Role of random electric fields in relaxors

Area of Science:

• Materials Science
• Solid State Physics
• Crystallography

Background:

• Lead-oxide perovskites, including lead zirconate titanate (PZT) and lead magnesium niobate-lead titanate (PMN-xPT), exhibit significant piezoelectric properties.
• These properties are particularly pronounced in pseudorhombohedral compositions near a tetragonal phase boundary.

Purpose of the Study:

• To investigate the structural differences between PZT and PMN-xPT relaxors.
• To correlate nanoscale structure with enhanced piezoelectric coefficients.
• To elucidate the role of quenched random fields in establishing the relaxor phase.

Main Methods:

• Comparative analysis of dielectric, structural, lattice dynamical, and piezoelectric measurements.
• Examination of nanoscale structure in PZT and PMN-xPT.
• Investigation of materials representing weak and strong random electric field limits.

Main Results:

• PMN-xPT exhibits a unique nanoscale structure absent in PZT.
• This nanoscale structure correlates with over a 100% enhancement in the longitudinal piezoelectric coefficient in PMN-xPT compared to PZT.
• Quenched random fields were identified as the key factor establishing the relaxor phase.

Conclusions:

• The presence of a unique nanoscale structure in PMN-xPT is critical for its superior piezoelectric performance.
• Random electric fields play a crucial role in defining the relaxor behavior in these perovskites.
• Understanding these structure-property relationships can guide the development of advanced piezoelectric materials.