Role of an intermediate phase (Ba,Sr)2Ti2O5CO3 in doped (Ba0.7Sr0.3)TiO3 thin films

Structures and Role of the Intermediate Phases on the Crystallization of BaTiO3 from an Aqueous Synthesis Route

“…Stabilization of the calcite modification of BaCO 3 has been reported in mixed alkaline earth carbonates or by quenching . Intermediate carbonates with the calcite structure are also reported in YBa 2 Cu 3 O 7– x , Ba 1– x SrTiO 3 , and Ba 1– x Ca x Zr y Ti 1– y O 3 systems. Controlling the carbonate formation was reported to be crucial for phase purity in Ba 0.85 Ca .15 Zr 0.1 Ti 0.9 O 3 thin films .…”

“…Wet chemical synthesis studies of BaTiO 3 -based powders and thin films generally report BaCO 3 compounds as intermediate and secondary phases. , Using sol–gel-related methods based on organic solvents, the precursors tend to decompose to form aragonite-type carbonate (BaCO 3 (A)) and TiO 2 , where BaTiO 3 nucleates through the solid-state reactions of these above 600 °C. − However, in Pechini-based synthesis methods and from aqueous processing, a so-called oxycarbonate phase with the global proposed stoichiometry Ba 2 Ti 2 O 5 CO 3 is observed. − Recently, aqueous chemical solution deposition (CSD) synthesis routes for BaTiO 3 -based thin films have been reported, − where this intermediate oxycarbonate phase was observed to form prior to the perovskite, dependent on the thermal processing. The pyrolysis reactions and the formation of the oxycarbonate were reported to play an integral part in the texture formation, phase purity, and quality of the films. , The oxycarbonate seems to inhibit the formation of BaCO 3 (A) and therefore also shifts the BaTiO 3 formation from the solid - state reaction of TiO 2 and BaCO 3 (A) to proceed through decomposition of the oxycarbonate.…”

Low-temperature synthesis of superfine barium strontium titanate powder by the citrate method

“…It has been reported that the formation of BST at low temperatures can be realized via a thermal decomposition of the intermediate phase BSTOC, as described by the following equation [13,15]:…”