Phase transformation of molybdenum trioxide to molybdenum dioxide: An in-situ transmission electron microscopy investigation

We use in-situ environmental transmission electron microscopy (ETEM) to investigate the phase transformation of α-MoO3 in vacuum. In-situ selected area electron diffraction (SAED) indicates that α-MoO3 directly transfers to monoclinic MoO2 without intermediate phase; however, high resolution transmission electron microscopy (HRTEM) study reveals that Mo4O11 precipitates on the surface of MoO2 matrix. Judging from the size of Mo4O11 and its orientation relationship with MoO2, we believe that the formation of Mo4O11 is due to the reaction between MoO2 and the untransformed MoO3.