Structural phase transition from rhombohedral to monoclinic phase and physical properties of (1-x) Bi0.85La0.15FeO3 – (x) Ca0.5Sr0.5TiO3 ceramics prepared by the solid-state route

• Published in: Materials chemistry and physics Vol. 328; p. 130033
• Main Authors: López, J.R.D. Ruiz, Sharma, Subhash, Brown, Francisco, Alvarez-Montano, V.E., Siqueiros, Jesús M., Herrera, Oscar Raymond
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-12-2024
• Subjects: BiFeO3; Ca0.5Sr0.5TiO3; Dielectric properties; Ferroelectric properties; Optical properties; Rietveld analysis; BiFeO3; Ferroelectric properties; Rietveld analysis; Optical properties; Dielectric properties; Ca0.5Sr0.5TiO3
• ISSN: 0254-0584
• DOI: 10.1016/j.matchemphys.2024.130033

In the present work, a series of solid solutions were synthesized using the solid-state reaction method for x = 0.0, 0.05, 0.10, and 0.15 in system (1-x)Bi0.85La0.15FeO₃-(x)Ca0.5Sr0.5TiO3 or ((1-x)BLFO-(x)CSTO) ceramics. Structural, optical, dielectric, and ferroelectric properties were studied in detail to investigate the impact of CSTO doping in BFO. Rietveld analysis of X-ray diffraction data of all samples revealed the formation of a single-phase solid solution with a distorted rhombohedral perovskite structure for x = 0.00 and 0.05, characterized by R3c symmetry, a mix of rhombohedral (R3c) and monoclinic (Cc) phases for x = 0.10 (R3c 31 % and Cc 69 %), whereas for x = 0.15 a single-phase solid solution with Cc symmetry was found. UV–visible analysis demonstrated that the optical band gap was increased from 2.11 eV for x = 0.0 to 2.21 eV for x = 0.15 in the visible range, and can be used in photovoltaics applications. The room temperature dielectric properties were measured, and a crucial role of CSTO was revealed in modifying the dielectric properties of BLFO ceramics; the dielectric constant and dielectric loss at 10 kHz change from εr = 82 and tanδ = 0.88 for x = 0.0 to εr = 116 and tanδ = 1.08 for x = 0.15. The leakage current density decreases while increasing the CSTO % from x = 0.0 to 0.15 due to the suppression of oxygen and Bi vacancies, a fact that is further reflected in the ferroelectric properties of CSTO-doped BFO ceramics. Room temperature ferroelectric properties improved with CSTO doping, and Pr was found to be 0.24 μC/cm2, 0.28 μC/cm2, and 0.84 μC/cm2 for x = 0.05, 0.10, and 0.15, respectively.
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•Structural phase transition from R3c to Cc observed for higher concentration for CSTO doping in BFO.•CSTO doping significantly changes the optical properties of BFO material due to changes in FeO6 octahedra.•A notable decrease in leakage current density was observed for increasing concentration of CSTO.•Ferroelectric properties improve with a higher concentration of CSTO doping.