Influence of Zn2+ ions on the structural and electrical properties of Mg1-xZnxFeCrO4 spinels

K. A M Khalaf*, A. D. Al-Rawas, H. M. Widatallah, K. S. Al-Rashdi, A. Sellai, A. M. Gismelseed, Mohd Hashim, S. K. Jameel, M. S. Al-Ruqeishi, K. O. Al-Riyami, M. Shongwe, A. H. Al-Rajhi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

The polycrystalline magnesium-zinc ferrite chromate having the chemical formula Mg1-xZnxFeCrO4 (0.0 ≤ x ≤ 1.0) were prepared by conventional solid phase reaction using high purity reagents. The structural and electrical properties at room temperature have been investigated by XRD, TEM, SEM, EDS, TGA, DTA, FT-IR and DC electrical resistivity techniques. The lattice parameters such as the lattice constant, average particle size, bonds length, density, porosity and volume shrinkage were found to vary with increasing Zn2+ content in the sample. The lattice constant "a" increases from 8.361 Å for MgFeCrO4 to 8.382 Å for ZnFeCrO4 spinels. The IR spectra confirm the presence of two main absorption bands υ1 and υ2 in the frequency range of 400-1000 cm-1, arising due to the tetrahedral (A) and octahedral (B) stretching vibrations respectively. Values of υ1 and υ2 decrease with increasing Zn+2 content over the whole composition range. The scanning electron microscope (SEM) and transmission electron microscope (TEM) micrographs showed aggregates of stacked large grains. Values of the room temperature DC electrical resistivity decrease as Zn2+ content increases. The low values of the vacancy model parameters indicate that the Mg1-xZnxFeCrO4 spinels are strongly defective and the participation of the Zn2+ vacancies in the improvement of the electrical conductivity in these spinels. The thermo-gravimetric, TGA and differential thermal analysis, DTA show loss of mass caused by vaporization of the surface and trapped water molecules at higher temperatures.

Original languageEnglish
Pages (from-to)733-747
Number of pages15
JournalJournal of Alloys and Compounds
Volume657
DOIs
Publication statusPublished - Feb 5 2016

Keywords

  • DTA
  • EDS
  • IR
  • Mg-Zn-Cr spinels
  • SEM
  • TEM
  • TGA
  • Vacancy model
  • XRD

ASJC Scopus subject areas

  • Mechanical Engineering
  • Mechanics of Materials
  • Materials Chemistry
  • Metals and Alloys

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