High-temperature, high-pressure hydrothermal synthesis, crystal structure and photoluminescent properties, of K3[Gd1−xTbxGe3O8(OH)2] (x = 0, 0.3, 0.1, 1)

Abstract

A family of 2D-layered lanthanide germanates K₃[Gd_1−xTb_xGe₃O₈(OH)₂] (x = 0, 0.3, 0.1, and 1), have been synthesized by a high-temperature, high-pressure hydrothermal method and characterized by single-crystal X-ray diffraction, photoluminescence, IR spectra, and Energy-Dispersive Spectroscopy (EDS). The X-ray powder diffraction patterns of these compounds reveal that they are isostructural. The single-crystal X-ray diffraction analysis of K₃[GdGe₃O₈(OH)₂] reveals that it is a 2D-layered [LnGe₃O₈(OH)₂]_n³ⁿ⁻ anionic framework which is built up from GeO₄H/GeO₄ tetrahedra and GdO₆ octahedra by sharing vertex O atoms. K⁺ ions locate in the free void space to achieve the charge balance of the framework. A sample containing only Tb³⁺ emits mainly from one transition, ⁵D₄ → ⁷F₅ (552 nm). Mixed lanthanide samples, K₃[Gd_1−xTb_xGe₃O₈(OH)₂] (x = 0.3, and 0.1), have also been prepared and efficient Gd → Tb energy transfer has been observed.