Rational Design of Nitride Phosphor-In-Glass with Robust Stability and Photoluminescence Performance.

Phosphor-in-glass represents a promising avenue for merging the luminous efficiency of high-quality phosphor and the thermal stability of a glass matrix. Undoubtedly, the glass matrix system and its preparation are pivotal factors in achieving high stability and preserving the original performance of embedded phosphor particles. In contrast to the well-established commercial Y3Al5O12:Ce3+ oxide phosphor, red nitride phosphor, which plays a critical role in high-quality lighting, exhibits greater structural instability during the high-temperature synthesis of inorganic glasses. A telluride glass with a refractive index (RI = 2.15@615 nm) akin to that of nitride phosphor (∼2.19) has been devised, demonstrating high efficiency in photon utilization. The lower glass-transition temperature plays a crucial role in safeguarding phosphor particles against erosion resulting from exposure to high-temperature melts. Phosphor-in-glass retains 93% of the quantum efficiency observed for pure phosphor. The assembled white light-emitting diodes module has precise color tuning capabilities, achieving an optimal color rendering index of 93.7, a luminous efficacy of 80.4 lm/W, and a correlated color temperature of 5850 K. These outcomes hold potential for advancing the realm of inorganic package and high-quality white light illumination.

Systematic Crystallization of NH4Ln(MoO4)2 as a Family of Layered Compounds (Ln = La-Lu and Y), Derivation of Ln2Mo4O15, Crystal Structure, and Photoluminescence.

NH4Ln(MoO4)2 (Ln = La-Lu lanthanide, Y) was crystallized via hydrothermal reaction as a new family of layered materials, from which phase-pure Ln2Mo4O15 was successfully derived via subsequent annealing at 700 °C for the series of Ln elements excluding Ce and Lu. Detailed structure analysis revealed that the ionic size of Ln3+ decisively determined the crystal structure and Mo/Ln coordination for the two families of compounds. NH4Ln(MoO4)2 was analyzed to be orthorhombic (Pbcn space group, no. 60) and monoclinic (P2/c, no. 13) for the larger and smaller Ln3+ of Ln = La-Gd and Ln = Tb-Lu (including Y), respectively, where both the crystal structures have a layered topology featured by the alternative stacking of a [Ln(MoO4)2]- three-tier infinite anionic layer and interlayer NH4+. Four types of crystal structures were found for the Ln2Mo4O15 series, which are monoclinic (P21/a, no. 14) for Ln = La, triclinic (P1̅, no. 2) for Ln = Pr-Sm, triclinic (P1̅, no. 2) for Ln = Eu and Gd, and monoclinic (P21/c, no. 14) for Ln = Tb-Yb (including Y). The photoluminescence of NH4Ln(MoO4)2 (Ln = Eu, Tb) and Ln2Mo4O15:Eu3+ (Ln = La, Gd, Y) was thoroughly investigated in terms of spectral features, quantum efficiency, fluorescence decay, and CIE chromaticity. The thermal stability of luminescence was also studied for Ln2Mo4O15:Eu3+, and the observed charge-transfer excitation components were successfully correlated with the features of the Mo-O polyhedron/unit.

New Mg2+/Ge4+-Stabilized Gd3MgxGexAl5-2xO12:Ce Garnet Phosphor with Orange-Yellow Emission for Warm-White LEDs (x = 2.0-2.5).

By stabilization of the Gd3Al5O12 garnet by replacing 80% or more of Al3+ with Mg2+/Ge4+ pairs, a series of new orange-yellow-emitting Gd3MgxGexAl5-2xO12:Ce (x = 2.0-2.5) phosphors were successfully developed for potential application in warm-white-light-emitting diodes (WLEDs). Rietveld structure refinement proved that Mg2+ first substitutes the octahedral Al3+ ion, followed by the replacement of the tetrahedral Al3+ together with Ge4+. The band structure of the x = 2.0 typical garnet was analyzed via density functional theory (DFT) calculations. The incorporation of an increasing content of Mg2+/Ge4+ was experimentally shown to narrow the band gap and expand the unit cell of the garnet host and blue shift the emission/excitation wavelength and shorten the fluorescence lifetime of Ce3+. The photoluminescence behaviors were rationalized by considering the influence of Mg2+/Ge4+ on the crystal structure, band structure, and local coordination. An LED lamp fabricated by combining the (Gd2.97Ce0.03)Mg2Ge2AlO12 optimal phosphor with a 450 nm-emitting InGaN blue LED chip exhibited a color-rendering index of 71.6, luminous efficacy of 16.1 lm/W, and a low correlated color temperature of 2201 K under a driving current of 20 mA, indicating that phosphor may have potential application in warm WLEDs.

Morphology Tailoring of ZnWO4 Crystallites/Architectures and Photoluminescence of the Doped RE3+ Ions (RE = Sm, Eu, Tb, and Dy).

Tartrate (Tar2-) was originally employed in this work as a chelating/structure-directing agent for hydrothermal crystallization of ZnWO4, where the decisive roles of Tar2-/Zn2+/WO42- molar ratio, solution pH (7-10), and the use of ethylene glycol (EG) cosolvent in phase/morphology evolution were deciphered in detail. It was unambiguously manifested that Tar2- may remarkably retard the intrinsically preferred [001] growth of ZnWO4, transform 1D nanorods to 0D nanoparticles and then to 2D platelets, and meanwhile induce face-to-face alignment of the platelets to form spheroidal, ellipsoidal and snowflakelike 3D architectures, where the 2D crystallites were revealed to develop via oriented attachment (colattice) of non-(00l) facets. A lower solution pH and excessive WO42- were clearly shown to enhance and offset the effect of Tar2-, which led to ellipsoidal assemblies of substantially larger 2D crystallites and suppressed 2D growth/3D assembly of ZnWO4 crystallites, respectively. With the spheroidal architectures for example, doping ZnWO4 with RE3+ yielded (Zn0.98RE0.02)WO4 phosphors (RE = Sm, Eu, Tb, and Dy, respectively) that show luminescence overlapped from the typical linelike and broad-band (∼350-700 nm) emissions of RE3+ and WO6, respectively. The luminescence color of the sample was found to drift away from the blue corner of the CIE chromaticity diagram with RE3+ doping and to be dependent on the type of RE3+.

Multi-Color Luminescent m-LaPO4:Ce/Tb Monospheres of High Efficiency via Topotactic Phase Transition and Elucidation of Energy Interaction.

Monoclinic (m-) structured (La0.96- xCe0.04Tb x)PO4 phosphor monospheres ( x = 0-0.12) of excellent dispersion and morphology uniformity were calcined (≥600 °C) from their precipitated precursor spheres (∼2.0 µm) of a hexagonal (h-) structure for efficient and multicolor luminescence. The h → m phase transition, driven by dehydration, was originally proposed to proceed in a topotactic manner, which involves displacement of the RE-O polyhedra (RE: rare-earth) along the a/ b axis and slight expansion of the {010} and {100} interplanar spacings of the hydrated h-phase to form the {120} and {100} planes of the anhydrous m-phase, respectively. Analysis of the energy process involving the optically active Ce3+ and Tb3+ ions found efficient Ce3+ → Tb3+ energy transfer occurring via electric dipole-quadrupole interaction, whose efficiency reached the highest value of ∼44.48% at x = 0.10. The Tb3+ codoped phosphors simultaneously displayed the characteristic emissions of Ce3+ (∼313 nm) and Tb3+ (∼545 nm) upon exciting the Ce3+ ions with 275 nm UV light, with which the emission color was finely tuned from dark blue to green by increasing the Tb3+ content. Fluorescence decay analysis found decreasing and almost constant lifetime values for the Ce3+ and Tb3+ emissions at a higher Tb3+ content, respectively, and the phosphor presented the highest external quantum efficiency of ∼84.67% at x = 0.10. The excellent luminescent performance and morphology uniformity may allow the monospheres to find application in lighting and display technologies.

Upconversion luminescence and favorable temperature sensing performance of eulytite-type Sr3Y(PO4)3:Yb3+/Ln3+ phosphors (Ln=Ho, Er, Tm).

Phase-pure eulytite-type Sr3Y0.88(PO4)3:0.10Yb3+,0.02Ln3+ upconversion (UC) phosphors (Ln = Ho, Er, Tm) were synthesized via gel-combustion and subsequent calcination at 1250°C. Their UC luminescence, temperature-dependent fluorescence intensity ratio of thermally and/or non-thermally coupled energy levels, and performance of optical temperature sensing were systematically investigated. The phosphors typically exhibit green, orange-red and blue luminescence under 978 nm NIR laser excitation for Ln = Er, Ho and Tm, respectively, which were discussed from two- and three-photon processes. The 524 nm green (Er3+), 657 nm red (Ho3+) and 476 nm blue (Tm3+) main emissions were analyzed to have average decay times of ~52 ± 2, 260.6 ± 0.7 and 117 ± 1 µs, respectively. It was shown that (1) the Er3+ doped phosphor has a better overall performance of temperature sensing with thermally coupled 2H11/2 and 4S3/2 energy levels, whose maximum absolute (S A) and relative (SR ) sensitivities are ~5.07 × 10-3 K-1 at 523 K and ~1.16% at 298 K, respectively; (2) the Ho3+ doped phosphor shows maximum S A and SR values of ~0.019 K-1 (298-573 K) and 0.42% at 573 K for the non-thermally coupled energy pairs of 5F5/(5F4,5S2) and 5I4/5F5, respectively; (3) the Tm3+ doped phosphor has a maximum S A of ~12.74 × 10-3 K-1 at 573 K for the non-thermally coupled 3F2,3/1G4 energy levels and a maximum SR of ~1.74% K-1 at 298 K for the thermally coupled 3F2,3/3H4 levels. Advantages of the current phosphors in optical temperature sensing were also revealed by comparing with other typical UC phosphors.

Downregulation of RASSF6 promotes breast cancer growth and chemoresistance through regulation of Hippo signaling.

This study aims to investigate the clinical significance and biological function of RASSF6 in human breast cancers. RASSF6 protein was found to be downregulated in 42 of 95 human breast cancer tissues by immunohistochemistry, which was associated with advanced TNM stage and nodal metastasis. The rate of RASSF6 downregulation was higher in Triple-negative breast cancer (TNBC). Downregulation of RASSF6 protein was also found in breast cancer cell lines, especially in TNBC cell lines. Overexpression RASSF6 inhibited cell growth rate and colony formation ability in MDA-MB-231 cell line. Depletion of RASSF6 promoted proliferation rate and colony formation ability in T47D cell line. Flow cytometry/PI staining demonstrated that RASSF6 inhibited cell cycle transition. AnnxinV/PI analysis showed that RASSF6 overexpression upregulated apoptosis induced by cisplatin (CDDP) while RASSF6 depletion inhibited apoptosis. JC-1 staining showed that RASSF6 overexpression inhibited mitochondrial membrane potential. Western blot analysis demonstrated that RASSF6 repressed cyclin D1, YAP while upregulated p21, cleaved caspase 3 and cytochrome c expression. In addition, RASSF6 activated Hippo signaling pathway by upregulating MST1/2 and LATS1 phosphorylation. Restoration of YAP inhibited cleaved caspase 3 and cytochrome c which were induced by RASSF6. Restoration of YAP also reduced the rate of CDDP induced apoptosis. In conclusion, this study provided evidence that RASSF6 functions as a potential tumor suppressor in human breast cancer through activation of Hippo pathway.

Crystal Structure of NaLuW2O8·2H2O and Down/Upconversion Luminescence of the Derived NaLu(WO4)2:Yb/Ln Phosphors (Ln = Ho, Er, Tm).

Hydrothermally reacting Lu(NO)3 and Na2WO4·2H2O at 200 °C and pH = 8 produced the new compound NaLuW2O8·2H2O, which was analyzed via the Rietveld technique to crystallize in the orthorhombic system (space group: Cmmm) with cell parameters a = 21.655(1), b = 5.1352(3), and c = 3.6320(2) Å and cell volume V = 403.87(4) Å3. The crystal structure presents -(NaO6)-(NaO6)- and -(LuO4(H2O)2WO5)-(LuO4(H2O)2WO5)- alternating layers linked together by the O2- ion common to NaO6 octahedron and WO5 triangle bipyramid. Tetragonal structured and phase-pure Na(Lu0.87Ln0.03Yb0.1)(WO4)2 phosphors (Ln = Ho, Er, and Tm) were directly produced by calcining their NaLuW2O8·2H2O analogous precursors at 600 °C for 2 h, followed by a detailed study of their downconversion/upconversion (DC/UC) photoluminescence. It was shown that the UC luminescence is dominated by a red band at ∼650 nm for Ho3+ (5F5 → 5I8 transition), green bands at ∼500-575 nm for Er3+ (2H11/2/4S3/2 → 4I15/2 transitions) and a blue band at ∼476 nm for Tm3+ (1G4 → 3H6 transition), all via a three-photon process. DC luminescence of the phosphors is characterized by a ∼545 nm green emission for Ho3+ (5F4/5S2 → 5I8 transition, λex = 453 nm), ∼500-575 nm green emissions for Er3+ (2H11/2/4S3/2 → 4I15/2 transitions, λex = 380 nm), and a ∼455 nm blue emission for Tm3+ (1D2 → 3F4 transition, λex = 360 nm), with CIE chromaticity coordinates of around (0.27, 0.71), (0.26, 0.72), and (0.15, 0.04), respectively.

NaLaW2O7(OH)2(H2O): Crystal Structure and RE3+ Luminescence in the Pristine and Annealed Double Tungstates (RE = Eu, Tb, Sm, and Dy).

Hydrothermal reaction of La(NO3)3 and Na2WO4·2H2O at 100 °C and pH 8 resulted in the formation of new compound NaLaW2O7(OH)2(H2O), as confirmed by the X-ray diffraction results, chemical composition, Fourier transform infrared, thermogravimetric/differential thermal analysis, and transmission electron microscopy analyses. The crystal structure was determined in the triclinic system (space group P1̅), with lattice constants a = 5.8671(2) Å, b = 8.2440(2) Å, and c = 9.0108(3) Å, axis angles α = 93.121(2)°, ß = 75.280(2)°, and γ = 94.379(2)°, and cell volume V = 420.03(2) Å3. The structure contains two-dimensional layers of -(W1O6)-(W1O6)-(W2O6)-(W2O6)-(W1O6)-(W1O6)- and -LaO9-LaO9- chains alternating in the a-b plane, which are linked together through NaO6 octahedral trigonal prisms by edges to form a three-dimensional net. Dehydration of the compound proceeds up to a low temperature of ∼350 °C and results in the formation of technologically important NaLa(WO4)2 double tungstate, which is thus a unique precursor for the latter. Na(La,RE)W2O7(OH)2(H2O) and Na(La,RE)(WO4)2 solid solutions separately doped with the practically important activators for which RE = Eu, Tb, Sm, and Dy were also successfully synthesized and investigated for their structural features and photoluminescence properties, including excitation, emission, quantum yield, emission color, and fluorescence decay kinetics. The compounds were shown to exhibit dominantly strong red (∼616 nm for Eu3+; λex = 395 or 464 nm), green (∼545 nm for Tb3+; λex = 278 or 258 nm), deep red (∼645 nm for Sm3+; λex = 251 nm), and yellow (∼573 nm for Dy3+; λex = 254 nm) emission upon being irradiated with the peak wavelengths of their strongest excitation bands.

Selective Crystallization of Four Tungstates (La2W3O12, La2W2O9, La14W8O45, and La6W2O15) via Hydrothermal Reaction and Comparative Study of Eu3+ Luminescence.

Hydrothermal reaction at 200 °C was systematically undertaken in wide ranges of solution pH (4-13) and W/La molar ratio ( R = 0.5-2), without using any organic additive, to investigate the effect of hydrothermal parameter on product property and the underlying mechanism. Combined analysis by X-ray diffraction (XRD), inductively coupled plasma (ICP) spectroscopy, elemental mapping, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that either a decreasing pH or increasing R value yielded a product richer in W and, conversely, richer in La. The results were interpreted from the solution chemistry of La3+ and tungstate ions. As an outcome of our 40 well-designed experiments, four La tungstates-La2W3O12, La2W2O9, La14W8O45, and La6W2O15-were successfully obtained in a phase-pure form by calcining their hydrothermal precursors. Phase and morphology evolution, structure features, and properties of Eu3+ emission were, for the first time, comparatively investigated for the four compounds. Spectral analysis found that the 5 at. % Eu3+-doped La2W3O12 phosphor exhibits the highest quantum efficiency (∼47%), more red component, and the shortest fluorescence lifetime of luminescence (∼0.72 ms).

Controlled Hydrothermal Crystallization of Anhydrous Ln2 (OH)4 SO4 (Ln=Eu-Lu, Y) as a New Family of Layered Rare Earth Metal Hydroxides.

Anhydrous hydroxide sulfates Ln2 (OH)4 SO4 (Ln=Eu-Lu, Y) were hydrothermally synthesized as a new family of layered rare earth metal hydroxides (LRHs). They crystallize in the monoclinic system (space group C2/m) with structures built up by alternate stacking of interlayer SO42- and the two-dimensional host layer composed of tricapped [LnO9 ] trigonal prisms along the a axis. In distinct contrast to the recently discovered hydrated LRHs Ln2 (OH)4 SO4 ⋅2 H2 O, which only exist for Ln=La-Dy, the host layers of the anhydrous phase are linked together by sharing edges instead of an O node of the SO42- tetrahedron. Rietveld refinement showed that the cell dimension tends to decrease for smaller Ln3+ , while the axis angle (ß=98.78-100.31°) behaves oppositely. Comparative thermogravimetric/differential thermal analysis in air revealed that the dehydroxylation and desulfurization temperatures become gradually higher and lower, respectively, for smaller Ln3+ , and thus the temperature range of Ln2 O2 SO4 existence is narrowed. The newly discovered Ln2 (OH)4 SO4 , together with their hydrated counterparts, allow for the first time green synthesis of Ln2 O2 SO4 with water as the only exhaust for the full spectrum of lanthanides. Calcining Ln2 (OH)4 SO4 in H2 yielded phase-pure Ln2 O2 S for Eu and Gd and a mixture of Ln2 O2 S and Ln2 O3 for the other Ln. The effects of the lanthanide contraction were clearly revealed, and photoluminescence was found for the anhydrous LRHs of Eu and Tb.

Oriented and Yellow-Emitting Nano-Phosphor Films of High Transparency Assembled from Exfoliated Nanosheets of Layered Rare-Earth Hydroxide (LRH).

(Y0(.975− x)) Gd(x)Dy(0.025)(2)(OH)(5)NO(3) · nH2O (0 ≤ x ≤ 0.975) LRH crystals with tens of micron sized laterals have been hydrothermally synthesized by adding mineralizer NH(4)NO(3). Smaller LRHs particles, expanded main layer, and shorter interlayer distance were found at a higher Gd incorporation. Free anions NO− 3 at the interlayer of LRHs have been completely replaced by oleate anions with the help of hydrothermal processing, thus weakening the interaction of layers. Therefore, tens of micron sized LRH nanosheets can be easily exfoliated from the oleate-intercalated LRHs in toluene. Highly [111] oriented and transparent films of (Y0975− x Gd x Dy0.025)2O3 (0 ≤ x ≤ 0.975), with thicknesses of ~12 nm, have been constructed through spin-coating the colloidal suspension of exfoliated nanosheets on quartzs, followed by calcination at 800 °C. Under excitation at 270 nm, the oxide films exhibit typical yellow emission at 576 nm, whose intensity shows a clear dependence on Gd3+ concentration. Increasing the Gd content from 0 to 97.5 at.% yielded a 450% increase in the yellow emission intensity, owing to the energy transfer from Gd(3+) to Dy(3+). Because Gd(3+) content has little influence on fluorescence lifetime, fluorescence decay analysis yields similar lifetimes of ~1.45 ± 0.30 ms for all the samples.

EDTA-assisted phase conversion synthesis of (Gd0.95RE0.05)PO4 nanowires (RE = Eu, Tb) and investigation of photoluminescence.

Hexagonal (Gd0.95RE0.05)PO4·nH2O nanowires ~300 nm in length and ~10 nm in diameter have been converted from (Gd0.95RE0.05)2(OH)5NO3·nH2O nanosheets (RE = Eu, Tb) in the presence of monoammonium phosphate (NH4H2PO4) and ethylene diamine tetraacetic acid (EDTA). They were characterized by X-ray diffraction, thermogravimetry, electron microscopy, and Fourier transform infrared and photoluminescence spectroscopies. It is shown that EDTA played an essential role in the morphology development of the nanowires. The hydrothermal products obtained up to 180 °C are of a pure hexagonal phase, while monoclinic phosphate evolved as an impurity at 200 °C. The nanowires undergo hexagonal→monoclinic phase transformation upon calcination at ≥600 °C to yield a pure monoclinic phase at ~900 °C. The effects of calcination on morphology, excitation/emission, and fluorescence decay kinetics were investigated in detail with (Gd0.95Eu0.05)PO4 as example. The abnormally strong 5D0→7F4 electric dipole Eu3+ emission in the hexagonal phosphates was ascribed to site distortion. The process of energy migration was also discussed for the optically active Gd3+ and Eu3+/Tb3+ ions.

Recent progress in advanced optical materials based on gadolinium aluminate garnet (Gd3Al5O12).

This review article summarizes the recent achievements in stabilization of the metastable lattice of gadolinium aluminate garnet (Gd3Al5O12, GAG) and the related developments of advanced optical materials, including down-conversion phosphors, up-conversion phosphors, transparent ceramics, and single crystals. Whenever possible, the materials are compared with their better known YAG and LuAG counterparts to demonstrate the merits of the GAG host. It is shown that novel emission features and significantly improved luminescence can be attained for a number of phosphor systems with the more covalent GAG lattice and the efficient energy transfer from Gd3+ to the activator. Ce3+ doped GAG-based single crystals and transparent ceramics are also shown to simultaneously possess the advantages of high theoretical density, fast scintillation decay, and high light yields, and hold great potential as scintillators for a wide range of applications. The unresolved issues are also pointed out.

Tens of micron-sized unilamellar nanosheets of Y/Eu layered rare-earth hydroxide: efficient exfoliation via fast anion exchange and their self-assembly into oriented oxide film with enhanced photoluminescence.

Layered rare-earth hydroxide (LRH) crystals of (Y0.95Eu0.05)2(OH)5NO3·nH2O with a lateral size of ∼ 300 µm and a thickness of ∼ 9 µm have been synthesized via a hydrothermal reaction of mixed nitrate solutions in the presence of mineralizer NH4NO3 at 200 °C for 24 h. LRH exhibits the ability to undergo intercalation and anion exchange with DS- (C12H25OSO3-) via hydrothermal treatment. Compared with traditional anion exchange at room temperature, hydrothermal processing not only shortens the anion exchange time from 720 to 24 h but also increases the basal spacing. The arrangements of DS- in the interlayer of LRH are significantly affected by the DS- concentration and reaction temperature, and the basal spacing of the LRH-DS sample in the crystal edge is assumed to be larger than that in the crystal center. A higher DS- concentration and reaction temperature both induce more intercalation of DS- anions into the interlayer gallery, thus yielding a larger basal spacing. Unilamellar nanosheets with a lateral size of ≽60 µm and a thickness of ∼ 1.6 nm can be obtained by delaminating LRH-DS in formamide. The resultant unilamellar nanosheets are single crystalline. Transparent (Y0.95Eu0.05)2O3 phosphor films with a uniform [111] orientation and a layer thickness of ∼ 90 nm were constructed with the nanosheets as building blocks via spin-coating, followed by proper annealing. The oriented oxide film exhibits a strong red emission at 614 nm (the 5D0-7F2 transition of Eu3+), whose intensity is ∼ 2 times that of the powder form owing to the significant exposure of the (222) facets.

Facile and green synthesis of (La0.95Eu0.05)2O2S red phosphors with sulfate-ion pillared layered hydroxides as a new type of precursor: controlled hydrothermal processing, phase evolution and photoluminescence.

This study presents a facile and green route for the synthesis of (La0.95Eu0.05)2O2S red phosphors of controllable morphologies, with the sulfate-type layered hydroxides of Ln2(OH)4SO4·2H2O (Ln = La and Eu) as a new type of precursor. The technique takes advantage of the fact that the precursor has had the exact Ln:S molar ratio of the targeted phosphor, thus saving the hazardous sulfurization reagents indispensable to traditional synthesis. Controlled hydrothermal processing at 120 °C yielded phase-pure Ln2(OH)4SO4·2H2O crystallites in the form of either nanoplates or microprisms, which can both be converted into Ln2O2S phosphor via a Ln2O2SO4 intermediate upon annealing in flowing H2 at a minimum temperature of ∼ 700 °C. The nanoplates collapse into relatively rounded Ln2O2S particles while the microprisms retain well their initial morphologies at 1 200 °C, thus yielding two types of red phosphors. Photoluminescence excitation (PLE) studies found two distinct charge transfer (CT) excitation bands of O2- → Eu3+ at ∼ 270 nm and S2- → Eu3+ at ∼ 340 nm for the Ln2O2S phosphors, with the latter being stronger and both significantly stronger than the intrinsic intra-f transitions of Eu3+. The two types of phosphors share high similarities in the positions of PLE/PL (photoluminescence) bands and both show the strongest red emission at 627 nm (5D0 → 7F2 transition of Eu3+) under S2- → Eu3+ CT excitation at 340 nm. The PLE/PL intensities show clear dependence on particle morphology and calcination temperature, which were investigated in detail. Fluorescence decay analysis reveals that the 627 nm red emission has a lifetime of ∼ 0.5 ms for both types of the phosphors.

Prognostic significance of body mass index in breast cancer patients with hormone receptor-positive tumours after curative surgery.

PURPOSE: Obesity has been recognized as a significant risk factor for postmenopausal breast cancer. The aim of this study is to investigate the prognostic significance of body mass index (BMI) in hormone receptor-positive, operable breast cancer. METHODS: In this retrospective cohort study, 1,192 consecutive patients with curative resection of primary breast cancer were enrolled. Patients were assigned to two groups according to BMI: normal or underweight (BMI < 23.0 kg/m²) and overweight or obese (BMI ≥ 23.0 kg/m²). Associations among BMI and clinicopathological characteristics and prognosis of patients were assessed. RESULTS: A high BMI was significantly (P < 0.01) correlated with age, nodal stage, ALNR, ER positivity, PR positivity and menopausal status at diagnosis. Univariate analysis revealed that BMI, pathologic T stage, nodal stage, axillary lymph node ratio (ALNR) and adjuvant radiotherapy history were significantly (P < 0.05) associated with disease-free survival and overall survival, irrespective of tumour hormone receptor status. Multivariate analysis revealed BMI as an independent prognostic factor in all cases and in hormone receptor-positive cases. CONCLUSION: A high BMI (≥ 23.0 kg/m²) is independently associated with poor prognosis in hormone receptor-positive breast cancer.

Controlled processing of (Gd,Ln)2O3:Eu (Ln = Y, Lu) red phosphor particles and compositional effects on photoluminescence.

Synthesis of (Gd0.95-x Ln x Eu0.05)2O3 (Ln = Y and Lu, x = 0-0.95) powders via ammonium hydrogen carbonate (AHC) precipitation has been systematically studied. The best synthesis parameters are found to be an AHC/total cation molar ratio of 4.5 and an ageing time of 3 h. The effects of Y3+ and Lu3+ substitution for Gd3+, on the nucleation kinetics of the precursors and structural features and optical properties of the oxides, have been investigated. The results show that (i) different nucleation kinetics exist in the Gd-Y-Eu and Gd-Lu-Eu ternary systems, which lead to various morphologies and particle sizes of the precipitated precursors. The (Gd,Y)2O3:Eu precursors display spherical particle morphologies and the particle sizes increase along with more Y3+ addition. The (Gd,Lu)2O3:Eu precursors, on the other hand, are hollow spheres and the particle sizes increase with increasing Lu3+ incorporation, (ii) the resultant oxide powders are ultrafine, narrow in size distribution, well dispersed and rounded in particle shape, (iii) lattice parameters of the two kinds of oxide solid solutions linearly decrease at a higher Y3+ or Lu3+ content. Their theoretical densities linearly decrease with increasing Y3+ incorporation, but increase along with more Lu3+ addition and (iv) the two kinds of phosphors exhibit typical red emissions at ∼613 nm and their charge-transfer bands blue shift at a higher Y3+ or Lu3+ content. Photoluminescence/photoluminescence excitation intensities and external quantum efficiency are found to decrease with increasing value of x, and the fluorescence lifetime mainly depends on the specific surface areas of the powders.

Layered rare-earth hydroxide and oxide nanoplates of the Y/Tb/Eu system: phase-controlled processing, structure characterization and color-tunable photoluminescence via selective excitation and efficient energy transfer.

Well-crystallized (Y0.97-x Tb0.03Eu x )2(OH)5NO3·nH2O (x = 0-0.03) layered rare-earth hydroxide (LRH) nanoflakes of a pure high-hydration phase have been produced by autoclaving from the nitrate/NH4OH reaction system under the optimized conditions of 100 °C and pH ∼7.0. The flakes were then converted into (Y0.97-x Tb0.03Eu x )2O3 phosphor nanoplates with color-tunable photoluminescence. Detailed structural characterizations confirmed that LRH solid solutions contained NO3- anions intercalated between the layers. Characteristic Tb3+ and Eu3+ emissions were detected in the ternary LRHs by selectively exciting the two types of activators, and the energy transfer from Tb3+ to Eu3+ was observed. Annealing the LRHs at 1100 °C produced cubic-lattice (Y0.97-x Tb0.03Eu x )2O3 solid-solution nanoplates with exposed 222 facets. Multicolor, intensity-adjustable luminescence was attained by varying the excitation wavelength from ∼249 nm (the charge transfer excitation band of Eu3+) to 278 nm (the 4f8-4f75d1 transition of Tb3+). Unitizing the efficient Tb3+ to Eu3+ energy transfer, the emission color of (Y0.97-x Tb0.03Eu x )2O3 was tuned from approximately green to yellowish-orange by varying the Eu3+/Tb3+ ratio. At the optimal Eu3+ content of x = 0.01, the efficiency of energy transfer was ∼91% and the transfer mechanism was suggested to be electric multipole interactions. The phosphor nanoplates developed in this work may be incorporated in luminescent films and find various lighting and display applications.

The development of Ce3+-activated (Gd,Lu)3Al5O12 garnet solid solutions as efficient yellow-emitting phosphors.

Ce3+-activated Gd3Al5O12 garnet, effectively stabilized by Lu3+ doping, has been developed for new yellow-emitting phosphors. The powder processing of [(Gd1-x Lu x ) 1-y Ce y ]3Al5O12 solid solutions was achieved through precursor synthesis via carbonate precipitation, followed by annealing. The resultant (Gd,Lu)AG:Ce3+ phosphor particles exhibit typical yellow emission at ∼570 nm (5d-4f transition of Ce3+) upon blue-light excitation at ∼457 nm (the 2F5/2-5d transition of Ce3+). The quenching concentration of Ce3+ was determined to be ∼1.0 at% (y = 0.01) and the quenching mechanism was suggested to be driven by exchange interactions. The best luminescent [(Gd0.9Lu0.1)0.99Ce0.01]AG phosphor is comparative to the well-known YAG:Ce3+ in emission intensity but has a substantially red-shifted emission band that is desired for warm-white lighting. The effects of processing temperature (1000-1500 °C) on the spectroscopic properties of the phosphors, especially those of Lu3+/Ce3+, were thoroughly investigated and discussed from the centroid position and crystal field splitting of the Ce3+ 5d energy levels.