Pressureless sintering of LRH nanoplates on amorphous alumina for near‐infrared GAP:Mn⁴⁺ transparent ceramic film

Abstract

Transparent ceramics have become a research hotspot in the preparation of fluorescent materials in recent years, because of their excellent physical and chemical properties and high transparency. Gadolinium aluminate, as a stable matrix material, is often doped with various active ions to obtain luminescence with different colors. However, it is very difficult to fabricate gadolinium aluminate transparent ceramics by a traditional method, although they are the charming solid lighting materials. Here, we developed a pressureless sintering method to prepare GdAlO 3 :Mn (GAP:Mn) transparent ceramic films, which were prepared by spin coating layered rare-earth hydroxide (LRH) on amorphous alumina substrate and sintering at 1550 • C for 2 h. Through the interface reaction, the Al 2 O 3 reacted with Gd 2 O 3 to form mesophase Gd 4 Al 2 O 9 below 1550 • C. However, the final products are GdAlO 3 at 1550 • C. The GAP:Mn 4+ film exhibits a high transmittance of about 90%. Under UV excitation at 310 nm, the ceramic film outputs deep red and NIR emissions, which are both arising from the 2 E g -4 A 2g transition of Mn 4+ . Due to the electron traps arising from unequal valence substitution, the ceramic film exhibits a negative thermal quenching phenomenon. The ceramic film has a good luminescence thermal stability, because its emission intensity at 150 • C maintains over 72% that at room temperature. This work may pave a new way to fabricate transparent ceramics using LRHs.

Dy3+‐doped Y2Zr2O7 highly transparent ceramics for ultraviolet excitable warm white light‐emitting applications

“…Benefited from the emission originating from the 4 F 9/2 → 6 H 13/2 transition of Dy 3+ centered at about 580 nm; thus, Dy 3+ ‐doped phosphor materials have emerged as an especially robust representative to obtain the effective warm white luminescence 4 . However, the conventional Dy‐based composite luminescence converters fabricated by embedding phosphor powders in organic binders with poor chemical, thermal, and optical stability, which limited their further development in high‐power, high‐brightness solid‐state lighting 4,8,10 . As an alternative, some Dy‐doped glass converters have been developed, but the poor physical and chemical stabilities of the glass–ceramics make them unsuitable to be served in some harsh cases 11,12 .…”

“…4 However, the conventional Dy-based composite luminescence converters fabricated by embedding phosphor powders in organic binders with poor chemical, thermal, and optical stability, which limited their further development in high-power, high-brightness solid-state lighting. 4,8,10 As an alternative, some Dy-doped glass converters have been developed, but the poor physical and chemical stabilities of the glass-ceramics make them unsuitable to be served in some harsh cases. 11,12 To address these shortcomings, researchers have been working on developing innovative light-emitting converter materials with the potential for extreme environmental use, among which the polycrystalline ceramic phosphors are becoming a promising candidate due to their good optical transparency, high strength, corrosion and high-temperature resistance, and so on.…”