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  • Structural characterization and magnetic property determination of nanocrystalline ▫${\mathrm Ba_3Fe_2WO_9}$▫ and ▫${\mathrm Sr_3Fe_2WO_9}$▫ perovskites prepared by a modified aqueous sol-gel route [Elektronski vir]
    Bijelić, Jelena ...
    ▫${\rm Sr_3Fe_2WO_9}$▫ and ▫${\rm Ba_3Fe_2WO_9}$▫ triple perovskites have been prepared in nanocrystalline form using a modified sol-gel route with citric acid as a chelating agent. These materials ... have been studied by X-ray powder diffraction (PXRD), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and unpolarized Raman spectroscopy, while their magnetic properties have been determined using SQUID measurements. At room temperature, the crystal structure of 6Hperovskite ▫${\rm Ba_3Fe_2WO_9}$▫ is hexagonal, space group ▫$P6_3/mmc$▫, with ▫$a=5.7577(2)$▫ and ▫$c=14.1095(5) \; \AA$▫, whereas ▫${\rm Sr_3Fe_2WO_9}$▫ presents a tetragonal lattice, space group ▫$I4/m$▫, with ▫$a=5.5803(1)$▫ and ▫$c=7.8745(3) \; \AA$▫. Both compounds are nanocrystalline with average crystallite sizes of 25.6(1) nm for ▫${\rm Sr_3Fe_2WO_9}$▫ and 35.9(1) nm for ▫${\rm Sr_3Fe_2WO_9}$▫ with moderate microstrain. They exhibit a disordered perovskite structure, in which ▫${\rm Fe^{3+}}$▫ and ▫${\rm W^{6+}}$▫ cations distribute randomly at the B-sites of the perovskite lattice: ▫${\rm Sr_2[Fe_{0.72}W_{0.28}]^{2a} [Fe_{0.61}-W_{0.39}]^{2b}O_6}$▫ and ▫${\rm Ba_6[Fe_{1.71}W_{0.29}]^{2a}[Fe_{2.29}W_{1.71}]^{4f}O_{18}}$▫. The detected hysteresis loops with non-zero remanent magnetization and a rather large coercive field reveal ferrimagnetic ordering with ordering temperatures of 373 K for ▫${\rm Sr_3Fe_2WO_9}$▫ and 330 K for v${\rm Ba_3Fe_2WO_9}$▫. Magnetic measurements show the onset of ferrimagnetic ordering at relatively high temperatures of 717 and 711 K for the Sr and Ba compounds, respectively; however the magnetization isotherms at 2 K exhibit, for ▫$H = 50$▫ kOe, maximum magnetization values close to $v{\rm 0.8 \mu_B (f.u.)^{-1}}$▫ and ▫${\rm 0.35 \mu_B (f.u.)^{-1}}$▫ for Sr and Ba compounds, respectively, although full saturation is not reached.
    Vir: CrystEngComm [Elektronski vir]. - ISSN 1466-8033 (Vol. 21, no. 2, Jan. 2019, str. 218-227)
    Vrsta gradiva - e-članek ; neleposlovje za odrasle
    Leto - 2019
    Jezik - angleški
    COBISS.SI-ID - 18593625

    Povezava(-e):

    http://dx.doi.org/10.1039/c8ce01483c
    DOI

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