β-ALUMINA-BASED SINTERED BODY

PROBLEM TO BE SOLVED: To obtain a highly moisture-resistant β-alumina-based sintered body improved in durability against moisture and applicable to the various applications such as gas sensor to be exposed in the atmosphere over a long period of time. SOLUTION: In the β-alumina-based sintered body containing an aluminum component, a rare earth element component, a sodium component and at least lithium component or magnesium component, the weight increase in the case when the sintered body is exposed in the atmosphere having >=85% relative humidity for 1,000 hr. is <=12×10-3 kg/m2.