NaAlSiO₄: Eu²⁺ Glass Ceramics: Self‐Reduced In Situ Growth and High‐Power LED/LD Lighting

Abstract

Currently, exploiting luminescent materials with super thermal stability and high luminous efficiency are highly urgent to meet the needs of fast developing high-power solid-state lighting (SSL). Glass ceramic (GC) bulk material is an optimal medium with rigid glass network structure and controllable glass crystallization. Herein, an in situ glass crystallization strategy combined with self-reduced Eu 2+ is developed to fabricate Eu 2+ doped NaAlSiO 4 (NASO) GC composites in air. Structural and spectroscopic characterizations verify that the in situ precipitated NASO nanocrystals with high crystallization density can accommodate Eu 2+ emitting centers in the same glass region, which facilitates the separation of Eu 2+ dopants from glass into crystalline lattice without the requirement of long-distance ionic diffusion and provides strong crystal-field environment for Eu 2+ 5d-4f transition. Particularly, the present composites can produce intense greenish-yellow emission with apparent photoluminescence quantum yield (PLQY) of ≈70%, intrinsic PLQY of ≈100%, superior thermal stability with 90% PL remained at 150 °C and excellent water-resistance. Employing NSAO: Eu 2+ GC as a color converter, the performance of constructed light-emitting diode (LED)/laser diode (LD) lighting devices is extraordinary and stable during long-term working. These findings would expand the application of GC composites and open up new avenues for exploration of novel GC materials and glass crystallization strategies.

Stable CsPbX3 (X = Cl, Br, I) Nanocrystal‐in‐Glass Composite (NGC) for Solid‐State Laser‐Driven White Light Generation

“…Besides, CsPbX 3 do not interact chemically with the silica coating and glass matrix in the range of room temperature to 200 °C due to the inert nature of the silica material. What is more, the thermal activation energy of CsPbBr 3 NGC is evaluated to be 436.2 meV (Figure S7, Supporting Information) by Mott–Seitz model [ 54–56 ] $$\[ \begin{array}{*{20}{c}}{I\left( T \right)\; = \frac{{{I_0}}}{{1 + A\exp \left( { - {E_{\rm{b}}}{\rm{/}}{k_{\rm{b}}}T} \right)}}}\end{array} \]$$where I 0 is the initial luminescence intensity at 0 K, T is the absolute temperature, K B is the Boltzmann constant, E b is the thermal activation energy. The thermal activation energy of NGC is about ten times [ 57,58 ] than that of colloidal perovskite quantum dots.…”

“…Besides, CsPbX 3 do not interact chemically with the silica coating and glass matrix in the range of room temperature to 200 °C due to the inert nature of the silica material. What is more, the thermal activation energy of CsPbBr 3 NGC is evaluated to be 436.2 meV (Figure S7, Supporting Information) by Mott-Seitz model [54][55][56]…”

Tetrahedrally coordinated rigid crystal structure enables partial self-reduction of mixed-valence europium for optical thermometric application

“…[40][41][42][43][44]49 These behaviors are due to Eu 2+ ions having relatively high stability in some special structures and the low reduction potential (Eu 2+ /Eu 3+ = 0.35 V). 45,46 It was proposed by Su et al 43 that the necessary conditions determining whether self-reduction occurs in the oxidizing atmosphere are: (a) the compounds having an appropriate structure with the tetrahedral anion groups (BO 4 , SO 4 , PO 4 , SiO 4 , or AlO 4 ) with no oxidizing ions; (b) the divalent cation of the host being replaced by Eu 3+ ions and the substituted cation possessing a similar radius as the Eu 2+ ions. [47][48][49] To construct a Eu 2+ /Eu 3+ couple co-activated ratiometric thermometer, herein, we focused on the CaBPO 5 compound.…”

An orange-yellow-emitting Lu2−xMg2Al2−yGaySi2O12:xCe3+ phosphor-in-glass film for laser-driven white light

“…17,20 Furthermore, red-emitting phosphors should be fabricated into an all-inorganic bulk/film form to withstand high-density blue laser irradiation, but the available all-inorganic material forms with high performance are also limited and are mostly difficult or costly to prepare. [21][22][23][24][25][26][27] Aiming for laser-driven high-color-quality white lighting, herein, we pay attention to a new kind of Ce 3+ -activated garnet-structured solid-solution phosphor, Lu 2Àx Mg 2 Al 2Ày -Ga y Si 2 O 12 :xCe 3+ (x = 0.02-0.14, y = 0.00-1.00, abbreviated as LMAGS:Ce 3+ ), and its all-inorganic composite by co-sintering it together with glass in the form of a phosphor-in-glass (PiG) film loaded on a high-thermal-conductivity sapphire plate (SP). LMAGS is derived from the previously-reported Lu 2 Mg 2 Al 2 -Si 2 O 12 which is isostructural to Lu 3 Al 5 O 12 (LuAG) via the chemical unit co-substitution of LuO 8 /AlO 6 by MgO 8 /MgO 6 and 2AlO 4 by 2SiO 4 .…”

“…17,20 Furthermore, red-emitting phosphors should be fabricated into an all-inorganic bulk/film form to withstand high-density blue laser irradiation, but the available all-inorganic material forms with high performance are also limited and are mostly difficult or costly to prepare. 21–27…”