Method for producing ceramic sintered body, ceramic sintered body, and light emitting device

A method for producing a ceramic sintered body, comprising:

• a step of heat-treating a raw material mixture containing:
• a first nitride containing at least one alkaline earth metal element M′ selected from the group consisting of Ba, Sr, Ca, and Mg,
• a second nitride containing at least one metal element M2 selected from the group consisting of Eu, Ce, Tb, and Mn,
• and a third nitride containing Si,
• at a temperature in a range of 980° C. or more and 1,680° C. or less—in an atmosphere containing nitrogen to obtain a nitride fluorescent material having a composition containing:
• the at least one alkaline earth metal element M′ selected from the group consisting of Ba, Sr, Ca, and Mg;
• the at least one metal element M2 selected from the group consisting of Eu, Ce, Tb, and Mn;
• Si;
• and N, wherein a total molar ratio of the alkaline earth metal element M1 and the metal element M2 in 1 mol of the composition is 2, a molar ratio of the metal element M2 is a product of 2 and a parameter y wherein y is in a range of 0.001 or more and less than 0.5, a molar ratio of Si is 5, and a molar ratio of N is 8, and wherein the nitride fluorescent material has a crystallite size, as calculated by X-ray diffraction measurement using the Halder-Wagner method, of 550 Å or less,
• preparing a molded body that contains the nitride fluorescent material and
• calcining the molded body at a temperature in a range of 1,600° C. or more and 2,200° C. or less to obtain a sintered body.