Unraveling the Charge State of Oxygen Vacancies in Monoclinic ZrO₂ and Spectroscopic Properties of ZrO₂:Sm³⁺ Phosphor

Abstract

Ion beam analysis methods are very sensitive to analyze the defects and impurities in insulators and semiconductors. The present study focuses on an investigation of the nature of defects in monoclinic ZrO 2 and spectroscopic properties of ZrO 2 :Sm 3+ (1 mol %) phosphor using ionoluminescence (IL) under the excitation of 100 MeV Si 7+ ions. The structures of the combustion-synthesized ZrO 2 and ZrO 2 :Sm 3+ samples were revealed to be monoclinic as analyzed through X-ray diffraction, Raman spectroscopy, and selected area electron diffraction methods. Structural parameters were assessed utilizing Rietveld refinement of the obtained XRD data using GSAS II software. The average particle size of ZrO 2 and ZrO 2 :Sm 3+ samples was found to be 77 ± 2 and 72 ± 3 nm, respectively, as determined from transmission electron microscopy images. The electronic structure and the oxygen vacancy defect population were analyzed using experimental measurements [viz ionoluminescence (IL), photoluminescence (PL), PL lifetime decay, electron paramagnetic resonance (EPR), and diffuse reflectance spectroscopy (DRS)]. The prominent IL and PL emission peaks seen at 499 nm in monoclinic ZrO 2 are attributed to the F + type center that was assigned to the F 2 + centeran aggregate of the singly ionized oxygen vacancies. ZrO 2 :Sm 3+ (1 mol %) samples display Sm 3+ characteristic IL emission peaks between 562−582, 600−620, 635−673, and 719 nm, corresponding to ( 4 G 5/2 → 6 H 5/2 ), ( 4 G 5/2 → 6 H 7/2 ), ( 4 G 5/2 → 6 H 9/2 ), and ( 4 G 5/2 → 6 H 11/2 ) transitions under 100 MeV Si 7+ ion excitation for various fluences. The 100 MeV Si 7+ ion-induced ion track radius (damaged cross section) and local temperature were estimated through the thermal spike model to be 0.53 nm and 700 K (the duration is about 10 −13 second), respectively. CIE coordinates fall near the yellow color region and then slightly shift toward the green color region with an increase of fluence because of the lattice distortion and change of the Sm 3+ symmetry site.

Bright and Stable Luminescence of CsPbX3 Nanocrystals in ZrO2 Skeletons for White Light Emitting Diodes

“…In comparison, the other sharp peak around 476.6 cm −1 occurs in both tetragonal and monoclinic phases. 25,34 These results demonstrate that ZrO 2 is a compound with t-ZrO 2 and m-ZrO 2 coexisting, which is consistent with the XRD results. Figure S2 (see Supporting Information) shows the crystallize phase that is well matched with the PDF standard card, demonstrating successful preparation of cubic phase CsPbBr 3 NCs.…”

“…The Raman spectrum of ZrO 2 consists of two strong peaks centered at 147.6 and 268.3 cm –1 , which are mainly the t-ZrO 2 . In comparison, the other sharp peak around 476.6 cm –1 occurs in both tetragonal and monoclinic phases. , These results demonstrate that ZrO 2 is a compound with t-ZrO 2 and m-ZrO 2 coexisting, which is consistent with the XRD results.…”

“…23 In addition, zirconia is promising matrix material for optical devices due to a series of advantages such as low phonon energy, high thermal and chemical stability, and wide band gap. 25 ZrO 2 was also applied as a coating material of perovskite NCs or for forming heterostructures to improve the stability and PL properties. For example, Liu et al acquired the type I and II heterojunctions by modulating the halogen components in CsPbX 3 /ZrO 2 Janus nanoparticles.…”

Highly Efficient Hydrosilylation of Ethyne over Pt/ZrO2 Catalysts with Size-Dependent Metal–Support Interactions

“…53 The other signal at g = 1.973 is assigned to Zr 3+ ions located at the axially symmetric sites. 54 As is known, the bulk Zr 4+ ions, which are adjacent to the bulk OVs, could capture electrons, thus forming Zr 3+ defects. For 2Pt/ZrO 2 , its EPR spectrum shows an enhanced signal intensity at g = 2.002, indicating more OV formation.…”

“…The signal appearing at g = 2.002 is the characteristic indicator of oxygen vacancies (OVs) . The other signal at g = 1.973 is assigned to Zr 3+ ions located at the axially symmetric sites . As is known, the bulk Zr 4+ ions, which are adjacent to the bulk OVs, could capture electrons, thus forming Zr 3+ defects.…”