Abstract:

Ceramics with strongly negative coefficients of thermal expansion (CTE) of -70 to -80 x 10^-7/°C have been investigated as “athermalizing” substrates for fiber Bragg gratings in optical devices.  These CTEs can be achieved for ceramics comprised of ZrW₂O₈ (CTE » -90) with 10 to 30% Zr₂P₂WO₁₂ (CTE » -40).  However, the fabrication of fully dense ZrW₂O₈-Zr₂P₂WO₁₂ ceramics presents several challenges.  The grain size or agglomerate size of the Zr₂P₂WO₁₂ phase must be controlled to avoid microcracking; porosity must be minimized by small additions of certain metal oxide sintering aids; and rates of densification and ZrW₂O₈ formation must be controlled to avoid extensive fracturing during firing.

 

Dr. Gregory Merkel earned a Bachelor of Science in Geology from the University of Massachusetts at Amherst and a Doctor of Philosophy in Geochemistry and Mineralogy from The Pennsylvania State University.

 

Joined Corning in 1981, Dr. Merkel is widely recognized as an expert in microcracked ceramics and more broadly, in high thermal shock resistant ceramics.  He was a key contributor for a long list of automotive ceramic substrate and diesel filter products successfully introduced to the market place for Corning Environmental Technologies. His contribution to the invention and the successful development of thin-wall and ultra thin-wall product family is based on his discovery of the proper combination of raw materials to provide low expansion, as well as the fundamental understanding of the interrelationship among raw material properties and firing cycles. 

 

Besides the commercial impact of his applied research based on first-principle approaches, Dr. Merkel has also led ground-breaking research in many ceramic materials systems including unique non-microcracked negative expansion materials for Fiber Bragg grating substrates and ultra-high thermal conductivity substrates for integrated circuits.

 

Due to his significant contribution, Dr. Merkel was named as a Corning Research Fellow in 2008.  Dr. Merkel currently holds 31 patents with 10 additional applications pending.