Structure, luminescence and scintillation properties of theMgWO4–MgMoO4 system

Abstract

The importance of luminescent tungstates and molybdates in several technological applicationsmotivated the study of the structural, luminescence and scintillation properties of theMgWO4–MgMoO4 system.X-ray diffraction studies allowed the identification of three main types of structures in the pseudo-binaryMgWO4–MgMoO4 system(sanmartinite β-MgMoO4,cuprosheelite α-MgMoO4, andwolframite MgWO4) and the refinement of the parameters of the crystal lattice. It is found that the single-phase solidsolution MgMo1−xWxO4 with a β-MgMoO4 structure iscreated only at x<0.10, while for a higher tungsten content a mixture of different phases isformed. The x-ray luminescence spectra of a series of samples of theMgWO4–MgMoO4 system aremeasured at T = 8 K. The principal emission bands are assigned to the main structural phases as follows:β-MgMoO4,520 nm; α-MgMoO4,590 nm; MgWO4 (wolframite), 480 nm. The phase composition of the sample determines theactual shape of the observed spectra. Possible relations between the crystalstructure and luminescence properties of different phases are discussed interms of a configuration coordinate model. Of all the compounds under test,MgWO4 is found to have the best scintillation response for particle excitation(0.90 ± 0.15 thatof ZnWO4 at T = 295 K). Further, the light yield also remains high with decreasing temperature, which makesthis material potentially useful for cryogenic applications.