Abstract
Plate-like Bi 4 Ti 3 O 12 particles were synthesized using a one-step, molten-salt method from Bi 2 O 3 and TiO 2 nanopowders at 800 °C. The reaction parameters that affect the crystal structure and morphology were identified and systematically investigated. The differences between various Bi 4 Ti 3 O 12 plate-like particles were examined in terms of the ferroelectric-to-paraelectric phase transition and the photocatalytic activity for the degradation of Rhodamine B under UV-A light irradiation. The results encouraged us to conduct further testing of the as-prepared Bi 4 Ti 3 O 12 plate-like particles as templates for the preparation of plate-like SrTiO 3 perovskite particles using a topochemical conversion under hydrothermal conditions. The characteristics of the Bi 4 Ti 3 O 12 plates and the reaction parameters for which the SrTiO 3 preserved the shape of the initial Bi 4 Ti 3 O 12 template particles were determined.
Highlights
Bi4Ti3O12 (BIT) is a member of the Aurivillius-type perovskites that have a layered structure in which pseudo-perovskite (Bi2Ti3O10)2– units are alternating with (Bi2O2)2+ layers
Bi4Ti3O12 was formed in the molten salt by dissolution-precipitation. This means that Bi2O3 and TiO2 firstly dissolved in the molten salt and Bi4Ti3O12 plates precipitated at a high degree of supersaturation
The phase composition and morphology of the Bi4Ti3O12 particles obtained at 800 °C after 2 hours in the first experiment (BIT1) and 20 minutes in the second experiment (BIT2) were examined and compared (Fig. 1, Table 1)
Summary
Bi4Ti3O12 (BIT) is a member of the Aurivillius-type perovskites that have a layered structure in which pseudo-perovskite (Bi2Ti3O10)2– units are alternating with (Bi2O2)2+ layers. As a piezoelectric material with a high Curie temperature of 675 °C, Bi4Ti3O12 has the potential for use in high-temperature piezoelectric applications.[1,2]. In contrast to the thickness, the side length of the plates was not uniform, varying from 0.25 μm to 3 μm The most common synthesis approaches for the preparation of Bi4Ti3O12 ceramics and particles are solid-state, molten-salt, hydrothermal and some other methods with lower reaction temperatures, e.g., coprecipitation and sol-gel.[3,4,5] During the preparation of Bi4Ti3O12 from Bi2O3 and TiO2 in molten salt or by solid-state reaction, secondary phases such as Bi12TiO20 or Bi2Ti2O7 are commonly formed and must be removed from the product prior to further use due to their detrimental effect on the piezoelectric properties of Bi4Ti3O12 ceramics.[6,7,8] Platelike Bi4Ti3O12 particles with a side length of around 1 μm and a thickness of 50 nm were formed in molten NaCl/KCl at 800 °C.9 In contrast to the thickness, the side length of the plates was not uniform, varying from 0.25 μm to 3 μm
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