On the formation mechanism of Ba0.85Ca0.15Zr0.1Ti0.9O3 thin films by aqueous chemical solution deposition

Tailoring Preferential Orientation in BaTiO3‐based Thin Films from Aqueous Chemical Solution Deposition

“…Then a final annealing step for crystallization should be carried out with a high heating rate (3–20 °C s −1 and a final annealing temperature in Region 2, where for the BaTiO 3 films this means T max >650 °C for improved crystallinity. The same increase in crystallinity with higher annealing temperature in Region 2 was also reported in BCZT films based on the same aqueous precursor solutions [17] …”

“…The preparation of the aqueous precursor solution has been reported previously [13–14,17] . Separate Ba‐, Ca‐, Zr‐ and Ti‐complex solutions were prepared and then mixed in stochiometric ratios to make final BaTiO 3 , Ba 0.92 Ca 0.08 TiO 3 (BCT) and Ba 0.85 Ca 0.15 Zr 0.1 Ti 0.9 O 3 (BCZT) precursor solutions with concentrations of 0.26 m , 0.25 m and 0.23 m respectively.…”

“…Based on this work, Khomyakova et al. recently developed a CSD synthesis for polycrystalline BCZT thin films [17] …”

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. The formation of the intermediate oxycarbonate phase has been linked to the presence of a “carbonate-like” linkage in the barium carboxylates or to the formation of a mixed metal citric acid complex in the precursor solution. − …”