Synthesis, cation ordering, and magnetic properties of the (Sb1-xPbx)(2)(Mn1-ySby)O-4 solid solutions with the Sb2MnO4-Type structureстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:Single phase (Sb1-xPbx)(2)(Mn1-ySby)O-4 (0.0 less than or equal to x less than or equal to 0.608, 0.0 less than or equal to y less than or equal to 0.372) samples with the Sb-2-MnO4-type structure were prepared at 650 C by solid-state reaction in evacuated sealed silica tubes. A replacement of Sb by Pb results in the oxidation of Sb3+ to Sb5+, which in turn replaces Mn2+ cations in octahedrally coordinated positions within the infinite rutile-type chains. The crystal structures of Pb-0.44-Sb1.64Mn0.92O4, Pb0.75Sb1.48Mn0.77O4, Pb1.07Sb1.26Mn0.67O4, and Pb1.186Sb1.175Mn0.639O4 were refined from X-ray powder diffraction data. Increasing the Pb content leads to a decrease of the a parameter from a = 8.719(2) Angstrom to a = 8.6131(8) Angstrom and to an increase of the c parameter from c = 5.999(2) Angstrom to c = 6.2485(7) Angstrom (for Sb2MnO4 and Pb1.216Sb1.155Mn0.628O4, respectively). This occurs due to increasing average cation size at the Pb/Sb position and decreasing cation size at the Mn/Sb position that leads to strong deformation of the (Mn/Sb)O-6 octahedra. Starting from the Pb(0.75)Sb(1.48)Mno(0.77)O(4) composition a modulated structure with q = yc* was observed by electron diffraction. Hig-resolution electron microscopy observations revealed that Mn and Sb ions order forming layers of octahedrally coordinated positions filled either by Mn2+ or by Sb5+ cations and alternating along the c axis. The dilution of the magnetic Mn-2divided by cations by nonmagnetic Sb5+ entities leads to a suppression of the antiferromagnetic intrachain interaction and disappearance of long-range magnetic order at high doping level. At T = 20 K the A(xy) spin component was found to be dominant in the AFM structure of the Pb(0.44)Sp(1.64)Mn(0.92)O(4) sample by neutron diffraction.