Effects of W/Co co-doping on the structural, multiferroic, dielectric and optical properties of filled tungsten bronze Ba4Sm2Fe2Nb8O30 ceramics

• Published in: Results in physics 2024-01, Vol.56, p.107230, Article 107230
• Main Authors: Zuo, Xuzhong, Song, Dongpo, Zheng, Yifeng, Hui, Zhenzhen, Guo, Teng, Dong, Wei, He, Enjie, Qin, Yanfu, Guan, Banggui, Yang, Jie, Zhu, Xuebin, Dai, Jianming
• Format: Article
• Language: English
• Subjects: Ferroelectricity; Ferromagnetism; Magneto-dielectric effect; Optical bandgap; Tungsten bronze
• ISSN: 2211-3797; 2211-3797
• DOI: 10.1016/j.rinp.2023.107230

[Display omitted] •All samples exhibited the ferromagnetic state at room temperature.•The ferromagnetic transition temperatures are as high as ∼850 K.•The sample x = 0.2 has a superior multiferroicity with Mr = 0.15 emu/g and Pr = 2.1μC/cm2.•The magneto-dielectric effect was described by the Ginzburg-Landau theory.•Two different absorption edges were firstly obtained in these tungsten bronze ceramics. The structural, magnetic, ferroelectric, dielectric, magneto-dielectric and optical properties of W/Co co-substituted tungsten bronze Ba4Sm2Fe2Nb8-3x(W2Co)xO30 (0 ≤ x ≤ 0.3) ceramics were studied in detail. All the samples can be indexed with the tetragonal structure with the space group of P4bm. The room-temperature ferromagnetism with rather high ferromagnetic Curie temperature Tc was obtained in all compositions. The co-doping of W/Co ions obviously optimized the ferromagnetism and ferroelectricity. The composition x  = 0.2 showed a superior multiferroicity with the remnant magnetization Mr of 0.15 emu/g and the remnant polarization Pr of 2.1μC/cm2 as well as the Tc of 886 K. The low-temperature relaxation was related to the thermal process of oxygen vacancies, while the another one around 300 K was ascribed to the localized hopping of electrons. The relative increment of magneto-dielectric constant (MDC) obeyed with the square term of magnetization in Ginzburg-Landau theory, implying the existence of intrinsic magneto-electric coupling effect. A relatively large MDC of 0.17 % was achieved in pure sample. In addition, two direct inter-band transitions with the narrow band gaps of ∼2.0 eV and ∼2.5 eV were demonstrated.