Abstract
In the present work, we investigate the structural, microstructural, vibrational and luminescence properties of the system (1−x)CaWO4−xCdWO4 with x ranging between 0 and 1. Polycrystalline samples were elaborated using a coprecipitation technique followed by thermal treatment at 1000°C. The samples were then characterized using X-ray diffraction, scanning electron microscopy, Raman spectroscopy and luminescence analyses. X-ray diffraction profile analyses using Rietveld method showed that two kinds of solid solutions Ca1−xCdxWO4 having scheelite and wolframite structures, with respectively tetragonal and monoclinic crystal cells, were observed, with a biphasic system for compositions x=0.6 and 0.7. The scanning electron microscopy experiments showed a complex evolution of morphologies and crystallite sizes as x increased. The vibration modes of Raman spectra were characteristic of composition-dependent disordered solid solutions with decreasing wavenumbers as x increased. Luminescence experiments were performed under UV-laser light irradiation. The energies of emission bands increased linearly with cadmium composition x. The integrated intensity of luminescence reached a maximum value for the substituted wolframite phase with composition x=0.8.
Highlights
Ca and Cd ions form CaO8 and CdO6 polyhedra, respectively in the tetragonal and monoclinic structures
X-ray diffraction patterns showed a strong evolution in the phase system as cadmium atom fraction increases
We have synthesized two types of solid solutions Ca1ÀxCdxWO4 having scheelite and wolframite structures and a two-phase system from a coprecipitation method followed by thermal treatment at 1000 1C
Summary
Ca and Cd ions form CaO8 and CdO6 polyhedra, respectively in the tetragonal and monoclinic structures. In other terms, [CaO8–WO4] and [CdO6–WO6] structural groups characterize the tetragonal and monoclinic phases, respectively. We investigate the structures and microstructures, the vibrational Raman spectra and the luminescence properties of this (1À x)CaWO4À xCdWO4 mix system. The phase diagram was partly determined in previous works [19]. As very few investigations on these solid solutions are available in the literature, we investigate a specific isotherm of the phase diagram by synthesizing various phases at 1000 1C. We attach particular importance to the study of the luminescence under UV excitation of this series of materials, with x varying between 0 and 1
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
