Synthesis and characterization of possible pigments in the Mg-Yb-S system

The structure-microstructure and color parameters of the Mg1-xYb(2/3)x□(1/3)xS (0≤x≤0.45) (□: cation vacancy) were investigated. The samples present exclusively the NaCl-type average structure up to x=0.35, when a phase with spinel-type structure is observed. Its composition, measured with X-ray energy dispersive spectroscopy (XEDS), corresponds to an intermediate phase between the NaCl-type (MgS) and the normal spinel (MgYb2S4) structures. The selected area electron diffraction patterns (SAEDPs) show diffuse scattering attributed to short-range order (SRO) in the cation sublattice. Extended defects along <1 1 1>NaCl (x=0.30) and along <1 1 1>spinel (x=0.35 and x=0.45) have been observed both in the SAEDPs and in the corresponding high resolution transmission electron microscopy (HRTEM) images. The samples yellow color variation was characterized with reflectance spectra in the visible region. This system has possible applications as inorganic pigments in plastics and paints due to its high color quality