High temperature far-infrared dynamics of orthorhombic NdMnO₃: emissivity and reflectivity

We report on near normal far- and mid-infrared emission and reflectivity of NdMnO₃ perovskite from room temperature to sample decomposition above 1800 K. At 300 K the number infrared active phonons is in close agreement with the 25 calculated for the orthorhombic D¹⁶<sub>2h</sub>-Pbnm (Z...

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Autores principales: Massa, Néstor Emilio, Campo, Leire del, De Sousa Meneses, Domingos, Echegut, Patrick, Martínez-Lope, María Jesús, Alonso, José Antonio
Formato: Articulo
Lenguaje:Inglés
Publicado: 2013
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Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/131374
Aporte de:
id I19-R120-10915-131374
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Exactas
Física
Química
infrared emission
reflectivity
emissivity
spellingShingle Ciencias Exactas
Física
Química
infrared emission
reflectivity
emissivity
Massa, Néstor Emilio
Campo, Leire del
De Sousa Meneses, Domingos
Echegut, Patrick
Martínez-Lope, María Jesús
Alonso, José Antonio
High temperature far-infrared dynamics of orthorhombic NdMnO₃: emissivity and reflectivity
topic_facet Ciencias Exactas
Física
Química
infrared emission
reflectivity
emissivity
description We report on near normal far- and mid-infrared emission and reflectivity of NdMnO₃ perovskite from room temperature to sample decomposition above 1800 K. At 300 K the number infrared active phonons is in close agreement with the 25 calculated for the orthorhombic D¹⁶<sub>2h</sub>-Pbnm (Z=4) space group. Their number gradually decreases as we approach the temperature of orbital disorder at ~1023 K where the orthorhombic O' lower temperature cooperative phase coexists with the cubic orthorhombic O. At above ~1200 K, the three infrared active phonons coincide with the expected for cubic Pm-3m (Z=1) in the high temperature insulating regime. Heating samples in dry air triggers double exchange conductivity by Mn³⁺ and Mn⁴⁺ ions and a small polaron mid-infrared band. Fits to the optical conductivity single out the octahedral antisymmetric and symmetric vibrational modes as main phonons in the electron-phonon interactions at 875 K. For 1745 K, it is enough to consider the symmetric stretching internal mode. An overdamped defect induced Drude component is clearly outlined at the highest temperatures. We conclude that Rare Earth manganites e<sub>g</sub> electrons are prone to spin, charge, orbital, and lattice couplings in an intrinsic orbital distorted perovskite lattice favoring embryonic low energy collective excitations.
format Articulo
Articulo
author Massa, Néstor Emilio
Campo, Leire del
De Sousa Meneses, Domingos
Echegut, Patrick
Martínez-Lope, María Jesús
Alonso, José Antonio
author_facet Massa, Néstor Emilio
Campo, Leire del
De Sousa Meneses, Domingos
Echegut, Patrick
Martínez-Lope, María Jesús
Alonso, José Antonio
author_sort Massa, Néstor Emilio
title High temperature far-infrared dynamics of orthorhombic NdMnO₃: emissivity and reflectivity
title_short High temperature far-infrared dynamics of orthorhombic NdMnO₃: emissivity and reflectivity
title_full High temperature far-infrared dynamics of orthorhombic NdMnO₃: emissivity and reflectivity
title_fullStr High temperature far-infrared dynamics of orthorhombic NdMnO₃: emissivity and reflectivity
title_full_unstemmed High temperature far-infrared dynamics of orthorhombic NdMnO₃: emissivity and reflectivity
title_sort high temperature far-infrared dynamics of orthorhombic ndmno₃: emissivity and reflectivity
publishDate 2013
url http://sedici.unlp.edu.ar/handle/10915/131374
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