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- Azad, Abul Kalam, 1966, et al.
(författare)
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Electron doping effect on structural and magnetic phase transitions in Sr2-xNdxFeMoO6 double perovskites
- 2006
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Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 179:5, s. 1303-1311
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Tidskriftsartikel (refereegranskat)abstract
- Polycrystalline Sr2−xNdxFeMoO6 (x=0.0, 0.1, 0.2, 0.4) materials have been synthesized by a citrate co-precipitation method and studied by neutron powder diffraction (NPD) and magnetization measurements. Rietveld analysis of the temperature-dependent NPD data shows that the compounds (x=0.0, 0.1, 0.2) crystallize in the tetragonal symmetry in the range 10–400 K and converts to cubic symmetry above 450 K. The unit cell volume increases with increasing Nd3+ concentration, which is an electronic effect in order to change the valence state of the B-site cations. Antisite defects at the Fe–Mo sublattice increases with the Nd3+ doping. The Curie temperature was increased from 430 K for x=0 to 443 K for x=0.4. The magnetic moment of the Fe-site decreases while the Mo-site moment increases with electron doping. The antiferromagnetic arrangement causes the system to show a net ferrimagnetic moment.
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| 2. |
- Azad, Abul Kalam, 1966, et al.
(författare)
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Synthesis, structural and magnetic characterisation of the double perovskite A(2)MnMoO(6) (A = Ba, Sr)
- 2004
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Ingår i: Journal of Alloys and Compounds. - 0925-8388. ; 364:1-2, s. 77-82
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Tidskriftsartikel (refereegranskat)abstract
- A study of the crystallographic structure and magnetic properties of the double perovskites Ba2MnMoO6 and Sr2MnMoO6 in polycrystalline form has been carried out by means of neutron powder diffraction (NPD) and magnetization measurements. The Rietveld analysis of room temperature data shows that the Mn2+ and Mo6+ ions are B-site ordered, i.e. the structure is a NaCl-type ordered double perovskite. Ba2MnMoO6 crystallizes in the cubic space group Full-size image (<1 K) (a=8.1680(1)) and Sr2MnMoO6 crystallizes in the space group P42/n (a=7.9575(5), c=7.9583(9)). Bond valence sum (BVS) calculation revealed that these compounds have the valency pair of {Mn2+(3d5;t32ge2g), Mo6+(4d0)}. The magnetic measurements suggest that these compounds transform to an antiferromagnetic state below 10 K.
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