Structure and Dielectric Properties of the Ba(Mg\u3csub\u3e1/3\u3c/sub\u3eNb\u3csub\u3e2/3\u3c/sub\u3e)O\u3csub\u3e3\u3c/sub\u3e–La(Mg\u3csub\u3e2/3\u3c/sub\u3eNb\u3csub\u3e1/3\u3c/sub\u3e)O\u3csub\u3e3\u3c/sub\u3e System

A complete range of perovskite solid solutions can be formed in the (1 - x)Ba(Mg1/3Nb2/3)O3–xLa(Mg2/3Nb1/3)O3 (BMN–LMN) pseudobinary system. While pure BMN adopts a 1:2 cation ordered structure, 1:1 ordered phases are stabilized for 0.05 ≤ x ≤ 1.0. Dark-field TEM images indicate that the La-doped solid solutions are comprised of large 1:1 ordered domains and no evidence was found for a phase-separated structure. This observation coupled with the systematic variations in the intensities of the supercell reflections supports a charge-balanced random-site model for the 1:1 ordering. The substitution of La also induces a transformation from a negative to positive temperature coefficient of capacitance in the region 0.25 ≤ x ≤ 0.5