[Springer Proceedings in Physics] Nanophotonics, Nanooptics, Nanobiotechnology, and Their Applications Volume 222 (Selected Proceedings of the 6th International Conference Nanotechnology and Nanomaterials (NANO2018), August 27-30, 2018, Kyiv, Ukraine) || Synthesis, Morphology, Structure, and Luminescence Properties of Bi-Containing Phosphates: Review and Detailed Consideration on the Example of Pr3+-doped BiPO4 Nanopowders