Role of random electric fields in relaxors.
PbZr(1-x)Ti(x)O3 (PZT) and Pb(Mg1/3Nb2/3)(1-x)Ti(x)O3 (PMN-xPT) are complex lead-oxide perovskites that display exceptional piezoelectric properties for pseudorhombohedral compositions near a tetragonal phase boundary. In PZT these compositions are ferroelectrics, but in PMN-xPT they are relaxors because the dielectric permittivity is frequency dependent and exhibits non-Arrhenius behavior. We show that the nanoscale structure unique to PMN-xPT and other lead-oxide perovskite relaxors is absent in PZT and correlates with a greater than 100% enhancement of the longitudinal piezoelectric coefficient in PMN-xPT relative to that in PZT. By comparing dielectric, structural, lattice dynamical, and piezoelectric measurements on PZT and PMN-xPT, two nearly identical compounds that represent weak and strong random electric field limits, we show that quenched (static) random fields establish the relaxor phase and identify the order parameter.
NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899.
Daniel
D
Phelan
Christopher
C
Stock
Jose A
JA
Rodriguez-Rivera
Songxue
S
Chi
Juscelino
J
Leão
Xifa
X
Long
Yujuan
Y
Xie
Alexei A
AA
Bokov
Zuo-Guang
ZG
Ye
Panchapakesan
P
Ganesh
Peter M
PM
Gehring
lead zirconate titanate; neutron scattering; piezoelectricity; short-range order; soft modes