Eu Sites Research Articles

Administration of BPX-501 Cells Following Αβ T and B-Cell-Depleted HLA-Haploidentical HSCT (haplo-HSCT) in Children with Malignant or Non-Malignant Disorders

BackgroundAllogeneic hematopoietic stem cell transplantation (HSCT) is an established treatment for children with leukemia or life-threatening non-malignant disorders. Approximately 25% of patients have a HLA-matched sibling and ~50% have a suitable matched unrelated donor, leaving ~25% of patients who require an alternative donor. HLA-partially matched (haploidentical, haplo) donors represent a suitable alternative for these children; extensive T-cell depletion of the graft is largely employed to minimize the risk of graft-versus-host disease (GvHD).BPX-501 is an allogeneic product consisting of T cells modified to express the inducible caspase-9 (iC9) safety switch and truncated CD19 to allow monitoring and expansion of CD3+ CD19+ T-cells following transplant. The polyclonal nature of the BPX-501 T cells provides broad virus and tumor-specific immunity, while the safety switch provides the unique ability to promptly and durably resolve graft-versus-host disease (GvHD) symptoms following the administration of rimiducid.AimsTo evaluate the safety and efficacy of BPX-501 T cells administered after a T-cell receptor αβ and B-cell-depleted haplo-HSCT in pediatric patients with malignant or non-malignant disorders. The primary endpoint is event-free survival at 180 days (events include TRM (or NRM for malignant patients), severe GVHD (acute Grade 2-4 organ or extensive chronic GVHD) and life-threatening infections (Grade 4).MethodsThis multicenter EU (NCT02065869), prospective trial utilizes αβ-T and B-cell-depleted haplo-HSCT followed by infusion of donor lymphocytes genetically modified with iC9 (BPX-501). BPX-501 cells were planned to be infused on day14±4 after the allograft. No post-transplant pharmacological GvHD prophylaxis was employed. Patients who develop GvHD resistant to conventional steroid therapy could receive ≥1 dose of dimerizing rimiducid activating iC9.The efficacy evaluable population (EEP) was defined as any patient who received HSCT, BPX-501 infusion and at least one follow-up assessment.ResultsAt the time of clinical cut-off (June 30, 2018) 166 patients met the EEP definition. All patients were from EU sites. Key baseline and transplant characteristics are shown in Table 1.In patients who obtained sustained engraftment of donor cells, the median time for neutrophil and platelet engraftment was 16 (15-17) and 11 (11-12) days, respectively. No patients experienced graft failure. Thirty-one patients developed Grade I-IV aGvHD (18.7% [95% CI;12.8 - 24.7%]). Three patients developed Grade III-IV aGvHD (1.8% [95% CI; 5.2 - 14.1%]). Of 132 evaluable patients, 9 developed cGvHD (7.2% [95% CI; 2.6 - 11.7%]) with only 2 patients experiencing moderate - severe cGvHD (95% CI: 0.0 - 3.1). Rimiducid was administered to 11 patients. Ten patients had ≥ 1 response assessment following administration of rimiducid. The best overall response rate (CR/PR) was 100% with 9 patients (90%) achieving complete response.At the time of clinical cut off, EFS at 180 days was 92.7% (95% CI: 88.7 - 96.7%). An interim analysis with approximately 100 patients from a concurrent Matched Unrelated Donor (MUD) HSCT comparator trial and previously published data is planned for the time of the congress.At a median follow-up of 17.6 mos (1.5 - 43.7 mos) 5 patients experienced transplant related mortality (TRM) (3.3% [95% CI: 0.4 - 6.2%]). DFS was 89.4% (95% CI: 84.7 - 94.2%). Overall survival (OS) was 94.2% (95% CI: 90.5 - 97.9%).CD3+ and CD3+CD4+ T cells above 500 cells/ml were achieved by day 100. IgA and IgM levels achieved normal values by day 180. The percentage of circulating and median absolute BPX-501 T-cells at Day 100 were 9.06% ± 10.52% (0 - 54.9%) and 109.49 ± 213.99 cells/ml (0 - 1001 cells/ml), respectively.ConclusionPreliminary evaluation of the primary endpoint and additional time-dependent efficacy outcomes, shows that the adoptive transfer of BPX-501 T cells following αβ-T and B-cell depleted haplo-HSCT followed by infusion of BPX-501 represents a novel and highly effective transplantation strategy for pediatric patients with malignant or non-malignant disorders. Despite the addition of BPX-501, overall rates of GvHD were low with few cases of high-grade aGvHD or cGvHD. Rimiducid was shown to be an effective treatment for patients who developed steroid-refractory GvHD. [Display omitted] DisclosuresQasim:Bellicum: Research Funding; Autolus: Equity Ownership; Servier: Research Funding; Orchard: Equity Ownership. Slatter:Medac: Other: Travel assistance. Locatelli:bluebird bio: Consultancy; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees; Miltenyi: Honoraria; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Structure, Thermal Stability, and Spectroscopic Properties of Triclinic Double Sulfate AgEu(SO4)2 with Isolated SO4 Groups.

Silver-europium double sulfate AgEu(SO4)2 was obtained by solid-phase reaction between Ag2SO4 and Eu2(SO4)3. The crystal structure of AgEu(SO4)2 was determined by Monte Carlo method with simulated annealing, and after that, it was refined by the Rietveld method from X-ray powder diffraction data. The compound crystallizes in the triclinic symmetry, space group P1̅ ( a = 0.632929(4), b = 0.690705(4), c = 0.705467(4) nm, α = 98.9614(4), β = 84.5501(4), γ = 88.8201(4)°, V = 0.303069(3) nm3). Two types of sulfate tetrahedra were found in the structure, which significantly affects the spectroscopic properties in the IR-range. In the temperature range of 143-703 K, the average linear thermal expansion coefficients of cell parameters a, b, and c are very similar, (1.11-1.67) × 10-5 K-1 in magnitude, and therefore, AgEu(SO4)2 expands almost isotropically. Upon heating in argon flow, AgEu(SO4)2 is stable up to 1053 K. The luminescence spectra in the region of ultranarrow 5D0-7F0 transition contain a single narrow and symmetric line at 579.5 nm that is evidence of good crystalline quality of AgEu(SO4)2 and uniform local environment of Eu3+ ions in the structure. Distribution of luminescence bands is determined by the environment of Eu3+ ions in the structure. Influence of Ag+ ions on the electron density distribution at Eu sites is detected.

Amorphous Europium Hexaboride: A Potential Room Temperature Formaldehyde Sensing Material.

Amorphous EuB6 was successfully prepared having a high specific surface area (221.3 m2 g-1) via the reaction between EuCl3 and B2H6 in the presence of liquid plasma in an ionic liquid environment. The material exhibits an immediate, lasting, and highly selective response toward formaldehyde at room temperature with a detection limit of 50 ppb. The good sensing performance of the amorphous EuB6 material is attributed to the strong interaction between formaldehyde and the increased number of accessible electron-rich surface Eu sites.

Full-color tuning in europium doped phosphosilicate phosphors via adjusting crystal field modulation or excitation wavelength

A series of Eu ions activated in Sr9-xLa1+x(PO4)7-x(SiO4)x (x = 1, 3, 5, 7) prepared from powder-based precursors have been investigated firstly. The luminescence evolution in response to crystal structure variations was investigated using X-ray diffraction, Rietveld refinement, photoluminescence (PL) and PL excitation spectra, and CIE coordination. As x increased from 1 to 7, the crystal structure changed from whitlockite to apatite, and the ligand bonds between the Eu2+ and O2− ions became shorter. Both crystal structures include two different kinds of Eu sites. The peak positions of the PL bands caused by the Eu2+ ions shifted from 416 nm to 505 nm as x increased with 365 nm excitation. This shift is mainly attributed to the fact that Eu2+ ions prefer higher energy sites in the whitlockite structure and lower energy sites in the apatite structure. The red PL originating from the trivalent europium ions appeared due to the increase in the La3+/Sr2+ ratio with increasing x. Under the various excitation wavelengths, the PL spectra changed tremendously. CIE coordination measurements and 2D PL contour map profiles demonstrated that the phosphor series could be tuned from blue to red by adjusting x, and a tunable phosphor covering full color could be achieved by adjusting the excitation wavelength. Moreover, the PL emission from the x = 1 sample provided an internal quantum efficiency of up to 100%.

Full-color tuning by controlling the substitution of cations in europium doped Sr8-xLa2+x(PO4)6-x(SiO4) xO2 phosphors

A full-color tunable phosphor by co-substituting Sr2+ and P5+ for La3+ and Si4+ in the single phased oxy-apatite Sr8-xLa2+x (PO4)6-x (SiO4)xO2: Eu2+ (SLPSiO; x = 0, 2, 4, 6) phosphor were prepared via solid state reaction method from powder based precursors. The crystal structure information of cell parameters and average bond lengths from luminescence centers to its ligands was analyzed using Rietveld refinement. All the crystal structure of series of phosphors include two different sites of Eu2+, the 7-coordinated Sr1 sites and the 9-coordinated Sr2 sites. The different behaviors of luminescence evolution were due to the Eu2+ ions prefer higher energy sites in the Sr8La2(PO4)6O2 (for x = 0) host, but lower energy sites in the Sr2La8(SiO4)6O2 host (for x = 6). Also, the red PL originating from the trivalent europium ions appeared due to the increase in the La3+/Sr2+ ratio with increasing x. The blue point (0.2016, 0.1144), bluish white (5000–8300 K CCT), and yellowish white point (2600–3700 K CCT) in the CIE coordination through red colors are included in the ‘Fabricated LED’ curve, which are suitable for the application of these blends in white-light near UV LEDs. Moreover, the internal quantum efficiency of the x = 0 phosphor approached up to 90%.

Structure, site-occpancy and luminescent properties of a novel blue phosphor Na3ZrMgP3O12: Eu2+

Single-phase Na3ZrMgP3O12: Eu2+ (NZMP: Eu2+) phosphor was prepared via high-temperature solid-state reaction. The crystal structure, lattice parameters and occupied sites of Eu2+-doped Na3ZrMgP3O12 are elucidated by powder X-ray diffraction and Rietveld refinement. It is found that majority of Eu2+ ions occupy 8-coordianted Na2 site while minority of Eu2+ are in 6-coordianted Na1 site of NZMP host. NZMP: Eu2+ shows a strong blue emission broadband with peak at 450 nm under UV excitation, which can be decomposed into two sub-bands peaking at 446 and 474 nm based on the substitution of two kinds of Na+ sites by Eu2+ ions. Luminescence properties of NZMP: Eu2+ phosphors were investigated in detail, including excitation and emission spectra, decay lifetime, concentration quenching and temperature-dependent emission spectra.

Mössbauer spectroscopy measurements on the 35.5 K superconductor Rb1−δEuFe4As4

The results of x-ray diffraction and $^{57}\mathrm{Fe}$ and $^{151}\mathrm{Eu}$ M\"ossbauer spectroscopy measurements, supplemented with ab initio hyperfine-interaction parameter calculations, on the new 35.5 K superconductor ${\mathrm{Rb}}_{1\ensuremath{-}\ensuremath{\delta}}{\mathrm{EuFe}}_{4}{\mathrm{As}}_{4}$ are presented. The superconductor crystallizes in the tetragonal space group $P4/mmm$ with the lattice parameters $a=3.8849(1)$ \AA{} and $c=13.3370(3)$ \AA{}. It is shown that there is no magnetic order of the Fe magnetic moments down to 2.1 K and that the ferromagnetic order is associated solely with the Eu magnetic moments. The Curie temperature ${T}_{\mathrm{C}}=16.54(8)$ K is determined from the temperature dependence of both the hyperfine magnetic field at $^{151}\mathrm{Eu}$ nuclei and the transferred hyperfine magnetic field at $^{57}\mathrm{Fe}$ nuclei that is induced by the ferromagnetically ordered Eu sublattice. The Eu magnetic moments are demonstrated to be perpendicular to the crystallographic $c$ axis. The temperature dependence of the principal component of the electric field gradient tensor, at both Fe and Eu sites, is well described by a ${T}^{3/2}$ power-law relation. Good agreement between the calculated and measured hyperfine-interaction parameters is observed. The Debye temperature of ${\mathrm{Rb}}_{1\ensuremath{-}\ensuremath{\delta}}{\mathrm{EuFe}}_{4}{\mathrm{As}}_{4}$ is found to be 391(8) K.

Electronic and magnetic properties of defect complexes in Eu-doped GaN: First-principles calculations

Various forms of defect complexes are studied in Eu-doped GaN by first-principles calculations with the framework of density functional theory. We consider defect complexes formed by dopant Eu and vacancies or insterstitals with the neutral charge states in GaN, i.e., EuGa-VGa, EuGa-VN, EuGa-Ni, and EuGa-Oi, where EuGa represents the Eu site substituting for Ga site, and VGa, VN, Ni and Oi are Ga vacancies, N vacancies, interstitial N and interstitial O, respectively. The formation energies are calculated for all defect configurations. The formation energies of native Ga vacancies are found to be higher compared to those of N vacancies, while the tetrahedral interstitials are energetically more stable than the octahedral interstitial. The Eu-4f electrons introduce a magnetic moment of about 6.15 μB in the case of single dopant Eu, i.e., EuGa, which is probably suppressed in the presence of octahedral interstitial N around Eu. And Ga vacancies and octahedral interstitial O can contribute the magnetic moments to the systems, while other intrinsic defects do almost not promote the formation of local magnetic moments.

Magnetism of the 35 K superconductor CsEuFe4As4

The results of ab initio hyperfine-interaction parameters calculations, and of x-ray diffraction and 57Fe and 151Eu Mössbauer spectroscopy study of the new 35 K superconductor CsEuFe4As4 are reported. The superconductor crystallizes in the tetragonal space group P4/mmm with the lattice parameters Å and Å. It is demonstrated unequivocally that there is no magnetic order of the Fe magnetic moments down to 2.1 K and that the ferromagnetic order is associated with the Eu magnetic moments. The Curie temperature K determined from the temperature dependence of the hyperfine magnetic field at 151Eu nuclei is shown to be compatible with the temperature dependence of the transferred hyperfine magnetic field at 57Fe nuclei that is induced by the ferromagnetically ordered Eu sublattice. The Eu magnetic moments are shown to be perpendicular to the crystallographic c-axis. The temperature dependence of the principal component of the electric field gradient tensor, both at Fe and Eu sites, is well described by a T3/2 power-law relation. Good agreement between the calculated and measured hyperfine-interaction parameters is observed. The Debye temperature of CsEuFe4As4 is found to be 295(3) K.

Spectral redshift mechanism of N doped Sr2SiO4:Eu2+ phosphors

By using the first principle methods, the electronic structure and spectral characteristics of N-doped and un-doped Sr2SiO4:Eu2+ phosphors is studied. It is found that after nitrogen doping the shorter bond lengths of EuN leads to the splitting of Eu5d states due to the crystal field effect, and the stronger covalencies of EuN bonds results in the down shift of Eu5d states because of the nephelauxetic effect. These two factors come together to bring about the red-shift of the of the PL properties. Lower Eu5d energy level and wider energy band of Eu5d states for Eu(II) site occurs due to shorter bond length and greater covalency of Eu(II)N bond. Consequently, the Eu(II) site was effectively substituted with nitrogen. By increase of nitrogen content, the number of EuN bonds increases and the luminescence intensity for the phosphors increase correspondingly.

Thiazide-Associated Hyponatremia, Report of the Hyponatremia Registry: An Observational Multicenter International Study

Background: Hyponatremia is a frequent and potentially life-threatening adverse side effect of thiazide diuretics. This sub-analysis of the Hyponatremia Registry database focuses on current management practices of thiazide-associated hyponatremia (TAH) and compares differences between TAH and syndrome of inappropriate antidiuretic hormone secretion (SIADH). Methods: We analyzed 477 patients from 225 US and EU sites with euvolemic hyponatremia ([Na⁺] ≤130 mEq/L) who were receiving a thiazide diuretic. Of these, 118 met criteria for true thiazide-induced hyponatremia (TIH). Results: Thiazide was withdrawn immediately after hyponatremia was diagnosed only in 57% of TAH; in these patients, the median rate of [Na⁺] change (Δ_daily[Na⁺]) was significantly higher than those with continued thiazide treatment (3.8 [interquartile range: 4.0] vs. 1.7 [3.8] mEq/L/day). The most frequently employed therapies were isotonic saline (29.6%), fluid restriction (19.9%), the combination of these two (8.2%), and hypertonic saline (5.2%). Hypertonic saline produced the greatest Δ_daily[Na⁺] (8.0[6.4] mEq/L/day) followed by a combination of fluid restriction and normal saline (4.5 [3.8] mEq/L/day) and normal saline alone (3.6 [3.5] mEq/L/day). Fluid restriction was markedly less effective (2.7 [2.7] mEq/L/day). Overly rapid correction of hyponatremia occurred in 3.1% overall, but in up to 21.4% given hypertonic saline. Although there are highly significant differences in the biochemical profiles between TIH and SIADH, no predictive diagnostic test could be derived. Conclusions: Despite its high incidence and potential risks, the management of TAH is often poor. Immediate withdrawal of the thiazide is crucial for treatment success. Hypertonic saline is most effective in correcting hyponatremia but associated with a high rate of overly rapid correction. We could not establish a diagnostic laboratory-based test to differentiate TIH from SIADH.

Phase formation and spectral evolution of (Sr,Ba)2Si(O,N)4:Eu2+ phosphors

AbstractSr2‐xBaxSi(O,N)4:Eu2+ (SBxSON:Eu2+) oxynitridosilicate phosphors were prepared via incorporation of N3−, Eu2+, and Ba2+ ions into Sr2SiO4 (SSO) lattices. X‐ray diffraction patterns of the prepared powders revealed that SBxSON:Eu2+ was a solid‐solution form of SSO. An increase in x values caused a phase transition and an expansion of the unit cell. The photoluminescence excitation (PLE) spectra of SBxSON:Eu2+ were broad, covering the ultraviolet range to the visible range. Corresponding PL emission spectra strongly depended on the excitation wavelengths and consisted of two emission bands, one in the green‐blue region (A‐band) and the other in the red region (B‐band), which were assigned to Eu(I) and Eu(II), respectively. The B‐band resulted from a dramatic red‐shift of the green emission band assigned to Eu(II) of SSO:Eu2+, revealing that the nitridation process preferentially affected the Eu(II) sites. This behavior was explained by crystal field splitting, the fluorescence decay time, and thermal quenching. The Ba2+ substitution caused evolution of the PL spectra, and its effects on the spectra were discussed under consideration of ionic size and covalence.

Structural evolution induced preferential occupancy of Eu2+ in Na2(Ba, Gd)6(Si2O7)(SiO4)2 phosphor

By substituting Gd3+ for Ba2+ ions in the single-phased Na2(Ba5.99-2mEu0.01Gd mNa m)(Si2O7)(SiO4)2 (0≤m≤0.30) phosphors, the asymmetric emission peaks of three Eu luminescence centers monitored around 444, 494 and 552nm varied accordingly under 365nm excitation and caused the shift of CIE color coordinates from (0.1569, 0.2122) to (0.1697, 0.3082). Furthermore, the thermal stability and quantum yield of phosphors could be affected via the different cation substitution of Gd3+. Combined with the change tendencies of Ba-O bond lengths by Rietveld refinement, the possible mechanism of the luminescence transformation of Eu2+ ion was the preferential occupancy at different crystallographic sites of Eu2+. Generally, this work sheds some new lights on the design and structure explanation of preferential occupancy at different crystallographic sites in phosphors.

Effectiveness of Lenalidomide in Patients with Mantle Cell Lymphoma Who Relapsed/Progressed after or Were Refractory/Intolerant to Ibrutinib: The MCL-004 Study

Effectiveness of Lenalidomide in Patients with Mantle Cell Lymphoma Who Relapsed/Progressed after or Were Refractory/Intolerant to Ibrutinib: The MCL-004 Study

Synthesis, Characterization, and Low Temperature Transport Properties of Eu11-xYbxCd6Sb12 Solid-Solution Zintl Phases.

Eu11-xYbxCd6Sb12 Zintl solid solutions have been prepared by tin flux reaction by employing the elements Eu/Yb/Cd/Sb/Sn in the ratio 11 - xp:xp:6:12:30, where xp is an integer less than 11 representing the preparative amount of Eu (11 - xp) and Yb (xp). Efforts to make the Yb compositions for x exceeding ∼3 resulted in structures other than the Sr11Cd6Sb12 structure type. The crystal structures and compositions were determined by single-crystal and powder X-ray diffraction and wavelength-dispersive X-ray analysis measurements. The title solid-solution Zintl compounds crystallize in the centrosymmetric monoclinic space group C2/m (no. 12, Z = 2) as the Sr11Cd6Sb12 structure type (Pearson symbol mC58), and the lattice parameters decrease with increasing ytterbium content. Single crystal X-ray diffraction shows that Yb atoms are not randomly distributed in the Eu sites but have a site preference which can be attributed to size effects. The influence of the rare earth (RE) metal sites on thermal and electronic properties of RE11Cd6Sb12 solid solutions has been studied by measuring their thermoelectric properties from 5 to 300 K after consolidation by either spark plasma sintering (SPS) or hot pressing (HP). Electron microprobe analysis reveals that some of the rare earth metal is lost during SPS; as a result pellets formed through SPS have lower electrical resistivity by an order of magnitude due to increased hole-charge carrier concentrations. While the carrier concentration increases, the mobility decreases due to deficiencies in Eu content. Refinement of powder X-ray diffraction shows that Eu loss is mainly from the Eu1 crystallographic site, which has a unique coordination suggesting that this site plays a key role in the transport properties of RE11Cd6Sb12.

Responding to ‘crisis’: Education policy research in Europe

This paper discusses the significance of international and transnational developments for education policy research, with a focus on the European Union. The rise of policy projects at the EU level since 2000, has altered the relationships between the state, EU institutions and education policy, in terms of the definition of values, purposes, and mechanisms of education change, in what is often referred to as the europeanisation of education policy and governance. In a time of financial crisis and extensive population migrations to and within the European space, the paper argues for further critical research on the EU institutions and their relationship to national education systems, as well as on the social justice dimensions and implications of considering both national and EU sites of policy for addressing young and vulnerable peoples' education and social futures.

Controlling Magnetic Ordering in Ca1–xEuxCo2As2 by Chemical Compression

To investigate the interplay between electronic structure and itinerant magnetism, Ca1–xEuxCo2As2 solid solutions (x = 0, 0.1, 0.3, 0.4, 0.5, 0.6, 0.65, 0.7, 0.9, 1.0) were prepared by reactions between constituent elements in molten Bi. All of the samples crystallize in the ThCr2Si2 structure type. The crystal structure refinement revealed the formation of Co vacancies, the concentration of which decreases as the Eu content increases. The Eu site exhibits mixed valence in all samples. X-ray absorption near-edge structure spectroscopy revealed that the average Eu oxidation state decreases from +2.17 at 0 < x ≤ 0.6 to +2.14 at x ≥ 0.65. The same borderline behavior is observed in magnetic properties. The substitution of Eu for Ca causes the transition from the antiferromagnetic (AFM) ordering of Co moments in CaCo2As2 to ferromagnetic (FM) ordering of Co moments in Ca1–xEuxCo2As2 with 0.1 ≤ x ≤ 0.6. At higher Eu content, AFM ordering of Eu moments is observed, whereas the Co sublattice exhibits only parama...

Optical sites in Eu- and Mg-codoped GaN grown by NH3-source molecular beam epitaxy

Mg codoping can improve the luminescence properties of Eu-doped GaN. However, the enhanced optical sites differ depending on the fabrication method. In this study, the optical sites in Eu- and Mg-codoped GaN [GaN:(Eu, Mg)] grown by NH3-source molecular beam epitaxy (MBE) were evaluated. The optical properties of an Eu–Mg-related site grown by NH3-MBE were highly stable against thermal annealing. Although the luminescence at sites A (622.3 and 633.8 nm) and B (621.9 and 622.8 nm) was dominant under indirect excitation of Eu ions through GaN, four different optical site groups in addition to sites A and B were observed under resonant excitation. These optical sites are inconsistent with the Eu–Mg-related sites reportedly observed in GaN:(Eu, Mg) fabricated by organometallic vapor phase epitaxy, indicating that the optical site constitution strongly depends on the growth method. Furthermore, site A, with a high cross section, contributed to as much as 22% of the total photoluminescence (PL) integrated intensity for GaN:(Eu, Mg) grown by NH3-MBE, which resulted in a high PL intensity.

Fluorescence properties with red-shift of Eu2+ emission in novel phosphor-silicate apatite Sr3LaNa(PO4)2SiO4 phosphors

A series of Eu2+-activated novel phosphor-silicate apatite Sr3LaNa(PO4)2SiO4 phosphors were synthesized by solid-state reaction. The X-ray diffraction (XRD) and Rietveld refinement, diffuse reflectance spectra, luminescent spectra, decay curves and thermal quenching properties were applied to characterize the obtained phosphors. The XRD result revealed that all the samples possessed only a single phase with hexagonal structure and the doping of Eu2+ ions were successfully incorporated into the crystal lattice. The reflectance spectra showed an obvious red-shift of the wavelength from 400 to 700nm with increasing Eu2+ ion concentration. The three different crystallographic sites of Eu2+ ions had been confirmed by their lifetimes. All the samples exhibited broad absorption bands from 200 to 450nm, revealing the phosphor-silicate phosphor interesting for application in the near-UV used phosphor-converted LED chips. These results suggested that the Eu2+-activated phosphor-silicate Sr3LaNa(PO4)2SiO4 phosphors have the potential for near-UV pumped white-light-emitting diodes (w-LEDs).

Broadband Yellowish-Green Emitting Ba4Gd3Na3(PO4)6F2:Eu(2+) Phosphor: Structure Refinement, Energy Transfer, and Thermal Stability.

A series of Ba4Gd3Na3(PO4)6F2:Eu(2+) phosphors with a broad emitting band have been synthesized by a traditional solid state reaction. The crystal structural and photoluminescence properties of Ba4Gd3Na3(PO4)6F2:Eu(2+) are investigated. The different crystallographic sites of Eu(2+) in Ba4Gd3Na3(PO4)6F2:Eu(2+) phosphors have been verified by means of their photoluminescence (PL) properties and decay times. Energy transfer between Eu(2+) ions, analyzed by excitation, emission, and PL decay behavior, has been indicated to be a dipole-dipole mechanism. Moreover, the luminescence quantum yield as well as the thermal stability of the Ba4Gd3Na3(PO4)6F2:Eu(2+) phosphor have been investigated systematically. The as-prepared Ba4Gd3Na3(PO4)6F2:Eu(2+) phosphor can act as a promising candidate for n-UV convertible white LEDs.