Facile Preparation of SrZr(1-x)Ti(x)O(3) and SrTi(1-x)Zr(x)O(3) Fine Particles Assisted by Dehydration of Zr(4+) and Ti(4+) Gels under Hydrothermal Conditions

In recent decades, perovskite-type compounds (ABB′O(3)) have been exhaustively studied due to their unique ferroelectric properties. In this work, a systematic study aiming to prepare fine particles in the binary system SrZrO(3)–SrTiO(3) was conducted under hydrothermal conditions in a KOH (5 M) solution at 200 °C for 4 h under a constant stirring speed of 130 rpm. The precursors employed were SrSO(4) powder (<38 μm size) and coprecipitated hydrous gels of Zr(OH)(4)•9.64 H(2)O (Zr-gel) and Ti(OH)(4)•4.5H(2)O (Ti-gel), which were mixed according to the stoichiometry of the SrZr(1-x)Ti(x)O(3) in the compositional range of 0.0 > x > 100.0 mol% Ti(4+). The XRD results revealed the formation of two crystalline phases rich in Zr(4+), an orthorhombic structured SrZr(0.93)Ti(0.07)O(3) and a cubic structured SrZr(0.75)Ti(0.25)O(3) within the compositional range of 0.1–0.5 mol of Ti(4+). A cubic perovskite structured solid solution, SrTi(1-x)Zr(x)O(3), was preferentially formed within the compositional range of 0.5 > x > 0.1 mol% Ti(4+). The SrZrO(3) and SrZr(0.93)Ti(0.07)O(3)-rich phases had particle sizes averaging 3 μm with a cubic morphology. However, a remarkable reduction in the particle size occurred on solid solutions prepared with hydrous Ti-gel over contents of 15 mol% Ti(4+) in the reaction media, resulting in the formation of nanosized particle agglomerates with a cuboidal shape self-assembled via a 3D hierarchical architecture, and the sizes of these particles varied in the range between 141.0 and 175.5 nm. The limited coarsening of the particles is discussed based on the Zr-gel and Ti-gel dehydration capability differences that occurred under hydrothermal processing.