Enhancing the electrical properties of NBT ceramics by the addition of small amounts of Yb

• Published in: Journal of alloys and compounds Vol. 873; p. 159845
• Main Authors: França, E.L.T., Romanholo, P.V.V., Simões, S.S., Falcão, E.H.L., Franco, A., Machado, F.L.A.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25.08.2021; Elsevier BV
• Subjects: Ceramics; Density; Dielectric loss; Diffraction patterns; Electrical properties; Lattice vibration; Magnetic moments; Magnetic properties; Morphology; NBT; Permittivity; Perovskite structure; Perovskites; Room temperature; X-ray diffraction; Electrical properties; NBT; Magnetic properties
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.159845

•Ceramic samples of Na0.5Bi0.5−xYbxTiO3 (x = 0.005, 0.010, 0.015 and 0.020) were prepared.•The addition of Yb distorted the structure, increased the crystalline density and the porosity.•The magnetic moment associated to the ions of Y3+ introduced paramagnetism.•The addition of Yb enhanced the permittivity and reduced the dielectric losses.•For x = 0.020 the permittivity is higher than 103 for a broad range of frequencies. In the present work, the magnetic and electrical properties of ceramic samples of Na0.5Bi0.5−xYbxTiO3 with x = 0.005, 0.010, 0.015 and 0.020 prepared by a solid-state reaction were investigated. X-ray diffraction (XRD) patterns revealed that the addition of Yb3+ ions led to distortions in the rhombohedral perovskite structure. The microstructure morphology investigated by scanning electron microscopy revealed the presence of micro-pores, diminishing the overall mass density of the ceramics for increasing values of x. This behaviour is opposite to the one observed for the mass density determined by using the XRD data. Despite of the contraction in the lattice parameter, the<Ti–O>bond length was found to increase for increasing values of x, shifting the corresponding Raman modes towards lower values of energy. The magnetization and the ac and dc magnetic susceptibilities were measured from 300 K down to 5 K. The magnetic moment associated to the Yb3+ ions added a paramagnetic behavior to the NBT samples that increases for increasing values of x. The electrical permittivity was measured at room temperature by impedance spectroscopy for frequencies (f) in the range 20 Hz–2.0 GHz. The f-dependence for the permittivity was accounted for by using the Cole-Davidson model. It was observed that the addition of the Yb3+ ions enhances the values of the dielectric constants, yielding an increase of about 70% for x = 0.020, while the overall dielectric losses are significantly reduced.