Synthesis of Hydrated Ternary Lanthanide-Containing Chlorides Exhibiting X-ray Scintillation and Luminescence

A series of new ternary lanthanide-based chlorides, Cs₂EuCl₅(H₂O)₁₀, Cs₇LnCl₁₀(H₂O)₈ (Ln = Gd or Ho), Cs₁₀Tb₂Cl₁₇(H₂O)₁₄(H₃O), Cs₂DyCl₅(H₂O)₆, Cs₈Er₃Cl₁₇(H₂O)₂₅, and Cs₅Ln₂Cl₁₁(H₂O)₁₇ (Ln = Y, Lu, or Yb), were prepared as single crystals via a facile solution route. The compounds with compositions of Cs₇LnCl₁₀(H₂O)₈ (Ln = Gd or Ho) and Cs₅Ln₂Cl₁₁(H₂O)₁₇ (Ln = Y, Lu, or Yb) crystallize in a monoclinic crystal system in space groups C2 and P2₁/c, respectively, whereas Cs₂EuCl₅(H₂O)₁₀, Cs₁₀Tb₂Cl₁₇(H₂O)₁₄(H₃O), and Cs₈Er₃Cl₁₇(H₂O)₂₅ crystallize in orthorhombic space groups Pbcm, Pnma, and P2₁2₁2₁, respectively. Cs₂DyCl₅(H₂O)₆ crystallizes with triclinic symmetry in space group P1̅. All of these compounds exhibit complex three-dimensional structures built of isolated lanthanide polyhedral units that are linked together by extensive hydrogen bonds. Cs₂EuCl₅(H₂O)₁₀ and Cs₁₀Tb₂Cl₁₇(H₂O)₁₄(H₃O) luminesce upon irradiation with 375 nm ultraviolet light, emitting intense orange-red and green color, respectively, and Cs₁₀Tb₂Cl₁₇(H₂O)₁₄(H₃O) scintillates when exposed to X-rays. Radioluminescence (RL) measurement of Cs₁₀Tb₂Cl₁₇(H₂O)₁₄(H₃O) in powder form shows that the RL emission integrated in the range of 300-750 nm was ∼16% of BGO powder.