Structural and Dielectric Characteristics of Barium Lanthanum Zinc Niobate

The dielectric properties and microstructural characteristics in solid solutions of Ba_{1− x} La _x Zn_{(1+ x )/3}Nb_{(2− x )/3}]O₃ (BLZN) are investigated by measuring and observing these properties, respectively, by means of transmission electron microscopy and Raman spectroscopy. The 1:1 ordered structure of BLZN can be explained by the random-site model for the distribution of B-site cations. The decrease in the tolerance factor ( t ) by lanthanum substitution causes the tilting of oxygen octahedra. It appears that the onset of antiphase and inphase tilting causes the variation in the temperature coefficient of resonant frequency (τ_f). In the untilted region where t ≥1.01, the τ_f shows a linear increase with decreasing tolerance factor. The region of antiphase tilting, where 0.965≤ t <1.01, causes a rapid decrease in τ_f, including the reverse sign. The τ_f slowly increases, where t <0.965, which is due to the presence of inphase tilting of oxygen octahedra. The τ_f can be predicted by using the tolerance factor, and the near zero of τ_f can be obtained with lanthanum substitution in the solid solution of the BLZN system.