Introduction of Copper Ions in the Hexagonal Channels of the Apatite Type La–Sr and La–Ca Silicates

Abstract

AbstractCopper‐containing and copper‐free La–M (M = Sr, Ca) silicates with an apatite‐type structure were prepared by solid state reaction at 1400 °C in air. Samples were studied by powder X‐ray diffraction, electron microscopy with EDX analysis, and magnetic measurements. The crystal structures of the samples were refined by the Rietveld method. Copper was incorporated into the hexagonal channels forming linear O–Cu–O groups with the site occupancies up to 0.37 for M = Sr and 0.31 for M = Ca. The impact of the introduced copper was a substantial increase of the hexagonal channel diameter and a somewhat smaller increase of the lattice parameters. Copper‐containing samples were diamagnetic and not brightly colored in contrast to copper‐doped phosphate apatites.