Microstructure evolution and mechanism during nitridation of carbon-containing internal gelation-derived zirconia. (December 2021)

• Record Type: Journal Article
• Authors: Zhao, Shijiao; Xu, Rui; Ma, Jingtao; Deng, Changsheng; Cheng, Xing; Zhao, Xingyu; Hao, Shaochang; Li, Jianjun
• Is Part Of: Materials today communications. Volume 29(2021)
• Publication Date: 2021-12
• Subjects: Nitridation mechanism -- Microstructure -- Evolution -- Zirconium compounds; Materials science -- Periodicals; 620.11
• DOI: 10.1016/j.mtcomm.2021.102968
• Languages: English
• ISSNs: 2352-4928

Abstract

Abstract: Zirconium nitride is an increasingly attractive material, owning to its wide range of applications. Nitridation with carbon as a reductant is a commonly used process for the preparation of transition metal nitrides. In this study, the nitridation of carbon-containing zirconia gels was studied as a method to synthesize zirconium nitride. The behavior of the gel upon heat treatment was investigated online. The evolution of the microstructure during nitridation was investigated using high-resolution transmission electron microscopy (HRTEM). The relationships between the gaseous species, crystalline phases, microstructure, and chemical elements of the resulting materials were established. The results showed that NH3, CH2 O, CO2, CO, H2 O, and HCN were the gaseous products in the nitridation process. Nucleation of the nanograins started with zirconium oxynitride. Transformation from oxynitride to nitride led to the occurrence of open-mouth-like defects on the particles. The enrichment of N atoms was accompanied by a core-shell structure. Finally, a systematic nitridation mechanism involving five stages was proposed. This study is important for understanding the nitridation process and controlling the structure and properties of transition metal nitrides. Graphical Abstract: ga1 Highlights: A systematic nitridation mechanism of carbon-containing zirconia was proposed. The nitridation mechanism could be divided into five steps. The presence of open mouth-like defects signaled the crystal structure transformation. The core-shell structure was related to the chemical element evolution of zirconium nitride. The removal of O atoms was the rate-controlling factor of the carbothermal nitridation process.