Average and Local Structure, Debye Temperature, and Structural Rigidity in Some Oxide Compounds Related to Phosphor Hosts

Abstract

The average and local structure of the oxides Ba2SiO4, BaAl2O4, SrAl2O4, and Y2SiO5 are examined to evaluate crystal rigidity in light of recent studies suggesting that highly connected and rigid structures yield the best phosphor hosts. Simultaneous momentum-space refinements of synchrotron X-ray and neutron scattering yield accurate average crystal structures, with reliable atomic displacement parameters. The Debye temperature ΘD, which has proven to be a useful proxy for structural rigidity, is extracted from the experimental atomic displacement parameters and compared with predictions from density functional theory calculations and experimental low-temperature heat capacity measurements. The role of static disorder on the measured displacement parameters, and the resulting Debye temperatures, are also analyzed using pair distribution function of total neutron scattering, as refined over varying distance ranges of the pair distribution function. The interplay between optimal bonding in the structure, structural rigidity, and correlated motion in these structures is examined, and the different contributions are delineated.

Recent progress in luminescence tuning of Ce3+and Eu2+-activated phosphors for pc-WLEDs

“…Furthermore, some newly C-A substitution types such as (5) and (6) in Fig. Therefore, modifying the current Pc-WLED phosphors or developing newly efficient phosphors for application in WLEDs by this strategy is necessary.…”

“…Phosphors are indispensable components of pc-WLED devices, and the exploration and development of pc-WLED phosphors for use as lighting and display backlight sources is one of the most important and urgent challenges, which can be met by advanced science and technology. [5][6][7][8][9][10][11][12][13][14][15] 1a.…”

Controlling of Structural Ordering and Rigidity of β-SiAlON:Eu through Chemical Cosubstitution to Approach Narrow-Band-Emission for Light-Emitting Diodes Application

“…The Debye temperature, ΘD, is used as a proxy to quantify structural rigidity of a material, which can be experimentally determined by low temperature heat capacity ( Figure 4f). The ΘD can be extracted by fitting the heat capacity to the Debye model in the low temperature limit, 30,31 ≈ 12…”

Phosphors by Design: Approaches Toward the Development of Advanced Luminescent Materials

“…This can be rationalized based on a reduction of non-radiative (vibrational) relaxation pathways that arise from rigid, highly connected structures. 65 Although searching for highly connected structures with a large Θ D can yield potential new phosphor hosts, it is not enough to produce an excellent phosphor. The band-gap (E g ) is also an essential material parameter because it must be wide enough to accommodate the electronic transitions (4f r 5d) of the rare-earth luminescent center.…”