X-Ray Study on the Binding Properties of Cu₂O and Ag₂O Crystals

Abstract

Crystallographical properties of the chemically prepared powder samples of Ag₂O and Cu₂O were investigated by an X-ray diffractometer, in relation to their bonding characters. The lattice constant is 4.720±0.004A for Ag₂O and 4.268±0.001A for Cu₂O. The thermal expansion coefficient of the lattice is 1.9×10⁻⁶ for Cu₂O. The root-mean-square amplitude of the thermal lattice vibration is determined as 0.26A for Cu₂O and 0.40A for Ag₂O at room temperature. The mean lattice strain is 1.4% for Ag₂O and 0.15% for Cu₂O, respectively. The thermal decomposition of Ag₂O was also observed. The obtained results suggest that the binding force between metallic and oxygen atoms is much weaker in Ag₂O than in Cu₂O, which can not be expected from the purely ionic model for the present crystals.