Complex thermal evolution of V2O5 and MoO3 cell parameters in the range 15<T (K)<900

Cell parameter evolution versus temperature has been established for both V2O5 and MoO3, from 15 to 953 and 893 K, respectively. Both oxides preserve their orthorhombic crystal system and their respective space groups Pmmn and Pnma in the whole temperature range. Unusual evolution of the unit cells have been detected in these oxides and proposals are made to follow them based on detailed structural analysis. Three temperature domains have been evidenced for V2O5 marked by breaks at RT and 800 K; for MoO3, only two domains are defined below and above 400 K. For each domain the quality of cell parameters and X-ray powder pattern indexing, have been checked by mathematical functions to buttress their coherent evolution within each temperature domain.