Facile Preparation of SrZr[sub.1-x]Ti[sub.x]O[sub.3] and SrTi[sub.1-x]Zr[sub.x]O[sub.3] Fine Particles Assisted by Dehydration of Zr[sup.4+] and Ti[sup.4+] Gels under Hydrothermal Conditions

In recent decades, perovskite-type compounds (ABB′O[sub.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[sub.3] –SrTiO[sub.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[sub.4] powder ( x > 100.0 mol% Ti[sup.4+] . The XRD results revealed the formation of two crystalline phases rich in Zr[sup.4+] , an orthorhombic structured SrZr[sub.0.93] Ti[sub.0.07] O[sub.3] and a cubic structured SrZr[sub.0.75] Ti[sub.0.25] O[sub.3] within the compositional range of 0.1–0.5 mol of Ti[sup.4+] . A cubic perovskite structured solid solution, SrTi[sub.1-x] Zr[sub.x] O[sub.3] , was preferentially formed within the compositional range of 0.5 > x > 0.1 mol% Ti[sup.4+] . The SrZrO[sub.3] and SrZr[sub.0.93] Ti[sub.0.07] O[sub.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[sup.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.