Tesis
Mn-Based Nanostructured Building Blocks: Synthesis, Characterization and Applications
Autor
Beltran Huarac, Juan
Morell, Gerardo (Consejero)
Institución
Resumen
The quest for smaller functional elements of devices has stimulated increased
interest in charge-transfer phenomena at the nanoscale. Mn-based nanostructured
building blocks are particularly appealing given that the excited states of high-spin Mn2+
ions induce unusual d-d energy transfer processes, which is critical for better
understanding the performance of electronic and spintronic devices. These nanostructures
also exhibit unique properties superior to those of common Fe- and Co-based
nanomaterials, including: excellent structural flexibility, enhanced electrochemical
energy storage, effective ion-exchange dynamics, more comprehensive transport
mechanisms, strong quantum yield, and they act as effective luminescent centers for more
efficient visible light emitters. Moreover, Mn-based nanostructures (MBNs) are crucial
for the design and assembly of inexpensive nanodevices in diluted magnetic
semiconductors (DMS), optoelectronics, magneto-optics, and field-effect transistors,
owing to the great abundance and low-cost of Mn. Nonetheless, the paucity of original
methods and techniques to fabricate new multifunctional MBNs that fulfill industrial
demands limits the sustainable development of innovative technology in materials
sciences. In order to meet this critical need, in this thesis we develop and implement
novel methods and techniques to fabricate zero- and one-dimensional highly-crystalline
new-generation MBNs conducive to the generation of new technology, and provide
alternative and feasible miniaturization strategies to control and devise at nanometric
precision their size, shape, structure and composition.
Herein, we also establish the experimental conditions to grow Mn-based
nanowires (NWs), nanotubes (NTs), nanoribbons (NRs), nanosaws (NSs), nanoparticles (NPs) and nanocomposites (NCs) via chemical/physical deposition and co-precipitation
chemical routes, and determine the pertinent arrangements to our experimental schemes
in order to extend our bottom-up approaches towards the fabrication of different types of
functional MBNs. Likewise, strategic procedures that advance the facile integration of
these self-assembled nanostructures with carbon-based and magnetic/optical materials,
chalcogenides, oxides, and ferroics are widely analyzed and discussed.
Furthermore, we present the attractive peculiarities of three versatile MBN
systems (bridging the gap between their advantageous properties and the lack of methods
for their fabrication): single-crystal saw-like MnS NRs, and single-crystal MnS NWs
conformally coated with carbon; doped rare-earth manganite NCs, and carbon NTs
conformally coated with doped rare-earth manganite; and ZnS:Mn NPs, and
Fe3O4/ZnS:Mn NCs. Concerning the applicative significance, the main features of these
three systems obtained by our method are suitable to advance direct applications in
nanotechnology. In this regard, this work represents a step ahead in the following areas: i)
alternative anode materials to enhance the capacity and cycling performance of lowdrain,
long-life, low-cost, high-energy density light-weight and safer lithium-ion
batteries; ii) promising luminescent materials to improve the optoelectronic performance
of visible light emitters; iii) new elements for field-effect transistors that outperform the
transport properties of conventional carbon-based channels; iv) bifunctional materials
exhibiting optical response sensitive to external magnetic fields vital for DMS; v) novel
types of nanocantilevers useful for nanosensors and nanotweezers; vi) unique
multiferroics materials that exhibit magnetoelectric coupling at room temperature for
spintronics; vii) potential core-shell materials showing stress-free and protective carbon shells for shock-resistance semiconductors; and viii) high-quality ceramics useful as
starting materials to deposit films by pulsed laser deposition, sputtering and thermal
evaporation techniques.