Evidence of Phase Transitions in MoO$_{\mathrm{2}}$ single crystals

In this work, physical and structural properties are revisited in the MoO$_{\mathrm{2}}$ compound. MoO$_{\mathrm{2}}$ single crystals were grown by chemical vapor transport. Heat capacity and electrical resistance as a function of temperature were performed using a 9 T cryo-free Physical Properties Measurement System (PPMS). Thermal expansion (TE) was measured using a high-resolution capacitive dilatometer cell constructed from fused quartz. High-resolution Synchrotron x-ray powder diffraction was measured using a Shimazu diffractometer (XRD 6000) at several temperatures in the Brazilian Synchrotron Light Laboratory. Furthermore, Neutron powder diffraction data were collected using the BT-1 32 detector neutron powder diffractometer at the NIST. Electrical resistivity, heat capacity, and TE measurements show two clear features near 220 K and 267 K suggesting two phase transitions in MoO$_{\mathrm{2}}$ compound. The transition at \textasciitilde 267 K has been related to a structural phase transition by high resolution synchrotron x-ray diffratometry measurements. Low temperature neutron diffraction measurements suggest that the phase transition near 220 K is electronic or magnetic in nature.