Electromechanical properties of Pb(Mg1/3Nb2/3)O3-7%PbTiO3 thin films made by pulsed laser deposition

Thin film capacitors of Au/Pb(Mg1/3Nb2/3)O-3-7%PbTiO3 [PMN-(0.07)PT]/(La1/2Sr1/2)CoO3 were made by pulsed laser deposition on single crystal {001} MgO substrates. The PMN-(0.07)PT dielectric was perovskite dominated, and demonstrated functional behavior typical of relaxors. Electrostrictive behavior was observed at fields up to 200 kV cm(-1), however, the maximum strain was disappointingly low at only similar to0.14%. The macroscopic electromechanical d(33) and Q(33) coefficients were determined using piezo-response atomic force microscopy. At 100 kV cm(-1) the macroscopic Q(33) was found to be (2.6+/-0.2)x10(-2) C-2 m(4). The crystallographic electrostrictive coefficient was determined using in-situ x-ray diffraction and at the same field found to be significantly higher: (4.9+/-0.2)x10(-2) C-2 m(4). Since these electrostrictive coefficients are of the same order of magnitude as found in single crystal experiments (2.5-3.8x10(-2) C-2 m(4)), it appears that the low out-of-plane strain is simply the result of poor polarizability in the thin films. An effective Q(13) component of the electrostrictive tensor was also determined, and found to be similar to-0.32 x10(-2) C-2 m(4). (C) 2002 American Institute of Physics.