In the case of the nanoparticles, the situation is more complicated and confused because of the inversion of the cation distribution, size effects, and nonstoichiometry. If the noninverted stoichiometric nanoparticles have an antiferromagnetic ground state ( T N = 13 K) like the bulk material, the ground state of nanosized inverted zinc ferrites is magnetic with a large magnetization which is generally explained by the distribution of the cations. − ,,,− ,, Indeed, in the partially inverted stoichiometric spinel, some Zn 2+ ions occupy B-sites while some Fe 3+ ions are in the tetrahedral ones leading to a magnetically active A sublattice which strongly interacts with the B sublattice. Values of δ ranging from 0.03 to 0.6 are reported in the literature, depending strongly upon the preparation procedures. ,− ZnFe 2 O 4 nanoparticles have been synthesized with a large variety of methods: coprecipitation, ,,− ,,,, ,,,, microemulsion, , supercritical sol−gel processing, − hydrothermal synthesis, , or high-energy ball milling. ,− , The magnetization has been found to increase with grain size reduction.…”

“…If the noninverted stoichiometric nanoparticles have an antiferromagnetic ground state ( T N = 13 K) like the bulk material, the ground state of nanosized inverted zinc ferrites is magnetic with a large magnetization which is generally explained by the distribution of the cations. − ,,,− ,, Indeed, in the partially inverted stoichiometric spinel, some Zn 2+ ions occupy B-sites while some Fe 3+ ions are in the tetrahedral ones leading to a magnetically active A sublattice which strongly interacts with the B sublattice. Values of δ ranging from 0.03 to 0.6 are reported in the literature, depending strongly upon the preparation procedures. ,− ZnFe 2 O 4 nanoparticles have been synthesized with a large variety of methods: coprecipitation, ,,− ,,,, ,,,, microemulsion, , supercritical sol−gel processing, − hydrothermal synthesis, , or high-energy ball milling. ,− , The magnetization has been found to increase with grain size reduction. This feature is generally associated with the increase of the cation inversion and with the diminution of the size of the grains. ,, The size polydispersity and the mutual interaction between magnetic particles complicate the interpretation of the magnetic properties of powder nanoparticles. , …”