Nitridophosphate phosphors for solid state lighting and method of production

A method of forming a luminescent nitridophosphate comprising:

• forming a precursor mixture by combining a metal source material, a phosphorus source material, a nitrogen source material, and a dopant source;
• and
• heating the precursor mixture at a maximum temperature between 800° C. and 1300° C. in an atmosphere consisting of nitrogen gas at a pressure between 2 MPa and 300 MPa, or consisting of a mixture of nitrogen gas at a partial pressure between 2 MPa and 300 MPa and an inert gas at a partial pressure between 10 MPa and 200 MPa, wherein the mixture of nitrogen gas and inert gas has an overall pressure between 2 MPa and 500 MPa.