Multiferroic properties of sol-gel derived Bi5Fe1-xCoxTi3O15 thin films

Co-doped Bi 5 FeTi 3 O 15 thin films (BFCT-x,Bi 5 Fe 1-x Co x Ti 3 O 15) were prepared using a sol-gel technique.XRD patterns confirm their single phase Aurivillius structure,and the corresponding powder Rietveld analysis indicates the change of space group around x=0.12.The magnetic hysteresis loops are obtained and ferromagnetism is therefore confirmed in BFCT-x thin films.The remanent magnetization (M r) first increases and reaches the maximum value of 0.42 emu/cm 3 at x=0.12 due to the possible Fe 3+-O-Co 3+ ferromagnetic coupling.When x=0.25,the M r increases again because of the dominant Fe 3+-O-Co 3+ ferromagnetic coupling.The remanent polarization (2P r) of BFCT-0.25 was measured to be as high as 62 μC/cm 2,a 75% increase when compared with the non-doped BFCT-0 films.The 2P r remains almost unchanged after being subjected to 5.2 × 10 9 read/write cycles.Greatly enhanced ferroelectric properties are considered to be associated with decreased leakage current density.     

Multiferroic properties of solben gel derived Bi5Fe1-xCoxTi3O15 thin films

Co-doped Bi₅FeTi₃O₁₅ thin films (BFCT-x, Bi₅Fe_1-xCo_xTi₃O₁₅) were prepared using a sol—gel technique. XRD patterns confirm their single phase Aurivillius structure, and the corresponding powder Rietveld analysis indicates the change of space group around x=0.12. The magnetic hysteresis loops are obtained and ferromagnetism is therefore confirmed in BFCT-x thin films. The remanent magnetization (M_r) first increases and reaches the maximum value of 0.42 emu/cm³ at x=0.12 due to the possible Fe³⁺—O—Co³⁺ ferromagnetic coupling. When x = 0.25, the M_r increases again because of the dominant Fe³⁺—O—Co³⁺ ferromagnetic coupling. The remanent polarization (2P_r) of BFCT-0.25 was measured to be as high as 62 μC/cm², a 75% increase when compared with the non-doped BFCT-0 films. The 2P_r remains almost unchanged after being subjected to 5.2 × 10⁹ read/write cycles. Greatly enhanced ferroelectric properties are considered to be associated with decreased leakage current density.