Ferroelectric Pb1−xLaxTiO3 (PLT, x = 0.00 ˜ 0.28) thin films have been prepared on MgO(001) substrates using pulsed laser deposition. The degree of c-axis orientation in PLT films increased as the La concentration (x) increased with systematic changes in lattice constants and transformation strains. For x ≥ 12, the PLT films showed full c-axis orientation.
In order to understand why the domain evolution in PLT films changes with the La concentration, we have conducted high temperature X-ray diffraction to simulate the cooling process during which the domain structure is evolved. Lattice constants, degree of c-axis orientation, crystal quality of PLT films were characterized as a function of temperature. Lattice constants along substrate normal direction showed similar characteristics with those of powder. The degree of c-axis orientation just after the phase transformation at the Curie temperature also increased with La concentration. The crystal quality, which is quantified by the line width of diffraction peak, is insensitive to La concentration in paraelectric phase. However, it shows significant variation after the domain structure is evolved.