Structural and dielectric characteristics of barium lanthanum zinc niobate

The dielectric properties and microstructural characteristics in solid solutions of Ba _1-xLa _x[Zn _(1+x)/3Nb _(2-x)/3]O ₃ (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.