Grain Growth Behavior of 0.95(Na0.5Bi0.5)TiO3–0.05BaTiO3 Controlled by Grain Shape and Second Phase

Sang-Chae Jeon,Suk-Joong L Kang,Kyoung-Seok Moon,John G Fisher

doi:10.3390/ma13061344

Abstract

The grain growth behavior of 0.95(Na0.5Bi0.5)TiO3 –0.05BaTiO3 (mole fraction, NBT–5BT) grains was investigated with excess Bi2O3 addition. The powder compacts of NBT–5BT were sintered at 1200 °C for various sintering times and with various amounts of Bi2O3 (0.1, 1.5, 4.0 and 10.0 mol%). When Bi2O3 was added to round-edged cubic NBT–5BT, the grain shape changed to a more faceted cube and the amount of liquid phase increased during sintering. A more faceted cubic grain shape indicates an increase in the critical driving force for appreciable growth of grains. However, obvious abnormal grain growth did not appear in any of the NBT–5BT samples with excess Bi2O3. The amount of liquid phase increased as the amount of Bi2O3 increased. Therefore, the rate of grain growth could be decreased by the increasing the distance for the diffusion of atoms. These observations allowed us to conclude that the growth of Bi2O3-excess NBT–5BT grains is governed by the growth of facet planes via the two-dimensional nucleation grain growth mechanism during changing grain shape and amount of liquid.

Highlights

The physical properties of ceramic materials are closely related to the microstructure via grain growth and densification, which depends on the structure, composition, shape of grains, and interfacial structure
When Bi2 O3 was added to round-edged cubic NBT–5BT, the average grain size decreased for 0.1 mol% Bi2 O3 -excess NBT–5BT
Compared with undoped NBT–5BT, but the average grain size increased as the amount of Bi2 O3 increased

Summary

Introduction

The physical properties of ceramic materials are closely related to the microstructure via grain growth and densification, which depends on the structure, composition, shape of grains, and interfacial structure. Physical and chemical properties of materials can be dramatically improved by the development of microstructure via control of grain growth behavior with changing physicochemical properties of the interfaces such as surfaces, liquid/solid interfaces, and grain boundaries [1,2,3,4,5,6]. Studies on microstructural development have reported that interface motion is closely related to the interface structure associated with step free energy, critical driving force for growth, and grain shape [2,3,9,10,11,12,13,14,15,16,17,18,19,20,21]

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