KCS

Intense green-emission of Y₂(OH)₅NO₃·nH₂O:Tb (LYH:Tb) was induced by ‘antenna effect’ of tungstate anions (WO₄^2-). The adsorption of tungstate anions has been completed within a few minutes on LYH:Tb surface. No shift of ( 0 0 l ) reflections in X-ray diffraction patterns and observed W-O vibration modes from infrared spectra indicated that highly enhanced green-emission of LYH:Tb results from an surface adsorption of tungstate anions instead of ion-exchange process in the interlayer space. Based on photoluminescence (PL) spectra, the luminescence property of LYH:Tb is generally quenched by hydroxyl groups coordinated to Y atoms in the intralayer, while the tungstate adsorbed on the surface of LYH:Tb shows a bright green-emission due to the energy transfer from the oxygen to metal charge transfer (OMCT, O^2- → W⁶⁺) band. Thus, the tungstate groups located on the surface of LYH play a role as light harvesters (such as antenna). These WO₄^2-/LYH:Tb hybrid compounds obtained by simple surface adsorption would have potential applications for various fields, such as optical device, catalyst, and sensor.