Complex oxide ceramic sintered body and solid-electrolyte fuel cell comprising the same

Abstract

A complex oxide ceramic sintered body has a perovskite-type crystal structure and is represented by a general formula: (La,Sr,),(Cr,Al,Co,),O,, where x+z≧0.06; z≧0.02; x+y+3z≦0.25; 2x+3y+5z≧0.40; x+y≧0.12; and 1.00≦b/a≦1.04. The sintered body has a relative density of about 94% or more and the bending strength of about 15 kgf/mm,or more both at room temperature and at room temperature after the sintered compact is treated for 24 hours in an atmosphere of humidified hydrogen having an oxygen partial pressure of 10,atm at 1,000° C. The sintered body further has a lattice volumetric expansion coefficient of about 0.3% or less at room temperature after treated for 24 hours in an atmosphere of humidified hydrogen having an oxygen partial pressure of 10,atm at 1,000° C., an average thermal expansion coefficient in a range of about 9.8 to 11.0×10,K,at 30 to 1,000° C., and a phase transition temperature, from a rhombic system to a rhombohedral system, of about −20° C. or less.