Method for producing luminescent particles with a protective layer and luminescent particles having a protective layer

A method for producing phosphor particles with at least one first protective layer, the method comprising:

• providing the phosphor particles;
• and
• applying the at least one first protective layer to a surface of the phosphor particles, wherein the at least one first protective layer comprises:
• depositing a first starting compound by a first atomic layer deposition on the surface of the phosphor particles;
• and
• depositing a second starting compound by a second atomic layer deposition on the surface of the phosphor particles,
• wherein a phosphor of the phosphor particles has the general formula:
• Sr(SraM1−a)Si2Al2(N,X)6:Z,
• wherein Z is selected from the group consisting of D, A, B, E, G, L and combinations thereof,
• wherein M is selected from the group consisting of Ca, Ba, Mg alone and combinations thereof,
• wherein D is selected from one, two or more elements from the group consisting of Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Li, Na, K, Rb, Cs, Tm and Yb,
• wherein A is selected from divalent metals which are different from M and D,
• wherein B=trivalent metals,
• wherein E=monovalent metals,
• wherein G=tetravalent elements,
• wherein L=trivalent elements, and
• wherein X=O or halogen and 0.6≤a<1.