Ceramic sintered body comprising magnesium aluminate spinel

A method of making a ceramic sintered body, the method comprising the steps of:

• a. combining magnesium oxide powder and aluminum oxide powder to make a powder mixture, wherein the powder mixture has a total purity of higher than 99.995%;
• b. calcining the powder mixture by applying heat to raise the temperature of the powder mixture to a temperature of from 600° C. to 1000° C. and maintaining the calcination temperature for a duration of from 4 to 12 hours to form a calcined powder mixture;
• c. disposing the calcined powder mixture inside a volume defined by a tool set of a sintering apparatus and creating vacuum conditions inside the volume;
• d. applying from 5 to 60 MPa of pressure to the calcined powder mixture while heating to a sintering temperature of from 1000 to 1700° C. and performing sintering to form the ceramic sintered body;
• and,
• e. lowering the temperature of the ceramic sintered body, wherein the ceramic sintered body comprises magnesium aluminate spinel of composition MgAl2O4 having from 90 to 100% by volume of a cubic crystallographic structure and a density of from 3.47 to 3.58 g/cc.