Polarization enhancement of compositionally graded BaZrxTi2−xO5 thin films prepared by sol–gel method

highlights
• The compositionally graded BaZrxTi2−xO5 films were prepared by the sol–gel method.
• The single-phase compositionally up and down graded BaZrxTi2−xO5 films were obtained.
• The polarization of compositionally graded film was enhanced due to the wedge domain.
• The upgraded BaZrxTi2−xO5 thin film had εr of 75 (at 1 MHz) and 2Pr=0.66 μC cm−2.

The compositionally up- and down-graded BaZrxTi2−xO5 (x=0, 0.01, 0.02, 0.03 and 0.04) thin films normal to Pt/Ti/SiO2/Si substrates were prepared by the sol–gel method. Their microstructure, dielectric and ferroelectric properties were investigated. The single phase compositionally graded thin films were obtained, and the upgraded thin film had better crystallization. The polarization enhancement of the compositionally graded BaZrxTi2−xO5 thin films was observed. Compared with the downgraded film, the upgraded BaZrxTi2−xO5 thin film showed better properties of dielectric constant (εr=75, at 1 MHz) and remnant polarization (2Pr=0.66 μC cm−2) due to the BaTi2O5 seeding layer.