Formation mechanism of barium zirconate nanoparticles under supercritical hydrothermal synthesis

• Published in: Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology 2014-04, Vol.16 (4), p.1-9, Article 2330
• Main Authors: Yoko, Akira, Akizuki, Makoto, Oshima, Yoshito
• Format: Article
• Language: English
• Subjects: Barium; Barium zirconates; Characterization and Evaluation of Materials; Chemical synthesis methods; Chemistry and Materials Science; Coalescence; Coalescing; Continuous flow; Cross-disciplinary physics: materials science; rheology; Defects; Exact sciences and technology; Inorganic Chemistry; Lasers; Materials Science; Methods of nanofabrication; Nanocrystalline materials; Nanoparticles; Nanoscale materials and structures: fabrication and characterization; Nanostructure; Nanotechnology; Optical Devices; Optics; Photonics; Physical Chemistry; Physics; Research Paper; Synthesis; Uptakes; Zirconium
• ISSN: 1388-0764; 1572-896X
• DOI: 10.1007/s11051-014-2330-5

In this study, supercritical hydrothermal synthesis of BaZrO 3 and its formation mechanism during the synthesis were studied using a continuous flow reactor. The Mono-phase, nano-sized BaZrO 3 was successfully synthesized at a temperature of 400 °C and a pressure of 30 MPa using oxy-zirconium nitrate and excess barium hydroxide as the starting materials. The formation mechanism of BaZrO 3 was studied by examining the time dependence of size and composition using XRD, TEM, and ICP. As a result of the time-resolved experiment, the following formation mechanism was revealed. At the first stage of the reaction (~0.1 s), a perovskite structure forms though it has many defects of Ba site. The particle size increases to 20 nm range by coalescence at the middle stage (~1 s) and becomes constant at the last stage (1–10 s). Ba site defects are filled by the uptake of Ba with increasing time until the last stage (~10 s). The elucidated formation mechanism, i.e., the coalescence of nuclei and uptake of Ba, is significant to develop a new methodology for controlling the size and composition of the BaZrO 3 nanoparticles.