Structural stability and microwave dielectric properties of (1-x)Ln_(1/3)NbO_3-xLn_(2/3)TiO_3 (Ln: La, Nd; 0 ≤x ≤ 0.8)

摘要

The structural stability, phase compositions and microwave dielectric properties of (1-x)Ln_(1/3)NbO_3-xLn_(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 per-ovskites 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 ofx. 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.