Influence of annealing environment on magnetic and ferroelectric properties of chemical solution derived nanocrystalline Bi3.15La0.85Ti3O12 thin films

Bi3.15La0.85Ti3O12 (BLT) thin films grown on LaNiO3 (LNO) buffered Si (100) substrates were prepared by chemical solution deposition. The samples were annealed at 600 °C by rapid thermal annealing in oxygen and nitrogen atmosphere, respectively. X-ray diffraction results showed that the sample annealed in oxygen atmosphere exhibited pure perovskite with random orientation. Field-emission scanning electron microscopy (FE-SEM) results revealed that the average grain size of the sample is about 50 nm. The remanent polarization (Pr) and coercive electric field (Ec) values for the BLT films annealed in pure oxygen and nitrogen atmosphere were 47.9 μC/cm2 and 39.3 kV/cm, 42.8 μC/cm2 and 54.9 kV/cm, respectively. The leakage current density is 8 × 10−4 A/cm2 in oxygen atmosphere which is about one order of magnitude lower than that of BLT thin films annealing in nitrogen atmosphere. The saturation magnetizations of BLT films on Si substrate with and without LNO buffer-layer were 0.112 and 0.057 emu/cm3, respectively. The magnetic property in the BLT originates from oxygen vacancies.