Influences of Ar Flow-Rate and Sublimation Temperature on the Sublimation Product of Analytical Reagent MoO3

In this work, the influences of the Ar flow-rate and sublimation temperature on the phase composition and morphological structure of the sublimation products of analytical reagent MoO3are investigated. The results show that the sublimation products are always composed of thermodynamically stable orthorhombic molybdenum trioxide (α-MoO3) and metastable monoclinic molybdenum trioxide (β-MoO3) under different reaction conditions, among which the proportion of β-MoO3gradually increases with the increase in Ar flow-rate and the decrease in sublimation temperature. The formation temperature of α-MoO3is mainly between 780 K and 847 K, with the particles exhibiting an obvious sheet-like morphology. This work also finds that β-MoO3is mainly generated below 500 K; however, due to the co-actions of the deposition of gaseous MoO3molecules, the adsorption of Ar molecules, and the collision effect between the different particles, the newly formed β-MoO3is more inclined to take a spherical-shaped morphology in order to maintain its lowest energy state.