Phase evolution during conventional and reactive flash sintering of (Mg,Ni,Co,Cu,Zn)O via in situ X-ray diffraction

Author(s)

Yoon, Bola ; Campos, Joao, V ; Lavagnini, Isabela R. ; Avila, Viviana ; Gardner, James M. ; Ghose, Sanjit K. ; Jesus, Lilian M.

• Document type: Journal article
• Source: Journal of the American Ceramic Society; v. 107, n. 2, p. 12-pg., 2023-10-24.

Abstract

Reactive flash sintering (RFS) enables the simultaneous synthesis and sintering of ceramics and has been shown to affect the reaction pathway of different materials. Herein, in situ synchrotron X-ray diffraction (XRD) is used to investigate the (Mg,Ni,Co,Cu,Zn)O entropy-stabilized oxide formation during: (i) conventional heating and (ii) RFS under current rate-controlled mode. The same reaction pathway is verified in both instances: the starting rock-salt (RS), spinel (Co3O4), tenorite (CuO), and wurtzite (ZnO) phases transform into a single RS phase with a (1 1 1) to (2 0 0) intensity ratio of 0.67, consistent with a random distribution of the cations into the structure. Pt lattice peak shift from the XRD patterns is used as standard to monitor the sample surface temperature, revealing a strong endothermic reaction during the RS single-phase formation (Pt peaks shift toward higher angles while increasing sample temperature/current density). In RFS, the single-phase RS structure is formed in just 60 s at a furnace temperature of 600 degrees C and a current rate of 220 mA mm-2/min. Therefore, RFS greatly accelerates the synthesis of (Mg,Ni,Co,Cu,Zn)O, however, it does not play a role in the reaction pathway for this material formation. (AU)

• FAPESP's process: 18/19370-6 - Electric-Field Assisted Processing of Electroceramics: (micro)structural characteristics and dielectric properties
• Grantee: Lilian Menezes de Jesus
• Support Opportunities: Scholarships abroad - Research
• FAPESP's process: 21/06509-9 - Ionic conductor glass-ceramics sintering with concurrent crystallisation using flash sintering
• Grantee: João Vitor Campos
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 19/03786-1 - Instrumentation and automation of a tube furnace adapted to flash sintering
• Grantee: João Vitor Campos
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)