High-temperature instability of Li- and Ta-modified (K,Na)NbO(3) piezoceramics

作者：Wang Yongli^*; Damjanovic Dragan; Klein Naama; Setter Nava

来源：Journal of the American Ceramic Society, 2008, 91(6): 1962-1970.

DOI：10.1111/j.1551-2916.2008.02392.x

This paper addresses the high-temperature instability of Li- and Ta-modified (K,Na)NbO(3) piezoeeramics. The grains with abnormal size evolve out of the fine matrix grains during high-temperature annealing. They are found to be precipitates with a tetragonal tungsten bronze structure, which result from the volatilization and segregation of the alkali metal elements. With the growth of the abnormal grains the composition of the perovskite matrix phase also changes remarkably, as has been suggested by EDX analysis (for Na) and electric measurements (for Li). These variations lead to a large increase in the tetragonal/orthorhombic phase transition temperature and appreciable variations in the dielectric, ferroelectric, and piezoelectric properties of the ceramic samples. Control of the volatilization of the alkali metal elements can efficiently depress the abnormal grain growth and the compositional segregation.

• 出版日期2008-6