Calcination Syntheses of a Series of Potassium Titanates and Their Morphologic Evolution

In the present study, K 2 Ti 2 O 5 ·0.5H 2 O, K 2 Ti 2 O 5, K 2 Ti 4 O 9, K 2 Ti 6 O 13 (I), and K 2 Ti 6 O 13 (II) were synthesized by calcination from TiO 2 · n H 2 O hydrate at 650, 820, 920, 1080, and 1123 °C, respectively. K 2 Ti 2 O 5 ·0.5H 2 O and K 2 Ti 2 O 5 are composed of grain aggregates and single crystals, respectively. K 2 Ti 4 O 9, K 2 Ti 6 O 13 (I), and K 2 Ti 6 O 13 (II) all have whisker morphology. The K 2 Ti 4 O 9 whiskers and hydrosoluble surface wrappage occurred simultaneously in the K 2 Ti 2 O 5 single crystals at 920 °C during calcination. Subsequently, K 2 Ti 6 O 13 (I) whiskers, coated by more hydrosoluble wrappage generated from both the K 2 Ti 2 O 5 single crystals and the K 2 Ti 4 O 9 whiskers, evolved in the K 2 Ti 4 O 9 whiskers at 1080 °C. K 2 Ti 6 O 13 (I) whiskers converted into K 2 Ti 6 O 13 (II) whiskers through a crystal lattice deformation occurring at 1123 °C. The sinters of K 2 Ti 4 O 9, K 2 Ti 6 O 13 (I), and K 2 Ti 6 O 13 (II) are all composed of the axial-array whisker sheaves.