Blue to UV up-converter comprising lanthanide ions such as Pr3+ activated and optionally Gd3+ co-activated silicates and its application for surface disinfection purposes

A process for the production of a silicate-based material, the process comprising:

• combining the following components i), ii), and iii),
• i) and/or lanthanide oxide,
• wherein a lanthanide ion in the at least one lanthanide salt and/or lanthanide oxide is selected from the group consisting of praseodymium, gadolinium, erbium, and neodymium,
• ii) a silicate, and
• iii) at least one earth alkali salt and at least one alkali salt selected from the group consisting of a lithium salt, a lithium compound, a sodium salt, and a potassium salt,
• wherein the combining comprises:
• a) blending i), ii), and iii) by milling, and obtaining a mixture, or
• b) blending i), ii), and iii) in an organic polar or non-polar solvent that is not a protic solvent, and obtaining a mixture, wherein the obtained mixture of b) is calcinated at 600° C. to 1000° C. to remove organic components, and to obtain a calcinated mixture,
• performing a calcination of the mixture of a) or the calcinated mixture of b) in a calcination at a temperature below a melting temperature of the silicate-based material, wherein at least partial crystallization occurs, and
• performing a further calcination under a reducing atmosphere, wherein the lanthanide ion is reduced to an Ln3+ ion, and
• obtaining the silicate-based material,
• wherein the obtained silicate-based material is milled, and
• wherein the obtained silicate-based material is subjected to tribological impacts at 100 to 500 rotations/min for 1 to 6 hours, using corundum as milling material.