140. synthesis and processing of nanocrystalline aluminum nitride for high powered laser applications

Department: Mechanical & Aerospace Engineering
Research Institute Affiliation: Graduate Program in Materials Science and Engineering
Faculty Advisor(s): Javier E. Garay | Matthew Duarte

Primary Student
Name: Matthew Adalberto Duarte
Email: m8duarte@ucsd.edu
Phone: 310-972-8564
Grad Year: 2020

Abstract
Aluminum nitride (AlN) is a ceramic material with outstanding properties such as high thermal conductivity, high electrical resistivity and low thermal expansion coefficient. Although AlN exhibits high stability in inert environments, it shows high reactivity under the presence of water and oxygen. Therefore, obtaining pure AlN nano powder and bulk nanocrystalline ceramics is challenging. Here we present the success of bulk nanocrystalline AlN prepared through gas-nitridation (GN) and Current Activated Pressure Assisted Densification (CAPAD). The former process was able to synthesize AlN powder with grain sizes below 100 nm from oxide precursors. Processing parameters of GN such as time and temperature were studied. The latter process succeeded to produce bulk AlN (>97% theoretical density). Nano AlN powder shows higher densification kinetics compared with microcrystalline powders. The X-Ray diffraction and SEM analysis showed the crystallite size and the grain size of the bulk were below 100 nm. Thermal management continues to be one of the major challenges in the development of high powered light sources such as solid state lasers. In particular, the relatively low thermal conductivity of standard materials limits the overall power output and/or duty cycle. We present a method based on CAPAD for the fabrication of high thermal conductivity photo luminescent materials: rare earth doped polycrystalline bulk AlN. These light emitting properties coupled with very high thermal conductivity should enable the development of a wide variety of more powerful light sources.

Industry Application Area(s)
Aerospace, Defense, Security | Electronics/Photonics | Materials

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