Fluorination of La<SUB>2</SUB>NiO<SUB>4</SUB> and La<SUB>2</SUB>CuO<SUB>4+&#948;</SUB>

We have carried out fluorination on La<SUB>2</SUB>NiO<SUB>4</SUB> and La<SUB>2</SUB>CuO<SUB>4+δ</SUB>. Only a small fraction of fluorine enters the bulk; the rest resides on the surface. The cuprate after fluorination exhibits greater departures from tetragonal symmetry than the parent material and transforms at ~40 K to the superconducting state. By contrast, the nickelate deviates less from tetragonal symmetry upon fluorination; no superconductivity was observed down to 4.2 K