Chemical-Pressure-Modulated BaTiO3 Thin Films with Large Spontaneous Polarization and High Curie Temperature

Although BaTiO3 is one of the most famous lead-free piezomaterials, it suffers from small spontaneous and low Curie temperature. Chemical pressure, as a mild way to modulate the structures and properties of materials by element doping, has been utilized to enhance the ferroelectricity of BaTiO3 but is not efficient enough. Here, we report a promoted chemical pressure route to prepare high-performance BaTiO3 films, achieving the highest remanent polarization, P-r (100 mu C/cm(2)), to date and high Curie temperature, T-c (above 1000 degrees C). The negative chemical pressure (similar to-5.7 GPa) was imposed by the coherent lattice strain from large cubic BaO to small tetragonal BaTiO3, generating high tetragonality (c/a = 1.12) and facilitating large displacements of Ti. Such negative pressure is especially significant to the bonding states, i.e., hybridization of Ba 5p-O 2p, whereas ionic bonding in bulk and strong bonding of Ti e(g) and O 2p, which contribute to the tremendously enhanced polarization. The promoted chemical pressure method shows general potential in improving ferroelectric and other functional materials.

Automated summary

A promoted chemical pressure route has been utilized to prepare high-performance BaTiO3 films, achieving the highest remanent polarization and high Curie temperature. The negative chemical pressure imposed during the process significantly enhances the bonding states and contributes to the improved polarization.