Annealing temperature and initial iron valence ratio effects on the structural characteristics of nanoscale nickel zinc ferrite

作者：Calvin S^*; Shultz M D; Glowzenski L; Carpenter E E

来源：Journal of Applied Physics, 2010, 107(2): 024301.

DOI：10.1063/1.3269706

• annealing
• EXAFS
• ferrites
• magnetisation
• magnetometers
• nanoparticles
• nanotechnology
• nickel compounds
• surfactants
• zinc compounds

Nickel zinc ferrite (NZFO) nanoparticles were synthesized via a reverse micelle method with a nonionic surfactant. Three different initial Fe(3+)/Fe(2+) ratios were employed along with three different firing temperatures (200, 500, 1000 degrees C) to investigate the effects on the NZFO system. Extended x-ray absorption fine structure (EXAFS) results reveal zinc loss at high annealing temperatures; at 1000 degrees C, the loss is nearly total for Fe(3+)/Fe(2+) ratios other than 10:90. Annealing at 500 degrees C, however, appears necessary for fully incorporating the zinc and nickel into the spinel phase. The best nanoferrite was thus obtained using an initial Fe(3+)/Fe(2+) ratio of 10:90 and a moderate firing temperature of 500 degrees C. This sample exhibits a room temperature saturation magnetization of 58 emu/g as measured via vibrating sample magnetometry, comparable with bulk values and greater than that of confirmed nano-NZFOs found in the literature. EXAFS also indicates that in all cases in which the elements adopted a spinel structure, the nickel occupies only octahedral sites and the zinc primarily tetrahedral sites.

• 出版日期2010-1-15