Controllable synthesis of beta-Mn2V2O7 microtubes and hollow microspheres

β-Mn₂V₂O₇ microtubes with the range of 15-25 μm in length, 2.5-3.5 μm in external diameter, and ca 0.4 μm of the wall in thickness, as well as β-Mn₂V₂O₇ hollow microspheres with an average outer diameter of 2 μm were successfully synthesized in a suitable molar ratio of NH₄VO₃ and MnCO₃ powders via a hydrothermal process. XRD and FESEM were used to characterize the products, and the magnetic susceptibility curve was also measured. In the whole process, the concentration of Mn²⁺ cations derived from MnCO₃ dissolution plays a crucial role in the formation of β-Mn₂V₂O₇ microtubes and hollow microspheres.