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

Abstract

Current high-performing piezoelectric materials are dominated by perovskites that 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 structural families with similar resilience, we develop a firstprinciples sensitivity analysis approach to determine the effect of disorder on the piezoelectric response for structures in the Materials Project database. In well-known piezoelectric systems, the lattice dynamics, rather than internal strain or dielectric, control the polar response. Additionally, multiple stable optical phonon modes are found to contribute to the piezoelectric response, providing a fingerprint for disorder tolerance. A multiple-phonon mode criterion is used to evaluate candidate materials for disordertolerant piezoelectric prototype systems. Five promising structures are altered through chemical substitution, generating potential MPB end points with large piezoelectric responses beyond perovskites including Akermanite Sr 2x Ca 2 − 2x CoSi 2 O 7 , which exhibits a nearly 20% increase in response at the 50% composition.

The role of disorder in the synthesis of metastable zinc zirconium nitrides

“…The optoelectronic properties of the synthesizable polymorphs in this system remain to be investigated, and Table I indicates promising properties for device applications such as contact materials, solar cell absorbers, photocatalysts, piezoelectric and ferroelectric materials. [16,44] In particular, the synthesized BN-derived polymorph has >2 eV band gap and low (<1.5) well-matched electron and hole effective masses, making it interesting for electronic devices that can operate at elevated temperatures. Additionally, this non-polar BN polymorph is the transition state between two variants of the polar WZ structure, suggesting a pathway to tuning its predicted and measured ferroelectric response.…”

Theory-Guided Exploration of the Sr2Nb2O7 System for Increased Dielectric and Piezoelectric Properties and Synthesis of Vanadium-Alloyed Sr2Nb2O7

“…We note that the dielectric and piezoelectric tensors are often correlated due to the inclusion of the Born effective charges and force constants. , We neglect the contribution of the electronic term in the piezoelectric calculation, e̅ , in this study as it generally does not contribute significantly to the total piezoelectric tensor for the materials currently computed in the Materials Project database . Once the piezoelectric properties for the fully substituted alloys are computed, we approximate the piezoelectric tensor for the intermediate compositions of the substitutional alloy systems by employing a Vegard’s-law-like linear approximation for the Born effective charges, internal stain tensors, and force constants of the alloy.…”

“…Following the recommendations obtained by DFT calculations for enhanced polar behavior, the system is synthesized through pulsed-laser deposition and increased dielectric properties are found. Along with this general methodology for systematically exploring disorder-tolerant piezoelectric alloy systems, we identify Sr 2 Nb 2–2 x V 2 x O 7 as a promising system with confirmed increased dielectric and predicted increased piezoelectric properties.…”

“…We then choose a layered perovskite structure, Sr 2 Nb 2 O 7 , and explore the possibility of increased polar response as a function of alloying with a high-throughput framework. Recent work, which focused on identifying defect-tolerant materials and structural classes which retain much of their piezoelectric response with respect to disorder, identified Sr 2 Nb 2 O 7 as a promising parent compound. The layered perovskite Sr 2 Nb 2 O 7 has been synthesized previously and is a known ferroelectric material with a Curie temperature above 1200 °C. , In addition, substitutional alloy systems of Sr 2 Nb 2 O 7 with barium, vanadium, and tantalum have also been synthesized, demonstrating the ability of this system to support stable, disordered solid solutions. − Focusing on the lattice dynamic properties of this system, we explore suitable substitutions on both the Sr and Nb cation sites for improved piezoeletric and dielectric responses near regions of softened phonon modes.…”

Exploring the Pb1−xSrxHfO3 System and Potential for High Capacitive Energy Storage Density and Efficiency

“…Recent ab initio predictions have shown that even apart from a prospective structural‐phase boundary, Pb 1− x Sr x HfO 3 could exhibit enhanced piezoresponse as a function of ionic disorder (associated with the strontium alloying). [ 28 ] Finally, strontium alloying is well known to improve the leakage and breakdown strength of lead‐based perovskites [ 29 ] and thus there is potential that the Pb 1− x Sr x HfO 3 system could provide a pathway to improved capacitive energy storage performance. The key parameters underlying capacitive‐energy storage of any dielectric material are the recoverable energy density in the charge–discharge process (, where P r and P max are the remanent and maximum polarization, respectively) and the energy‐storage loss ( U loss , which is determined by the area enclosed within the double hysteresis loops).…”