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http://cimav.repositorioinstitucional.mx/jspui/handle/1004/2677| Synthesis of Ferroelectric and Multiferroics Thin films of BiMnO3/ SrTiO3 and Structural, Piezoelectric, Magnetic, Optical, and Mechanical Properties Characterization | |
| Glory Valentine Umoh | |
| Abel Hurtado MacÍas | |
| Acceso Abierto | |
| Sin Derechos Reservados | |
| SÍNTESIS DE MATERIALES Materiales Multiferroicos | |
| Multiferroic characteristics of BiMnO3 thin films offer great prospects to explore, either in terms of ferroelectricity, ferromagnetism, or ferroelasticity. Ferroelectric and ferromagnetic materials can be used in data storage due to their electrical and magnetic properties. Ferroelastic can find its application in microelectromechanical systems devices. This dissertation focused on the synthesis, characterization, and improvement of the multiferroic properties of polycrystalline BiMnO3 thin films as well as the elaboration influence of Cu on the magnetism of BiMnO3 thin films. BiMnO3 films were grown on three different substrates, Si (001), Pt-buffered Si (001), Nb-doped SrTiO3 (100), and also doped with different amounts of Cu. The films were characterized using techniques such as X-Ray diffraction (XRD), scanning electron microscope (SEM), HRTEM observations, by energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Visible-near-IR spectroscopy (Vis-NIR), electron energy loss spectrometer (EELS), nanoindenter, superconductor quantum interference device (SQUID) magnetometer, and finally, the polarization-electric field (P-E) hysteresis loops of the BiMnO3 thin films were conducted at 200 and 300 K. There are several studies on the growth of thin films, however, they are not clear and in some cases contradictory, therefore, different parameters were controlled during the deposition in terms of working pressure, RF power, substrate, deposition 10 temperature, and target to substrate distance. After deposition ex-situ thermal treatment was carried out in order to compensate for the volatility of bismuth and also to eliminate secondary phase. Kramer’s–Krӧnig analysis was used to determine bandgap, via a polynomial fit in the energy loss function (ELF) plot with an Eg = 1.63 eV, complex dielectric function, and static dielectric constant, ε* = 4.68 of the grown BiMnO3 thin films. The reflection coefficient Ґl of the BiMnO3 thin films was used to elucidate the reflection loss in the BiMnO3 thin films. XPS analysis revealed the existence of Mn charge transition of 3+ and 4+ states. Resistivity result describes BIMnO3 as a semiconductor. The nanomechanical characterization demonstrated that the region of penetration depth was below 10% of BiMnO3 film thickness. Young's modulus (E), hardness (H), and Stiffness (S) were measured to be 142 ± 3 GPa, 8 ± 0.2 GPa, and 44072 ± 45 N/m respec | |
| 2022-12 | |
| Tesis de doctorado | |
| Inglés | |
| OTRAS | |
| Versión revisada | |
| submittedVersion - Versión revisada | |
| Aparece en las colecciones: | Doctorado en Ciencia de Materiales |
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| Tesis - Glory Umoh.pdf | 2.82 MB | Adobe PDF | Visualizar/Abrir |