Blue to UV Up-Converter Comprising Lanthanide Ions such as Pr3+ Activated Garnet and its Application for Surface Disinfection Purposes

A garnet is doped with a lanthanide ion selected from praseodymium, gadolinium, erbium, and neodymium. For co-doping, at least two of the lanthanide ions are selected. The lanthanide ion doped garnet converts electromagnetic radiation energy of a longer wavelength of below 530 nm to electromagnetic radiation energy of shorter wavelengths in the range of 220 to 425 nm. The garnet is crystalline and is obtainable from a mixture of salts or oxides of the components, in the presence of a chelating agent, that are dissolved in acid. This is followed by a specific calcination process to produce the garnet and, optionally, to adjust particle size and increase the crystallinity of the particles. The garnet can be used to inactivate microorganisms or cells covering a surface containing silicate-based material under exposure of electromagnetic radiation energy of a longer wavelength of below 500 nm.