High dielectric permittivity of SrBi^sub 2^Nb^sub 2^O^sub 9^(SBN) added Bi^sub 2^O3 and La^sub 2^O3

In this paper, the structural and dielectric properties of SrBi^sub 2^Nb^sub 2^O^sub 9^ (SBN) as a function of Bi^sub 2^O3 or La^sub 2^O3 addition level in the radio (RF) and microwave frequencies were investigated. The SBN, were prepared by using a new procedure in the solid-state reaction method with the addition of 3; 5; 10 and 15Â wt.% of Bi^sub 2^O3 or La^sub 2^O^sub 3.^ A single orthorhombic phase was formed after calcination at 900Â °C for 2Â h. The analysis by x-ray diffraction (XRD) using the Rietveld refinement confirmed the formation of single-phase compound with a crystal structure (aâ[euro][per thousand]=â[euro][per thousand]5.5129Â Ã..., bâ[euro][per thousand]=â[euro][per thousand]5.5183Â Ã... and câ[euro][per thousand]=â[euro][per thousand]25.0819Â Ã...; [alpha]â[euro][per thousand]=â[euro][per thousand][beta]â[euro][per thousand]=â[euro][per thousand][gamma]â[euro][per thousand]=â[euro][per thousand]90°). Scanning Electron Microscope (SEM) micrograph of the material shows globular morphologies (nearly spherical) of grains throughout the surface of the samples. The Curie temperature found for the undoped sample was about 400Â °C, with additions of Bi^sup 3+^, the temperature decreases and with additions of La^sup 3+^ the Curie temperature increased significantly above 450Â °C. In the measurements of the dielectric properties of SBN at room temperature, one observe that at 10Â MHz the highest values of permittivity was observed for SBN5LaP (5%La^sub 2^O3) with values of 116,71 and the lower loss (0.0057) was obtained for SBN15LaP (15%La^sub 2^O3). In the microwave frequency region, Bi^sub 2^O3 added samples have shown higher dielectric permittivity than La^sub 2^O3 added samples, we highlight the SBN15BiG (15Â % Bi^sub 2^O3) with the highest dielectric permittivity of 70.32 (3.4Â GHz). The dielectric permittivity values are in the range of 28â[euro]"71 and dielectric losses are of the order of 10^sup â '2^. The samples were investigated for possible applications in RF and microwave components.[PUBLICATION ABSTRACT]