Study on the inhomogeneity of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystal along the growth direction

The bulk single crystals Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3(PIN-PMN-PT) were grown spontaneously using the Bridgman method. The properties of as-grown PIN-PMN-PT single crystals along the growth direction were measured: along the crystal length, its structure was transformed from the mixed phase to tetragonal phase; the piezoelectric constants d33 of (001) and (110) samples decreased from 1900 to 1100 pC/N, and from 1200 to 500 pC/N respectively; the Curie temperature Tc increased from 206.0 to 223.4 °C; and the melting as well as crystallizing points all decreased by about 25-30 °C. These phenomena indicated the inhomogeneous properties of the PIN-PMN-PT single crystals. The experiment of elemental analysis verified that gradually increasing the concentration of the cation Ti along the growth direction would result in unstable properties of the crystal. Apparently, such a disadvantage decreased the effective ratio of the PIN-PMN-PT single crystal, and would further limit its applications.