Cuili Chen

Optical Thermometry Based on Vibration Sidebands in Y2MgTiO6:Mn4+ Double Perovskite

Mn4+-doped Y2MgTiO6 phosphors are synthesized by the traditional solid-state method. Powder X-ray diffraction, scanning electron microscope, and energy-dispersive X-ray spectrometer are employed to characterize the samples. The Mn4+-doped Y2MgTiO6 phosphors show the far-red emission at ∼715 nm, which is assigned to the 2Eg → 4A2 spin-forbidden transition of Mn4+. The temperature-dependent luminescent dynamics of Mn4+ is described by a complete model associated with electron-lattice interaction and spin-orbit coupling. The noncontact optical thermometry of Y2MgTiO6:Mn4+ is discussed based on the fluorescence intensity ratio of thermally coupled anti-Stokes and Stokes sidebands of the efficient ∼715 nm far-red emission in the temperature range of 10-513 K. The maximum sensor sensitivity of Y2MgTiO6:Mn4+ is determined to be as high as 0.001 42 K-1 at 153 K, which demonstrates potential applications for the optical thermometry at low-temperature environments.

In situ hydroxyapatite nanofiber growth on calcium borate silicate ceramics in SBF and its structural characteristics.

A novel calcium silicate borate Ca11Si4B2O22 ceramic was firstly prepared by the conventional solid-state reaction. In vitro hydroxyapatite mineralization was investigated by soaking the ceramics in simulated body fluid (SBF) solutions at body temperature (37 °C) for various time periods. Scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) measurements were applied to investigate the samples before and after the immersion of ceramics in SBF solution. The elemental compositions of a hydroxyapatite layer on the ceramics during the mineralization were confirmed by X-ray energy-dispersive spectra (EDS). Meanwhile, the bending strength and elastic modulus of Ca11Si4B2O22 ceramics were also measured, which indicate that the biomaterials based on Ca11Si4B2O22 ceramics possess bioactivity and might be a potential candidate as biomaterials for hard tissue repair. The bioactive mineralization ability was evaluated on the base of its crystal structural characteristics, i.e., silanol (Si-OH) and B-OH groups can be easily induced on the surface of Ca11Si4B2O22 ceramics soaked in SBF solutions.

Synthesis, structure and optical performance of red-emitting phosphor Ba5AlF13:Mn4+

Mn4+-activated cubic phase Ba5AlF13 red phosphors were prepared by the two-step coprecipitation method. The structural and optical features were characterized on the basis of X-ray diffraction (XRD), transmission electron microscopy (TEM), emission and excitation spectra, and luminescence decay curves. The Ba5AlF13:Mn4+ phosphors can be efficiently excited by near-UV to blue light and exhibit bright red emission at around 627 nm, which is assigned to the 2Eg → 4A2g transition of the 3d3 electrons in [MnF6] octahedra. Temperature dependent emission spectra and decay curves from 10 to 550 K were measured to deeply understand the luminescence mechanism of Mn4+ in the Ba5AlF13 lattice. Notably, this novel red phosphor shows excellent anti-thermal quenching behaviour (∼700% of emission intensity at 300 K relative to 10 K).

Luminescence of Eu2+ and Eu2+-Mn2+ in sodium scandium diphosphate NaScP2O7 crystal

Abstract In this work, the photoluminescence (PL) of NaScP 2 O 7 :Eu 2+ and NaScP 2 O 7 :Eu 2+ ,Mn 2+ was investigated. Phase purity was checked using X-ray powder diffractometry (XRD). PL excitation and emission spectra were recorded to elucidate the PL properties of NaScP 2 O 7 :Eu 2+ and NaScP 2 O 7 :Eu 2+ ,Mn 2+ . Furthermore, fluorescence lifetime measurements were performed. PL and lifetime measurements were carried out from 10 to 525 K. Moreover, the Eu 2+ site occupation was discussed. It turned out that the incorporated Eu 2+ ions substituted for Na + site and occupied two different sites. Temperature dependent PL measurements indicated the emission intensity decreased with increasing temperature due to temperature quenching in NaScP 2 O 7 :Eu 2+ . Fluorescence lifetimes of Eu 2+ in NaScP 2 O 7 :Eu 2+ almost did not change with a decay constant τ =∼0.53 μs in the temperature range of 10–280 K, and then shortened due to temperature quenching. The luminescent lifetime reached ∼0.05 μs at T =525 K. Finally, it was found that energy transfer occurred from Eu 2+ to Mn 2+ in co-doped NaScP 2 O 7 :Eu 2+ ,Mn 2+ .

Luminescence and color center distributions in K3YB6O12:Ce3+phosphor

Polycrystalline Ce3+-doped K3YB6O12 (1–14 mol%) phosphors were prepared by facile chemical sol–gel synthesis. The phase formation of the phosphors was confirmed by x-ray powder diffraction (XRD) analysis. The photoluminescence excitation spectra (PLE), emission spectra (PL) and the luminescence decay curves were tested. Under the near-UV light, the phosphors present the emission from blue color to yellowish green due to the allowed 4f –5d transitions of Ce3+ ions. The absolute quantum efficiency (QE) of K3YB6O12:Ce3+ can reach 53% under the excitation of near-UV light. The luminescence thermal quenching of the phosphor was investigated by the temperature-dependent spectra. The crystallographic site of Ce3+ ions in the lattice was identified and discussed on the basis of luminescence characteristics and structural data. There is only one isolated Ce3+ center occupying the Y(II) sites in the lightly doped samples presenting a typical doublet emission profile. While the Ce3+ multi-centers could be created with the enhancement of the doping levels, which could induce the distinct red-shift of the spectra due to the dipole–dipole interactions. The result in this work could be useful for the further investigation of other rare earth ions in this host.

Correction: Synthesis, structure and optical performance of red-emitting phosphor Ba5AlF13:Mn4+

Correction for ‘Synthesis, structure and optical performance of red-emitting phosphor Ba5AlF13:Mn4+’ by Lin Qin et al., RSC Adv., 2017, 7, 49473–49479.