Piezoelectric resonators offer the potential of enabling high-resolution gas, chemical, and physical sensing in a wide variety of applications in manufacturing, aerospace, defense, engines, energy production, and research. However, substantial challenges to implementing such sensors are associated with the temperature limits, thermally activated defect evolution, material damping, and temperature dependence of physical properties of piezoelectric materials. During the past two decades, innovative single-crystalline piezoelectric materials, including a number with the crystal structure of langasite, have emerged as candidates for operation at temperatures well above the limit of quartz (~ 500^o C). The current stage of research on these materials is analogous to that on synthetic quartz half a century ago, with much to be determined about crystal growth, defect evolution, and dependence on crystallographic orientation before high-performance devices become commercially feasible. Success in addressing this challenge will require a collaborative interdisciplinary research effort, including physics, chemistry, and engineering expertise. Current research on this subject at NIST-Boulder focuses primarily on identifying and minimizing defect contributions to high-temperature acoustic damping and determining crystallographic orientations with minimal change in resonant frequencies over a broad range of temperatures.

 

Reference

Johnson WL, et al: Journal of Applied Physics 110: 123528, 2011

 

key words

Piezoelectric materials; Acoustic sensors; Crystal resonators; Gas sensors; High-temperature sensors; Frequency control; Crystal defects; Anelasticity; langatate;

Citizenship:  Open to U.S. citizens

Level:  Open to Postdoctoral applicants