Syntheses, Structure, and Selected Physical Properties of CsLnMnSe ₃ (Ln = Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y) and AYbZnQ₃ (A = Rb, Cs; Q = S, Se, Te)

CsLnMnSe₃ (Ln = Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y) and AYbZnQ₃ (A = Rb, Cs; Q = S, Se, Te) have been synthesized from solid-state reactions at temperatures in excess 1173 K. These isostructural materials crystallize in the layered KZrCuS₃ structure type in the orthorhombic space group Cmcm. The structure is composed of LnQ₆ octahedra and MQ₄ tetrahedra that share edges to form ²_∞[LnMQ₃] layers. These layers stack perpendicular to [010] and are separated by layers of face- and edge-sharing AQ₈ bicapped trigonal prisms. There are no Q-Q bonds in the structure of the ALnMQ₃ compounds so the formal oxidation states of A/Ln/M/Q are 1+/3+/2+/2-. The CsLnMnSe₃ materials, with the exception of CsYbMnSe₃, are Curie-Weiss paramagnets between 5 and 300 K. The magnetic susceptibility data for CsYbZnS₃, RbYbZnSe ₃, and CsYbMSe₃ (M = Mn, Zn) show a weak cusp at approximately 10 K and pronounced differences between field-cooled and zero-field-cooled data. However, CsYbZnSe₃ is not an antiferromagnet because a neutron diffraction study indicates that CsYbZnSe₃ shows neither long-range magnetic ordering nor a phase change between 4 and 295 K. Nor is the compound a spin glass because the transition at 10 K does not depend on ac frequency. The optical band gaps of the (010) and (001) crystal faces for CsYbMnSe₃ are 1,60 and 1.59 eV, respectively; the optical band of the (010) crystal faces for CsYbZnS₃ and RbYbZnSe₃ are 2,61 and 2,07 eV, respectively.