Synthesis, structure, and properties of Sr sub 2 CuO sub 2 Cl sub 2

Syntheses of single-crystal specimens and single-phase polycrystalline samples of Sr{sub 2}CuO{sub 2}Cl{sub 2} are reported. Differential-thermal-analysis measurements indicate that this compound melts incongruently at 990 {degree}C in air and at 970 {degree}C in helium. Rietveld refinement of powder neutron diffraction data confirms the body-centered-tetragonal ({ital I}4/{ital mmm}) K{sub 2}NiF{sub 4}-type structure found earlier using x-ray techniques by Grande and Mueller-Buschbaum. The CuO{sub 2} planes are the same as in (tetragonal) La{sub 2}CuO{sub 4}, but the out-of-CuO{sub 2}-plane oxygens in the latter are replaced by Cl. The temperature dependences of the lattice parameters and thermal factors are reported; the tetragonal structure is retained from 300 K down to at least 25 K. Electrical-resistivity measurements exhibit essentially insulating behavior near room temperature, with {rho}{sub {ital ab}}{congruent}3000 {Omega} cm and {rho}{sub {ital c}}{congruent}6.5{times}10{sup 5} {Omega} cm.