Acentric phase formation in AgLnX, (Ln = Dy, Ho, Er; X = S, Se, Te) compounds

• AgLnX2 compounds for heavy lanthanides crystallize in several structural types depending upon temperature and anion type. • At high temperatures AgLnX2, compounds form the cubic structure with disordered cations. • Phase diagrams are observed for AgHoSe2, and AgDySe2. Wide homogeneity ranges are observed for binary compounds. • Crystal-chemical regularities of acentric phase formation are clear only in general terms. Crystal structures are known only for certain compounds. • Physical properties, including magnetic ones, have been almost not studied.