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Dual-emitting and thermochromic manganese ion single doped ZnGa2-yAlyO4 phosphors were prepared by solid-state reaction. The regulation of the valence state and the luminescent properties, especially the luminescent thermal stability of manganese ions in ZnGa2-yAlyO4, are discussed in detail. When excited by ultraviolet (UV) light, the emission spectra of ZnGa2O4:Mn2+,Mn4+ present an ultranarrow green emission band at 503 nm with a fwhm of 22 nm, which derives from the Mn2+ ions formed by the self-reduction of doped Mn4+, and a red emission band of the Mn4+ ions at 669 nm. In addition, a ZnGa2-yAlyO4:Mn2+,Mn4+ solid solution was designed and synthesized by Al3+ replacing Ga3+. The doping of Al3+ effectively inhibited the degree of Mn4+ self-reduction to Mn2+, thus realizing the regulation of valence state of manganese ions. Interestingly, the thermal stability of luminescence shows that the response of Mn2+ and Mn4+ to temperature is obviously different in ZnGa2-yAlyO4, implying the potential of the prepared phosphors as optical thermometers. Subsequently, three kinds of optical thermometers with superior color discrimination and high relative sensitivity (Sr) based on the fluorescence intensity ratio (FIR) technique were realized in 100-475 K. The Sr value of ZGO:0.005Mn/ZGA0.5O:0.005Mn/ZGAO:0.005Mn phosphors can be as high as 4.345%/4.001%/3.488% K-1 (at 350/325/400 K), reflecting the great potential of ZnGa2O4:Mn2+,Mn4+ for optical thermometry applications.

Novel La8Ba2(Si4P2O22N2)O2:Eu2+/Ce3+/Tb3+ apatite phosphors with tuneable light emission have been successfully synthesized by the conventional solid-state method. The structural and luminescence properties of the newly obtained samples have been studied systematically. The photoluminescence properties show that the Eu2+-, Ce3+- and Tb3+-doped La8Ba2(Si4P2O22N2)O2 samples have strong absorption in the near ultraviolet (n-UV) region. Under n-UV light irradiation, Eu2+-doped samples exhibit a narrow bluish green emission band peaking at 496 nm with a full width at half-maximum (FWHM) of 55 nm, which is comparable to the commercial blue emitting BaMgAl10O17:Eu2+ (FWHM = 55 nm) phosphor, while La8Ba2(Si4P2O22N2)O2:Ce3+,Tb3+ presents adjustable emission colour from violet to green by adjusting the concentration of Tb3+. The energy-transfer efficiencies and mechanisms have been discussed in detail. The temperature dependent luminescence measurements show that the obtained samples have low thermal quenching. Moreover, a series of white LED devices have been obtained by using the La8Ba1.99(Si4P2O22N2)O2:0.01Eu2+/(Sr,Ca)AlSiN3:Eu2+/(Ba,Sr)SiO4:Eu2+/(Sr,Ba,Ca)10(PO4)Cl2:Eu2+/Sr2SiO4:Eu2+ phosphor blend. By adding the as-prepared narrow bluish-green-emitting La8Ba1.99(Si4P2O22N2)O2:0.01Eu2+ phosphor, the Ra values can increase from 68 to 98, the R9 values increase from 42 to 95, and the corresponding CCT continuously decreases from 6210 to 3086 K, respectively. Our results reveal that the Eu2+, Ce3+ and Tb3+ activated phosphors are promising candidates for WLEDs.

We study from first principles the stability of neutral and charged oxygen vacancies in lutetium oxyorthosilicate, Lu2SiO5, as well as its possible modification due to the presence of Ce 3 + , as present in commercial scintillators. We show that the neutral oxygen vacancy with the lowest formation energy forms at the oxygen sites within the [SiO4] tetrahedra instead of the interstitial oxygen site bonded exclusively to lutetium atoms. The discrepancy with a previous study is attributed to the quality of the pseudopotential. Support for these results is found by performing a bonding analysis of the oxygen sites, as well as oxygen vacancy calculations in the iso-structural Y2SiO5 compound. In addition, we find that the incorporation of Ce 3 + ion does not affect the stability of oxygen vacancies in Lu2SiO5.

We performed a Raman scattering study of thin films of ${\mathrm{LiTi}}_{2}{\mathrm{O}}_{4}$ spinel oxide superconductor. We detected four out of five Raman active modes, with frequencies in good accordance with our first-principles calculations. Three ${\mathrm{T}}_{2g}$ modes show a Fano lineshape from 5 K to 295 K, which suggests an electron-phonon coupling in ${\mathrm{LiTi}}_{2}{\mathrm{O}}_{4}$. Interestingly, the electron-phonon coupling shows an anomaly across the negative to positive magnetoresistance transition at 50 K, which may be due to the onset of other competing orders. The strength of the electron-phonon interaction estimated from the Allen's formula and the observed lineshape parameters suggest that the three ${\mathrm{T}}_{2g}$ modes at 0 momentum are not sufficient to drive superconductivity.

Multifunctional BaGdF5 nanospheres with mesoporous, luminescent, and magnetic properties have been successfully synthesized with the assistance of trisodium citrate by a hydrothermal method. The mesoporous structure is revealed by scanning electron microscope and transmission electron microscope images as well as N2 adsorption-desorption isotherm. The as-synthesized BaGdF5 nanospheres exhibit an intense broad bluish emission (centered at 450 nm) under the excitation of 390 nm, which might originate from the CO2·(-) radical-related defect produced by Cit(3-) groups. It is also shown that these BaGdF5 nanospheres brightened the T1-weighted images, suggesting that they could act as T1 contrast agents for magnetic resonance imaging. Using metformin hydrochloride as the model drug, the luminescent porous spheres show good drug storage/release capability. Furthermore, the emission intensity varies as a function of the cumulative drug release, making the drug-carrying system easily trackable and monitorable by detecting the luminescence intensity. Additionally, the paramagnetic property, originating from the unpaired electrons of Gd(3+) ions, opens the possibility of directing the magnetic targeted carrier to the pathological site by magnetic field gradient.

Pseudo-octahedrons of Ba2GdF7 were successfully synthesized through a solution-based method in a hydrothermal environment for the first time. The preferential adsorption of ethylene glycol (EG) molecules on the {111} planes contributed to the formation of the octahedral shape. Hydrazine was employed as the alkaline source to adjust the adsorption affinity of EG and the hydrolysis rate of NaBF4 (fluorine supply), thereby controlling the morphology and phase structure. A series of contrast experiments were conducted to investigate the growth mechanism of the Ba2GdF7 nanocrystals. As a proof-of-concept experiment, Eu3+, Tb3+, Dy3+, and Yb3+/Er3+ ions were doped to demonstrate the potential of the Ba2GdF7 crystals as host material for phosphors.

We reported a single-phased CaScAlSiO 6 :Ce 3+ , Tb 3+ , Eu 3+ as a potential full-color emitting phosphor for the application in fluorescent lamps. The CaScAlSiO 6 :Ce 3+ , Tb 3+ , Eu 3+ phosphor exhibits three bands under 254 nm excitation: one band situated at 380 nm is attributed to the 5d → 4f transitions of Ce 3+ ions, the second band with sharp lines peaked at 542 nm is assigned to the 5 D 4 → 7 F J transitions of Tb 3+ ions, the third band in the orange–red region (580–700 nm) is originated from 5 D 0 → 7 F J transitions of Eu 3+ ions. The Commission Internationale de I’Eclairage (CIE) chromaticity coordinates (0.30, 0.30) and high color rendering index (CRI=88) can be achieved upon excitation of 254 nm light. It is suggested that CaScAlSiO 6 :Ce 3+ , Tb 3+ , Eu 3+ can serve as a potential single-phased full-color emitting phosphor for phosphor-converted fluorescent lamps.

A series of Ca2SrAl2O6:Ce(3+),Li(+),Mn(2+) phosphors have been synthesized by traditional solid state reactions. The structure and photoluminescence properties of the samples together with the energy transfer from Ce(3+) to Mn(2+) ions have been investigated in detail. The obtained phosphors can be excited efficiently by UV excitation and exhibit a broad blue-green emission band peaking at 470 nm and an orange-red emission band at 610 nm, which result from the f-d transition of the Ce(3+) and the (4)T1-(6)A1 transition of the Mn(2+) ions, respectively. By varying the doping concentration of the Mn(2+) ion, a series of tunable colors including white are obtained at an irradiation of 355 nm. The possible energy transfer mechanism was proposed in terms of the experimental results and analysis of photoluminescence spectra and decay curves of the phosphors. The critical distance between the Ce(3+) and Mn(2+) ions has been calculated by both the concentration quenching method and the spectral overlap method. Preliminary studies on the properties of the phosphor indicated that our prepared Ca2SrAl2O6:Ce(3+),Li(+),Mn(2+) phosphor might have potential application as a single-phase white-emitting phosphor for 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.

Monodispersed CaWO4 and CaWO4:Mo/Eu, Tb microspheres have been obtained hydrothermally with excellent reproducibility. X-ray diffraction, field-emission scanning electron microscopy and photoluminescence were used to characterize the as-synthesized samples. The results uncover the formation process of the microspheres and the influence of ethylenediamine. Doping proper concentration of Mo into CaWO4 micropheres can extend the excitation range as the incorporation induces obvious redshift. We have also tuned the color from blue to pink blue, white and green only by varying the relative content of Eu-Tb in the CaWO4 host. (C) 2011 Elsevier B.V. All rights reserved.

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.

A series of single-component Sr3Lu(PO4)3:Eu2+,Mn2+ phosphors were successfully synthesized by solid-state reaction, and their photoluminescence properties were investigated. The Sr3Lu(PO4)3:Eu2+,Mn2+ phosphor system was efficiently excited at wavelength ranging from 250 to 420 nm, which is well-matched with ultraviolet (UV) light-emitting diode (LED) chips. As a result of fine-tuning of the emission composition of the Eu2+ and Mn2+ ions, warm white light emission can be realized by combining the emission of Eu2+ and Mn2+ in a single host lattice under UV light excitation. Efficient resonant energy transfer from the Eu2+ to Mn2+ ions was demonstrated to be a dipole–quadrupole mechanism in such system, and the energy transfer efficiency increases with an increase in the Mn2+ doping content, which was confirmed by the luminescence spectra and fluorescence decay curves. In addition, the energy transfer efficiency and critical distance were also calculated. The results indicate that the developed phosphor can ...

A facile method is demonstrated to obtain CeO2 by hydrolyzing coordination polymer nanowires Ce(1,3-BDC)(1,5)center dot 6H(2)O (1,3-BDC = 1,3-benzene dicarboxylate) in basic solution. The products that preserved the morphologies of the precursors were constituted from plenty of CeO2 nanoparticles. This method can increase the surface areas significantly, which is important for its application in catalytic activities. Importantly, La (OH)(3) nanoparticles could be obtained after the basic treatment of corresponding coordination polymer, indicating that this method is general to be applied to obtain other lanthanide oxides and hydroxides. After calcinations. well crystallized oxides exhibited different properties from their bulk counterparts due to their increased surface areas. (C) 2012 Elsevier B.V. All rights reserved.

The title phosphor is synthesized by solid state reaction of NaNO3, BaCO3, SiO2, CeO2, and MnCO3 (5% H2—95% N2, 1050 °C, 8 h) and characterized by XRD and photoluminescence spectroscopy.

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).

Near-UV convertible Eu(3+)-activated orange oxynitride phosphors have been obtained via a Ce(3+)→ Tb(3+)→ Eu(3+) energy transfer mechanism. The Tb(3+) ions play the role of an energy transfer bridge to connect the Ce(3+) and Eu(3+) ion pairs, and an optimal concentration of the Tb(3+) ion is necessary for maximum intensity of the Eu(3+) ion emission.

A series of single-component red/white-emitting Ce3+,Tb3+,Mn2+-doped CaScAlSiO6 phosphors are synthesized by solid state reaction of CaCO3, Sc2O3, SiO2, Al2O3, CeO2, Tb4O7, and MnCO3 (10% H2/N2, 1400 °C, 4 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.

The new title phosphor is synthesized by solid state reaction of MgO, Lu2O3, Al2O3, SiO2, CeO2, and MnCO3 (CO atmosphere, 1350 °C, 3 h) and characterized by XRD and photoluminescence spectroscopy.

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.

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.

The monodisperse submicroplates of Gd1−yCayF3−y solid solution were successfully synthesized by a simple and facile hydrothermal method for the first time. The structure of the as-synthesized Gd1−yCayF3−y was determined to be tysonite-type instead of the usual fluorite-type via a Rietveld refinement method with GSAS. Detailed contrast experiments revealed that the addition amounts of ethylene glycol, calcium chloride, and sodium fluoroborate played critical roles in the formation of the Gd1−yCayF3−y solid solution. Desirable multicolor outputs were successfully realized by doping activator ions (Eu3+, Tb3+, and Dy3+) in the Gd1−yCayF3−y crystals where the Gd3+ ions served as an energy intermediate. Furthermore, the energy transfer from the Gd3+ to Eu3+ ions in the obtained Gd1−yCayF3−y solid solution was more efficient than that in the orthorhombic GdF3.

Inorganic-salt-induced morphological evolution of GdF3 crystals was demonstrated for the first time in a mild hydrothermal process. By varying the amount of inorganic salt, the GdF3 crystals could transform from uniform elliptic nanostructures to submicroplates. The increase of ionic strength, hindered diffusion of reactant ions, and selectively adsorption of barium cations were responsible for such morphological transformation. Besides, relatively low concentration of F(-) contributed to the formation of GdF3 in the presence of foreign inorganic salt, instead of ternary fluoride. In addition, the luminescence properties of the as-formed nanostructures were investigated by singly doping Eu(3+), Tb(3+), and Dy(3+) into the GdF3 matrix.

A series of Eu(3+), Tb(3+), Tm(3+) singly and triply doped Ca3Bi(PO4)3 (CBP) phosphors were synthesized by solid-state reaction. Their structure and photoluminescence (PL) properties were first investigated in detail. Rietveld refinement analysis confirmed that the CBP has a cubic unit cell. Its space group was determined to be I4[combining macron]3d with cell parameters a = b = c = 9.941 Å and Z = 4. In addition, the Ca3Bi(PO4)3 shows both cation disorder and oxygen sublattice disorder. For the CBP:Eu(3+) phosphor, the charge transfer bands in the PLE spectra were different at 293 K and 4.3 K, and a model was presented to give a possible explanation for this phenomenon. CBP:Eu(3+) shows intense red emission due to (5)D0-(7)F2 transition and its integral emission intensity and quantum efficiency are higher than the commercial Y2O3:Eu(3+) phosphor under irradiation of 397 nm, indicating that the CBP:Eu(3+) phosphor might have potential application in the NUV range for solid-state lighting. The CBP:Tb(3+) and CBP:Tm(3+) phosphors show intense green and blue emission due to (5)D4-(7)F2 transition of the Tb(3+) ions and the (1)D2-(3)F4 transition of the Tm(3+) ions, respectively. The energy transfer from the Tb(3+) to Eu(3+) ions was also validated by the spectra and decay curves of the Tb(3+) ions. Tunable emission colors were obtained by triply doping Eu(3+), Tb(3+) and Tm(3+) activators in a single host and adjusting their relative ratio.

Monodisperse YVO4:Eu3+ submicrocrystals with uniform morphologies have been successfully synthesized via a facile ethylene glycol (EG) assisted hydrothermal route. The particle shape and size could be effectively manipulated by tuning the thermodynamic (e.g. temperature) and kinetic (e.g. reactant concentration, pH value) parameters. Flower-like, spherical, octahedral, and revolving door-like YVO4:Eu3+ submicrocrystals were obtained by fine-tuning the pH values. The possible growth mechanism of octahedral YVO4:Eu3+ submicrocrystals was presented on the basis of systematic time-dependent experiments. The luminescent spectra reveal that both the post-calcinated spherical and octahedral YVO4:Eu3+ samples show a typical red emission of the Eu3+ ions dominated by strong 617 nm peak with dramatic difference in intensity. This difference may arise from the changes of the adsorbates, surface defects, and crystallinity. Our facile hydrothermal route may provide some new guidance in the design and controlled synthesis of inorganic nano/micromaterials.

Lanthanide-based coordination polymer yttrium 1,2-benzenebicarboxylate ultralong nanobelts have been successfully prepared through a simple and mild one-step approach on a large scale. Electron microscopy images show that the uniform nanobelts are about 100–150 nm in width, 20–40 nm in thickness and up to several hundreds of micrometers in length. The crystal structure of the obtained nanobelts belongs to the triclinic crystal system with space group P1. The exact chemical composition was obtained by X-ray powder diffraction (XRD), elemental analysis, thermal gravimetric analysis (TGA) and Fourier-transform infrared spectra (FT-IR). The ultralong nanobelts growth was explored by time-dependent experiments and a possible formation mechanism was proposed. The investigation of the luminescent properties reveals that the luminescence colors of yttrium 1,2-benzenebicarboxylate nanobelts co-doped with Tb3+ and Eu3+ ions under ultraviolet light can be tuned from green, through green–yellow and yellow, to red by changing the relative doping concentration of the activator ions. It is expected that the synthetic strategy can be used to prepare other nanoscale metal–organic frameworks.

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.

Ordered NaLa(MoO4)2 shuttle-like nanorods composed of nanoparticles have been prepared under hydrothermal environment using Na2MoO4 as a precipitator and ethylene glycol as ligand to decrease the reaction rate and control the morphology of the product. The experimental results indicate that the proportions of the ethylene glycol to water (v/v), the temperature, the pH values, and the reaction time have important effects on the phase structures and the morphologies of the products. Luminescent spectra reveal that most of Eu3+ ions occupy a center of asymmetry in the host lattice.