may contain at least one metal ion as a dopant these ions incorporated in the base ceramic are ba sr ti yb la and na the starter materials used can be the oxides or carbonates of baco 3 sro tio 2 yb 2 o 3 la 2 o 3 and naco 3 which contain the dopants the mole percentage of one particular dopant added into the base ceramic does not exceed 5 mole percent as shown in fig1 and 3 and table 1 it is found that it may be difficult to maintain the temperature stability and the pseudo cubic crystal structure of the solid solutions if more than 5 mole of the dopant is added the composite of this invention can be manufactured by mixing lead ii oxide pbo indium iii oxide in 2 o 3 magnesium ii oxide mgo according to the above stoichiometric ration and then calcinated at above 800 u00b0 c preferably at about 800 u00b0 c to 900 u00b0 c for about two to four hours and then sintered at above 1000 u00b0 c preferably about 1050 u00b0 c to 1250 u00b0 c for about one to two hours if dopants are required to present in the composite the dopants may be added in the oxide form of baco 3 sro tio 2 yb 2 o 3 la 2 o 3 and naco 3 before calcinations in the ceramics doped with 2.