Low temperature synthesis of ATiO₃ (A: Mg, Ca, Sr, Ba) by using molten salt

Abstract

Alkaline earth metal titanates ATiO 3 (A: Mg, Ca, Sr, Ba) were prepared from two types of layered potassium titanates [K 2 Ti 2 O 5 and K 0.6 Ti 1.85 O 4 (hereafter, Lss)] by using alkaline earth metal molten salts [ACl 2 + A(NO 3 ) 2 (1:1)]. For A = Ca a single phase of perovskite-type compound was prepared at 600°C by using both starting compounds and the reaction temperature was lower than in 400°C that of the solid state reaction with TiO 2 (anatase) and CaCO 3 . A single phase of perovskite-type SrTiO 3 was obtained at 600 and 700°C for K 2 Ti 2 O 5 and Lss, respectively and these temperatures were much lower than that (1200°C) of the solid state reaction with TiO 2 (anatase) and SrCO 3 . In the case of perovskite-type BaTiO 3 a single phase of perovskite-type compound was prepared at 700°C by using both starting compounds and also this temperature was much lower than that (above 1300°C) of the solid state reaction with TiO 2 (anatase) and BaCO 3 . Although neither K 2 Ti 2 O 5 nor Lss could produce a single phase of ilmenite-type MgTiO 3 , it was prepared by the solid state reaction with TiO 2 (anatase) and magnesium basic carbonate at 900°C. A single phase of ilmenite-type CdTiO 3 was prepared from K 2 Ti 2 O 5 by using cadmium molten salts [CdCl 2 + Cd(NO 3 ) 2 (1:1)] at 500°C. By taking account of the fact that ilmenite-type CdTiO 3 transforms to perovskite-type structure, this preparative method using layered potassium titanates with molten salts preferred to crystallize perovskite-type titanates at lower temperature rather than ilmenite-type ones.

The Emerging Career of Strontium Titanates in Photocatalytic Applications: A Review

“…Interestingly, the nature of the strontium salt used drastically affects the temperature conditions for the calcination. For instance, the study by Kumada et al showed that the use of nitrate precursors drastically reduced the temperature requirements to 600-700 • C, in comparison to the carbonate salt where temperatures as high as 1300 • C were used [24].…”

Texturing of hydrothermally synthesized BaTiO3 in a strong magnetic field by slip casting

“…. [10,18,19,21,[31][32][33][34][35][36][37] In the case of Li-based salt systems mixed phases and even unreacted reagents were found. Hydroxide ions, in a flux for example, were said to be actively participating in the reaction.…”

“…Homogeneous powders with controllable particle size and morphology are one of the advantages of MSS. [18][19][20][21] It is believed that the features obtained by the molten-salt technique are related to the surface and interface energies between the constituents and the salt, resulting in a tendency to minimize the energies by forming a specific morphology. [22] The hydrothermal process is an effective method due to its attractive processing feature of low temperature processing.…”