Strong Orange Research Articles

Experimental study on combustion characteristics of engineered bamboo considering smoldering and self-extinction

Bamboo and wood materials have the characteristics of low carbon and high strength, making them the best building material for building green buildings. Compared to traditional building materials, the easy to burn characteristic has become an obstacle to the promotion and widespread application of bamboo and wood materials, so it is urgent to study their combustion characteristics. This article investigated the combustion characteristics of engineered bamboo at different heat fluxes, taking into account the smoldering and self-extinction characteristics through cone calorimeter experiments. The combustion performance, mass loss rate, heat release rate, etc. were studied, and the self-extinction phenomenon of the specimens was explored. The results indicated that the direction of heating had a certain impact on the combustion characteristics of glued laminated bamboo (LBL), and the fire resistance of parallel strand bamboo (PSB) was better than that of LBL. When the heat flux exceeded 50 kW/m2, the color of the flame on the surface of the specimen would change from bright yellow to strong orange, which is an important sign that the flame will self-extinguish. The self-extinction of flames at different heat fluxes was caused by insufficient supply of combustible gas generated by bamboo pyrolysis, with slightly different specific reasons. The multi-layer structure of glued laminated bamboo also makes it more difficult to self-extinguish than PSB, cross-laminated timber (CLT), and solid wood is the most prone to self-extinguish. The impact of adhesive layer delamination was not considered in this experiment, and further research is needed.

The Mn2+‐Doped Chiral 2D Perovskite with Strong Orange Fluorescent and Enhanced Circularly Polarized Luminescence

AbstractRecently, the potential circularly polarized luminescence (CPL) property of chiral 2D organic–inorganic hybrid perovskites has garnered attention due to their strong stability. However, the photoluminescence (PL) intensity of chiral 2D perovskite is generally low, which undoubtedly limits its development. Therefore, improving the PL and CPL intensity of chiral 2D perovskite has become an important focal point. To overcome this problem, a series of Mn2+‐doped R/S‐(MPEA)2PbBr4 thin films is successfully synthesized. The Mn2+‐doped films can produce strong orange emission under UV excitation with the highest photoluminescence quantum yield (PLQY) of 37.37%, a high value among reported chiral 2D perovskites. Moreover, all Mn: (R/S‐MPEA)2PbBr4 films show symmetric CPL signals. The flexible regulation of CPL is meaningful for applications, which is generally lacking in current studies. Here, it is found that the strength of CPL can be effectively regulated by doping guanidine (Gua), and the maximum glum value of 1.4 × 10−2 and PLQY of 51.31% is achieved, which are the highest among reported chiral 2D perovskites. This work provides a new idea for the development of CPL‐active materials and lays the foundation for spin devices based on chiral hybrid 2D perovskite.

Microwave-assisted solvothermal synthesis of Eu3+-doped CsY2F7 and RbY2F7 phosphorescent nanoparticles

We synthesized Eu3+-doped CsY2F7 and RbY2F7 nanoparticles (orthorhombic crystal structure, Pnna space group, No. 52) by the microwave-assisted solvothermal technique and investigated the influence of reaction temperature and fluoride ion concentration on the particles’ phase and crystal structure. Fluoride ions were added in excess of the stoichiometric amount to achieve the orthorhombic phase for CsY2F7 and to convert the cubic RbY3F10 to the orthorhombic RbY2F7. Mild synthesis conditions yielded nanoparticles with crystallites ranging in size from 19 to 37 nm and a combination of spherical, rod-like, and hexagonal shapes. Nanoparticles emit a strong orange and red light when excited into the Eu3+5L6 level, which is centered around 390 nm. The strongest emission peak is around 612 nm, which comes from the 5D0→7F2 electronic transitions. Emission intensity dependence on Eu3+ concentration revealed that nanoparticles can be heavily doped with Eu3+, up to 25 % with respect to Y3+. Emission decay measurements provided values of excited state lifetimes of 6.2 ms for the Cs(Y0.75Eu0.25)2F7 and 6.0 ms for the Rb(Y0.75Eu0.25)2F7.

Yellow and Orange–Red Room‐Temperature Phosphorescence from Amorphous Nonaromatic Polymers

AbstractMany nontraditional luminogens (NTLs) without any large π‐conjugated structures are reported to exhibit room‐temperature phosphorescence (RTP). Unfortunately, the reported NTLs mostly emit blue or green RTP. Achieving more redshifted RTP from NTLs remains a great challenge. Herein, a series of nonaromatic polymers exhibiting yellow and orange–red RTP are reported. Poly(itaconic anhydride) (PITA) does not exhibit RTP, its hydrolyzed product poly(itaconic acid) (PITAc) exhibits weak yellow RTP, but the ionized product poly(sodium itaconate) (PITANa) can emit stronger and redshifted RTP. Moreover, the ionized copolymers poly(vinyl pyrrolidone‐co‐sodium itaconate) (PIVPNa) and poly(vinyl pyrrolidone‐co‐sodium maleate) (PMVPNa), the mixture of PITANa/poly(vinyl pyrrolidone) (PVP), and the full hydrolyzed product of poly(vinyl caprolactam‐co‐sodium itaconate) (PIVCNa) all exhibit strong orange–red RTP emissions at ≈600 nm. Structural characterizations and theoretical calculations prove that hydrogen bonding and ionic bonds lead to the rigidification of polymer chain conformations, and more importantly, both intra‐ and interchain nonaromatic electron donor–acceptor (nDA) structures and hence through‐space charge transfer are formed between carboxylate and lactam groups in proper conformations, which facilitates the occurrence and redshift of RTP in NTLs. This work provides a novel strategy to design NTLs with redshifted RTP and improves the understanding of the photoluminescence mechanism of NTLs.

A study on structural and luminescence properties of novel orange-red emitting Sm3+ doped Sr3LiSbO6 nanorod phosphor with high color purity for W-LEDs

Being a simple synthesis technique, solid state reaction (SSR) method seldom generates 1D nanorod structured phosphors. In this article, we present a systematic study on the structural, morphological and spectroscopic properties of double perovskite type Sr3LiSbO6:Sm3+ phosphors prepared by the conventional SSR method. X-ray diffraction (XRD) analysis confirm the successful synthesis of hexagonal structured Sr(3−x)LiSbO6:xSm3+(x = 0,0.06,0.08,0.1,0.2,0.4 mol) phosphors and Fourier-Transform Infrared spectra (FTIR) revealed the molecular vibrations present in the samples. The surface morphology was confirmed by Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) analysis. The TEM images illustrate the one – dimensional nanorod structure of the phosphor with an average diameter of 35 nm and length of 350 nm. In photoluminescence (PL) spectroscopy, under an excitation of 406 nm the characteristic emissions at 564, 601, 649 and 710 nm, which correspond to the transitions from 4G5/2 to 6H5/2, 6H7/2, 6H9/2 and 6H11/2 respectively of Sm3+ were obtained with strong orange - red emission at 601 nm. The concentration quenching was observed at x = 0.1 mol and the critical distance for energy transfer between Sm3+ ions was calculated to be 14.32 Å. The energy transfer mechanism was determined to be dipole-dipole interaction. The decay analysis confirms the shorter life time of the activator ions in the microseconds (µs) range. The estimated CIE coordinates are (0.6057, 0.397) in the warm CCT region with 100 % color purity. Hence these results suggests that Sm3+ doped Sr3LiSbO6 to be a potential orange-red nanorod phosphor in the design of various photonic devices such as phosphor converted LEDs (pc- LEDs).

Multicolor and warm white luminescence from Dy3+/Eu3+ co-activated glasses for indoor and solid-state lighting applications

Multicolor emitting Dy3+/Eu3+ coactivated lithium zinc borate (LZB) glasses were prepared by the melt-quenching method and their structural, vibrational, morphological, and luminescence properties were investigated. Dy3+ glasses exhibited blue, yellow, and red photoluminescence (PL) bands at 481 nm (4F9/2 → 6H15/2), 576 nm (4F9/2 → 6H13/2), and 665 nm (4F9/2 → 6H11/2) under 386 nm excitation. Eu3+ glasses exhibited strong orange and reddish-orange emissions at 589 nm (5D0→7F1) and 612 nm (5D0→7F2) at 393 nm of excitation. 0.5 mol% Dy3+ is codoped with various Eu3+ concentrations and the energy transfer mechanism is analyzed from the spectral overlay of Dy3+ emission and Eu3+ absorption, Dy3+/Eu3+ PL, and decay profiles as well as from energy transfer parameters. Dy3+/Eu3+ codoped glasses stimulated under different excitation wavelengths of Dy3+ (349, 363, and 386 nm) displayed a decline in the intensity of Dy3+ PL bands and a simultaneous rise in Eu3+ PL bands, demonstrating efficient energy transfer from Dy3+: 4F9/2 → Eu3+: 5D0 due to dipole-dipole interaction. The energy transfer process is supported by a decrement in the lifetimes of Dy3+ when co-doped with Eu3+ compared with singly doped Dy3+ones. The color coordinates and corresponding color temperatures were shifted from neutral to a warm white light region depending on the Eu3+ concentration. The aforementioned results demonstrate the importance of the near-ultraviolet-driven LZB: Dy3+/Eu3+ glasses for their potential application in warm white light and multicolor emitting devices.

Ophiocordyceps asiana and Ophiocordyceps tessaratomidarum (Ophiocordycipitaceae, Hypocreales), two new species on stink bugs from Thailand

Two new Ophiocordyceps species from Thailand, which belong to Ophiocordyceps nutans species complex and attack adult and nymph of stink bugs, are described: Ophiocordyceps asiana and O. tessaratomidarum. Molecular phylogenetic analyses of ITS and a combined sequence data of LSU, RPB1 and TEF1 revealed that these two new species are distinct from other known species in Ophiocordyceps nutans species complex. Based on the findings on morphological studies, they further support the naming of these two novel species. Ophiocordyceps asiana is parasitic on adult and nymph stink bugs, members of Coreidae and Pentatomidae which were recorded from China, Japan and Thailand, while O. tessaratomidarum is reported from Thailand for the first time and is only found as a parasite on adult stink bug, Tessaratoma papillosa (Tessaratomidae, Hemiptera). The fertile heads of O. asiana are shorter than reported for O. tessaratomidarum, and the colours of fertile heads producing teleomorph of these two species differs from each other by having strong reddish orange or light yellowish pink in O. asiana and pale yellow in O. tessaratomidarum.

First description of color variations in the annual killifish Millerichthys robustus, and preliminary observations about its geographical distribution

Millerichthys robustus is the only annual killifish distributed in America with phenotypic color variations, not yet described. Accordingly, we first describe the color pattern in both sexes to define its phenotypical variations. We then analyze the frequency of these phenotypes on a geographical scale, in four localities that represent opposite points of Millerichthys’s distribution in the Mexican southeast. Color analysis based on the RGB system allowed us to define five-color phenotypes in males continuously distributed in various perceptual units between two extreme colors (yellow-red): yellow, moderate orange, dark orange, strong orange and red. These color patterns found in M. robustus could be attributed to melanin, carotenoid, and pteridine pigments. The orange phenotypes was present in all localities studied. The yellow phenotype was present only in northeastern and northwestern locations, and the red phenotype was present only in northern populations. Female color variations were observed in the number of ocelli (from 1 to 15) at the base of the caudal peduncle and dorsal region. Ocelli have been associated with anti-predator functions because they resemble the eyes of vertebrates, thus shifting the target of predator attacks to less vital body parts. Females with 3 ocelli were the most frequent phenotype, and females with 13–15 ocelli occurred only in the northern populations. We concluded that male and female of M. robustus are not randomly distributed along their distribution range, which suggest that color phenotypes may react differently to biotic and abiotic factors that probably determine their distribution and frequency within the studied population.

An insight into the luminescent properties and Judd–Ofelt analysis of Eu3+ doped CaZn2(PO4)2 phosphors

A batch of Eu3+ doped CaZn2(PO4)2 orange–red emitting phosphors were synthesized by the conventional high temperature solid state reaction method. The structural, morphological and spectroscopic properties of the prepared samples were investigated by experimental and theoretical studies. Powder XRD and FTIR results were used to evaluate the structural aspects of the prepared phosphors and morphology was investigated by TEM analysis. The elemental composition analysis of the representative sample was made using energy dispersive x-ray spectroscopy (EDS). The optical properties were analyzed with the aid of UV–Vis-NIR spectroscopy and photoluminescence (PL) spectroscopy. The PL excitation spectra revealed that the prepared phosphors can be efficiently excited under 393 nm that matches well with the dominant emission band of near UV- LED chip. The PL emission studies demonstrate the emission of an orange–red light with CIE coordinates (0.6075, 0.3920) with color purity 100.0% under an excitation of 393 nm. The maximum emission intensity was observed at Eu3+ concentration of 4 mol%, from which the critical distance (Rc = 1.98 nm) of quenching was calculated. The emission spectra were further used to interpret the site symmetry of Eu3+ ions. Judd–Ofelt theory was employed to predict various radiative properties such as branching ratio (βr), total transition probability (AT), radiative life time (τcalc) and stimulated emission cross section (σe). The thermal stability of the prepared phosphor was investigated using temperature dependent luminescence spectra and the emission intensity was observed to remain at 70.83% of its initial value when the temperature is raised from 310 K to 430 K. The decay kinetics analysis confirms the lifetime of the activator ions to be in the millisecond (ms) range. The better stimulated emission cross section and strong orange–red emission suggest the Eu3+ doped CaZn2(PO4)2 system as a promising candidate in the design of various optoelectronic devices such as phosphor converted LEDs (pc- LEDs) and display panels.

Sm3+ induced-SrWO4 phosphor: analysis of photoluminescence and photocatalytic properties with electron density distribution studies

In the present study, we designed a spherical shape like Sr1−xSmxWO4 (x = 0.0, 0.01, 0.02, 0.03, 0.04 and 0.05) materials by simple co-precipitation route and evaluated its photoluminescence and photocatalytic properties. The structural and morphological properties of as-prepared materials were studied by powder X-ray diffraction method, X-ray photoelectron spectroscopy, scanning electron micrographic images and transmission electron micrographic images. The photoluminescence behavior of Sm3+-doped SrWO4 for visible excitation (405 nm) was examined to analyze its use as white LED. The emission spectra consist of intra 4f transition of Sm3+ such as 4$${\text{G}}_{5/2}\to$$6$${\text{H}}_{5/2}$$ (561 nm), 4$${\text{G}}_{5/2}\to$$6$${\text{H}}_{7/2}$$ (601 nm), 4$${\text{G}}_{5/2}\to$$6$${\text{H}}_{9/2}$$ (642 nm) and 4$${\text{G}}_{5/2}\to$$6$${\text{H}}_{11/2}$$ (711 nm), respectively. Furthermore, the emission wavelength at 601 and 642 nm suggests a strong orange and red emission, which can be applied for the application for near-UV excitation. On the other hand, Sm3+-doped SrWO4 played excellent catalyst towards the photodegradation of Ibuprofen (IBF). The obtained results from the UV-Vis spectroscopy suggested that 3% of Sm3+-doped SrWO4 had high photocatalytic activity compared to other materials. The degradation efficiency of Sr0.97Sm0.03WO4 toward IBF was observed about 97% within 80 min under visible irradiation and it showed good stability by observing the reusability of catalyst. These results suggested that the Sm3+-doped SrWO4 material are suitable candidate for application in photoluminescence and photocatalysis.

Synthesis, physical properties and electroluminescence of functionalized pyrene derivative

Developing novel polycyclic aromatic hydrocarbons with high stability is of great importance, as well for opto-electronic applications as to provide novel materials for organic soft matter devices. Here the synthesis of a cyclized arene 13 and the corresponding acene-functionalized pyrene derivative 8 are described. Both molecules have been characterized by FT-IR, NMR spectroscopy, and mass spectroscopy. Their opto-electronic properties were determined from their absorption and emission spectra and electrochemistry and by theoretical calculations. Molecules 13 and 8 exhibit respectively a strong orange and cyan fluorescence in dichloromethane with high fluorescence quantum yields of 0.45 and 0.84 respectively, and present enhanced photo- and thermal stability compared to other large acenes. The organic light-emitting diodes using 13 and 8 as emitters were fabricated by via spin-coating way. After optimization they exhibited a maximum brightness of 2647 cd m−2 at 16.4 V with CIE coordinate of (0.61, 0.39) and 5620 cd m−2 at 7.2 V with CIE coordinate of (0.28, 0.64), respectively.

Gordonia oryzae sp. nov., isolated from rice plant stems (Oryza sativa L.).

A novel endophytic actinomycete, designated strain RS15-1ST, was isolated from surface-sterilized stems of Oryza sativa L. collected from Sisaket province, Thailand. The colony of strain was strong orange, catalase-positive and oxidase-negative. Growth occurred at a temperature range of 17-37 °C, at pH 4.0-9.0 and in the presence of 0-13 % (w/v) NaCl. Phylogenetic analyses based on the 16S rRNA sequences showed that strain RS15-1ST belonged to the genus Gordonia and was closely related to Gordonia polyisoprenivorans DSM 44302T (98.8 %) and Gordonia rhizosphera DSM 44383T (98.4 %). The major cellular fatty acids were C16 : 0, C18 : 0 10-methyl (tbsa), C16 : 1ω7c/C16 : 1ω6c and C18 : 1ω9c. The menaquinones were MK-9(H2) and MK-8(H2). Strain RS15-1ST contained meso-diaminopimelic acid, arabinose, galactose, mannose and ribose in whole-cell hydrolysates. The polar lipids of the strain were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol mannosides, an unidentified polar lipid and two unidentified phospholipids. The DNA G+C content was 66.3 mol%. In silico DNA-DNA hybridization of strain RS15-1ST showed 48.3 and 20.5 % relatedness to its closest neighbours, Gordonia polyisoprenivorans DSM 44302T and Gordonia rhizosphera DSM 44383T, respectively. Based on data of genotypic, phenotypic, phylogenetic and chemotaxonomic analysis, strain RS15-1ST represents a novel species of the genus Gordonia, for which the name Gordonia oryzae sp. nov. is proposed. The type strain is RS15-1ST (=TBRC 8485T=NBRC 113446T).

Kestabilan Fenotip Tanaman Labu Susu (Cucurbita moschata (Duchesne) Poir “Butternut”) Hasil Budidaya di Sleman D.I Yogyakarta

Butternut pumpkin ( Cucurbita moschata 'Butternut') is a horticultural commodity with great potential to be developed as food and medicine. Nutrients and unique shape cause butternut pumpkin to be popular. To supply of butternut pumpkin, required an increase in production which has superior and stable characters. This research aims to determine the stability phenotypic characters of butternut pumpkin in Sleman, Yogyakarta using quantitative data analysis of variance ( One Way ANOVA ) and qualitative analysis through descriptive phenotype. Based on the results, butternut pumpkin have a uniform phenotype characters but unstable in fruit’s shape and size of plant. Butternut pumpkin plants have 3 different shapes of pear or paprika form including dumbbell shape and gooseneck ( pyriform ), crispy texture, pale yellow (RHS greyed grange group 65) peel of fruit, strong orange (RHS orange group 24) flesh of fruit, 3-5°brix level of sweetness, long shelf life, and short harvest age (70-90 HST). The cultivated butternut pumpkin in PIAT UGM farmland has greater productivity of 3.1±0.99 kg/plant.

Photoluminescent properties of nanocrystalline Sm3+-doped CaO–CeO2system synthesized by an auto-igniting combustion synthesis technique

This study investigates the optical properties of samarium-doped microstructured and nanostructured CaO–CeO2mixed solutions. Conventional solid state method and auto-igniting combustion synthesis were used for the preparation of the samples. The as-prepared samples were characterized using X-ray diffraction, Fourier Transform Infrared spectroscopy, Transmission Electron Microscopy, UV-Visible spectroscopy and photoluminescence spectroscopy. A mixed phase formation with phases of CaO, CeO2and Ca(OH)2was observed form X-ray diffraction studies. The transmission electron microscopic studies have shown that the average particle size of the as-prepared powder was in the range of 30–40 nm. A blueshift is observed in the bandgap of the nanocrystalline samples. Strong orange–red emission was observed for Sm[Formula: see text]-doped samples and the chromaticity values were calculated using CIE chromaticity diagram.

From Sm3+:La2O3-ZnO-Na2O-TeO2 glasses to transparent glass ceramics containing ZnTeO3 and La2Te4O11 nanocrystals – Influence of the heat treatment on crystal growth and fluorescence properties

The paper presents the synthesis and spectroscopic properties of Sm3+-doped transparent TeO2-based glass ceramics containing ZnTeO3 and La2Te4O11 nanocrystals. The impact of heat treatment is presented and discussed. X-ray diffraction and transmission electron microscope results demonstrate that nanocrystals are precipitated homogenously among the glass matrix. Excitation in the 6P3/2 bands of Sm3+ produces a strong orange and red emission from the 4G5/2 level. The results show noticeable differences between glass precursor, bulk and nanocrystalline Sm3+:La2Te4O11 in luminescence experimental data.

Synthesis of Protein-Directed Orange/Red-Emitting Copper Nanoclusters via Hydroxylamine Hydrochloride Reduction Approach and Their Applications on Hg2+ Sensing

Herein, we report a facile one-pot method for the synthesis of orange/red-emitting fluorescent copper nanoclusters (Cu NCs), in which bovine serum albumin (BSA) served as the capping scaffold (Cu NCs@BSA) and hydroxylamine hydrochloride (NH2OH[Formula: see text][Formula: see text][Formula: see text]HCl) as the reducing agent. To the best of our knowledge, this is the first time to adopt this mild reductant to synthesize fluorescent Cu NCs. The as-prepared Cu NCs@BSA exhibits strong orange or red fluorescence at room temperature depending on the synthesis process, and the maximum excitation and emission peaks were at 355[Formula: see text]nm and 615[Formula: see text]nm, 395[Formula: see text]nm and 645[Formula: see text]nm, respectively. Synthesis conditions including the amounts of NH2OH[Formula: see text][Formula: see text][Formula: see text]HCl, the selection of reducing agent, the molar ratio of BSA/Cu(NO3)2, the pH value, the reaction temperature, the reaction time, and various kinds of Cu sources have been systematically studied. Importantly, these Cu NCs exhibit excellent stability for at least 2 months when stored at 4[Formula: see text]C in the dark, and they also show strong oxidation resistance toward H2O2. Moreover, the prepared Cu NCs have been successfully applied to sensitively and selectively sensing Hg[Formula: see text] without suffering any interference from other metal ions and anions.

Structure and Luminescence Characteristics of Eu3+‐Activated Trigonal Layered Perovskite Ba2La2ZnW2O12

Eu3+‐doped tungstate Ba2La2ZnW2O12 phosphors with perovskite‐structure were prepared by the high temperature solid‐state reaction. The X‐ray powder diffraction (XRD) patterns and structure refinements indicate that the phosphors crystalized in the trigonal layer‐perovskite. The luminescence properties of the phosphors were investigated such as photoluminescence (PL) excitation and emission spectra, decay lifetimes, and color coordinates. It was found that the pure host shows self‐activated emission excited by the UV light. Moreover, Ba2La2ZnW2O12 also shows scintillation characteristics under the X‐ray irradiation. The near‐UV and blue light can efficiently excite Eu3+‐doped Ba2La2ZnW2O12 phosphors inducing the strong orange–red luminescence. The optimal Eu3+ doping concentration in this host is 40 mol%. The luminescence spectra and the luminescence color of the phosphors strongly depend on the doping levels and excitation wavelength. The different luminescence features were discussed on the base of crystal structure. Eu3+ ions have two possible substitutions on A or B sites in this trigonal layered perovskite. The phosphor could act as a candidate for the potential application in near‐UV excited white‐LEDs lighting.

Synthesis and luminescence properties of highly uniform SiO2@LaPO4:Eu3+ core–shell phosphors

Abstract SiO 2 @LaPO 4 :Eu 3+ core–shell phosphors have been successfully synthesized by a one-step and economical wet-chemical route at low temperature. The as-obtained products were characterized by means of photoluminescence spectroscopy (PL), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). The SEM, EDS and XPS analysis indicate that SiO 2 @LaPO 4 :Eu 3+ core–shell phosphors can only be synthesized in a pH range of 8–11 and the possible mechanism has been proposed. The XRD results demonstrate that the structure of LaPO 4 :Eu 3+ layers is transferred into monoclinic phase from hexagonal phase after annealing at 800 °C for 2 h. The SiO 2 @LaPO 4 :Eu 3+ phosphors show strong orange–red luminescence under ultraviolet excitation. The relative emission intensity of Eu 3+ increases with increasing the annealing temperature and the number of coating cycles, and the optimum concentration for Eu 3+ was determined to be 5 mol% of La 3+ in SiO 2 @LaPO 4 phosphors.

Intense orange emission in Pr3+ doped lead phosphate glass

Spectroscopic properties of one mol% Pr2O3 embedded in 40%PbO–60%P2O5 glass have been investigated at room temperature. From the absorption spectra energy levels of the observed bands are assigned. Using free ion Hamiltonian theoretical values of energy of 13 multiplets of Pr3+ are calculated. Judd–Ofelt intensity parameters have been estimated by including and excluding the hypersensitive transition (3H4→3P2). The best set of Judd–Ofelt parameters are obtained by omitting 3H4→3P2 transition from the calculation. These parameters are used to evaluate the important laser parameters for various emission lines. Our investigation reveals that the present glass may be utilized as a laser active medium corresponding to 3P0→3H4 and 1D2→3H4 transitions respectively, for 484.6nm (blue) and 599.5nm (strong orange) emissions. Indirect and direct optical band gap energies of Pr3+ doped lead phosphate glass matrix have also been reported.

Fabrication of ZnWO4:Sm3+, Bi3+, Li+ with tunable white light-emitting properties for W-LEDs

The color-tunable phosphor ZnWO4:Sm3+, Bi3+, Li+ has been prepared via a solid–state reaction method. The white light was attributed to the color mixture of blue–green and orange–red emission, which originated from the charge transfer transition of W–O and the transition emission of Sm3+, respectively. The obtained phosphors exhibited a strong traditional band at 305nm and a new band at about 351nm which comes from the 1S0–3P1 transition of Bi3+. White light with tunable color emission for ZnWO4:Sm3+, Bi3+, Li+ phosphors were demonstrated by simply controlling the ratio of Sm3+/Li+. The calculated chromaticity coordinates were varying from blue to white region. When excited at about 351nm, these phosphors have a strong orange–red light. These results indicate that the phosphor of ZnWO4:Sm3+, Bi3+, Li+ which can generate tunable blue–white–red light may be a promising element for cost-effective diodes with near ultraviolet white light emitting properties.