Rishi Raj

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Rishi Raj (born July 21, 1943) is an Indian professor at the University of Colorado Boulder. He is best known as the pioneer of flash sintering, a process that quickly densifies materials using electricity.

Early life and education
Raj left India after completing a two-year program in mathematics, chemistry, and physics at Allahabad University. He earned a Bachelor of Science in electrical engineering from the University of Durham in England, graduating with First Class Honors. He then earned a PhD in applied sciences from Harvard University in 1970, studying under Michael F. Ashby and David Turnbull.

Career
After a brief stint as a staff engineer at Standard Telephones and Cables, Raj worked for Chase Brass and Copper Company in Cleveland. He began his teaching career at the University of Colorado Boulder as an assistant professor of mechanical engineering, and in 1976 moved to the Materials Science Department at Cornell University. He returned to the University of Colorado Boulder in 1996 after 21 years at Cornell.

Research
Raj has published extensively on ceramics, focusing on mechanical properties and the processing of oxides and non-oxides at high temperatures. His work also explored polymer-derived ceramics and how electric fields affect defects in high-temperature ceramics.

Flash sintering
In 2010, Raj and his students Marco Cologna and Boriana Rashkova discovered flash sintering. This technique can rapidly sinter ceramics, oxides, semiconductors, and other materials at lower temperatures than traditional methods. In 2023, Raj and a new collaborator reported applying flash sintering to tungsten, the first time the method was shown to work with a metal. They achieved near-full density in under a minute at room temperature. The method has also been demonstrated with nickel.

Impact and recognition
Raj has been cited more than 30,000 times and has published over 500 academic works. A landmark early paper showed that yttria-stabilized zirconia could reach full density in seconds at about 850°C, highlighting the speed and energy savings of flash sintering. Since then, the technique has attracted widespread interest and funding from governments, industry, and universities. It has also been commercialized by Lucideon Limited since 2012.

Personal life
Raj is married to Jyotsna Raj. More about his work can be found through his lab’s website.