Synthesis, crystal structure and magnetic properties of a new pillared perovskite La5Mo2.75V1.25O16 |
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Authors: | Farshid Ramezanipour Shahab Derakhshan John E Greedan Lachlan MD Cranswick |
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Institution: | a Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1 b Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario, Canada L8S 4M1 c Canadian Neutron Beam Centre, National Research Council, Chalk River Laboratories, Chalk River, Ontario, Canada K0J 1J0 |
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Abstract: | A new pillared perovskite compound La5Mo2.76(4)V1.25(4)O16, has been synthesized by solid-state reaction and its crystal structure has been characterized using powder X-ray and neutron diffraction. The magnetic properties of this compound have been investigated using SQUID magnetometry, and the magnetic structure has been studied using neutron diffraction data. A theoretical calculation of relative strengths of spin interactions among different magnetic ions and through different pathways has been performed using extended Hückel, spin dimer analysis. The crystal structure of this material contains perovskite-type layers that are connected through edge-sharing dimeric units of octahedra. The structure is described in space group C2/m with unit cell parameters a=7.931(2) Å, b=7.913(2) Å, c=10.346(5) Å and β=95.096(5)°. The material shows both short-range ferrimagnetic correlations from ∼200 to 110 K and long-range antiferromagnetic order below Tc∼100 K. The magnetic structure was investigated by neutron diffraction and is described by k=(0 0 ) as for other pillared perovskites. It consists of a ferrimagnetic arrangement of Mo and V within the layers that are coupled antiferromagnetically between layers. This is the first magnetic structure determination for any Mo-based pillared perovskite. |
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Keywords: | Pillared perovskites Short-range and long-range magnetic order Crystal and magnetic structure Neutron diffraction |
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