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.