Abnormal Grain Growth in Barium Titanate Doped with Alumina

Abstract

The effect of additions of ≤1 mol% Al2O3 on abnormal grain growth in BaTiO3 sintered for periods of ≤60 min at 1350°C has been studied. Addition of ≤0.2 mol% Al2O3 caused an increase in the nucleation and growth rates of abnormal grains, with further additions causing a decrease. This behavior is explained by interface‐controlled growth. Dopant adsorption reduces both the edge free energy and the step velocity of a grain, causing the nucleation and growth rates of abnormal grains to increase, pass through a maximum, and then decrease with increasing dopant concentration.

Effect of TiO2 addition on grain shape and grain coarsening behavior in 95Na1/2Bi1/2TiO3–5BaTiO3

“…8,23,25 Fig. 3 shows TEM micrographs of undoped (0T), 0.7 mol% TiO 2 -doped (0.7T), and 1.5 mol% TiO 2 -doped NBT-5BT (1.5T) samples sintered at 1200 • C for 1 h. As the crystal structure of NBT-5BT is pseudo-cubic (rhombohedral with a = b = c = 3.8864Å and α = β = γ = 89.2 • ), 28,29 the selected area diffraction patterns in the insets of the figure indicate that the crystallographic planes of the three different grains have (0 0 1) orientation.…”

“…Some experimental studies have shown that the grain coarsening behavior was abnormal and normal for faceted and rounded grains, respectively, in the same system by changing temperature, 14,24 adding dopants, 7,8,11,17,25 or varying oxygen partial pressure. 8,26,27 Cho et al 14 studied the effect of temperature on grain shape and grain coarsening behavior in the NbC-Co system.…”

Microstructural changes in (K0.5Na0.5)NbO3 ceramics sintered in various atmospheres

“…This may be due to the broader grain size distribution of these samples, as in the case of BaTiO 3 doped with Al 2 O 3 . 43 In a sample with a bimodal grain distribution,r may be determined by the grains in the first peak, as these are dissolving. 44 The grains in the second peak then may have a large enough driving force to continue growing.…”

Structures and microwave dielectric properties of Ca(1−x)Nd2x/3TiO3 ceramics

“…This has been observed in several systems including BaTiO 3 24 Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 , 25 and columbite structured ceramics. 26 Fisher et al 24 suggested that the development of very large grains was encouraged by the faceting of interfaces between adjacent grains, and that the presence of a liquid phase would reduce the critical driving force required for abnormal grain growth.…”