A comparison between “second-sphere effects” in the excited state properties of coordination compounds and nonmolecular solids

Blasse, G.; Sabbatini, N.

doi:10.1016/0022-4596(87)90182-4

Cited by 18 publications

(5 citation statements)

References 35 publications

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“…Therefore, the edges and vertexes of the octahedrons stretched, causing heavy distortions, which may affect the spectral tuning and thermal quenching performance of the solid solution phosphors. [29,37] The morphologies of the CLGGG:Cr 3+ solid solutions prominently exhibited irregular shapes at ≈10-20 µm in size (Figure S2, Supporting Information). To provide further insight into the morphology and microstructure of the solid solutions, high-resolution transmission electron microscopy (HRTEM) analysis was used (Figure S3, Supporting Information).…”

Section: Phase and Structure Analysismentioning

confidence: 99%

Trade‐off Lattice Site Occupancy Engineering Strategy for Near‐Infrared Phosphors with Ultrabroad and Tunable Emission

Lang

Cai

Fang

et al. 2021

Advanced Optical Materials

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Accordingly, phosphor-converted (pc) NIR light-emitting diodes (LEDs) have received extensive scientific attention as lighting sources, owing to their conspicuous characteristics and range of applications. [8] The integration of blue InGaN LED chips with NIR phosphors is considered a promising strategy for yielding novel high-performance NIR light sources with broadband spectra. [9][10][11][12] Since NIR phosphors are key parts of these devices, affecting their overall luminescence performance and emission spectrum, selecting the appropriate phosphor is paramount. In this regard, for the design of efficient broadband NIR phosphors, applying a suitable activator as an ideal luminescence center is of vital importance.Chromium (Cr) exhibits a broadband absorption in the visible spectral range stemming from its distinctive 3d 3 electronic configuration. Besides, Cr 3+ ions can display a tunable narrowband or broadband spectrum (from deep red to the NIR region) depending on whether they are in a strong or weak crystal field environment, respectively. [9][10][11] Correspondingly, garnets possess a stable cubic crystal structure with a complex arrangement of different cations in the unit cell and exhibit several advantages, including a high thermal stability and long distances between alkali ions. The specific physicochemical Broadband near-infrared (NIR) luminescent materials have received notable attention due to their distinct photophysical properties for designing NIR light-emitting diodes (NIR LEDs). Here, a series of Ca 3−x Lu x Ga 2+x Ge 3−x O 12 :Cr 3+ (CLGGG:Cr 3+ ) (x = 0-1) NIR-emitting garnet phosphors with an emission range of 660-1200 nm are successfully developed and their lattice parameters are structurally analyzed. Upon 460 nm blue light excitation, the NIR phosphors exhibit both a substantial spectral broadening (FWHM: 129→267 nm) and a redshift of 37 nm (766→803 nm) with cosubstitution of [Lu 3+ -Ga 3+ ] pairs for [Ca 2+ -Ge 4+ ] sites. Furthermore, their luminescence thermal stability is substantially improved, maintaining ≈90% of the original photoluminescence intensity at 150 °C, owing to shrinkage of the second coordination sphere and rigid lattice, which are strongly associated with Cr 3+ trade-off occupancy and local structure evolutions. The relation between the trade-off site occupation of Cr 3+ in GaO 6 /CaO 8 polyhedrons and the NIR emission is also clarified by evaluating the decay and electron paramagnetic resonance behavior of Cr 3+ at different sites. The broadband NIR phosphors investigated here can serve as auspicious luminescent converters for phosphor-converted NIR LEDs and can provide an inspiring platform for future studies.

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Section: Phase and Structure Analysismentioning

confidence: 99%

Trade‐off Lattice Site Occupancy Engineering Strategy for Near‐Infrared Phosphors with Ultrabroad and Tunable Emission

Lang

Cai

Fang

et al. 2021

Advanced Optical Materials

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“…As x increases, larger Sr 2+ (1.18 ) is substituted by smaller Y 3+ (0.90 ) at second-neighbor sites to Ce 3+ cations, [22] while further N 3À (connected only to four silicon atoms) is replaced by C 4À . Thus the Sr 2+ /Y 3+ substitution in the second coordination sphere [23] has a strong effect at Ce 3+ activator sites. The local structures around Ce 3+ activator ions occupying Y 3+ sites in the x = 0 and x = 1 materials are shown in Figure 2 c and d, respectively.…”

mentioning

confidence: 96%

Nanosegregation and Neighbor‐Cation Control of Photoluminescence in Carbidonitridosilicate Phosphors

et al. 2013

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Blue, green, and yellow phosphors are obtained in the Sr1−xY0.98+xCe0.02Si4N7−xCx system (x=0→1). Decreases in thermal quenching barrier height with x result from a dominant neighboring‐cation effect, through which the replacement of Sr2+ by Y3+ reduces the covalency of CeN bonding. Green emission is observed from a cation‐segregated nanostructure of SrYSi4N7 and Y2Si4N6C domains in x=0.2–0.6 samples.

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“…The polyhedron colors of the activator sites of the first sphere represented the emission colors of x = 0 (red light) and x = 0.2 (orange light) samples. Moreover, the thermal quenching activation energy and quenching temperature were significantly affected by the second coordination sphere in the crystal lattice . The gradual substitution of smaller Si 4+ cations for larger Al 3+ cations resulted in the shrinkage of the second coordination sphere.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, the thermal quenching activation energy and quenching temperature were significantly affected by the second coordination sphere in the crystal lattice. 32 The gradual substitution of smaller Si 4+ cations for larger Al 3+ cations resulted in the shrinkage of the second coordination sphere. A smaller second sphere (i.e., higher number of Si 4+ ) resulted in higher thermal quenching activation energy and quenching temperature.…”

Section: Inorganic Chemistrymentioning

confidence: 99%

Domination of Second-Sphere Shrinkage Effect To Improve Photoluminescence of Red Nitride Phosphors

et al. 2014

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Red Ca0.99Al(1-4δ/3-x)Si(1+δ+x)N(3-x)C(x):Eu(2+)0.01 (δ = 0.345; x = 0-0.2) nitride phosphors exhibit a blue-shifted emission with increased eye sensitivity function and excellent thermal stability. The variations in the photoluminescence in the Ca0.99Al(1-4δ/3-x)Si(1+δ+x)N(3-x)C(x):Eu(2+)0.01 (δ = 0.345; x = 0-0.2) system are thoroughly investigated. The enhanced emission energy and the improved thermal stability with increasing x are dominated by the second-sphere shrinkage effect via the substitution of small Si(4+) for large Al(3+) with simultaneous charge compensation. Related proofs of the second-sphere shrinkage effect control for photoluminescence are confirmed via high-resolution neutron powder diffraction, EXAFS, and (29)Si solid-state NMR techniques.

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A comparison between “second-sphere effects” in the excited state properties of coordination compounds and nonmolecular solids

Cited by 18 publications

References 35 publications

Trade‐off Lattice Site Occupancy Engineering Strategy for Near‐Infrared Phosphors with Ultrabroad and Tunable Emission

Trade‐off Lattice Site Occupancy Engineering Strategy for Near‐Infrared Phosphors with Ultrabroad and Tunable Emission

Nanosegregation and Neighbor‐Cation Control of Photoluminescence in Carbidonitridosilicate Phosphors

Domination of Second-Sphere Shrinkage Effect To Improve Photoluminescence of Red Nitride Phosphors

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