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Chinchay, H., (2018). Tuning of multifunctional properties of undoped and doped BiFeO3 [Tesis, Universidad de Puerto Rico]. http://renati.sunedu.gob.pe/handle/sunedu/952652https://hdl.handle.net/20.500.11801/1722
Chinchay, H., Tuning of multifunctional properties of undoped and doped BiFeO3 [Tesis]. PR: Universidad de Puerto Rico; 2018. http://renati.sunedu.gob.pe/handle/sunedu/952652https://hdl.handle.net/20.500.11801/1722
@mastersthesis{renati/1285,
title = "Tuning of multifunctional properties of undoped and doped BiFeO3",
author = "Chinchay Espino, Héctor Almanzor",
publisher = "Universidad de Puerto Rico",
year = "2018"
}
Title: Tuning of multifunctional properties of undoped and doped BiFeO3
Other Titles: Variación de las propiedades multifuncionales de la ferrita de bismuto dopada y sin dopar
Authors(s): Chinchay Espino, Héctor Almanzor
Advisor(s): Perales, Oscar; Fernandez, Felix
Keywords: Ferromagnetismo; Ferroelectricidad; Bismuto; Nanocristales
OCDE field: http://purl.org/pe-repo/ocde/ford#1.03.02
Issue Date: 2018
Institution: Universidad de Puerto Rico
Abstract: Este trabajo estudió el efecto de la incorporación de especies de Co2+ y Mn2+ sobre las propiedades
estructurales y magnéticas de polvos nanocristalinos de BiFeO3 (BFO) sintetizados por el método
de sol-gel y tratamiento térmico a 700°C durante 15, 30 and 45 minutos. Mediciones de difracción
de rayos X (XRD) mostraron patrones de difracción que pertenecen a la estructura perovskita
rombohedral de la BFO para todas las muestras sin dopar. Presencia mínima de impurezas fue
obtenida en muestras tratadas térmicamente durante 30 minutos. Las mediciones de curvas de
histéresis magnética indicaron que las muestras de BFO no dopadas exhiben un ordenamiento
antiferromagnético, con una magnetización máxima obtenida a 30 minutos de tiempo de recocido.
Mediciones de XRD verificaron la estructura perovskita rombohedral para muestras de Co-BFO.
Sin embargo, una fase secundaria de Ferrita de Cobalto (CFO) fue detectada para 9, 10 y 15% de
Co; la formación de CFO inhibió el crecimiento de las fases de impureza. Mediciones de histéresis
magnética evidenciaron un comportamiento ferromagnético para todas las muestras Co-BFO
debido a la presencia de CFO. Una magnetización de saturación de 4.13 emu/g y una coercividad
de 1083.4 Oe fue alcanzada a 15% de Co. Por otro lado, mediciones de XRD mostraron que las
muestras de Mn-BFO exhibieron una estructura perovskita rombohedral sólo para 3% Mn.
Muestras a 5% y 7% Mn reportaron la estructura tetragonal, lo cual fue atribuido a la incorporación
de Mn(II) especies en los sitios del Bi. Las cantidades relativas de fases de impureza incrementaron
con el tiempo debido a la descomposición de BFO. Estas fases de impurezas paramagnéticas
afectaron las correspondientes propiedades magnéticas. La caracterización magnética reveló un
comportamiento ferrimagnético en los polvos a 7% Mn-BFO, mientras que una tendencia
paramagnética fue observada para otras composiciones. Las condiciones óptimas de dopaje fueron
alcanzadas a 7% Mn con un orden ferrimagnético y una magnetización máxima de 0.68 emu/g.
This work studied the effect of the incorporation of Co2+ and Mn2+ species on the structural and magnetic properties of nanocrystalline powders of BiFeO3 (BFO) synthesized by the sol-gel and thermal treatment method at 700°C for 15, 30 and 45 mins. X-ray diffraction (XRD) measurements showed diffraction patterns that belong to the rhombohedral perovskite structure of BiFeO3 for all undoped samples. Minimum presence of impurities was obtained for samples thermally annealed for 30 minutes. The measurements of magnetic hysteresis loops indicated that undoped BFO samples exhibited antiferromagnetic ordering, with a maximum magnetization obtained at 30 minutes of annealing time. XRD measurements verified the rhombohedral perovskite structure for Co-BFO samples. However, a secondary phase of Ferrite Cobalt (CFO) was detected for 9, 10 and 15% Co; the formation of CFO inhibited the growth of the impurity phases. Magnetic hysteresis measurements evidenced a ferromagnetic behavior for all Co-BiFeO3 samples due the presence of CFO. A saturation magnetization of 4.13 emu/g and a coercivity of 1083.4 Oe were achieved at 15 % of Co. On the other hand, XRD measurements showed that the Mn-doped BFO samples exhibited a rhombohedral perovskite structure only for 3% Mn. Samples at 5% and 7% Mn reported the tetragonal structure, which was attributed to the incorporation of Mn(II) species in Bi sites. The relative amount of impurity phases increased with time owing decomposition of BFO. These paramagnetic impurity phases affected the corresponding magnetic properties. Magnetic characterization revealed a ferrimagnetic behavior in the 7% Mn-BFO powder, whereas a paramagnetic trend was observed for other compositions. The optimal doping condition was reached at 7% Mn with a ferrimagnetic order and a maximum magnetization of ~ 0.68 emu/g.
This work studied the effect of the incorporation of Co2+ and Mn2+ species on the structural and magnetic properties of nanocrystalline powders of BiFeO3 (BFO) synthesized by the sol-gel and thermal treatment method at 700°C for 15, 30 and 45 mins. X-ray diffraction (XRD) measurements showed diffraction patterns that belong to the rhombohedral perovskite structure of BiFeO3 for all undoped samples. Minimum presence of impurities was obtained for samples thermally annealed for 30 minutes. The measurements of magnetic hysteresis loops indicated that undoped BFO samples exhibited antiferromagnetic ordering, with a maximum magnetization obtained at 30 minutes of annealing time. XRD measurements verified the rhombohedral perovskite structure for Co-BFO samples. However, a secondary phase of Ferrite Cobalt (CFO) was detected for 9, 10 and 15% Co; the formation of CFO inhibited the growth of the impurity phases. Magnetic hysteresis measurements evidenced a ferromagnetic behavior for all Co-BiFeO3 samples due the presence of CFO. A saturation magnetization of 4.13 emu/g and a coercivity of 1083.4 Oe were achieved at 15 % of Co. On the other hand, XRD measurements showed that the Mn-doped BFO samples exhibited a rhombohedral perovskite structure only for 3% Mn. Samples at 5% and 7% Mn reported the tetragonal structure, which was attributed to the incorporation of Mn(II) species in Bi sites. The relative amount of impurity phases increased with time owing decomposition of BFO. These paramagnetic impurity phases affected the corresponding magnetic properties. Magnetic characterization revealed a ferrimagnetic behavior in the 7% Mn-BFO powder, whereas a paramagnetic trend was observed for other compositions. The optimal doping condition was reached at 7% Mn with a ferrimagnetic order and a maximum magnetization of ~ 0.68 emu/g.
Link to repository: http://renati.sunedu.gob.pe/handle/sunedu/952652; https://hdl.handle.net/20.500.11801/1722
Discipline: Ciencias naturales
Grade or title grantor: Universidad de Puerto Rico
Grade or title: Maestría en Ciencias con Mención en Física
Register date: 3-Apr-2020
Files in This Item:
File | Description | Size | Format | |
---|---|---|---|---|
Chinchay_Espino_HA.pdf Restricted Access | Tesis_restringida | 3.86 MB | Adobe PDF | View/Open Request a copy |
Autorizacion.pdf Restricted Access | Formato de autorización | 772.51 kB | Adobe PDF | View/Open Request a copy |
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