High pressure FAST of nanocrystalline barium titanate
- Univ. of California, Davis, CA (United States)
- Sandia National Lab. (SNL-CA), Livermore, CA (United States)
- Univ. of California, Irvine, CA (United States)
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Here, this work studies the microstructural evolution of nanocrystalline (<1 µm) barium titanate (BaTiO3), and presents high pressure in field-assisted sintering (FAST) as a robust methodology to obtain >100 nm BaTiO3 compacts. Using FAST, two commercial ~50 nm powders were consolidated into compacts of varying densities and grain sizes. Microstructural inhomogeneities were investigated for each case, and an interpretation is developed using a modified Monte Carlo Potts (MCP) simulation. Two recurrent microstructural inhomogeneities are highlighted, heterogeneous grain growth and low-density regions, both ubiqutously present in all samples to varying degrees. In the worst cases, HGG presents an area coverage of 52%. Because HGG is sporadic but homogenous throughout a sample, the catalyst (e.g., the local segregation of species) must be, correspondingly, distributed in a homogenous manner. MCP demonstrates that in such a case, a large distance between nucleating abnormal grains is required—otherwise abnormal grains prematurely impinge on each other, and their size is not distinguishable from that of normal grains. Compacts sintered with a pressure of 300 MPa and temperatures of 900 °C, were 99.5% dense and had a grain size of 90±24 nm. These are unprecedented results for commercial BaTiO3 powders or any starting powder of 50 nm particle size—other authors have used 16 nm lab-produced powder to obtain similar results.
- Research Organization:
- Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Sandia National Laboratories, Livermore, CA (United States)
- Sponsoring Organization:
- AFRL; USDOE
- Grant/Contract Number:
- AC04-94AL85000
- OSTI ID:
- 1341402
- Alternate ID(s):
- OSTI ID: 1325373
- Report Number(s):
- SAND--2016-12477J; PII: S0272884216308136
- Journal Information:
- Ceramics International, Journal Name: Ceramics International Journal Issue: 12 Vol. 42; ISSN 0272-8842
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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