BaWO4:Ce Single Crystals Codoped with Na Ions

Abstract

Single crystals of BaWO4, BaWO4: 0.5 at. % Ce; BaWO4: 1 at. % Ce; BaWO4: 0.5 at. % Ce, 1 at. % Na; and BaWO4: 1 at. % Ce, 2 at. % Na were grown from an inductively heated iridium crucible by the Czochralski method on a Malvern MSR4 puller. They were investigated using Electron Paramagnetic Resonance (EPR) spectroscopy at helium temperatures. One isolated center of high (D2d or S4) symmetry was found and two or more other centers of lower symmetry were identified, depending on crystal doping. From the fitting using the EPR-NMR program, the following parameters of g-matrix for the high symmetry center were found: gx = 1.505, gy = 1.505, and gz = 2.731. The linewidth vs. temperature revealed an increasing exponential tendency with increasing temperature. It showed one phonon at the lower temperatures and a Raman + Orbach effect at the higher temperatures. Radioluminescence and pulse height spectra showed rather poor scintillation properties, without any contribution from cerium emission.

Structural Analysis of the BaWO4 Crystal Doped with Ce and Codoped with Na Ions Based on g-shift Parameters

“…Therefore, the Ce 3+ ion has an effective spin S = ½. This article continues our previous papers related to the investigation of BaWO4 single crystals doped with Ce and codoped with Na [8,9]. Barium tungstate doped and codoped with cerium and sodium (BaWO4: Ce, Na) with different amounts of impurities were investigated by Electron Paramagnetic Resonance (EPR).…”

“…for axial symmetry centers, and , , for lower symmetry centers [8,9]. Therefore, the use of the SPM model is impossible.…”

“…Newman suggested a method to extract structural information from the g-shift parameters [18,20]. In this paper, his method will be applied to results already published in previous articles [8,9,21]. The goal is to find out where the dopant ions are located in the host crystal and the changes in their surroundings.…”

“…The application of different methods may lead to different structural defects in grown crystals and changed optical properties. We decided to codope BaWO 4 : Ce single crystals with Na ions using the Czochralski growth method with inductive heating [8,9]. A deeper understanding of the influence of structural properties of BWO on their luminescent behavior and electro-optical properties is crucial for their applications [10,11].…”

“…Barium tungstate doped and codoped with cerium and sodium (BaWO 4 : Ce, Na) with different amounts of impurities were investigated by Electron Paramagnetic Resonance (EPR). New paramagnetic centers with axial or lower symmetry were detected and spin Hamiltonian parameters were established [8,9]. A few articles about investigations of BWO doped and codoped with different elements were found.…”