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Magnetic structure
About: Magnetic structure is a research topic. Over the lifetime, 10787 publications have been published within this topic receiving 207143 citations.
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TL;DR: A new ordered oxygen-deficient perovskite, LaBaMn2O5.5, has been synthesized, using the topotactic deoxygenation of the ordered LaBaN2O6 perovskiy as discussed by the authors.
Abstract: A new ordered oxygen-deficient perovskite, LaBaMn2O5.5, has been synthesized, using the topotactic deoxygenation of the ordered LaBaMn2O6 perovskite. The crystal structure of this manganite was solved in the space group Ammm (a = 3.86 A, b = 8.19 A, c = 15.47 A) from neutron powder diffraction data. The [Mn2O5.5]∞ framework is build up of row of MnO6 octahedra and MnO5 pyramids running along a. This structure is intermediate between that of the ordered LaBaMn2O6 perovskite and that of LaBaMn2O5: it consists of ordered barium and lanthanum layers stacked alternatively along c, oxygen vacancies being located at the level of the La layers. The magnetic structure is original: manganese spins form ferromagnetic spin-ladders along the b axis that are antiferromagnetically coupled along the a and c axis. The HREM investigation shows the existence of 90° oriented domains and twinning phenomena.
62 citations
62 citations
TL;DR: In this paper, a two-step synthesis of the Nanocrystalline phase pure CeCrO3 was performed by using high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy.
Abstract: Nanocrystalline phase pure CeCrO3 was synthesized by a two-step synthesis. The compound was investigated by a host of characterization techniques such as X-ray diffraction, high-temperature X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric−differential thermal analysis, magnetic and specific heat capacity data, ac impedance spectroscopy, diffuse reflectance DR UV−visible spectrophotometer, and dynamic light scattering. The magnetic structure of CeCrO3 was established using variable-temperature neutron diffraction data. On the basis of the detailed studies, this compound was found to exhibit multifunctionalities such as antiferromagnetism, relaxor behavior, and an optical band gap in the visible region. This newly developed synthesis route opens the immense possibilities of preparation of the hitherto unknown Ce3+-based mixed oxides, analogous to other rare earth (RE3+) counterparts.
62 citations
TL;DR: Mossbauer, ESR and magnetization measurements have been carried out on a basalt glass heat-treated at different temperatures (600, 650, 700, 800 and 900°C for 8 h).
Abstract: Mossbauer, ESR and magnetization measurements have been carried out on a basalt glass heat-treated at different temperatures (600, 650, 700, 800 and 900°C for 8 h). The as-annealed glass and the above five samples showed two-doublet Mossbauer spectra, while the last two samples also showed a six line magnetic hyperfine pattern at 300 K. At 4 K, the last four samples showed magnetic hyperfine patterns, while the as-annealed glass showed that there was already short range magnetic ordering present. High field Mossbauer data at 4 K showed that the surface spins are canted. The minimum quadrupole splitting and the maximum isomer shift around 700°C are related to the improved symmetry of the magnetite lattice. ESR spectra showed paramagnetic resonances at g = 4.3 and g = 2.0 for the first two samples, while the last four samples showed superparamagnetic resonance centred around g = 2.0 at 300 K. At lower temperatures, the 650 and 700°C samples showed ferrimagnetic resonance. Magnetization curves against H/T superpose well both at 300 and 77 K, showing the typical superparamagnetic behaviour of the small magnetite particles. The saturation magnetization (at 270 K) showed a sharp change around 700°C, showing the formation of magnetite. The magnetic structure of the small magnetite particles are discussed in terms of the above results.
62 citations
TL;DR: In this article, single-phase Bi1−xPrxFeO3 (x = 0.05, 0.10) nanoparticles have been synthesized by propylene glycol-gel route at a temperature of 400°C.
Abstract: Single-phase Bi1−xPrxFeO3 (x = 0.0, 0.05, and 0.10) nanoparticles have been synthesized by propylene glycol-gel route at a temperature of 400 °C. Rietveld refinement of X-ray diffraction data and Raman spectra reflect a structural phase transition from rhombohedral for x = 0 to triclinic for x = 0.10. Magnetic measurements reveal that Pr-doped BiFeO3 nanoparticles for x = 0.10 have enhanced remnant magnetization about 10 times as compared to pure BiFeO3 nanoparticles. It has been shown by 57Fe Mossbauer spectroscopy that the observed enhancement in magnetic properties of BiFeO3 with Pr doping is mainly due to suppression of modulated spiral spin structure near x = 0.10 and not due to Fe multiple valence, i.e., oxygen deficiency.
62 citations