Facile fabrication of VO2(M) by thermolysis of ammonium metavanadate (NH4VO3) under sealed condition

NH 4 VO 3 is an important vanadium source for the preparation of VO 2 . In the previous studies, the extra gas or solid reagents consumption is necessary for the preparation of VO 2 by using NH 4 VO 3 as vanadium source. The current work proposed a facile way for the fabrication of VO 2 (M) by the thermolysis of NH 4 VO 3 under the sealed atmosphere without extra gas or solid reagents consumption. The VO 2 (M) could be successfully synthesized by two step—thermolysis of NH 4 VO 3 at 400 ​°C under the sealed condition and heat treatment of VO 2 (B) at 500 ​°C under the N 2 condition. The dosage of NH 4 VO 3 and decomposition temperature had significant influences on the thermolysis process under the sealed condition. The NH 3 produced by the thermolysis provided a protective atmosphere that prevented the oxidization of VO 2 (B) by residual O 2 in the sealed reactor. Furthermore, the VO 2 (M) could be prepared directly under the sealed atmosphere by increasing reaction temperature to 700 ​°C. In this process, NH 4 VO 3 underwent a phase transition as the follows: NH 4 VO 3 →ammonium vanadium bronze→VO 2 (B)→VO 2 (M). The directly synthesized VO 2 (M) at 700 ​°C by the thermolysis of NH 4 VO 3 under the sealed condition showed great environmental stability and phase transition performance.