Highly Transparent Pure Alumina Fabricated by High-Pressure Spark Plasma Sintering

Highly transparent pure alumina with an average grain size of 200 nm was fabricated by means of high-pressure spark plasma sintering. The alumina sintered either at 950 degrees or at 1000 degrees C for 10 min under an applied pressure of 500 MPa had an in-line transmission of about 64% for a wavelength of 645 nm. The application of high pressure allowed to obtain highly transparent full dense alumina at low temperatures with no considerable grain growth.