SOLID ELECTROLYTE, SOLID ELECTROLYTE LAYER AND SOLID ELECTROLYTE BATTERY

A solid electrolyte includes a compound composed of an alkali metal, at least one metal element selected from Zr, Hf, Ti, Sn, Mg, Ca, Sr, Cs, Ba, Y, Al, Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Cu, Ag, Au, Pb, Bi, In, Sn, Sb, Nb, Ta and W and an element belonging to Group XVII of the periodic table.