Abstract
Twelve multicomponent spinels, comprised of (Mg, Cr, Mn, Co, Fe, Ni, Cu, and/or Zn)(Cr,Fe,orAl)2O4, were prepared using solid state synthesis methods, resulting in nine homogenous, single phase samples with a Fm-3m structure, and three samples with multiple phases. Using dc magnetometry in conjunction with x-ray diffraction, scanning electron microscopy with energy dispersive x-ray spectroscopy, and x-ray absorption spectroscopy, the effects of multicomponent material design on the structural, magnetic, and chemical properties are explored. The ferritic spinel high-entropy oxide (HEO) samples show high-temperature ferrimagnetic transitions and both ferritic and chromium-based HEO spinel samples show evidence of low-temperature antiferromagnetic ordering. Blocking temperatures are evident in some samples and magnetic transition temperatures are reported. Constituent valence states and temperature dependent valence is described for the example case of (Mg0.2Fe0.2Co0.2Ni0.2Cu0.2)Cr2O4, including the unexpected presence of Cr4+, indicating a 2-4 type spinel configuration. Valence trends for two ferritic HEO spinels are also discussed. Some of these compositions are synthesized for the first time and this work provides an investigation into the magnetic properties of the novel class of cubic spinel multicomponent oxides showing interesting behavior that warrants further investigation.
| Original language | English |
|---|---|
| Article number | 104416 |
| Journal | Physical Review Materials |
| Volume | 3 |
| Issue number | 10 |
| DOIs | |
| State | Published - Oct 21 2019 |
Funding
B.M. acknowledges the support of the Center for Materials Processing, a Tennessee Higher Education Commission (THEC) supported Accomplished Center of Excellence. Powder XRD and Microscopy was performed at the Joint Institute for Advanced Materials (JIAM) Diffraction Facility and Microscopy Facility, located at the University of Tennessee, Knoxville. Magnetic characterization supported by the US Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. This research used resources of the Advanced Light Source, which is a DOE Office of Science User Facility under Contract No. DE-AC02-05CH11231. Certain trade names and company products are identified to specify adequately the experimental procedure. In no case does such identification imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the products are necessarily the best for the purpose.