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Structural evolution and physical properties of Bi1−xGdxFeO3 ceramics / J.B. Li in Acta materialia, Vol. 58 N° 10 (Juin 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 10 (Juin 2010) . - pp. 3701–3708 Titre : Structural evolution and physical properties of Bi1−xGdxFeO3 ceramics Type de document : texte imprimé Auteurs : J.B. Li, Auteur ; G.H. Rao, Auteur ; Xiao, Y., Auteur Année de publication : 2011 Article en page(s) : pp. 3701–3708 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Bi-based  magnetoelectric  perovskites  Crystal  structure  Phase  transformation  X-ray  diffraction Résumé : The crystal structure and physical properties of Bi1−xGdxFeO3 ceramics with x ≤ 0.5 have been studied by X-ray diffraction, differential scanning calorimetry, dielectric and magnetic measurements. Bi1−xGdxFeO3 compounds crystallize at room temperature in R3c structure for x < 0.08 and in Pbnm structure for x ≥ 0.3. The R3c phase transforms to the Pbnm phase as temperature increases. Temperature-dependent dielectric response and low-temperature X-ray diffraction indicate a phase transition of the Pbnm phase at low-temperature. Detailed structural analysis indicates that the interaction between Bi and O plays an important role in the evolution of structure and physical properties. A phase diagram is constructed to illustrate the physical property–composition–temperature relations. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410001527 [article] Structural evolution and physical properties of Bi1−xGdxFeO3 ceramics [texte imprimé] / J.B. Li, Auteur ; G.H. Rao, Auteur ; Xiao, Y., Auteur . - 2011 . - pp. 3701–3708. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 10 (Juin 2010) . - pp. 3701–3708 Mots-clés : Bi-based  magnetoelectric  perovskites  Crystal  structure  Phase  transformation  X-ray  diffraction Résumé : The crystal structure and physical properties of Bi1−xGdxFeO3 ceramics with x ≤ 0.5 have been studied by X-ray diffraction, differential scanning calorimetry, dielectric and magnetic measurements. Bi1−xGdxFeO3 compounds crystallize at room temperature in R3c structure for x < 0.08 and in Pbnm structure for x ≥ 0.3. The R3c phase transforms to the Pbnm phase as temperature increases. Temperature-dependent dielectric response and low-temperature X-ray diffraction indicate a phase transition of the Pbnm phase at low-temperature. Detailed structural analysis indicates that the interaction between Bi and O plays an important role in the evolution of structure and physical properties. A phase diagram is constructed to illustrate the physical property–composition–temperature relations. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410001527

Tensile and compressive mechanical behavior of twinned silicon carbide nanowires / Z.G. Wang in Acta materialia, Vol. 58 N° 6 (Avril 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 6 (Avril 2010) . - pp. 1963–1971 Titre : Tensile and compressive mechanical behavior of twinned silicon carbide nanowires Type de document : texte imprimé Auteurs : Z.G. Wang, Auteur ; J.B. Li, Auteur ; F. Gao, Auteur Année de publication : 2011 Article en page(s) : pp. 1963–1971 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Twinning  Nanotructures  Fracture  Buckling  Molecular  dynamics Résumé : Molecular dynamics simulations with the Tersoff potential were used to study the response of twinned SiC nanowires under tensile and compressive strain. The critical strain of the twinned nanowires can be enhanced by twin stacking faults, and their critical strains are larger than those of perfect nanowires with the same diameters. Under axial tensile strain, the bonds of the nanowires are stretched just before failure. The failure behavior is found to depend on the twin segment thickness and the diameter of the nanowires. An atomic chain is observed for thin nanowires with small twin segment thickness under tension strain. Under axial compressive strain, the collapse of twinned SiC nanowires exhibits two different failure modes, depending on the length and diameter of the nanowires, i.e., shell buckling for short nanowires and columnar buckling for longer nanowires. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008180 [article] Tensile and compressive mechanical behavior of twinned silicon carbide nanowires [texte imprimé] / Z.G. Wang, Auteur ; J.B. Li, Auteur ; F. Gao, Auteur . - 2011 . - pp. 1963–1971. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 6 (Avril 2010) . - pp. 1963–1971 Mots-clés : Twinning  Nanotructures  Fracture  Buckling  Molecular  dynamics Résumé : Molecular dynamics simulations with the Tersoff potential were used to study the response of twinned SiC nanowires under tensile and compressive strain. The critical strain of the twinned nanowires can be enhanced by twin stacking faults, and their critical strains are larger than those of perfect nanowires with the same diameters. Under axial tensile strain, the bonds of the nanowires are stretched just before failure. The failure behavior is found to depend on the twin segment thickness and the diameter of the nanowires. An atomic chain is observed for thin nanowires with small twin segment thickness under tension strain. Under axial compressive strain, the collapse of twinned SiC nanowires exhibits two different failure modes, depending on the length and diameter of the nanowires, i.e., shell buckling for short nanowires and columnar buckling for longer nanowires. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409008180