SYNTHESIS AND CHARACTERIZATION OF LnHPO₄(NO₃)·3H₂O (Ln=Er-Lu), A NEW FAMILY OF PHOSPHATE-NITRATES

Abstract

LnHPO₄(NO₃)·3H₂O (Ln=Er-Lu) have been synthesized by reactions of corresponding Ln₂O₃with H₃PO₄ in presence of HNO₃. The compounds have been identified by chemical analysis, thin-layer chromatography, and IR spectroscopy. It was found by XRD studies of powder samples that the obtained compounds are isotypical having orthorhombic unit cell dimensions (Z=4): ErHPO₄(NO₃)·3H₂O (a=10.157 (2), b=11.913 (2), c=6.858 (3) Å), TmHPO₄(NO₃)·3H₂O (a=10.154 (2), b=11.882 (2), c=6.830 (2) Å), YbHPO₄(NO₃)·3H₂O (a=10.149 (2), b=11.843 (2), c=6.794 (1) Å), and LuHPO₄(NO₃)·3H₂O(a=10.146 (2),b=11.827 (2), c=6.786 (2) Å). Thermal decomposition of these compounds has been investigated in the 20-1000°C range.