Rare earth silicate compounds have a high potential for application in environmental thermal barrier coating, as laser diodes and x- and gamma rays scintillators, owing to their chemical, thermal and optical properties. We focus here on the apatite-like Dy4.67(SiO4)3O compound, which has a high melting point and has the potential for applications at a higher temperature compared to standard materials like yttria stabilized zirconia (1400°C) [1]. However, this structure has a partial occupancy of one of dysprosium sites which raises a concern on the slow ordering of dysprosium vacancies which might compromise the long-term stability of the material. In this work we will study the diffuse scattering signal of samples annealed in air at different temperatures in order to establish the long-term stability the local structure of this material.