| abstract |
Disclosed is a metal phosphate having high proton conductivity, which is useful for a fuel cell having higher output and produced at lower cost. The proton-conducting metal phosphate is a compound containing M (wherein M represents one or more elements selected from the group consisting of group 4A and group 4B elements of the long form periodic table), P and O, wherein a part of M is substituted with a dopant element J (wherein J represents one or more elements selected from the group consisting of group 3A, group 3B, group 5A and group 5B elements of the long form periodic table and at least contains an element selected from B, Al, Ga, Sc, Yb, Y, La, Ce, Sb, Bi, V, Ta and Nb). |