Structural properties of CaTi1−x(Nb2/3Li2/3)xO3−δ (CNLTO) and CaTi1−x(Nb1/2Ln1/2)xO3 (Ln=Fe (CNFTO), Bi (CNBTO)), modified dielectric ceramics for microwave applications

This paper presents an investigation of the structural characteristics of Nb1/2Bi1/2 (CNBTO), Nb1/2Fe1/2 (CNFTO) and Nb2/3Li1/3 (CNLTO) substitution into the B-site of calcium titanate ceramics. The modified CaTiO3 (CTO) ceramics were prepared by the conventional solid-state method. The compounds were investigated, by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDXS). The X-ray analysis shows that all samples have an orthorhombic structure. The refinement analysis of all samples were also performed and discussed in this paper. For all studied samples, a Raman mode at 805 cm−1 was detected and its intensity increases as the substitution increases. The dielectric permittivity and loss at microwave frequencies (MW) were investigated. The CNLTO phase, present the highest dielectric constant (k=35.8) at 3.9 GHz with loss (tg α=7×10−3). The lowest value of k=25.7 (f=4.8 GHz) and tg α=3×10−3, was obtained for the CNFTO phase. These measurements confirm the possible use of such material for microwave devices like dielectric resonator antennas.