MICROSTRUCTURE EFFECTS IN SOLID-STATE PHOTOLUMINESCENT PROPERTIES OF LANTHANIDE DOPED CaWO4 SCHEELITE

CARLOS A. LOPEZ; KARAH KNOPE; R. LEE AYSCUE III; GRISELDA E. NARDA; GERMÁN E. GOMEZ; MARÍA R. TORRES DELUIGI

Buenos Aires

Congreso; XIV Reunión Anual de la Asociación Argentina de Cristalografía; 2018

CAC - CNEA

Duringthe last decades, lanthanides ions have been used as components for the development of optically active materials for emergingapplications[1]. Moreover, thesheelite structure has been used as ?host-matrix? for lanthanides withemissions in visible and NIR region [2].Ca1-2xLnxNaxWO4 samples with x = 0and 0.1 and Ln = Eu and Sm, (bulk samples 1and 2) were obtained as crystalline whitepowders applying a mechanothermal method. After that the samples were calcinedat 700 °C obtaining the pure scheelite structure. In order to get nanoparticlesa re-milling was performed. These samples (1NPand 2NP) were used for photoluminescence(PL) studies. TheX-ray powder diffraction (XRPD) characterizations showed a tetragonal symmetry withI41/a (88) space group. Also, the milled samples were refined takingspecial attention in the broadening line. From the Rietveld method, usingFullprof,[3] the line shape was modelledusing the Thompson-Cox-Hastings pseudo-Voigt function. The crystallite size (~18nm) was highly reduced respect to bulk samples. From the PL studies of 1NP and 2NP, the 4G5/2 →6HJ and 5D0 → 7FJ transitions were located respectively.Moreover, the Eu-intrinsic and overall quantum yields (QYEu and QYoverall)for compound 1NP showing values of27.1% and 2.08% respectively, indicating promising emission performance withlow doping values. Besides the quantification of luminescence through thecalculation of the CIE x,y chromaticities was made, exhibiting red and orangeemissions (Figure 1). These result open up the potentialapplications of 1NP and 2NP in the sensing field.