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An emitting tunable Mg 2 Al 4 Si 5 O 18 :Ce 3+ /Mn 2+ /Tb 3+ phosphors have been synthesized by high-temperature solid-state reaction technique. In this system, Mg 2 Al 4 Si 5 O 18 :Ce 3+ , Mn 2+ samples exhibit two dominating bands situated at 430 and 640 nm, originating from the Ce 3+ , Mn 2+ ions, respectively. Photoluminescence and energy transfer in Mg 2 Al 4 Si 5 O 18 :Ce 3+ , Mn 2+ are investigated as a function of Mn 2+ concentrations. The intensity ratios of red to blue band as a function of Mn 2+ concentrations are calculated based on the analysis of the luminescence dynamical process as well as fluorescence lifetime measurements, and the results are in good agreement with that obtained directly from emission spectra. Additionally, by incorporation of Tb 3+ , an efficient energy transfer from Ce 3+ to Tb 3+ was found and the energy transfer efficiency reaches 52% at y = 0.05. Results indicated that the emitting colors can be adjusted from blue to red via the energy transfer of Ce 3+ → Mn 2+ and from blue to green via the energy transfer of Ce 3+ → Tb 3+ .

In this paper, Ce3+ doped and Ce3+,Mn2+ co-doped Na2Ba6(Si2O7)(SiO4)2 phosphors were synthesized via a high temperature solid-state reaction. The Rietveld refinement analysis of the X-ray diffraction patterns confirmed the formation of the single phase of Na2Ba6(Si2O7)(SiO4)2. The PL spectrum of the Ce3+ single-doped phosphor shows a broad asymmetric band extending from 350 to 600 nm peaking at 420 nm under the excitation of UV light. Also, the low temperature (5 K) PL spectrum shows clearly three peaks at 375, 420, and 451 nm, which is in accordance with the Ce3+ ion site in the host. The Ce3+,Mn2+ co-doped phosphors show a blue emission band and an orange emission band, and the corresponding CIE coordinates intuitively indicate the tunable colors from the blue to green area. And the energy transfer mechanism from Ce3+ to Mn2+ in the host has been verified to be a dipole–quadrupole interaction. In addition, the emission intensity of Na2Ba6(Si2O7)(SiO4)2:0.01Ce3+ phosphor slightly changed with the temperature increase from 300 to 450 K, revealing that the obtained phosphor possesses an excellent thermal stability, which makes it an attractive candidate phosphor for white lighting emitting diodes.

A series of Eu2+ and Ce3+/Tb3+ doped Ca2NaSiO4F (CNSOF) phosphors have been synthesized and their structure and photoluminescence properties have been investigated in detail. Rietveld structure refinement indicates that the phosphors crystalized in an orthorhombic system with a space group of Pnma (no. 62) and there are two kinds of cation sites for the doped ions to occupy in forming emission centers. The CNSOF:Eu2+ and CNSOF:Ce3+ phosphors both have broad excitation bands, which match well with the commercial UV LED chips. The CNSOF:Eu2+ phosphor can have intense green emission with a maximum at 530 nm under irradiation at 380 nm, while the CNSOF:Ce3+ sample can emit intense blue light, peaking at 470 nm with excitation at 365 nm. By codoping the Tb3+ and Ce3+ ions into an CNSOF host and varying their relative ratio, tunable blue-green colors are obtained due to efficient energy transfer from the Ce3+ to Tb3+ ions. Moreover, energy transfer mechanisms for the Eu2+ ions in CNSOF:Eu2+ and Ce3+ → Tb3+ in CNSOF:Ce3+,Tb3+ have been studied systematically. Our investigation indicates that CNSOF:Eu2+ and CNSOF:Ce3+,Tb3+ may be potential green and blue-green phosphors for UV WLEDs, respectively.

A series of Eu2+ and Mn2+ activated novel Sr3GdNa(PO4)3F phosphors have been prepared through a high temperature solid state reaction. The investigation revealed that Sr3GdNa(PO4)3F crystallized in a hexagonal crystal system with the space group P (no. 147). The Eu2+ activated phosphors can be efficiently excited in the range of 250 to 420 nm, which matches well with the commercial n-UV LED chips, and give intense blue emission centering at 470 nm. By codoping the Eu2+ and Mn2+ ions into the SGNPF host and singly varying the doping content of the Mn2+ ion, tunable colors from blue to white and then to yellow are obtained in SGNPF:Eu2+,Mn2+ phosphors under the irradiation of 390 nm. The energy transfer from the Eu2+ to Mn2+ ions is demonstrated to be a dipole–quadrupole mechanism in terms of the experimental results and analysis of photoluminescence spectra and decay curves of the phosphors. The critical distance between the Eu2+ and Mn2+ ions in SGNPF:Eu2+,Mn2+ was determined by the spectral overlap method. The investigation indicates that our prepared samples might have potential application in WLEDs.

In this paper, a novel green phosphor ca8mg3al2si7o28:eu2+ is synthesized via a conventional high-temperature solid-state reaction. the crystal structure of the phosphor is confirmed from the rietveld method. the obtained phosphor has a wide absorption band from the uv to the visible spectral region, ranging from 230 to 450 nm, which fits well with the characteristic emission of uv light-emitting diode (led) chips. upon excitation at 420 nm, the phosphor shows a bright and broad green color emission band with a maximum centered at 535 nm, which is attributed to the parity and spin allowed 5d-4f transition. the longer emission wavelength is caused by both the d orbital preferential orientation and the lowered symmetry of the eu2+ ions caused by the discrepancy of the tetrahedrons composed of mgo4, sio4, and alo4. additionally, the energy transfer mechanism among eu2+ ions is demonstrated via a dipole-dipole interaction by the luminescence spectra and the fluorescence decay analysis calculations on the basis of the inokuti-hirayama model. furthermore, the thermal stability of the phosphor is investigated in detail. these results suggest that the ca8mg3al2si7o28:eu2+ phosphor has great potential to be a green phosphor for white light emitting diodes (wleds).

Single-phased Ca3Si2O7:Ce3+,Eu2+ phosphor has been successfully prepared by the high temperature solid-state method. The phosphor shows efficient excitation bands from 200 to 400 nm and adjustable emission bands through the energy transfer from the Ce3+ to Eu2+ ions. The color hues can change from blue towards white ultimately to orange by adjusting the percentage content of doping ions. The investigation reveals that an electric dipole-dipole reaction mechanism should be responsible for the energy transfer from the Ce3+ to Eu2+ ions. The critical distance was obtained from the spectral overlap in terms of Dexter's theory. The developed phosphor Ca3Si2O7:Ce3+,Eu2+ exhibits two bands at 440 and 625 nm, respectively, which reveling that it has a great potentiality to be an UV-convertible phosphor for white-light emitting diodes with low color temperature. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.

Novel three-dimensional (3D) hierarchical architectures of Lu(2)O(3):Eu(3+) have been successfully prepared through a simple hydrothermal process followed by a subsequent calcination process without using any surfactant, catalyst, or template. According to the X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry, and Fourier transform infrared spectroscopy results, the precursors were determined to have the structure formula of Lu(4)O(OH)(9)NO(3). The morphologies of the precursors could be modulated by altering pH value of the reaction system. On the basis of detailed time-dependent experiments, the growth process of architectures was discussed. The as-formed precursors could transform into Lu(2)O(3):Eu(3+) with their original hierarchical structures maintained. The Lu(2)O(3):Eu(3+) submicro-architectures exhibit strong red emission corresponding to the (5)D(0)→(7)F(2) transition of the Eu(3+) ions under ultraviolet (UV) excitation, which have potential applications in novel optoelectronic devices.

A novel tunable full-color-emitting Sr3Gd(PO4)3:Eu2+,Mn2+ phosphor system was successfully developed. Its excitation wavelength ranging from 230 to 450 nm fits well with the characteristic emission of UV light-emitting diode (LED) chips. The color emission of these phosphors can be tuned across almost the entire visible light spectrum resulting in white light emission with varied hue and correlated color temperature (CCT) by varying the molar ratios of Eu2+ and Mn2+. Moreover, the efficient energy transfer from Eu2+ to Mn2+ was demonstrated via a dipole–quadrupole mechanism by the luminescence spectra and the fluorescence decay dynamics based on the Inokuti–Hirayama theoretical model. These results indicate that the developed phosphor may be promising as a single-component white-light-emitting phosphor for white LEDs.

The blue-emitting phosphors Ca (4− x ) Eu x Si 2 O 7 F 2 (0 x ⩽ 0.05) have been prepared by solid-state reaction and the photoluminescence properties have been studied systematically. The electronic structure of calcium fluoride silicate Ca 4 Si 2 O 7 F 2 was calculated using the CASTEP code. The calculation results of electronic structure show that Ca 4 Si 2 O 7 F 2 has an indirect band gap with 5 eV. The top of the valence band is dominated by O 2p and Si 3p states, while the bottom of the conduction band is mainly composed of Ca 3d states. Under the 350 nm excitation, the obtained sample shows a broad emission band in the wavelength range of 400–500 nm with peaks of 413 nm and 460 nm from two different luminescence centers, respectively. The relative intensity of the two peaks changes with the alteration of the Eu 2+ concentration. The strong excitation bands of the powder in the wavelength range of 200–420 nm are favorable properties for the application as lighting-emitting-diode conversion phosphor.

Presently considerable interest in phosphor-converted warm LEDs which meet the stringent requirements of general illumination is stimulated. Here we report warm white LEDs made by altering the crystal structure and doping ions, which can govern the luminescence pattern to modulate the correlated color temperature and color-rendering index.

A series of (Ba1-mEum) 3La1-nTbnNa(PO4)3F (m = 0—0.07; n = 0—0.60) phosphors are prepared by solid state reaction of BaCO3, BaF2, La2O3, Na2CO3, NH4H2PO4, Eu2O3, and Tb4O7 (20% H2/80% N2, 1050 °C, 3 h).

A series of single-component red/white-emitting CaScAlSiO6:Ce(3+),Tb(3+),Mn(2+) phosphors have been synthesized by a solid-state reaction. It is observed that CaScAlSiO6:Ce(3+),Tb(3+) phosphors exhibit two dominating bands situated at 380 and 542 nm, originating from the allowed 5d → 4f transition of the Ce(3+) ion and the (5)D4 → (7)F(J) = (J = 6, 5, 4, 3) transition of the Tb(3+) ion, respectively. As for CaScAlSiO6:Ce(3+),Mn(2+), our results indicate that Mn(2+) may occupy not only a Ca(2+) site to generate an orange emission [Mn(2+)(I)] at 590 nm but also a Sc(3+) site to generate a red emission [Mn(2+)(II)] at 670 nm. Both energy transfers from Ce(3+) to Tb(3+) and from Ce(3+) to Mn(2+) in the CaScAlSiO6 host are investigated and have been demonstrated to be of the resonant type via a dipole-dipole mechanism. By proper tuning of the relative composition of Tb(3+)/Mn(2+), white light can also be achieved upon excitation of UV light, indicating that the developed phosphor may potentially be used as a single-component red/white-emitting phosphor for UV-light-emitting diodes.

Eu(2+)-Mn(2+) codoped orange-yellow-emitting Ba(3)Lu(PO(4))(3) phosphors were synthesized by a solid-state reaction. The synthesis, structure refinement, and luminescence properties of the obtained phosphor were first investigated in detail. The crystal structure was refined with a split-atom model, where the oxygen atoms are distributed over two partially occupied sites. The refinement confirmed that BLuP:0.005Eu(2+),0.06Mn(2+) has a cubic unit cell with space group I43d (no. 220), cell parameters a = b = c = 10.4025 Å and Z = 4. The luminescent properties reveal that the developed phosphor can efficiently convert UV photons in a broad range from 230 to 430 nm into orange-yellow emission. On the basis of the luminescence spectra and fluorescence decay curves, we confirm that the energy transfer process from the Eu(2+) to Mn(2+) ions takes place in the codoped Ba(3)Lu(PO(4))(3):Eu(2+),Mn(2+) phosphor, and the energy transfer efficiency increases with an increase in the Mn(2+) content. The possible energy transfer mechanism was proposed in terms of the experimental results and analysis. In particular, our developed phosphor contains a larger amount of the red-emitting component, compared with the commercial YAG:Ce phosphor, possessing favorable properties for application in warm white LEDs with low correlated color temperature.

A novel orange-yellow-emitting Ba(3)Gd(PO(4))(3):xEu(2+),yMn(2+) phosphor is prepared by high-temperature solid-state reaction. The crystal structure of Ba(3)Gd(PO(4))(3):0.005 Eu(2+),0.04 Mn(2+) is determined by Rietveld refinement analysis on powder X-ray diffraction data, which shows that the cations are disordered on a single crystallographic site and the oxygen atoms are distributed over two partially occupied sites. The photoluminescence excitation spectra show that the developed phosphor has an efficient broad absorption band ranging from 230 to 420 nm, perfectly matching the characteristic emission of UV-light emitting diode (LED) chips. The emission spectra show that the obtained phosphors possess tunable color emissions from yellowish-green through yellow and ultimately to reddish-orange by simply adjusting the Mn(2+) content (y) in Ba(3)Gd(PO(4))(3):0.005 Eu(2+),y Mn(2+) host. The tunable color emissions origin from the change in intensity between the 4f-5d transitions in the Eu(2+) ions and the (4)T(1)-(6)A(1) transitions of the Mn(2+) ions through the energy transfer from the Eu(2+) to the Mn(2+) ions. In addition, the mechanism of the energy transfer between the Eu(2+) and Mn(2+) ions are also studied in terms of the Inokuti-Hirayama theoretical model. The present results indicate that this novel orange-yellow-emitting phosphor can be used as a potential candidate for the application in white LEDs.

A series of the solid-solution phosphors Lu(3-x-y)Mn(x)Al(5-x)Si(x)O(12):yCe(3+) is synthesized by solid-state reaction. The obtained phosphors possess the garnet structure and exhibit similar excitation properties as the phosphor Lu(3)Al(5)O(12):Ce(3+), but with an effectively improved red component in the emission spectrum. This can be attributed to the energy transfer from Ce(3+) to Mn(2+). Our investigation reveals that electric dipole-quadrupole interactions dominate the energy-transfer mechanism and that the critical distance determined by the spectral overlap method is about 9.21 A. The color-tunable emissions of the Lu(3-x-y)Mn(x)Al(5-x)Si(x)O(12):yCe(3+) phosphor as a function of Mn(3)Al(2)Si(3)O(12) content are realized by continuously shifting the chromaticity coordinates from (0.354, 0.570) to (0.462, 0.494). They indicate that the obtained material may have potential application as a blue radiation-converting phosphor for white LEDs with high-quality white light.

Ce(3+) and Eu(2+) singly doped and Ce(3+)/Eu(2+)-codoped Ca(7)Mg(SiO(4))(4) phosphors are synthesized by the conventional solid state reaction. The Ce(3+) activated sample exhibits intense blue emission under 350 nm excitation, the composition-optimized Ca(7)Mg(SiO(4))(4) : 4%Ce(3+) shows better color purity than the commercial blue phosphor, BaMgAl(10)O(17) : Eu(2+) (BAM : Eu(2+)) and exhibits superior external quantum efficiency (65%). The Ca(7)Mg(SiO(4))(4) : Eu(2+) powder shows a broad emission band in the wavelength range of 400-600 nm with a maximum at about 500 nm. The strong excitation bands of the Ca(7)Mg(SiO(4))(4) : Eu(2+) in the wavelength range of 250-450 nm are favorable properties for applications as light-emitting-diode conversion phosphors. Furthermore, the energy transfer from the Ce(3+) to Eu(2+) ions is observed in the codoped samples, the resonance-type energy transfer is determined to be due to the dipole-dipole interaction mechanism and the critical distance is obtained through the spectral overlap approach and concentration quenching method.

In this paper, a novel single-phased white light emitting phosphor Na2Ca4Mg2Si4O15:Eu2+, Mn2+ was prepared successfully via the high temperature solid state reaction. The obtained Na2Ca4Mg2Si4O15:Eu2+ phosphor exhibits a broad excitation band ranging from 200 to 450 nm and a blue light emission band peaking at 480 nm, originating from 4f7 ↔ 4f65 d1 (f-d) electric dipole allowed transitions of Eu2+ ions. Due to the energy transfer from Eu2+ to Mn2+ ions, the co-doped Eu2+ ions in the Na2Ca4Mg2Si4O15:Eu2+, Mn2+ phosphors markedly enhances the luminescence intensity of Mn2+ ions, providing highly attractive tunable color. The luminescent mechanism invoking the energy transfer between Eu2+ ions and Mn2+ ions has been certified to be dipole–quadrupole interaction predominantly through the investigations of the luminescence spectra and the fluorescence decay curves. Our results show that the novel Na2Ca4Mg2Si4O15:Eu2+, Mn2+ phosphor is a very promising candidate for UV white light emitting diodes.

Emission-tunable Mg2Al4Si5O18:Eu2+, Mn2+ and Mg2Al4Si5O18:Eu2+, Tb3+ cordierite phosphors have been synthesized by a high-temperature solid-state reaction technique. Photoluminescence and energy transfer in Mg2Al4Si5O18:Eu2+, Mn2+ occur via a resonance-type dipole–quadrupole interaction mechanism, and the critical distance of the energy transfer is calculated to be 11.1 A. We found that the emission colors could be tuned from blue (0.19, 0.26) to white (0.41, 0.37) via the energy transfer of Eu2+ → Mn2+ and from blue to green (0.28, 0.45) via the energy transfer of Eu2+ → Tb3+. The green emission is realized in the Mg2Al4Si5O18:Eu2+, Tb3+ phosphors on the basis of the highly efficient energy transfer from the Eu2+ to Tb3+ ions. Finally, the color tunable emission with varied hues has been obtained in Eu2+, Tb3+, or Mn2+ activated Mg2Al4Si5O18 phosphors, making them potential emission-tunable phosphors for near-UV LEDs.

Incorporating Tb3+ and Mn2+ into a high efficiency BaCa2MgSi2O8:Eu2+ phosphor generates a green line peaking at 542 nm and a red emission band peaking at 660 nm. Upon 365 nm excitation, the absolute quantum yields of BaCa2MgSi2O8:Eu2+ phosphors doped with various Tb3+ ions all exceed 77%, indicating that the phosphor is a suitable matrix for rare earth ion doping. Meanwhile, the luminescent properties of BaCa2MgSi2O8:Eu2+,Mn2+ were investigated and remarkable energy transfer from the blue emitting Eu2+ to both Tb3+ and Mn2+ can occur in the BaCa2MgSi2O8 system. This energy transfer is important in enabling the achievement of a broad emission spectrum, covering a red spectral region, suitable for a near-UV light-emitting diode (LED) excitation. The decay patterns of the red and blue fluorescence are discussed in relation to the effect of the energy transfer. Measurement of the thermal quenching properties reveals that BaCa2MgSi2O8:Eu2+,Mn2+ exhibits excellent characteristics.

An orange-emitting phosphor was obtained via efficient Ce3+–Mn2+ and Eu2+–Mn2+ energy transfers in La9.33(SiO4)6O2, and has been developed for solid state UV/near-UV white lighting applications. The luminescence properties and energy transfer from Ce3+ to Mn2+ and Eu2+ to Mn2+ are investigated. The La9.33(SiO4)6O2:Ce3+, Mn2+ phosphor shows a blue emission centered at 380 and an orange emission peaking at 590 nm, which could be ascribed to the allowed 5d → 4f transition of the Ce3+ ion and the 4T1g(4G) → 6A1g(6S) transition of the Mn2+ ion, respectively. Upon excitation at 365 nm, the Eu2+, Mn2+ co-doped La9.33(SiO4)6O2 phosphor exhibits the Eu2+ green emission band and the Mn2+ orange emission band. Non-radiative transitions between the Ce3+/Eu2+ and Mn2+ ions in the La9.33(SiO4)6O2 host are both demonstrated to be attributable to dipole–quadrupole interactions. The intensity ratio of the Mn2+ emission bands can be enhanced through the increase of the Mn2+ content, which is attributed to the efficient energy transfer from Ce3+/Eu2+ to Mn2+, and the corresponding chromaticity coordinates (0.50, 0.38), (0.51, 0.46) were obtained with the La9.33(SiO4)6O2:Ce3+, Mn2+ and La9.33(SiO4)6O2:Eu2+, Mn2+ samples. Results indicated that the as-prepared phosphors might have promising applications in white-light LEDs as an orange-emitting phosphor.

A n-UV convertible phosphor Sr3Tb(PO4)3:Mn(2+) with tunable-emitting color has been synthesized by solid state reaction. The GSAS refinement shows that the obtained powder crystallizes as a cubic unit cell with space group I43d, and Mn(2+) ions occupy the Sr(2+) crystallographic sites. Under (7)F6→(5)D3 of Tb(3+) excitation at 381 nm, Sr3Tb(PO4)3:Mn(2+) not only exhibits (5)D4→(7)F6-3 of Tb(3+) green emission lines but also (4)T1→(6)A1 of the Mn(2+) orange emission band. In addition, the intensity ratio of the orange/green emission bands can be enhanced through the increase of Mn(2+) content. The intense orange emission band of the Mn(2+) ions is attributed to the efficient energy transfer from the Tb(3+) to Mn(2+) ions, which has been justified through the luminescence spectra and fluorescence decay dynamics. The energy transfer mechanism was demonstrated to be the electric dipole-dipole interaction based on the Inokuti-Hirayama theoretical model, and the energy transfer efficiency was calculated. Optimal-composition samples show high external quantum efficiency, up to 59.3%, indicating the potential of the powder as a n-UV convertible phosphor for white LEDs.

A broadband direct warm-white-emitting phosphor Sr3Sc(PO4)3:Eu(2+), Mn(2+) (SSP:Eu(2+), Mn(2+)) was prepared by a solid-state reaction. The powder X-ray diffraction data, photoluminescence spectra, fluorescence decay curves, quantum efficiency, and chromaticity coordinates of the obtained phosphors were measured and discussed in detail. The results reveal that there is efficient energy transfer from the Eu(2+) to the Mn(2+) ions and the broadband direct warm-white-light comes from the emissions of the Eu(2+) and Mn(2+) ions. The possible energy transfer mechanism was proposed in terms of the experimental results and analysis. We demonstrate the ability to tune the color tone, the correlated color temperature (CCT), and the chromaticity coordinates which can approach the color properties required for solid state lighting. The developed phosphors can be efficiently excited in the UV region and exhibit a warm-white-light emission, making them attractive as single-component white-light-emitting conversion phosphors for UV-based white light emitting diodes.

A series of NaCa2LuSi2O7F2:xCe(3+),yMn(2+) phosphors are firstly prepared by a high-temperature solid-state reaction technique. The Rietveld refinement analysis confirmed that the obtained phosphors have a pure crystalline phase with cuspidine-group structure. NaCa2LuSi2O7F2:xCe(3+),yMn(2+) phosphors can be efficiently excited by UV light and have two emission bands at about 410 and 600 nm. The luminescent properties of the singly-doped samples reveal that the Ce(3+) ions occupy two different Lu(3+) sites in the host lattice. We observed an efficient energy transfer from the Ce(3+) to Mn(2+) ions. The investigation revealed that the mechanism of the energy transfer was a resonant type via a nonradiative dipole-quadrupole interaction. The hues can be adjusted and white light can be obtained by tuning the concentration of Mn(2+) ions in the codoped phosphors through the energy transfer from the Ce(3+) to Mn(2+) ions, hinting a promising application of NaCa2LuSi2O7F2:xCe(3+),yMn(2+) as a single-component phosphor that can produce white light from UV-based LEDs.

Novel dendrite-patterned triangles of Y4O(OH)9NO3:Eu3+ have been successfully prepared via a simple hydrothermal method without using any surfactant, catalyst, or template. The growth mechanism was interpreted as a modified diffusion-limited aggregation (DLA) model. Detailed contrast experiments revealed that the regulation of ethylene glycol/water ratio and pH value was essential for the formation of dendrites. The ethylene glycol served multiple functions in the formation of dendrites: to bind with Y3+ ions, change the viscosity of reaction solution, and selectively adsorb on certain faces of crystals. The as-formed precursors could transform into Y2O3:Eu3+ hierarchical dendrites after calcination, which exhibited strong red emission under ultraviolet excitation. Furthermore, the dependence of the luminescence performance on different morphologies was discussed in detail.

Several three-dimensional (3D) hierarchical architectures of Lu2O2S:Eu3+ have been successfully synthesized via a simple solvothermal method with polyvinylpyrrolidone (PVP) as surfactant, followed by a subsequent calcination process. The as-prepared products were well characterized by means of X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and photoluminescence (PL) spectra. The results reveal that the morphologies of precursors can be tuned by altering pH value of the reaction system. Detailed investigation indicates that the formations of different micro-structures are dominated by different growth mechanisms. The as-formed precursors could transform into Lu2O2S:Eu3+ with their original hierarchical structures maintained. Under ultraviolet (UV) excitation, the Lu2O2S:Eu3+ micro-architectures exhibit strong red emission corresponding to the 5D0→7F2 transition of the Eu3+ ions. Furthermore, the dependence of Lu2O2S:Eu3+ luminescence performance on different morphologies has been involved in the present work.

In this paper, the color point tuning of Y3Al5O12 : Ce3+ phosphor has been realized by the incorporation of Mn2+–Si4+. The Mn2+ ions occupy the dodecahedral crystallographic Y3+ site, while the Si4+ ions substitute the tetrahedral Al3+ crystallographic site in the obtained powder. Under 450 nm excitation, the YAG : Ce3+,Mn2+,Si4+ samples exhibit the typical yellowish-green emission band of the Ce3+ ions, as well as an orange emission band of the Mn2+ ions. Furthermore, the intensity ratio of the orange/yellowish-green band can be enhanced through the increase of Mn2+–Si4+ content. The intense orange emission band of the Mn2+ ions is attributed to the effective energy transfer from the Ce3+ to Mn2+ ions, which has been justified through the luminescence spectra and the fluorescence decay dynamics. The related mechanism was demonstrated to be the electric dipole–quadrupole interaction based on the Inokuti–Hirayama theoretical model, and critical distance is calculated to be 8.6 A by the spectral overlap method.

We report a novel method to synthesize Y2O3:Eu3+ nanoscrolls by hydrothermal and post-heat treatments. In the hydrothermal process, a precursor compound with well-defined urchinlike morphology has been obtained with the aid of BO33− and L-glutamic acid. The formed micro-urchins consist of numerous nanoscrolls rolled up from nanosheets. Condition experiments and analysis reveal that BO33− anions and L-glutamic acid were vital for the rolling process of the nanoscrolls. Under ultrasound treatment, the micro-urchins can break into separated nanoscrolls. In a subsequent calcination process, the as-prepared precursors can transform into Y2O3:Eu3+ with the same morphology. The resultant Y2O3:Eu3+ micro-urchins exhibit a strong red emission corresponding to the 5D0 →7F2 transition of the Eu3+ ions under UV light excitation. Moreover, our method may provide a new way to realize the “rolling-up” process of other compounds.

By direct precipitation in solution at room temperature, cerium benzendicarboxylate complexes with various morphologies have been obtained facilely for the first time. After calcination, CeO2 with large surface areas can be obtained, which inherited their parents' morphologies and exhibited better catalytic properties for CH4 oxidation than commercial CeO2.