SYNTHESIS AND SOME PHYSICAL-PROPERTIES OF A NEW SERIES OF LAYERED SELENIDES (LNO)CUSE (LN=LANTHANIDES)

A new series of layered selenides (LnO)CuSe (Ln = La, Ce, Nd, Sm, Gd, Th, Dy, Ho, Y) with (LaO)AgS-type structure was prepared. All the compounds were semiconductors. Magnetic susceptibility measurements revealed that the lanthanide ions are in the trivalent state and the values of Weiss temperature theta lie within +/- 15 K for all the compounds. The preparation and the electrical resistivity of (LaO)Cu(S1-xSex) (0 less-than-or-equal-to x less-than-or-equal-to s1) and (La1-xSrx)OCuSe (0 less-than-or-equal-to x less-than-or-equal-to 0.2) systems are also reported.