Crystallization and optical properties of CaWO4 and SrWO4

Abstract

Single crystals of calcium tungstate and strontium tungstate have been grown by double decomposition flux reaction technique using lithium chloride as flux. Growth conditions are optimized to synthesize well faceted crystals. Effect of primary and secondary flux density in the growth charge has been studied. Thermogravimetric study reveals that the grown crystals are highly stable in the temperature range 25 -1000°C. Analysis of optical absorption normal to the ab-plane in the spectral range of 200 -800 nm reveals the true absorption edge, the nature of transition being the allowed indirect one at 4.60 eV and 4.56 eV respectively for CaWO 4 and SrWO 4 . The crystals have been characterized by determining useful pertinent optical and dielectric parameters.

First-principles study on electronic states of SrWO4 crystals containing F-type color centers

“…The optical transition energies of CaWO 4 calculated were 1.89 eV and 2.42 eV (related to 660 nm and 515 nm bands), respectively [9], and the experimental 520 nm absorption band was ascribed to F + center. The transmission spectrum of SrWO4 indicates that the crystal has an absorption band peaked at 550 nm [11] just coincides with our calculated 545 nm absorption band of F + center. And the absorption band of F center should lie on the longer wavelength side at 685 nm.…”

Study of the annealing temperature effect on the structural and luminescent properties of SrWO4:Eu phosphors prepared by a non-hydrolytic sol–gel process

“…According to the literature [18,20,21,28,31,[39][40][41], the E gap is associated with intermediary energy levels within the material band gap. Fig.…”

Growth and characterization of large SrMoO4 crystals

“…Usually, when the crystal was doped, the thermal conductivity would decrease because the doped ions would decrease the mean free path of phonons, therefore, the doped crystal would have much lower optical damage threshold and stronger thermal effects during laser operations. Beside above, the doped ions would induce much more difficulties during crystal growth and achieving high-quality crystals [12,18,21,23].…”

“…There are, however, few reports on the single-crystal SrMoO 4 , especially the large dimension and high quality crystals, which are of special interest as SRS active material. As for crystal growing methods, in this research the Czochralski method is used, because this method, compared with other kinds of crystal growth methods, like hydrothermal method [19], flux method and float zone method [20], and flux reaction technique [21], is more direct and intuitive to monitor the process of growth, easier to control the size and diameter of the crystal being-grown, which in all makes it easier to get high optical quality and large dimensions single crystals [22]. The aim of this paper is to report whole procedure of the crystal growth using the Czochralski method, as well as its characteristics: the dimension of the as-grown SrMoO 4 crysal is with a +40 Â 45 mm, and the transmittance of the as-grown crystal is above 80% in the wavelength range of 305-3000 nm, which means it will be a promising Raman laser material.…”