Photoluminescence Properties of Efficient Blue-Emitting Phosphor α‑Ca_1.65Sr_0.35SiO₄:Ce³⁺: Color Tuning via the Substitutions of Si by Al/Ga/B

A series of Ce³⁺-doped α-Ca_1.65Sr_0.35SiO₄ (CSSO) phosphors without and with the substitutions of Si by Al/Ga/B were synthesized via the high-temperature solid-state reaction process. X-ray diffraction patterns and Rietveld refinements were used to demonstrate the successful incorporations of Al/Ga/B into CSSO:Ce³⁺. Without Al/Ga/B, the Ce³⁺ singly doped CSSO phosphors present intense blue emission, which correspond to the broad emission bands in visible region with the wavelength range from 360 to 580 nm upon 350 nm excitation. The optimal emission intensity occurs in CSSO:0.05Ce³⁺ sample with the emission peak wavelength at 436 nm. With the introduction of Al/Ga/B into the CSSO:0.05Ce³⁺, the emission peak shifts from 436 to 457/465/446 nm under 365 nm excitation, respectively. The red shift of Ce³⁺ emission is attributed to the polyhedral distortion of the cations, resulting in the enhancement of crystal field spitting due to the variations of the adjacent (Al/Ga/B,Si)­O₄ polyhedron. Moreover, the temperature-dependent photoluminescence was determined to be of light impact to CSSO:Ce³⁺ with the introduction of Al/Ga/B. This research is useful for enriching the emission colors of Ce³⁺-activated phosphors

Thermally Stable Red-Emitting Ca₁₈K₃Sc(PO₄)₁₄:Mn^<b>2</b>+ Phosphor and Enhanced Luminescence by Energy Transfer Between Ce^<b>3</b>+-Eu^<b>2</b>+-Mn^<b>2</b>+

It is significant and valuable to investigate novel and high-performance red-emitting phosphors for high-quality wLED applications. Based on this consideration, we developed a novel Mn2+-doped red Ca18K3Sc(PO4)14:Mn2+ (CKSP:Mn2+) phosphor. The emission peak of CKSP:Mn2+ is located at 640 nm, presenting a broadband red emission with a fwhm of 79 nm under 405 nm excitation. The CKSP:1.0Mn2+ phosphor shows superior thermal stability. At 150 °C, the integrated PL intensity and peak intensity of the CKSP:1.0Mn2+ phosphor maintain 93.2 and 85.7% of those at 25 °C, respectively. Through the strategy of energy transfer among Ce3+-Eu2+-Mn2+, the PL intensity of Mn2+ has increased by nearly 118 times, and the quantum yield has improved from 6 up to 72%. The structure-related photoluminescence and energy transfer mechanisms are discussed in detail. The as-fabricated wLED pumped by a 370 nm LED chip combining commercial the green (Sr,Ba)2SiO4:Eu2+ phosphor, blue BaMgAl10O17:Eu2+ phosphor, and the as-synthesized CKSP:1.0Mn2+, 0.02Eu2+, 0.40Ce3+ phosphor shows excellent color quality (CCT = 5555 K, Ra = 87), which indicates that the CKSP:1.0Mn2+, 0.02Eu2+, 0.40Ce3+ phosphor has extraordinary broad prospects in future wLED applications

Two-Site Occupation for Constructing Double Perovskite BaLaMgNbO₆:Cr³⁺ Ultrabroadband NIR Phosphors

Given the escalating significance of near-infrared (NIR) spectroscopy across industries, agriculture, and various domains, there is an imminent need to address the development of a novel generation of intelligent NIR light sources. Here, a series of Cr3+-doped BaLaMgNbO6 (BLMN) ultrabroadband NIR phosphor with a coverage range of 650–1300 nm were developed. The emission peak locates at 830 nm with a full width at half maximum of 210 nm. This ultrabroadband emission originates from the 4T2→4A2 transition of Cr3+ and the simultaneous occupation of [MgO6] and [NbO6] octahedral sites confirmed by low photoluminescence spectra (77–250 K), time-resolved photoluminescence spectra, and electron paramagnetic resonance spectra. The fluxing strategy improves the luminescence intensity and thermal stability of BLMN:0.02Cr3+ phosphors. The internal quantum efficiency (IQE) is 51%, external quantum efficiency (EQE) can reach 33%, and thermal stability can be maintained at 60%@100 °C. Finally, we successfully demonstrated the application of BLMN:Cr3+ ultrabroadband in the qualitative analysis of organic matter and food freshness detection

Color-Tunable and White Luminescence Properties via Energy Transfer in Single-Phase KNaCa₂(PO₄)₂:A (A = Ce³⁺, Eu²⁺, Tb³⁺, Mn²⁺, Sm³⁺) Phosphors

A series of single-phase phosphors based on KNaCa₂(PO₄)₂ (KNCP):A (A = Ce³⁺, Eu²⁺, Tb³⁺, Mn²⁺, Sm³⁺) have been prepared via the Pechini-type sol–gel method. Photoluminescence (PL) and cathodoluminescence (CL) properties of Ce³⁺-, Eu²⁺-, Tb³⁺-, Mn²⁺-, and Sm³⁺-activated KNCP phosphors were investigated. For the A singly doped KNCP samples, they exhibit the characteristic emissions of the A activator. Na⁺ ions exhibit the best charge compensation result among Li⁺, Na⁺, and K⁺ ions for Ce³⁺-, Tb³⁺-, and Sm³⁺-doped KNCP samples. The energy transfers from Ce³⁺ to Tb³⁺ and Mn²⁺ ions as well as Eu²⁺ to Tb³⁺ and Mn²⁺ have been validated. The emission colors of KNCP:Ce³⁺/Eu²⁺, Tb³⁺/Mn²⁺, Na⁺ samples can be adjusted by energy transfer process and changing the Tb³⁺/Mn²⁺ concentration. More importantly, white light emission in KNCP:Eu²⁺, Mn²⁺ system has been obtained. The KNCP:Tb³⁺, Na⁺ sample shows tunable luminescence from blue to cyan and then to green with the change of Tb³⁺ concentration due to the cross-relaxation from ⁵D₃ to ⁵D₄. A white emission can also be realized in the single-phase KNCP host by reasonably adjusting the doping concentrations of Tb³⁺ and Sm³⁺ (reddish-orange emission) under low-voltage electron beam excitation. Additionally, the temperature-dependent PL properties of as-prepared phosphors reveal that the KNCP host has good thermal stability. Therefore, the KNCP:A (A = Ce³⁺, Eu²⁺, Tb³⁺, Mn²⁺, Sm³⁺) phosphors could be regarded as good candidates for UV W-LEDs and FEDs

Regulation of Local Site Structures to Stabilize Mixed-Valence Eu^2+/3+ under a Reducing Atmosphere for Multicolor Photoluminescence

Co-doping mixed-valence Eu2+/3+ in a single-phase phosphor is an efficient method to realize the emission color regulation, which holds great potential for anticounterfeiting and ratiometric temperature sensing. Here, the mixed-valence Eu-doped Sr1.95+xLi1–xSi1–xAlxO4F (0 ≤ x ≤ 0.25) phosphors were designed and prepared under a reducing atmosphere. The correlation of local phase structures and luminescence properties was discussed. Replacing Si4+–Li+ ion pairs with Al3+–Sr2+ ion pairs compresses the Sr sites occupied by Eu2+, and it stabilizes Eu3+ in a reducing atmosphere and leads to the coexistence of Eu2+ and Eu3+ in single-phase Sr1.95+xLi1–xSi1–xAlxO4F:0.05Eu (0 ≤ x ≤ 0.25) phosphors. Based on the wavelength-dependent luminescence color behaviors of Sr1.95+xLi1–xSi1–xAlxO4F:0.05Eu phosphors, the fluorescent anticounterfeit papers/patterns containing Sr1.95+xLi1–xSi1–xAlxO4F:0.05Eu phosphors were the same as ordinary paper under ambient conditions. However, the hidden colors or images can be read out with green-orange luminescence under 365/300 nm light excitation. Benefiting from the diverse thermal response emission behaviors of Eu2+ (530 nm) and Eu3+ (703 nm), Sr1.95+xLi1–xSi1–xAlxO4F:0.05Eu phosphors exhibit temperature sensing performances, with the maximum absolute and relative sensitivity being 0.0294 K–1 at 573 K and 0.83% K–1 at 348 K. More importantly, Sr1.95+xLi1–xSi1–xAlxO4F:0.05Eu phosphors showed excellent stability in humid, acid, and alkali environments, which contributed to applying mixed-valence Eu2+/3+-doped Sr1.95+xLi1–xSi1–xAlxO4F to the fields of multicolor anticounterfeiting and noncontact optical thermometry

Influence of Anion/Cation Substitution (Sr²⁺ → Ba²⁺, Al³⁺ → Si⁴⁺, N^3– → O^2–) on Phase Transformation and Luminescence Properties of Ba₃Si₆O₁₅:Eu²⁺ Phosphors

A series of promising cyan, green, and yellow emission (Ba, Sr)₃(Si, Al)₆(O, N)₁₅:Eu²⁺ phosphors were synthesized by a Pechini-type sol–gel ammonolysis method. Variations in luminescence properties and crystal structure caused by the modification of phosphor composition were studied in detail. The prefired temperatures of the precursors play a key role in the process of forming the final products. Under UV light excitation, the as-prepared Ba₃Si₆O₁₅:Eu²⁺ phosphor presents a strong cyan emission located at 498 nm. Moreover, the as-prepared oxynitride phosphors, Eu²⁺-activated (Ba_1–<i>y</i>Sr_<i>y</i>)₃Si_6–<i>x</i>Al_<i>x</i>O_15−μN_δ (<i>x</i> = 0–1.2, <i>y</i> = 0–0.6), display a broader excitation band covering the entire visible region. Under blue light excitation, Ba₃Si_6–<i>x</i>Al_<i>x</i>O_15−μN_δ:Eu²⁺ phosphors show a intense and narrow green emission at 520 nm, and the luminescent intensity can be enhanced by increasing Al content within a certain range. However, (Ba_1–<i>y</i>Sr_<i>y</i>)₃Si₆O_15−μN_δ:Eu²⁺phosphors exhibit green (520 nm) to yellow (554 nm) emission with increasing Sr content. Unexpectedly, Eu²⁺ doped Ba₃Si₆O₉N₄-type Ba₃Si₆O_15−μN_δ–1300 °C phosphor exhibits a bluish green emission and strong thermal quenching behavior. The (Ba_1–<i>y</i>Sr_<i>y</i>)₃Si_6–<i>x</i>Al_<i>x</i>O_15−μN_δ:Eu²⁺ phosphors exhibit a small thermal quenching, and the quantum yields measured under 460 nm excitation could reach up to 89% for green Ba₃Si_6–<i>x</i>Al_<i>x</i>O_15−μN_δ:Eu²⁺ phosphor and 71% for yellow (Ba_1–<i>y</i>Sr_<i>y</i>)₃Si_6<i>x</i>O_15−μN_δ:Eu²⁺ phosphor. White LEDs with tunable color temperature and higher color rendering index were fabricated by combining the prepared cyan Ba₃Si₆O₁₅:Eu²⁺/green Ba_2.91Eu_0.09Si_6–<i>x</i>Al_<i>x</i>O_15−μN_δ (<i>x</i> = 0.06)/yellow (Ba_{0.97–<i>y</i>}Sr_<i>y</i>)₃Eu_0.09Si₆O_15−μN_δ (<i>y</i> = 0.4) phosphor and a red phosphor with a UV or blue LED chip, indicating that they are promising phosphors for white LEDs

Oxonitridosilicate Y₁₀(Si₆O₂₂N₂)O₂:Ce³⁺,Mn²⁺ Phosphors: A Facile Synthesis via the Soft-Chemical Ammonolysis Process, Luminescence, and Energy-Transfer Properties

Ce³⁺- and/or Mn²⁺-activated Y₁₀(Si₆O₂₂N₂)­O₂ phosphors have been prepared via a soft-chemical ammonolysis method. Structure refinement, scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared, and thermogravimetry analysis have been employed to characterize the phase purity, crystal structure, morphology, crystallization condition, chemical composition, and thermal stability of the products. The photoluminescence and cathodoluminescence properties for Ce³⁺- and Mn²⁺-doped Y₁₀(Si₆O₂₂N₂)­O₂ phosphors were studied in detail. For Ce³⁺/Mn²⁺ singly doped Y₁₀(Si₆O₂₂N₂)­O₂ phosphors, typical emissions of Ce³⁺ (blue) and Mn²⁺ (reddish-orange) ions can be observed. Especially, Ce³⁺ emission at different lattice sites 4f and 6h has been identified and discussed. Energy transfer from Ce³⁺(I) and Ce³⁺(II) to Mn²⁺ ions in Y₁₀(Si₆O₂₂N₂)­O₂:Ce³⁺,Mn²⁺ samples has been validated and confirmed by the photoluminescence spectra and luminescence decay times. A color-tunable emission in Y₁₀(Si₆O₂₂N₂)­O₂:Ce³⁺,Mn²⁺ phosphors can be achieved by an energy-transfer process and a change in the doping concentration of the activators. The temperature-dependent photoluminescence properties and degradation property of cathodoluminescence under continuous electron bombardment of as-synthesized phosphors prove that the Y₁₀(Si₆O₂₂N₂)­O₂ host has good stability. Therefore, the Y₁₀(Si₆O₂₂N₂)­O₂:Ce³⁺,Mn²⁺ phosphors may potentially serve as single-phase blue/reddish-orange phosphors for white-light-emitting diodes and field-emission displays

Data_Sheet_3_Transcriptome, Phenotypic, and Virulence Analysis of Streptococcus sanguinis SK36 Wild Type and Its CcpA-Null Derivative (ΔCcpA).pdf

Catabolic control protein (CcpA) is linked to complex carbohydrate utilization and virulence factor in many bacteria species, influences the transcription of target genes by many mechanisms. To characterize the activity and regulatory mechanisms of CcpA in Streptococcus sanguinis, here, we analyzed the transcriptome of Streptococcus sanguinis SK36 and its CcpA-null derivative (ΔCcpA) using RNA-seq. Compared to the regulon of CcpA in SK36 in the RegPrecise database, we found that only minority of differentially expressed genes (DEGs) contained putative catabolite response element (cre) in their regulatory regions, indicating that many genes could have been affected indirectly by the loss of CcpA and analyzing the sequence of the promoter region using prediction tools is not a desirable method to recognize potential target genes of global regulator CcpA. Gene ontology and pathway analysis of DEGs revealed that CcpA exerts an influence predominantly involved in carbon catabolite metabolism and some amino acid catabolite pathways, which has been linked to expression of virulence genes in many pathogens and coordinately regulate the disease progression in vivo studies. However, in some scenarios, differences observed at the transcript level could not reflect the real differences at the protein level. Therefore, to confirm the differences in phenotype and virulence of SK36 and ΔCcpA, we characterized the role of CcpA in the regulation of biofilm development, EPS production and the virulence of Streptococcus sanguinis. Results showed CcpA inactivation impaired biofilm and EPS formation, and CcpA also involved in virulence in rabbit infective endocarditis model. These findings will undoubtedly contribute to investigate the mechanistic links between the global regulator CcpA and the virulence of Streptococcus sanguinis, further broaden our understanding of the relationship between basic metabolic processes and virulence.</p

Photoluminescence and Energy Transfer Properties with Y+SiO₄ Substituting Ba+PO₄ in Ba₃Y(PO₄)₃:Ce³⁺/Tb³⁺, Tb³⁺/Eu³⁺ Phosphors for w‑LEDs

A series of Ce³⁺, Tb³⁺, Eu³⁺ doped Ba₂Y₂(PO₄)₂­(SiO₄) (BYSPO) phosphors were synthesized via the high-temperature solid-state reaction route. X-ray diffraction, high-resolution transmission electron microscopy, Fourier transform infrared, solid-state NMR, photoluminescence (PL) including temperature-dependent PL, and fluorescent decay measurements were conducted to characterize and analyze as-prepared samples. BYSPO was obtained by the substitution of Y+SiO₄ for Ba+PO₄ in Ba₃Y­(PO₄)₃ (BYPO). The red shift of PL emission from 375 to 401 nm occurs by comparing BYSPO:0.14Ce³⁺ with BYPO:0.14Ce³⁺ under 323 nm UV excitation. More importantly, the excitation edge can be extended from 350 to 400 nm, which makes it be excited by UV/n-UV chips (330–410 nm). Tunable emission color from blue to green can be observed under 365 nm UV excitation based on the energy transfer from Ce³⁺ to Tb³⁺ ions after codoping Tb³⁺ into BYSPO:0.14Ce³⁺. Moreover, energy transfer from Tb³⁺ to Eu³⁺ ions also can be found in BYSPO:Tb³⁺,Eu³⁺ phosphors, resulting in the tunable color from green to orange red upon 377 nm UV excitation. Energy transfer properties were demonstrated by overlap of excitation spectra, variations of emission spectra, and decay times. In addition, energy transfer mechanisms from Ce³⁺ to Tb³⁺ and Tb³⁺ to Eu³⁺ in BYSPO were also discussed in detail. Quantum yields and CIE chromatic coordinates were also presented. Generally, the results suggest their potential applications in UV/n-UV pumped LEDs

Data_Sheet_5_Transcriptome, Phenotypic, and Virulence Analysis of Streptococcus sanguinis SK36 Wild Type and Its CcpA-Null Derivative (ΔCcpA).xlsx

Catabolic control protein (CcpA) is linked to complex carbohydrate utilization and virulence factor in many bacteria species, influences the transcription of target genes by many mechanisms. To characterize the activity and regulatory mechanisms of CcpA in Streptococcus sanguinis, here, we analyzed the transcriptome of Streptococcus sanguinis SK36 and its CcpA-null derivative (ΔCcpA) using RNA-seq. Compared to the regulon of CcpA in SK36 in the RegPrecise database, we found that only minority of differentially expressed genes (DEGs) contained putative catabolite response element (cre) in their regulatory regions, indicating that many genes could have been affected indirectly by the loss of CcpA and analyzing the sequence of the promoter region using prediction tools is not a desirable method to recognize potential target genes of global regulator CcpA. Gene ontology and pathway analysis of DEGs revealed that CcpA exerts an influence predominantly involved in carbon catabolite metabolism and some amino acid catabolite pathways, which has been linked to expression of virulence genes in many pathogens and coordinately regulate the disease progression in vivo studies. However, in some scenarios, differences observed at the transcript level could not reflect the real differences at the protein level. Therefore, to confirm the differences in phenotype and virulence of SK36 and ΔCcpA, we characterized the role of CcpA in the regulation of biofilm development, EPS production and the virulence of Streptococcus sanguinis. Results showed CcpA inactivation impaired biofilm and EPS formation, and CcpA also involved in virulence in rabbit infective endocarditis model. These findings will undoubtedly contribute to investigate the mechanistic links between the global regulator CcpA and the virulence of Streptococcus sanguinis, further broaden our understanding of the relationship between basic metabolic processes and virulence.</p