Pressure-induced dark-to-bright transition inLu2O3:Ce

Abstract

Application of pressure to the nonemitting system Lu 2 O 3 :Ce 3ϩ leads to the generation of luminescence in the visible. The luminescence is assigned to the 5d→4 f transition of Ce 3ϩ , and is attributed to a pressureinduced electronic crossover of the excited 5d state of Ce 3ϩ and the conduction-band edge of Lu 2 O 3 . The results yield insight into the emission efficiency of 5d→4 f transitions, and provide a foundation for advancing new phosphors and tunable laser materials in the visible and ultraviolet based on the broad 5d→4 f emission of lanthanides.There is currently tremendous interest in the discovery of luminescent materials that emit at progressively shorter wavelengths. Short wavelength visible and ultraviolet ͑UV͒ emitting materials are desired for applications in imaging, lithography, optical data recording, tunable solid state lasers, scintillation, and displays. The challenges associated with obtaining efficient emission at short wavelengths has motivated work directed at creating materials systems with properties based on phenomena. Recent examples include the nitride semiconductors, 1 nanocrystalline materials, 2,3 and quantum cutting phosphors. 4 Lanthanide and transition-metal-doped insulators have enjoyed much success as luminescent materials, but have received relatively little attention for short-wavelength visible and UV-emitting applications. Because of efficient nonradiative decay from upper excited states, transition metals normally emit only from the first excited state. Since the first excited states of transition metals are located at energies corresponding to midvisible or near-infrared ͑NIR͒ wavelengths, the prospects for obtaining green, blue, or UV emission from transition-metal-activated materials appear to be limited. Short-wavelength visible and UV emission does occur from first or higher excited states in lanthanide ions. In most cases, lanthanide emission consists of narrow 4 f →4 f emission lines. As a result, lanthanide emission is oftentimes inconvenient to excite, and occurs at a limited number of discrete wavelengths, with little opportunity for achieving tunability.Most notable, Ce 3ϩ , Eu 2ϩ , and Sm 2ϩ lanthanide ions exhibit 5d→4 f emission. 5-10 5d→4 f emission is potentially advantageous for many applications because it combines the desirable broad absorption and emission features of transition metals with the high-energy emission properties of lanthanides. Although broad 5d→4 f emission has been observed in selected systems at wavelengths ranging from the NIR to the UV, its application has been limited and its potential for addressing current needs at short visible and UV wavelengths is only now becoming realized.The enigmatic nature of 5d→4 f transitions is one factor that has limited their application. Specifically, it has long been known that the emission efficiency of 5d→4 f transitions varies widely and randomly with the host lattice. Most studies have focused on Ce 3ϩ , and have shown that in some host lattices ͑e.g., Lu 2 SiO 5 ), Ce 3ϩ emits with high qu...

Luminescence in nano-size Y2O3:Ce

“…Auto-ionization of the excited electron, followed by a nonradiative decay to the 4f ground state, was understood to be the quenching mechanism [3], quite commonly accepted in explaining the properties of various systems [4]. A good experimental demonstration of the validity of this hypothesis comes from a set of recent high-pressure experiments [5,6]. Dark-to-bright transition due to hydrostatic pressure is shown to occur in a closely related material Lu 2 O 3 :Ce at about 70 kbar.…”

Efficiency considerations and emerging applications of novel wide band gap luminescent materials

“…luminescence from the lowest 5d state will be observed. Also in analogy to LSO, the pressure induced lowest 5d state in the oxide is subject to quenching through thermal activation back into the conduction band [15].…”

Highly transparent cerium‐doped yttria ceramics for full‐band UV‐shielding window applications

“…18 Moreover, Ce 3+ gives no photoluminescence emission in yttria matrix, because the 5d-4f transition of Ce 3+ is not enveloped in the bandgap of yttria. 19,20 Therefore, compared to YAG, AlON, and MgAl 2 O 4 , yttria is a better host material of Ce ions for UV absorption. In this study, the authors demonstrated the fabrication of highly transparent cerium-doped yttria ceramics by a pressureless sintering route.…”

“…briefly reported the fabrication and optical transparency of a Ce‐doped transparent yttria ceramic specimen, which showed an absorption edge at ∼370 nm 18 . Moreover, Ce 3+ gives no photoluminescence emission in yttria matrix, because the 5d–4f transition of Ce 3+ is not enveloped in the bandgap of yttria 19,20 . Therefore, compared to YAG, AlON, and MgAl 2 O 4 , yttria is a better host material of Ce ions for UV absorption.…”