The synthesis and crystal structures of the first rare-earth alkaline-earth selenite chlorides MNd 10(SeO 3) 12Cl 8 ( M=Ca and Sr)
Two new alkaline-earth Nd selenite chlorides MNd 10(SeO 3) 12Cl 8 ( M=Ca, Sr) were obtained using crystal growth from alkaline-earth chloride melts in quartz tubes. These new compounds crystallize in the orthorhombic system in space group C cca (#68). The compounds were studied by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction. It was shown that both compounds adopt the same structure type, constructed by complex [M 11(SeO 3) 12] 8+ slabs separated by chloride anion layers perpendicular to the longest cell parameter. The SeO 3 groups show a pyramidal shape and may be described as SeO 3E tetrahedra. Such SeO 3 groups decorate the Nd-O skeletons forming the [M 11(SeO 3) 12] 8+ slabs.