Structural stability and microwave dielectric properties of (1―x)Ln1/3NbO3―xLn2/3TiO3 (Ln: La, Nd; 0≤x≤0.8)

Abstract The structural stability, phase compositions and microwave dielectric properties of (1 −  x )Ln 1/3 NbO 3 – x Ln 2/3 TiO 3 (Ln: La, Nd; x  = 0, 0.2, 0.4, 0.5, 0.6, 0.8) have been investigated in this paper by XRD, SEM and network analyzer. Single phase of La 0.4667 Nb 0.6 Ti 0.4 O 3 and La(Nd)TiNbO 6 compounds with non-perovskite structure were obtained at x  = 0.4 and 0.5 composition, respectively. The structural stabilities of the perovskites were discussed in terms of the local charge imbalance between the two A-sites. The dielectric constant of La 1/3 NbO 3 is much larger than that of La 0.4667 Nb 0.6 Ti 0.4 O 3 or La(Nd)TiNbO 6 . The Q  ×  f value increased significantly from x  = 0 to x  = 0.5 and then decreased with the further increase of x . Maximum Q  ×  f values of 49,867 and 25,393 GHz were obtained for LaTiNbO 6 and NdTiNbO 6 ( x  = 0.5), respectively. The absolute value of τ f decreased with increasing x up to x  = 0.6 and then increased with the further increase of x .