Thermal stability studies of ion beam sputter deposited C/B4C X-ray multilayer mirror

► We reported the experimental results on thermal stability of C/B4C combination. ► Multilayer structure is stable even after 700 °C annealing. ► C/B4C can be used as a stable multilayer mirror both in soft and hard X-ray regions. ► C/B4C multilayer structure has shown good temporal stability.