Origin of Disorder Tolerance in Piezoelectric Materials and Design of Novel Polar Systems

Abstract

Current high-performing piezoelectric materials are heavily dominated by the perovskite structure family. They typically rely on soft optical phonon modes stabilized by disorder near a morphotropic phase boundary and a unique resilience of the polar response to that disorder. To identify new structural families with similar resilience, we here develop a first-principles sensitivity analysis approach to determine the effect of disorder on the piezoelectric response for any structure. Vibrational properties are found to control degradation in the piezoelectric effect with disorder. In well-known piezoelectric systems, e.g. perovskites and tungsten bronze structures, multiple stable optical phonon modes are found to contribute to the piezoelectric response, providing a fingerprint for disorder tolerance. Hence, a multiple-phonon mode criteria is used to evaluate candidate materials suggested by the Materials Project and to screen the database for novel, disorder- tolerant piezoelectrics prototype systems. Eight promising prototype structures are altered through chemical substitution, generating novel systems with large piezoelectric response, and structural families which may be explored to replace PZT, beyond perovskites. Tetragonally structured TaP is identified as a particularly promising new candidate exhibiting a maximum piezoelectric component of 9.90 C/m2.