FLUORINATION OF THE RUDDLESDEN-POPPER TYPE CUPRATES, LN(2-X)A(1-Y) (LN = LA, ND, A = CA, SR)(X)CU(2)O(6)

The low-temperature (200-350 degrees C) fluorination of the Ruddlesden -Popper type cuprates, Ln(2-x)A(1+x)Cu(2)O(6-y) (Ln = La, Nd; A = Ca, Sr) using F-2 gas, CuF2, and NH4F is reported. The incorporation of la rge levels of fluoride ions is observed for each of these fluorinating agents. The general characteristics of each method are discussed, and it is shown that for this system, fluorination mainly occurs by inser tion of fluorine for reaction with F-2, substitution of fluorine for o xygen for NH4F, and a mixture of the two processes for CuF2. For A = S r, it is assumed that fluorine inserts mainly between the two CuO2 lay ers, since large expansions of the unit cell along the c direction an observed. No evidence for bulk superconductivity has so far been obser ved after fluorination.