SOLID ION CONDUCTOR, SOLID ELECTROLYTE AND ELECTROCHEMICAL CELL COMPRISING THE SAME, AND METHOD OF PREPARING THE SOLID ION CONDUCTOR

A solid ion conductor, a solid electrolyte and electrochemical device including the same, and a method of preparing the solid ion conductor are disclosed. The solid ion conductor includes a compound represented by Formula 1: LiMM′XO Formula 1 wherein, in Formula 1, M is one or more metals selected from Lu, Ho, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, Yb, Ga, In, Ce, Pr, Ti, Zr, or Hf, each having an oxidation number of +3 or +4, M′ is one or more metals selected from Na, K, Cs, Cu, or Ag, each having an oxidation number of +1, X is one or more halogens, 0