CEQUINOR   05415
CENTRO DE QUIMICA INORGANICA "DR. PEDRO J. AYMONINO"
Unidad Ejecutora - UE
artículos
Título:
High temperature emissivity, reflectivity, and x-ray absorption of BiFeO3
Autor/es:
NESTOR E. MASSA; LEIRE DEL CAMPO; DOMINGOS DE SOUSA MENESES; PATRICK ECHEGUT; GILBERTO F.L. FABBRIS; GUSTAVO AZEVEDO; MARÍA JESUS MARTÍNEZ-LOPE; JOSÉ ANTONIO ALONSO
Revista:
JOURNAL OF APPLIED PHYSICS
Editorial:
AMER INST PHYSICS
Referencias:
Lugar: Mellville; Año: 2010 vol. 108 p. 84114 - 84122
ISSN:
0021-8979
Resumen:
We report on the lattice evolution of BiFeO3 as function of temperature using far infrared emissivity,
reflectivity, and x-ray absorption local structure. A power law fit to the lowest frequency soft phonon
in the magnetic ordered phase yields an exponent =0.25 as for a tricritical point. At about 200 K
below TN640 K it ceases softening as consequence of BiFeO3 metastability. We identified this
temperature as corresponding to a crossover transition to an order-disorder regime. Above 700 K
strong band overlapping, merging, and smearing of modes are consequence of thermal fluctuations
and chemical disorder. Vibrational modes show band splits in the ferroelectric phase as emerging
from triple degenerated species as from a paraelectric cubic phase above TC1090 K. Temperature
dependent x-ray absorption near edge structure XANES at the Fe K edge shows that lower
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
dependent x-ray absorption near edge structure XANES at the Fe K edge shows that lower
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
strong band overlapping, merging, and smearing of modes are consequence of thermal fluctuations
and chemical disorder. Vibrational modes show band splits in the ferroelectric phase as emerging
from triple degenerated species as from a paraelectric cubic phase above TC1090 K. Temperature
dependent x-ray absorption near edge structure XANES at the Fe K edge shows that lower
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
dependent x-ray absorption near edge structure XANES at the Fe K edge shows that lower
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
temperature as corresponding to a crossover transition to an order-disorder regime. Above 700 K
strong band overlapping, merging, and smearing of modes are consequence of thermal fluctuations
and chemical disorder. Vibrational modes show band splits in the ferroelectric phase as emerging
from triple degenerated species as from a paraelectric cubic phase above TC1090 K. Temperature
dependent x-ray absorption near edge structure XANES at the Fe K edge shows that lower
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
dependent x-ray absorption near edge structure XANES at the Fe K edge shows that lower
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
strong band overlapping, merging, and smearing of modes are consequence of thermal fluctuations
and chemical disorder. Vibrational modes show band splits in the ferroelectric phase as emerging
from triple degenerated species as from a paraelectric cubic phase above TC1090 K. Temperature
dependent x-ray absorption near edge structure XANES at the Fe K edge shows that lower
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
dependent x-ray absorption near edge structure XANES at the Fe K edge shows that lower
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
reflectivity, and x-ray absorption local structure. A power law fit to the lowest frequency soft phonon
in the magnetic ordered phase yields an exponent =0.25 as for a tricritical point. At about 200 K
below TN640 K it ceases softening as consequence of BiFeO3 metastability. We identified this
temperature as corresponding to a crossover transition to an order-disorder regime. Above 700 K
strong band overlapping, merging, and smearing of modes are consequence of thermal fluctuations
and chemical disorder. Vibrational modes show band splits in the ferroelectric phase as emerging
from triple degenerated species as from a paraelectric cubic phase above TC1090 K. Temperature
dependent x-ray absorption near edge structure XANES at the Fe K edge shows that lower
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition prior to melting. © 2010
A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced
irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking
of long-range coherence. We did not find an insulator to metal transition pr