Superparamagnetic and Perfect-Paramagnetic Zinc Ferrite Quantum Dots from Microwave-Assisted Tunable Synthesis

Abstract

The properties of quantum dot (QD)-size material depend directly upon its unit cell structure. Spinel zinc ferrite QD powder is produced via a one-pot microwave-assisted hydrothermal synthesis for just 5 min. Varying initial pH values of the preparation sol from 6 to 12 enlarges the Zn/Fe atomic ratio (by ca. 10%), unit cell volume (by ca. 0.5%), particle size (3.5–4.5 nm), and degree of inversion. This leads to a change in the magnetic behavior of the QD-size zinc ferrite from a superparamagnetic to a perfect-paramagnetic type. This novel finding points that the significant changes in the inherent structural parameters of spinel ZnFe 2 O 4 QDs (Zn/Fe ratio and degree of inversion) induced by the systematic pH change of the preparation sol are exclusively responsible for the observed unique magnetic behavior instead of mere QD (single domain) nanosizes.

Physical Property Variation of Ferrite Nanoparticles under Heavy Ion Irradiation

“…Thus, these examples show that size-dependent changes in physical properties are characteristics of ferrite nanoparticles. Depending upon the size, the physical behavior of ferrite having the same composition may differ (Mozaffari and Masoudi, 2014;Parmar et al, 2022a). The origin of size-dependent physical properties of ferrites is the result of a change in cation inversion in nanoregime (Siddique and Butt, 2010;Pham et al, 2023).…”