28. controlling the shape and particle size of lab6 nanostructures: a step towards developing new composite materials

Department: Mechanical & Aerospace Engineering
Research Institute Affiliation: Agile - CaliBaja Center for Resilient Materials & Systems
Faculty Advisor(s): Olivia A. Graeve

Primary Student
Name: Carlos Ingram Vargas Consuelos
Email: cvargasc@ucsd.edu
Phone: 858-257-9345
Grad Year: 2020

Abstract
Reinforced and armored materials, corrosion-resistant engineering components and thermionic coatings for electron emission sources play an important role in the aerospace industry in the current scenario. In particular, ceramics like lanthanum hexaboride (LaB6) are being used for many purposes. The study of new techniques to synthesize this material in an economic and a rapid way will lead to the development of advanced technologies. Presently, the synthesis of LaB6 is expensive and involves complicated chemical-physical procedures. Moreover, a new processing technique to obtain hexaboride materials by combustion synthesis has been proven to be both, cheap and simple. However, this synthesis technique is responsible for producing only agglomerated hexaboride structures, which limits its application in composite materials. Our research objective is to obtain deagglomerated nano-structures that can potentially be used as functional materials in new nano-composites by improving this combustion technique. By controlling the pH of the precursors before combustion we were able to demonstrate control over the shape and particle size of the lanthanum hexaboride crystals obtained at the end of the synthesis. Several ways to control the pH values were explored resulting in a variety of the final crystalline structures. Characterization techniques like x-ray diffraction (XRD), electron diffraction spectroscopy (EDS), and scanning electron microscopy (SEM) were used to analyze the obtained products. This new generation of boride nano-structures, particularly of Lanthanum hexaboride will allow the implementation of these ceramics as functional materials in new nano-composites for specific engineering technologies.

Industry Application Area(s)
Aerospace, Defense, Security | Materials | Semiconductor

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