Factors Affecting the Formation of Ba 2 Ti 9 O 20
1988; Wiley; Volume: 71; Issue: 10 Linguagem: Inglês
10.1111/j.1151-2916.1988.tb07538.x
ISSN1551-2916
Autores Tópico(s)Ferroelectric and Piezoelectric Materials
ResumoThe phase development sequence based on a composition equivalent to Ba 2 Ti 9 O 20 during heating is found to be in the following order: BaTi 5 O 11 > BaTi 4 O 9 > Ba 2 Ti 9 O 20 . The lowest rate of formation of Ba 2 Ti 9 O 20 is caused by its high surface energy and interface energy, which result in a low nucleation rate. The existence of BaTi 5 O 11 in calcined powder helps to form Ba 2 Ti 9 O 20 in sintered compacts. The effect of BaTi 5 O 11 on Ba 2 Ti 9 O 20 formation can be explained by their similar oxygen packing and by reduced volume change during transformation. The amount of BaTi 5 O 11 formed during heating depends greatly on the compositional homogeneity of powders. The addition of SnO 2 aids the formation of Ba 2 Ti 9 O 20 by reduced strain energy at transformation and reduced surface energy.
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