Large piezoelectricity response in Li and Ti (or Zr) co-alloyed w-AlN

Abstract

As one of the most important piezoelectric materials for piezoelectricity related devices, the performance of wurtzite-type aluminum nitride (w-AlN) is still inhibited by its low piezoelectric coefficients. Herein, we have proposed a new co-alloying w-AlN system by Li+ and Ti4+ (or Zr4+) in a ratio of 1:2 and systematically compared its piezoelectric properties with state-of-the-art Sc-alloyed w-AlN via the first-principle method. It is found that the co-alloyed w-AlN shows obvious advantages over Sc-alloyed w-AlN in nearly all aspects of piezoelectric performance. The piezoelectric strain coefficient (d33) of (LiTi2)0.375Al0.625N reaches 213.25 pC/N, about 8 times and 41 times that of Sc0.375Al0.625N and pure w-AlN, respectively. Additionally, the large enhancement of piezoelectricity of co-alloyed w-AlN was successfully related to the elastic softening, the increased Born effective charge [Formula: see text], and the decreased internal strain sensitivity [Formula: see text]. This work provides a new way to enhance the performance of incumbent piezoelectric materials by accessible elements instead of Sc.

Surface and bulk acoustic wave resonators based on aluminum nitride for bandpass filters

“…For TM1 x/2 TM2 x/2 Al 1-x N (TM1 = Ti, Zr, Hf; TM2 = Mg, Ca, Zn), the energy difference between zinc-blende and layered hexagonal phases of TM1 0.5 TM2 0.5 N was found to be a good descriptor for searching alloys with high piezoelectric performance [140]. Li x/3 TM 2x/3 Al 1-x N (TM = Ti and Zr) was predicted to show a larger piezoelectric constant than AlN [141]. From a high-throughput prediction, many double-TM-alloying AlN were also found to show higher piezoelectric performances [142].…”