کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1331686 979012 2009 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Mild hydrothermal synthesis, crystal structure, spectroscopic and magnetic properties of the [MxIIM2.5-xIII(H2O)2(HPIIIO3)y(PVO4)2-yF] [M=Fe, x=2.08, y=1.58; M=Co, Ni, x=2.5, y=2] compounds
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی معدنی
پیش نمایش صفحه اول مقاله
Mild hydrothermal synthesis, crystal structure, spectroscopic and magnetic properties of the [MxIIM2.5-xIII(H2O)2(HPIIIO3)y(PVO4)2-yF] [M=Fe, x=2.08, y=1.58; M=Co, Ni, x=2.5, y=2] compounds
چکیده انگلیسی

The [MxIIM2.5-xIII(H2O)2(HPIIIO3)y(PVO4)2-yF] [M=Fe (1), x=2.08, y=1.58; M=Co (2), x=2.5, y=2; Ni (3), x=2.5, y=2] compounds have been synthesized using mild hydrothermal conditions at 170 °C during five days. Single-crystals of (1) and (2), and polycrystalline sample of (3) were obtained. These isostructural compounds crystallize in the orthorhombic system, space group Aba2, with a=9.9598(2), b=18.8149(4) and c=8.5751(2) Å for (1), a=9.9142(7), b=18.570(1) and c=8.4920(5) Å for (2) and a=9.8038(2), b=18.2453(2) and c=8.4106(1) Å for (3), with Z=8 in the three phases. An X-ray diffraction study reveals that the crystal structure is composed of a three-dimensional skeleton formed by [MO5F] and [MO4F2] (M=Fe, Co and Ni) octahedra and [HPO3] tetrahedra, partially substituted by [PO4] tetrahedra in phase (1). The IR spectra show the vibrational modes of the water molecules and those of the (HPO3)2− tetrahedral oxoanions. The thermal study indicates that the limit of thermal stability of these phases is 195 °C for (1) and 315 °C for (2) and (3). The electronic absorption spectroscopy shows the characteristic bands of the Fe(II), Co(II) and Ni(II) high-spin cations in slightly distorted octahedral geometry. Magnetic measurements indicate the existence of global antiferromagnetic interactions between the metallic centers with a ferromagnetic transition in the three compounds at 28, 14 and 21 K for (1), (2) and (3), respectively. Compound (1) exhibits a hysteresis loop with remnant magnetization and coercive field values of 0.72 emu/mol and 880 Oe, respectively.

Polyhedral view of the crystal structure of the [MxIIM2.5-xIII(H2O)2(HPIIIO3)y(PIVO4)2-yF] [M=Fe, x=2.08, y=1.58; M=Co, Ni, x=2.5, y=2] compounds showing the sheets along the [001] direction.Figure optionsDownload as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Solid State Chemistry - Volume 182, Issue 8, August 2009, Pages 2191–2201
نویسندگان
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