Diffuse Ferroelectricity and Atypical Magnetism in Quadruple Perovskite Oxide Bi2/3Sr1.5Ba1.5 Ti4O12

Abstract-This research focuses on the study of structural, ferroelectric traits and atypical magnetism in Bi _2/3 Sr _1.5 Ba _1.5 Ti ₄ O ₁₂ (BSBT) ceramic and testifies a diffuse ferroelectric phase transition with the mechanisms responsible for such a diffuse phase transition (DPT) in BSBT ceramic. This ceramic possesses cubic crystal structure (space group: Pm3m). Diffuse peak temperature ( T_m ) at frequencies above 0.1 kHz lies in the range 360.5 ± 5 K confirming the weak relaxor characteristic in BSBT ceramic. The value of Curie-Weiss constant (C) is of the order of 10 ⁶ signifying displacive ferroelectricity in the studied ceramic and the magnitude of diffuseness coefficient (γ) at all frequencies for the BSBT sample is greater than or equal to 1.9 (i.e., very close to 2) signifying near complete (Gaussian model) DPT in the studied frequency range. The magnitude of degree of diffuseness (D) signifies the steepness of the asymmetric double well zones attained at frequencies 0.1 kHz, 1 kHz, 10 kHz, 100 kHz and 1 MHz. The asymmetric double well zone obtained at these frequencies lie between 373 K and 473 K. The magnetism study at 1000 Oe displays a weak antiferromagnetic (AFM) peak at 60 K( T_N ) with a peak magnetization of about 8 x 10 ^-5 μ _B /f.u. as well as negative magnetization (after 60 K in ZFC and after 75 K in FC) upto 303 K, describing the diamagnetic (DM) nature of the studied BSBT sample.