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Updated: Jan 27, 2026

Production and Targeting of Monovalent Quantum Dots
Published on: October 23, 2014
Extremely Large Magnetic-Field-Effects on the Impedance Response of TiO2 Quantum Dots
Dominique Mombrú1, Mariano Romero2, Ricardo Faccio3
1Centro NanoMat/CryssMat & Física, DETEMA, Facultad de Química, Universidad de la República (UdelaR), Montevideo, C.P., 11800, Uruguay.
Abstract:
Here, we report large magnetoresistance and magnetocapacitance response of undoped TiO2 quantum dots weighting the contribution of both grain and grain boundaries by means of impedance spectroscopy. We also performed a complete characterization of the TiO2 quantum dots (~5 nm) prepared by sol-gel via water vapor diffusion method, using X-ray diffraction, small angle X-ray scattering, transmission electron microscopy and Raman spectroscopy. In addition, we showed a complete theoretical study on the electronic properties of TiO2 surface and subsurface oxygen and titanium vacancies to shed some light in their electronic and magnetic properties. Based in our study, we can conclude that the presence of defects, mainly at the grain boundary of these undoped TiO2 quantum dots, could be responsible for the large positive magnetoresistance (+1200%) and negative magnetocapacitance (-115%) responses at low applied magnetic fields (1.8 kOe) and room temperature.
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