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To explore new emission-tunable phosphors with down-shifting and up-conversion properties, a series of Ca 8 MgGd(PO 4 ) 7 :Eu 2+ , Mn 2+ and Ca 8 MgGd(PO 4 ) 7 :Yb 3+ , Er 3+ , Ho 3+ , Tm 3+ samples were synthesized by solid-state reaction method, and their photoluminescence properties were studied. For down-shifting, Eu 2+ -single-doped Ca 8 MgGd(PO 4 ) 7 exhibits a very broad yellow–white emission from 400 to 800 nm upon 365 nm excitation, which originates from various Eu 2+ emission centers. When the Mn 2+ is introduced into Ca 8 MgGd(PO 4 ) 7 :Eu 2+ , an extremely efficient energy transfer from Eu 2+ to Mn 2+ occurs and decreases the Eu 2+ emission intensity strongly. The corresponding energy transfer efficiencies were evaluated from the decay curves. For different Mn 2+ concentrations, the emitting light colors can be tuned conveniently and red emission is obtained finally. For up-conversion, the red, green, and blue tri-color emissions upon 980 nm excitation have been gained in the Yb 3+ –Ho 3+ , Yb 3+ –Er 3+ , and Yb 3+ –Tm 3+ doped Ca 8 MgGd(PO 4 ) 7 , respectively. By varying the relative concentrations of Yb 3+ , Er 3+ , Ho 3+ , and Tm 3+ , tunable emission was realized upon near-infrared excitation, and an efficient energy transfer from Tm 3+ to Er 3+ has been found in the Yb 3+ –Er 3+ –Tm 3+ tridoped Ca 8 MgGd(PO 4 ) 7 samples. [ABSTRACT FROM AUTHOR]

To develop new emission-tunable upconversion (UC) phosphors, the Sr 3 AlO 4 F:5%Yb 3+ , xEr 3+ , yHo 3+ (0 ≤ x ≤ 1%, 0 ≤ y ≤ 1%) samples were prepared by conversional solid-state reaction method, and their luminescence properties upon 980 nm excitation were studied. Upon 980 nm excitation, Yb 3+ -Er 3+ codoped Sr 3 AlO 4 F shows a predominant emission peak between 645 and 700 nm which is attributed to the 4 F 9/2 - 4 I 15/2 transition of Er 3+ , and the Er 3+ green emissions have been almost quenched. In this case, the yellowish green emitting light is obtained. The possible reason was interpreted by the energy level diagram and the proposed UC mechanism. For Yb 3+ -Ho 3+ codoped Sr 3 AlO 4 F, three emissions are observed obviously which are all derived from the Ho 3+ ion. The corresponding chromaticity coordinates indicate a red emission has been gained. To realize the tunable emission, the typical Sr 3 AlO 4 F:5%Yb 3+ , 0.2%Er 3+ , 1%Ho 3+ phosphor was developed, and its emission spectrum includes the emission peaks of both Er 3+ and Ho 3+ . Correspondingly, the sample gives a yellow emission. [ABSTRACT FROM AUTHOR]

Highlights: [•] Different morphologies can be achieved by controlling the reaction conditions. [•] Nanocrystallines with diameter below 10nm are obtained for upconversion application. [•] Monodisperse microspheres with the suitable diameter are prepared for 3D PDP. [•] The Y0.89(V0.5, P0.5)O4:0.11Eu3+ shows good color purity and intense emission. [ABSTRACT FROM AUTHOR]

La 0.8 Ca 0.2 MnO 3 thin film grown on 0.67Pb(Mg 1/3 Nb 2/3 )O 3 –0.33PbTiO 3 (PMN–PT) substrate has shown very interesting transport properties, which is modulated by the ferroelectric polarization switching in the substrate. The ferroelectric poling reduces the in-plane strain by about 0.135% with the applied piezovoltage of 500 V to PMN–PT substrate. The resistance is lowered and the metal–insulator transition temperature ( T p ) is increased due to the reduced in-plane strain. Moreover, it is shown that the ferroelectric field effect competes strongly with the strain effect especially when the temperature is lowered below T p in our film. [ABSTRACT FROM AUTHOR]

Abstract: Blue-light emission at room temperature was observed in SrTiO3 film with SrRuO3 as buffer layer on LaAlO3 substrate. Other SrTiO3 films, such as grown directly on LaAlO3 and GaAs substrate or with DyScO3 as buffer layer on LaAlO3, which all have a single-orientated structure, showed no visible light excitation. A double-orientated structure was characterized in the SrRuO3 buffered SrTiO3 by multiple X-ray diffraction techniques. After post-annealing in nitrogen at 500°C for 12h, the photoluminescence signal increased moderately while the double-orientated structure did not change at all. And still, no visible light excitation was observed in the other single-orientated films after post-annealing. We argued that the structure disorder induced by the SrRuO3 buffer is the basis for the blue-light emission. [Copyright &y& Elsevier]

Abstract A series of Yb3+-Er3+, Yb3+-Ho3+, and Yb3+-Tm3+ doped Ca 2 Gd 8 (SiO 4) 6 O 2 (CGS) phosphors were synthesized by solid-state reaction method, and their upconversion (UC) luminescence properties for temperature sensing were studied. Upon 980 nm excitation, the green and red emissions of Er3+ were observed, and the optimal Er3+ concentration was determined to be 3 mol%. For the CGS:10%Yb3+,yHo3+ phosphors, three emission peaks in the green, red and near-infrared region appear. It was found that the relative intensities of Ho3+ different emissions change with Ho3+ concentration, which has been explained by the cross-relaxation process. The strongest Tm3+ emission appeared at 790 nm, attributed to the 3H 4 -3H 6 transition. The optimal Tm3+ concentration was determined to be 0.5 mol%. The temperature sensing behavior was evaluated by employing the thermally-coupled or non-thermally coupled levels of Er3+, Ho3+ and Tm3+. The maximum sensitivities obtained are 3.71 × 10 − 3 and 1.12 K-1 for CGS:10%Yb3+,3%Er3+, 0.111 K-1 for CGS:10%Yb3+,3%Ho3+ and 3.3 × 10 − 4 K−1 for CGS:10%Yb3+,0.5%Tm3+, respectively. The high sensitivities indicate the present phosphors could have potential application in temperature sensing. Highlights • Different strategies for temperature sensing were introduced in the present phosphors. • The present phosphors show smooth particle surface that benefits the UC luminescence. • High sensor sensitivity has been obtained in the CGS:Yb3+-Er3+/Ho3+/Tm3+. • The present phosphors could have potential application in optical temperature sensors. [ABSTRACT FROM AUTHOR]

Sr3AlO4F:5%Yb3+,xEr3+,yHo 3+ (x = 0-1%, y = 0-1%) powder samples are prepared by calcination of stoichiometric amounts of SrCO3, SrF2, Al2O3, and lanthanoide oxides (1. [ABSTRACT FROM AUTHOR]

To develop novel luminescent materials for multifunctional applications, CaLa 4 Si 3 O 13 (CLSO)-based phosphors were prepared by solid-state reaction method. Firstly, the tunable-emission was obtained in the Tb 3+ -Mn 2+ codoped CLSO, and the energy transfer from Tb 3+ to Mn 2+ was also found. The luminescence thermal stability for CLSO:0.8Tb 3+ ,0.07Mn 2+ reveals that the emission intensity of Mn 2+ decays faster than that of Tb 3+ with increasing temperature, resulting in the changing emission color. This observation indicates that the CLSO:Tb 3+ ,Mn 2+ could introduce a potential technique for temperature measurement. Secondly, the CLSO:0.05Eu 3+ ,zY 3+ phosphors reveal that the emission intensity and color both change with Y 3+ concentration, and the optimal Y 3+ concentration was determined for z = 0.8. This phosphor could apply to white LEDs. Thirdly, the upconversion luminescence upon 980 nm excitation was observed in the CLSO:Yb 3+ ,Er 3+ , CLSO:Yb 3+ ,Ho 3+ , and CLSO:Yb 3+ ,Tm 3+ phosphors. Green and red emissions were gained in the Yb 3+ -Er 3+ and Yb 3+ -Ho 3+ doped CLSO, respectively. Very strong near-infrared emission was generated in the Yb 3+ -Tm 3+ doped CLSO and the visible emission is almost quenched relative to the near-infrared emission. [ABSTRACT FROM AUTHOR]

The SrWO 4 and SrWO 4 :Tb 3+ samples were prepared by a simple precipitation method, and the morphology, photoluminescence and cathodoluminescence (CL) properties were investigated. The optical bandgap of SrWO 4 is determined to be 4.73 eV experimentally, and a red-shift of the absorption edge is observed when Tb 3+ is doped. The samples show spindle-like particles with average length of about 10 μm on the whole, but some particles of other shapes are also found. Under 254 and 147 nm excitation, the Sr 0.9 WO 4 :0.1Tb 3+ phosphor exhibits typical Tb 3+ green emission. The absorption bands of the WO 4 2 - group appear in the excitation spectra of both the SrWO 4 and Sr 0.9 WO 4 :0.1Tb 3+ . By measuring the CL spectra of Sr 0.9 WO 4 :0.1Tb 3+ , the typical Tb 3+ emission peaks are found. The above results indicate the SrWO 4 :Tb 3+ phosphor can be excited by both photons and electrons, which has potential application in PDPs and FEDs. [ABSTRACT FROM AUTHOR]

Si/SiO2 multilayers were fabricated by RF plasma enhanced chemical vapor deposition system, and phosphorus/ boron (P/B) co-doped silicon nanocrystals (Si NCs) were obtained under the constricted crystallization of multilayers structures. Microstructures of P/B co-doped Si NCs/SiO2 multilayers and impurities distributions were studied by Raman, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Low temperature electron paramagnetic resonance (EPR) results indicate that the non-radiative defects on Si NCs surfaces can be passivated by P and B impurities. Hall effect manifests that P and B impurities can substitutionally incorporate into Si NCs inner. Meanwhile, P impurity exhibits higher doping efficiency than B. Near-infrared photoluminescence near 1 200 nm with the wavelength compatible for optical telecommunication was detected in the small-sized P/B co-doped Si NCs. The emission intensity can be enhanced by regulating the nominal P-doping concentration. According to the time-resolved photoluminescence and EPR results, the physical mechanisms of P-doping on the radiative and non-radiative recombination processes of Si NCs were discussed, which are responsible for the enhancement of 1 200 nm photoluminescence. [ABSTRACT FROM AUTHOR]

A series of Er3 + doped and Er3 + / Yb3 + co-doped 0.96Na0.5 Bi0.5 TiO3 -0.04CaTiO3 (NBT-CT: xEr3 + / yYb3 +, x = 0.002 ~0.015, y = 0.010) lead-free piezoelectric ceramics were prepared by a solid-state sintering method. The phase structure and up-conversion luminescence properties of the samples were characterized and analyzed by X-ray diffraction and fluorescence spectrofluorometer, respectively. These results show that the main crystal phase of the samples is that of NBT. Under the excitation of a 980 nm near-infrared light, the Er3 + doped and Er3 + / Yb3 + co-doped NBT-CT ceramics exhibit characteristic emission of Er3 + with strong dominant green up-conversion emissions. The optimal up-conversion luminescence performance with x = 0.010 in NBT-CT: xEr3 + ceramics are obtained. Yb3 + can act as sensitizer and significantly enhance the up-conversion luminescence intensity of Er3 + . [ABSTRACT FROM AUTHOR]

Sm3+-Modified (1 − x)Na0.5Bi0.5TiO3-xCaTiO3 (NBT-xCT:Sm3+) piezo-luminescent ceramic materials were synthesized to investigate the influence of CaTiO3 (CT) concentration on their photoluminescence and electrical performance. Under 480 nm irradiation, the NBT-xCT:Sm3+ samples exhibit prominent orange-red emission, with a prime emission peak centered at 597 nm. A moderate amount of CT doping in the Sm3+-modified NBT ceramics boosts both their photoluminescence and piezoelectric properties significantly, with NBT-0.04CT:Sm3+ showing the optimal performance. Furthermore, outstanding luminescence thermal stability over a temperature range of 293–473 K and superior water resistance behavior are achieved in the NBT-0.04CT:Sm3+ ceramic. These results indicate that NBT-xCT:Sm3+ piezo-luminescent ceramics show great potential applications in white LEDs, as well as novel optical-electronic multifunctional devices. [ABSTRACT FROM AUTHOR]

• New Eu3+/Yb3+ doped LSO phosphors were designed. • The LSO:20%Eu3+ shows a much higher brightness than the commercial Y 2 O 3 :Eu3+. • The LSO:Eu3+ shows a higher T 0.5 value than many other phosphors. • The developed phosphors are promising for multifunctional applications. In this work, a series of Eu3+/Yb3+ doped La 1.55 SiO 4.33 (LSO) phosphors were prepared by solid state reaction method for multifunctional applications. The phase purity and particle morphology were characterized with XRD and SEM technique, respectively. Upon ultraviolet light excitation, the downshifting luminescence of Eu3+ was observed in the red region, and the strongest emission peak located at 612 nm is attributed to the forced electric dipole 5D 0 →7F 2 transition. The optimal Eu3+ doping concentration was determined to be 20 mol%, for which the internal quantum efficiency of the phosphor reaches 75.1%. The temperature-dependent emission spectra of LSO:20%Eu3+ revealed that the quenching temperature T 0.5 is 483 K. For the upconversion (UC) luminescence, the Yb3+-Eu3+ codoped LSO phosphors were designed, where the Yb3+ ion was used as a sensitizer. The UC mechanism for a cooperative energy transfer was learnt from the pump-power-dependent emission spectra. By excitation at various temperatures, the intensities of emissions from different excited states showed different changes with temperature. All the above spectral characteristics indicate that the LSO:Eu3+/Yb3+ phosphors can show potential applications in LEDs, anticounterfeiting and optical thermometer. [ABSTRACT FROM AUTHOR]

In this paper, the Yb3+-Ho3+ co-doped La 1.55 SiO 4.33 (LSO) phosphors were synthesized by the conventional solid-state reaction method. The phase purity and morphology of the samples were studied by XRD and SEM, respectively. Under 980 nm excitation, the upconversion (UC) luminescence of the LSO:Yb3+,Ho3+ phosphors was checked for different Ho3+ doping content and pump power. The corresponding UC mechanism was interpreted from the changing decay lifetimes and the energy transfer processes between Yb3+ and Ho3+ ions. Meanwhile, the temperature-dependent emission spectra were analyzed to learn the optical temperature-sensing behaviors with the fluorescence intensity ratio (FIR) method. The results revealed that the FIR (I 658 /I 544) value increased when the temperature rose, which followed a linear function. The sensor sensitivity was evaluated, and the LSO:10%Yb3+,2%Ho3+ phosphor showed the highest absolute sensitivity. Besides, the main population way on 5F 5 level of Ho3+ for red emission was clarified by the comparison of the UC spectra excited by continuous-wave and pulse light. Based on the above results, the LSO:Yb3+,Ho3+ phosphor can be considered as a new UC luminescent material for optical temperature sensors. • New Yb3+-Ho3+ co-doped La 1.55 SiO 4.33 phosphors are designed for optical thermometer. • The main population way on 5F 5 level of Ho3+ for red emission was clarified clearly. • High sensitivity is achieved in the La 1.55 SiO 4.33 :Yb3+,Ho3+ samples. • The phosphors are promising as potential candidates in optical thermometer. [ABSTRACT FROM AUTHOR]

Luminescent piezoelectric materials promise a stratagem for controlling the optical process by electric field, which would benefit for future optoelectronic devices. Here, Er3+ doped (Ba 0.85 Ca 0.15) (Zr 0.1 Ti 0.9)O 3 (BCZT: Er3+) piezoelectric ceramics are prepared to demonstrate the proof of concept. In addition to excellent intrinsic piezoelectricity and ferroelectricity, BCZT: Er3+ ceramics exhibit simultaneously strong green upconversion emissions under excitation of 980 nm. Remarkable photoluminescence (PL) quenching phenomenon as well as significant changes on relative intensities of stark lines are observed under external poling electric field. Furthermore, field dependent piezoelectric constant d 33 and photoluminescence quenching ratio show similar variation trend and finally saturate for E > 3.5 kV/mm, which provides a noncontact strategy to monitor the piezoelectric constant d 33. The PL quenching triggered by electric field in BCZT: Er3+ ceramics is ascribed to the decreased asymmetry originating from field-induced structural transformation from a significant fraction of the tetragonal phase to rhombohedral phase. Our work would be helpful for expanding the scope of luminescent piezoelectric materials and promising future optoelectronic and optical devices with cross-coupled physical properties. • Ferroelectricity and upconversion emissions coexist in BCZT: Er3+. • Electric field can modulate photoluminescence and relative intensity of stark lines. • A noncontact strategy to monitor the piezoelectric constant is proposed. • The mechanism of electric field-photoluminescence coupling is analyzed. [ABSTRACT FROM AUTHOR]

Abstract To develop long-afterglow luminescent materials for white LEDs application, a series of Sr 1·97 MgSi 2 O 7-1.5x N x :0.01Eu2+,0.02Dy3+ (0 ≤ x ≤ 0.49) phosphors were designed. The single-phase samples were confirmed and the introduction of N was verified by the XRD patterns and energy-dispersive X-ray spectrum. The average particle size of the phosphors was determined to be about 4.9 μm. When the N is doped, it has been found the Eu2+ emission intensity decreases gradually, which could be owing to the increasing crystal defects by the nonequivalent substitution between N and O. The excitation spectra reveal that the broad and strong excitation bands from 240 to 450 nm can well match the LED chip. It is interesting that the incorporation of N can improve the afterglow time, which has been interpreted by the thermoluminescence curves. The investigation of the temperature-dependent luminescence indicates a beneficial effect on the thermal stability by doping N in the phosphors. Graphical abstract Image 1 Hightlights • A meaningful idea by combining LEDs and afterglow was proposed in lighting field. • The long afterglow time can be increased by introducing N in the phosphors. • The Sr 1·97 MgSi 2 O 7-1.5x N x :0.01Eu2+,0.02Dy3+ shows potential applications in w-LEDs. • The present results could be constructive to the development of similar phosphors. [ABSTRACT FROM AUTHOR]

Eu3+ singly-doped Ba 2 La 6 Y 2 (SiO 4) 6 O 2 phosphors with hexagonal structure have been synthesized by the high-temperature solid-state reaction method. The crystal structure of the samples was analyzed. To investigate the site occupation of Eu3+ in Ba 2 La 6 Y 2 (SiO 4) 6 O 2 , the photoluminescence behavior of the phosphor was studied systematically. The emission spectra under specific wavelength excitations and the excitation spectra by monitoring emissions at 5D 0 →7F 0 transition wavelengths indicated that Eu3+ ions have entered two distinct sites in the compound. According to the concentration-dependent photoluminescence properties, the preferential site occupation was illustrated. In addition, the temperature-dependent PL measurement results revealed the high thermal stability of the sample and its application potential as a noninvasive optical thermometer. This work may help to provide an alternative approach to study the site occupation of Eu3+ ions in other functional materials. • A new Eu3+-activated Ba 2 La 6 Y 2 (SiO 4) 6 O 2 phosphor was synthesized via solid-state method. • The site occupation of Eu3+ was investigated according to the photoluminescence properties. • The phosphor has a high thermal stability. • The synthesized sample could have application potential as a noninvasive optical thermometer. [ABSTRACT FROM AUTHOR]

A series of Ho3+-doped 0.94Na 0.5 Bi 0.5 TiO 3 -0.06BaTiO 3 lead-free piezoelectric ceramics (NBT-0.06BT: x Ho3+, 0.0025≤ x ≤ 0.03) are prepared by a conventional solid-state reaction method. Under the excitation of 980 nm, all the samples exhibit strong green, red and near infrared upconversion emissions, which are ascribed to the 5F 4 /5S 2 →5I 8 (∼547 nm), 5F 5 →5I 8 (∼656 nm), 5F 4 /5S 2 →5I 7 (∼756 nm) transitions of Ho3+ ions, respectively. The NBT-0.06BT: 0.015Ho3+ ceramic displays the optimal emission among these Ho3+-doped NBT-0.06BT solid solutions. Optical thermometry behavior is evaluated via fluorescent intensity ratio (FIR) of green to red emissions of Ho3+ ions. The temperature sensing performances is investigated in the temperature range of 293–473 K based on non-thermally coupled levels (NTCL). The maximum relative sensitivity is found to be 0.35% K−1 at 293 K. The present investigation results imply the promising application of NBT-0.06BT: Ho3+ in non-contact optical thermometers. • Under a 980 nm diode excitation, the NBT-0.06BT: x Ho3+ specimens exhibit strong prominent green emission. • The upconversion photoluminescence intensity exhibits extremely sensitive to temperature in range of 293–473 K. • A maximum relative sensitivity of 0.35% K−1 at 293 K is obtained for NBT-0.06BT: 0.015Ho3+ ceramic. [ABSTRACT FROM AUTHOR]

• The quantum cutting was directly observed and confirmed in CGP:Tm3+. • The improved QC model was established in Tm3+ ion. • The effect of Tm3+ concentration on the spectral characteristics was clarified. • The investigations can help to understand the QC and ET processes in Tm3+. In this work, to develop new quantum cutting (QC) luminescent materials and clarify the QC process, a series of Tm3+-activated Ca 9 Gd(PO 4) 7 (CGP) phosphors were prepared by conventional high-temperature solid state reaction method. The phase purity of the samples was checked by XRD patterns, and the structural features were analyzed on the basis of Rietveld refinement. The emission spectra of Tm3+ were measured by exciting at different wavelengths, in which the QC was identified. The main QC model was proposed when the Tm3+ is excited into 1D 2 level. The occurrence of QC was further verified by comparing the decay lifetimes on 3H 4 level under 357, 470 and 685 nm excitation. With increasing Tm3+ concentration, it was found that the 3H 4 →3H 6 transition intensity around 806 nm exhibits faster increase rate than other ones by exciting at either 357 or 470 nm. This increase rate is more effective under 357 nm excitation thanks to the existence of QC process. The above investigation could show instructional significance for the development of other rare earth ions doped luminescent materials. [ABSTRACT FROM AUTHOR]

A series of Sm3+ doped 0.92(Na 0.5 Bi 0.5)TiO 3 -0.08(Ba 0.90 Ca 0.10)(Ti 0.92 Sn 0.08)O 3 (NBT-8BCTS: x Sm3+, x = 0–0.025) lead-free piezoelectric ceramics are fabricated via a conventional solid-state reaction method, and their phase structure, photoluminescence properties and temperature dependent of luminescence spectra are studied in detail. The emission spectra with dominant orange-red emission consist of four emission peaks at 542 nm, 598 nm, 644 nm and 709 nm, which are ascribed to the 4G 5/2 → 6H J/2 (J = 5, 7, 9, 11) transition of Sm3+ ions, respectively. Furthermore, the optical temperature sensing properties of the NBT-8BCTS: 0.01Sm3+ ceramic in the temperature range between 313 K and 533 K are analyzed with a maximum relative sensitivity 1.29%K−1 at T = 463 K. Besides, the phosphors exhibit excellent stable temperature sensing performance under repeated heat-cooling cycles. These results suggest that the Sm3+ doped NBT-8BCTS ceramics may have potential applications in multifunctional sensing devices by integrating its optical temperature sensing and intrinsic ferroelectric property. [Display omitted] • Ferroelectricity and photoluminescence emissions coexist in NBT-BCTS: x Sm3+. • A maximum relative sensitivity of 1.29% K−1 at 463 K is obtained. • Sm doped NBT-BCTS ceramics have potential for developing multifunctional optical-electric devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • A moderate amount of Dy3+ doping can enhance the ferroelectricity of the NBT host. • The NBT: x Dy3+ specimens exhibit intense prominent orange-yellow emission with optimal performance for x = 0.012. • The NBT: 0.012Dy3+ ceramic could be applied to optical temperature sensing. A series of Dy3+ doped Na 0.5 Bi 0.5 TiO 3 (NBT: x Dy3+, x = 0.003–0.018) lead-free ferroelectric ceramics were successfully prepared by a solid-state reaction method. The Dy3+ ions composition dependent photoluminescence properties were systematically studied. All the samples display intense characteristic emission of Dy3+ under an excitation wavelength of 454 nm, which are attributed to the transitions of 4F 9/2 → 6H J /2 (J = 13, 11 and 9). All the samples show strong orange-yellow emission, which could be applied to warm white light hopefully. When the content of Dy3+ is equal to 0.012, the ceramic has the optimal luminous performance. Remarkable thermal quenching of the luminous intensity ceramic occurs as the temperature is higher than initial temperature 293 K. Furthermore, Dy3+ activated photoluminescence performance combined with the presence of ferroelectricity in the NBT host can be applied to developing non-contact optical temperature sensitive materials and other future novel optoelectronic devices. [ABSTRACT FROM AUTHOR]

Luminescent ions doped lead free ferroelectric ceramics are the potential candidates to the widespread application of optoelectronic devices due to the coupling between their unique photoluminescence and inherent ferroelectric performance. In this work, the tunable photoluminescence response is successfully achieved in (1- x)Na 0·5 Bi 0·5 TiO 3 - x CaTiO 3 : Eu3+ (NBT- x CT: Eu3+, x =0.07, 0.1) via electric field poling. It is found that the enhancement of photoluminescence intensity became apparent for polarized NBT-0.07CT: Eu3+, wherein x =0.07 is near the morphotropic phase boundary region. However, for NBT-0.1CT: Eu3+ ceramic with a morphotropic phase boundary, the variation trend of the emission intensity after electric field poling is opposite. These results are ascribed to the lattice distortion and phase transition induced by an external field poling, which originates from ferroelectric and structural instability near and in the morphotropic phase boundary of NBT- x CT: Eu3+ (x =0.07, 0.1) ceramics. • The NBT- x CT: Eu3+ specimens exhibit strong prominent red emission. • The lattice distortion and phase transition are induced by an external field poling. • Electric-field-induced photoluminescence modulation is successfully achieved. • NBT-0.07CT: Eu3+ possesses more superior performance than NBT-0.1CT: Eu3+. [ABSTRACT FROM AUTHOR]

A train of Yb3+-Er3+ and Yb3+-Ho3+ doped KBaYSi 2 O 7 (KBYS) phosphors were synthesized via the solid-state reaction. The corresponding photoluminescence properties were investigated systematically. Under the excitation of 980 nm, the KBYS:Yb3+,Er3+ exhibits characteristic emissions of Er3+ at 520, 558 and 661 nm; the Ho3+ in KBYS shows a strong red emission at 664 nm and a weak green emission near 549 nm. The optical temperature-sensing properties were checked by employing different strategies, where the thermally-coupled-levels (TCLs) and non-TCLs were involved. It has been found the KBYS:Yb3+,Er3+ phosphor using I 660 /I 520 can produce higher absolute (S A) and relative (S R) sensitivities compared with that using I 520 /I 558. In Yb3+-Ho3+ codoped KBYS, the I 663 /I 547 value exhibits a linear relationship with absolute temperature. High S A has been achieved, and the S R is increased continuously with decreasing temperature. The above investigation results reveal that the phosphors in this work could be promising for applications in optical thermometer. • Different strategies for temperature sensing were studied in KBYS:Yb3+-Er3+/Ho3+. • The KBYS:Yb3+-Er3+/Ho3+ phosphors show high sensitivities for temperature sensing. • The spectral characteristics and upconversion mechanism were interpreted in detail. • The present phosphors could have potential application in optical thermometers. [ABSTRACT FROM AUTHOR]

A novel broadband (SrCa) 2 La(PO 4) 3 O: Eu2+ phosphor was successfully synthesized by the conventional high-temperature solid-state reaction. The samples are of phase purity demonstrated by XRD analysis. The photoluminescence properties of the (SrCa) 2 La(PO 4) 3 O: Eu2+ phosphor were investigated systematically. Under the excitation of 365 nm near-ultraviolet light, the phosphors exhibit absorption in the ultraviolet–visible spectral region of 280–420 nm and show an intense asymmetric broadband blue emission peaking at around 460 nm. The different crystallographic sites of Eu2+ in (SrCa) 2 La(PO 4) 3 O: Eu2+ phosphors have been verified via the photoluminescence properties. The concentration quenching mechanism, decay property, and thermal stability of the phosphor have been discussed in detail. The investigation results indicate that the as-prepared (SrCa) 2 La(PO 4) 3 O: Eu2+ phosphor will have application potential in near-ultraviolet pumped white light-emitting diodes. • A newly found compound (SrCa) 2 La(PO 4) 3 O was synthesized. • The emitting color of the (SrCa) 2 La(PO 4) 3 O: Eu2+ phosphor varies with Eu2+ concentration. • The synthesized sample could have application potential in NUV pumped wLEDs. [ABSTRACT FROM AUTHOR]

A series of Sr 3 La 2 (PO 4) 2 (SiO 4)O: Eu2+ phosphors were synthesized by conventional high-temperature solid-state reaction. The phase formation was confirmed by XRD analysis. The photoluminescence properties of Sr 3 La 2 (PO 4) 2 (SiO 4)O: Eu2+ phosphors were investigated systematically. The phosphors exhibit absorption in the ultraviolet–visible spectral region of 280–420 ​nm and show an intense asymmetric broadband blue emission peaking at 454 ​nm under the excitation at 365 ​nm. The concentration quenching mechanism, decay property, and thermal stability have been discussed in detail. The investigation results indicate that Sr 3 La 2 (PO 4) 2 (SiO 4)O: Eu2+ will have applications as the blue component in tricolor near-ultraviolet pumped white light-emitting diodes. The Sr 3 La 2 (PO 4) 2 (SiO 4)O: Eu2+ phosphor was reported, which shows the potential application as a blue component in tricolor n-UV pumped wLEDs. Image 1 [ABSTRACT FROM AUTHOR]

A series of Eu3+-doped Ca 3 La 7 (SiO 4) 5 (PO 4)O 2 (CLSPO) multifunctional phosphors were synthesized by a high-temperature solid-state reaction method. The crystal structure of the CLSPO host was explored using Rietveld refinement. The photoluminescence properties of CLSPO: Eu3+ phosphors were investigated systematically. Upon 392 nm near-ultraviolet light excitation, the phosphor exhibited strong characteristic emissions of Eu3+ ions with a dominant red emission peak around 613 nm, indicating its potential use in solid-state lighting. Calculations of Ω 2 and Ω 4 Judde-Ofelt intensity parameters provided insight into the structure-luminescence correlation in the CLSPO: Eu3+ system. By exploring the temperature sensitivity of photoluminescence intensity, the application potential of the sample to optical thermometry was studied. The multifunctional phosphor Ca 3 La 7 (SiO 4) 5 (PO 4)O 2 : Eu3+ exhibits efficient red emission under n-UV excitation, moreover, it also shows application potential in optical thermometry. Unlabelled Image • An insight into the structure-luminescence correlation in the Ca 3 La 7 (SiO 4) 5 (PO 4)O 2 : Eu3+ system was carried out. • Efficient red emission was obtained in the Ca 3 La 7 (SiO 4) 5 (PO 4)O 2 : Eu3+ sample. • The synthesized sample could have application potential in optical thermometry. [ABSTRACT FROM AUTHOR]