In this work, it has been demonstrated for the first time that CeO2 microcapsules with a unique vase-like morphology can be produced using a facile technique of spraying microdroplets of an aqueous Ce(NO3)3 solution
onto the alkaline solution surface of Na2SO4. It has been shown that layers of these microcapsules can be transferred from the solution surface to the substrate surface in two different ways, and depending on the transfer
method, they can form ordered, oriented arrays on the substrate. A peculiarity of one of these arrays is that in the layer on the substrate surface, almost all of the microcapsules are oriented with the hole in the wall toward the
substrate, while in the other type of array they are oriented in the opposite direction. The structural and chemical characteristics of these microcapsules were investigated using SEM, STEM, HRTEM, EDX, XRD, UV–Vis DR,
Raman and FT-IR spectroscopy. It has been established that the walls of these microcapsules are approximately 50–100 nm thick and consist of CeO2 nanocrystals with a size of 2–5 nm with fcc crystal structure of fluorite. On
the surface of these nanocrystals, there are adsorbed NO3􀀀 and SO42􀀀 anions that can be removed by heating the samples to temperatures of 400 ◦C and 600 ◦C, respectively. The use of a solution containing a mixture of Ce(III)
and Eu(III) nitrates as a reagent in the synthesis process allows for the production of microcapsules whose walls consist of CeO2 nanocrystals that were doped with Eu(III) cations. These microcapsules display photoluminescence bands in the visible range attributed to 5D0–7FJ transitions in europium ions upon λex = 330 nm and 462 nm. It is proposed that this technique for synthesizing microcapsules could be used to produce microcapsules based on CeO2 nanoparticles doped with a wide range of metal cations.