| dc.creator | Nowik, I | |
| dc.creator | Felner, I | |
| dc.creator | Awana, VPS | |
| dc.date | 1999 | |
| dc.date | FEB | |
| dc.date | 2014-12-02T16:29:05Z | |
| dc.date | 2015-11-26T16:46:21Z | |
| dc.date | 2014-12-02T16:29:05Z | |
| dc.date | 2015-11-26T16:46:21Z | |
| dc.date.accessioned | 2018-03-28T23:32:10Z | |
| dc.date.available | 2018-03-28T23:32:10Z | |
| dc.identifier | Journal Of Magnetism And Magnetic Materials. Elsevier Science Bv, v. 192, n. 1, n. 67, n. 72, 1999. | |
| dc.identifier | 0304-8853 | |
| dc.identifier | WOS:000078289900009 | |
| dc.identifier | 10.1016/S0304-8853(98)00383-7 | |
| dc.identifier | http://www.repositorio.unicamp.br/jspui/handle/REPOSIP/82402 | |
| dc.identifier | http://www.repositorio.unicamp.br/handle/REPOSIP/82402 | |
| dc.identifier | http://repositorio.unicamp.br/jspui/handle/REPOSIP/82402 | |
| dc.identifier.uri | http://repositorioslatinoamericanos.uchile.cl/handle/2250/1274494 | |
| dc.description | The compound PrSr2Fe3O9-delta (delta(similar to) < 0.1) has been studied by magnetization and Fe-57 Mossbauer spectroscopy measurements, The magnetization studies show magnetic hysteresis phenomena at low temperatures and three distinct phase transitions: an antiferromagnetic transition at T-N = 190 K, a transition at T-v = 170 K associated with change in iron valence and T-irr = 270 K, the merging temperature of the zero field and field cooled magnetization curves. Mossbauer studies confirm the T-N and T-v values. Well below and above T-N, the spectra are composed of two well-defined sub-spectra (ratio 2 : 1), though all Fe ions reside in one crystallographic site. At 4.2 K the subspectra differ in their isomer shift (IS) by 0.4 mm/s and in the magnetic hyperfine field (469 and 269 kOe) whereas above T-N the difference in the IS is only 0.24 mm/s. For 90 K < T < T-N the spectra ape complex: and cannot be interpreted in terms of well defined (2 or even 3) sub-spectra. All spectra, in the entire temperature range can be well explained and reproduced by a triple valence fluctuation model, assuming that Fe appear in three valence stares. (a) 2Fe(3+) + Fe5+ at low temperatures, (b) Fe3+ and 2Fe(4+) above T-N and (c) at 90 K < T < T-N triple valence fluctuations occur: Fe3+ <-> Fe5+ <-> Fe5+. An electron is transferred from Fe3+ to Fe5+ to form two nonmagnetic Fe4+ ions, This process dilutes the magnetic ions concentration to a point of collapse of the magnetic order. (C) 1999 Elsevier Science B.V. All rights reserved. | |
| dc.description | 192 | |
| dc.description | 1 | |
| dc.description | 67 | |
| dc.description | 72 | |
| dc.language | en | |
| dc.publisher | Elsevier Science Bv | |
| dc.publisher | Amsterdam | |
| dc.publisher | Holanda | |
| dc.relation | Journal Of Magnetism And Magnetic Materials | |
| dc.relation | J. Magn. Magn. Mater. | |
| dc.rights | fechado | |
| dc.rights | http://www.elsevier.com/about/open-access/open-access-policies/article-posting-policy | |
| dc.source | Web of Science | |
| dc.subject | phase transitions | |
| dc.subject | valence fluctuations | |
| dc.subject | canted antiferromagnetism | |
| dc.subject | Mossbauer spectroscopy | |
| dc.subject | irreversibility | |
| dc.subject | magnetic hysteresis | |
| dc.subject | Nonstoichiometric Perovskite Sr2lafe3o8+y | |
| dc.subject | Mossbauer-spectroscopy | |
| dc.subject | Charge Disproportionation | |
| dc.subject | Oxygen Vacancies | |
| dc.title | Magnetic properties and triple valence fluctuations of iron in PrSr2Fe3O9-delta | |
| dc.type | Artículos de revistas | |
