In:
ECS Meeting Abstracts, The Electrochemical Society, Vol. MA2022-02, No. 51 ( 2022-10-09), p. 1970-1970
Abstract:
Compared with Mn 4+ -activated polycrystalline phosphors in micro powder form, the Mn 4+ -activated red-emitting crystals with considerable size exhibit improved resistance to deterioration under water attack. Besides, large sized fluorescent crystal can be packaged on LED in the remote configuration. We recently developed a series of methods for growing Mn 4+ -doped red-emitting crystals which have different solubilities. (1) For the fluoride hosts that have large solubility in acid solution such as (NH 4 ) 2 SiF 6 , (NH 4 ) 2 TiF 6 , K 2 TiF 6 , a series of centimeter-sized crystalline ingots were prepared by a cooling induced crystallization method (cooling from 20 °C to minus 40 °C). During cooling, the solubility decreases and the centimeter-scale Na 2 SiF 6 :Mn 4+ ingots as well as the fluoride phosphors with similar physicochemical property including (NH 4 ) 2 SiF 6 :Mn 4+ , (NH 4 ) 2 TiF 6 :Mn 4+ and K 2 TiF 6 :Mn 4+ were successfully grown through the supersaturated crystallization process by cooling down. (2) For the fluoride hosts that are slightly soluble such as BaTiF 6 , we firstly prepared BaTiOF 4 as precursor, which is then mixed with K 2 MnF 6 and gradually fluorinated in HF acid solution at room temperature. After a continuous feeding process, epitaxial growth of the BaTiF 6 :Mn 4+ ended up with ingots up to a record-breaking length of 200−300 μm, which exhibit better water resistance than commercial K 2 SiF 6 :Mn 4+ micro phosphor. (3) For the oxide hosts that are insoluble such as MgAl 2 O 4 , we use the molten salt method, and by optimizing the type of molten salt to adjust the dissolution and migration of Mg 2+ /Al 3+ /Mn 4+ ions in it, the MgAl 2 O 4 :Mn 4+ crystals in tetragonal bipyramid shape with uniform size of 2−4 μm were prepared under relatively mild conditions at 950 °C. The phosphor exhibits a broadband emission peaking at 651 nm under the 450 nm excitation, which is the highest energy of the Mn 4+ 2 E→ 4 A 2 transition energy in oxides. Figure 1
Type of Medium:
Online Resource
ISSN:
2151-2043
DOI:
10.1149/MA2022-02511970mtgabs
Language:
Unknown
Publisher:
The Electrochemical Society
Publication Date:
2022
detail.hit.zdb_id:
2438749-6
