In-situ high-pressure x-ray diffraction study of zinc ferrite nanoparticles

Abstract

We have studied the high-pressure structural behavior of zinc ferrite (ZnFe2O4) nanoparticles by powder X-ray diffraction measurements up to 47 GPa. We found that the cubic spinel structure of ZnFe2O4 remains up to 33 GPa and a phase transition is induced beyond this pressure. The high-pressure phase is indexed to an orthorhombic CaMn2O4-type structure. Upon decompression the low-and high-pressure phases coexist. The compressibility of both structures was also investigated. We have observed that the lattice parameters of the high-pressure phase behave anisotropically upon compression. Further, we predict possible phase transition around 55 GPa. For comparison, we also studied the compression behavior of magnetite (Fe3O4) nanoparticles by X-ray diffraction up to 23 GPa. Spinel-type ZnFe2O4 and Fe3O4 nanoparticles have a bulk modulus of 172(20) GPa and 152(9) GPa, respectively. This indicates that in both cases the nanoparticles do not undergo a Hall-Petch strengthening.

High pressure in-situ X-ray diffraction study on Zn-doped magnetite nanoparticles

“…Interestingly, the bulk modulus and its pressure derivative are lower than the measured values for pure magnetite nanoparticles, B 0 = 152(9) GPa and B 0´ = 5.2 (9). They are also below the value of the bulk modulus reported for magnetite, which ranges from144 to 222 GPa [16]. We compare later systematically the compressibility obtained for same-size nanoparticles of that both doped samples have a similar compressibility [26], which is larger than that of Fe 3 O 4 and ZnFe 2 O 4 as we will discuss in the next section.…”

“…None of the samples undergoes a phase transition in the pressures measured. For both samples we have determined that obtained bulk modulus is lower than that of magnetite and of zinc ferrite [16]. We propose possible reasons for the observed decrease in compressibility and discuss potential consequences of such phenomenon.…”

“…Using the results of volume vs. pressure of magnetite and zinc ferrite nanoparticles (of similar grain size) reported previously by us [16] for adjusting a third-order Birch recently found in lanthanide doped UO 2 [27] and yttrium doped Ag 2 S [28]. Other reasonable hypothesis to explain the observed phenomenon is the presence in the doped samples of stoichiometric vacancies in the unit cell as it occurs in spinel sulfides [29] or the enhancement of cation migration under compression in the doped samples [30].…”

“…The details of the preparation as well as the characterization of the structural and magnetic properties at ambient pressure have been previously reported [6]. Samples of magnetite (of the same batch) and zinc ferrite (synthesized by sol-gel method [6,16]), with similar grain sizes, were earlier studied by means of X-ray diffraction (XRD) under compression [16].…”

“…In this work, we report X-ray powder diffraction high pressure studies performed on Zndoped magnetite nanoparticles with formula Fe (3-x) Zn x O 4 (x = 0.2 and 0.5) to study their compaction under high pressure. The obtained results are compared with a previous study on magnetite (x = 0) and zinc ferrite (x=1) nanoparticles [16] to test the way the content of Zn affects the compressibility of magnetite nanoparticles.…”