Ultra-high piezoelectric response in 〈110〉- oriented polydomain Pb(Mg1/3Nb2/3)O3- PbTiO3 single crystals

The piezoelectric constant and electromechanical coupling coefficients of 〈110〉-oriented polydomain0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 single crystals were determined experimentally by using resonance methods. It was confirmed that the single-crystal system has large electromechanical coupling coefficients k33 (∼91%), k′ 33 (∼83%), and k31 (∼81%), and piezoelectric constant d33 (∼1400 pC/N), which are comparable to those of 〈001〉-oriented crystals, and we also found that the values of k′ 33 and k31 are sensitive to the cuts of the crystals. X-ray-diffraction measurements on 〈110〉-oriented crystals have shown that the origin of the high piezoelectric response should be attributed to the orthorhombic distortion. Our results show that the 〈110〉-oriented crystals are also promising for a wide range of electromechanical transducer applications, since the 〈110〉-oriented crystals can be grown from 〈110〉-oriented seed crystals in the modified Bridgman technique.