Abstract
Crystalline orthorhombic rare earth carbonate hydroxides Ln [CO 3 ][OH] ( Ln =La, Pr, Nd, Sm, Eu, Gd) were synthesised as phase pure powders via a simple hydrothermal reaction. CO 2 from air acted as natural carbonate source and cetyltrimethylammonium bromide was added as templating agent to an aqueous rare earth nitrate solution. Single-crystal X-ray structure determination was performed on La[CO 3 ][OH] ( Pnma , a =7.4106(5), b =5.0502(3), c =8.5901(6) Å, 563 independent reflections, 38 refined parameters, wR 2=0.037), Pr[CO 3 ][OH] ( Pnma , a =7.2755(4), b =4.9918(3), c =8.5207(5) Å, 744 independent reflections, 38 refined parameters, wR 2=0.04), Eu[CO 3 ][OH] ( Pnma , a =7.1040(4), b =4.8940(3), c =8.4577(5) Å, 1649 independent reflections, 38 refined parameters, wR 2=0.05) and Gd[CO 3 ][OH] ( Pnma , a =7.069(7), b =4.874(5), c =8.464(9) Å, 431 independent reflections, 38 refined parameters, wR 2=0.051). These findings are supported by powder XRD, infrared spectroscopy, UV/Vis spectroscopy and, for Pr[CO 3 ][OH] and Eu[CO 3 ][OH], by measurements of the non-linear optical properties. Thermal analysis could demonstrate the possible use of the Ln [CO 3 ][OH] phases as precursors for rare earth carbonate dioxides Ln 2 [CO 3 ]O 2 and rare earth oxides Ln 2 O 3 . The decomposition products inherit the precursor’s morphology. The lattice parameters of Pr 2 [CO 3 ]O 2 were refined from high-temperature powder XRD data.