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BaSO 4 phosphor activated with Sm are prepared by the high temperature solid state reaction method in air, and its crystal structure, morphology, and luminescence properties are investigated. Broadband PLE spectrum are observed within the range 250–580 nm owing to mainly the 4f–5d transitions of Sm 2+ ions, and PL spectrum consists seven emission bands in the range of 550–780 nm owing to mainly 5 D 0 → 7 F J ( J = 0, 1, 2, and 3) transitions of Sm 2+ ion and 4 G 5/2 → 6 H J ( J = 5/2, 7/2, and 9/2) transitions of Sm 3+ ions. Sm 2+ ions can exist steadily in BaSO 4 :Sm phosphor sintered at different temperature and time in air. The optimum Sm 2+/3+ doping concentration, sintering temperature and time are about 2 mol%, 800 °C and 30 min, respectively. The luminous mechanisms are discussed by the schematic energy level diagrams of Sm 3+ and Sm 2+ ions. [ABSTRACT FROM AUTHOR]

A reddish orange emission Sr2P2O7:Sm3+ phosphor is prepared by the solid-state reaction method in air, and the crystal structure and luminescence properties of phosphors are investigated. Sr2P2O7:Sm3+ phosphor shows Commission International de I'Eclairage (CIE) chromaticity coordinates (x = 0.5753, y = 0.4147). White light-emitting diodes (W-LEDs) fabricated using Sr2P2O7:Sm3+ phosphor etc. show CIE chromaticity coordinates (x = 0.3471, y = 0.3124). These results indicate that Sr2P2O7:Sm3+ phosphor could be a potential suitable reddish orange emitting phosphor candidate for W-LEDs with excitation of a ~400 nm n-UV LED chip. [ABSTRACT FROM AUTHOR]

A series of Ca 3 Ti 2 O 7 :Eu 3+ , Ca 3 Ti 2 O 7 :Eu 3+ , Bi 3+ , Ca 3 Ti 2 O 7 :Eu 3+ , R + , and Ca 3 Ti 2 O 7 :Eu 3+ , Bi 3+ , R + ( R + =Li + , Na + , and K + ) phosphors are synthesized by solid-state reaction method in air. All phosphors show bright red emissions centered at ~617 nm upon excitation with UV light of 397 nm. Bi 3+ is a sensitizer for the luminescence of Eu 3+ , and can improve significantly the PL intensity of Ca 3 Ti 2 O 7 :Eu 3+ phosphor due to energy transfer between Bi 3+ and Eu 3+ ions. The sensitization mechanism is investigated and discussed by energy level diagrams of Bi 3+ and Eu 3+ ions. R + ion is used as the charge compensator to improve the luminescence intensity of Ca 3 Ti 2 O 7 :Eu 3+ and Ca 3 Ti 2 O 7 :Eu 3+ , Bi 3+ phosphors, and their PL intensities are enhanced in the sequence K + →Na + →Li + . These phosphors can be promising red emitting candidate for white LED with a ~397 nm near UV chip excitation owing to the high brightness. [ABSTRACT FROM AUTHOR]

Abstract: La2BaZnO5:Nd3+ phosphors are synthesized by a conventional high temperature solid state reaction method, and its crystal structure and luminescence properties are investigated. Photoluminescence bands peaking at ~496, 540, 630, 670, 905, 1070, and 1350nm of La2BaZnO5:Nd3+ phosphors are observed at room temperature due to f–f transition of Nd3+ ion. The optimum Nd3+ doped concentration is ~0.03. Lifetimes of La1.97BaZnO5:0.03Nd3+ phosphor with 496 and 1070nm monitoring wavelengths are ~280 and 250µs, respectively. The luminescence mechanism is explained by using simplified energy lever diagram of Nd3+ ion. La2BaZnO5:Nd3+ material can be applied to powerful solid-state lasers as high efficient light sources. [Copyright &y& Elsevier]

Li 2 Mg 3 SnO 6 :Mn 4+ deep red phosphor is synthesized by high-temperature solid-state reaction method in air. With excitation 330 and 480 nm, the emission band peaking at ∼670 nm within the range 600–790 nm is observed owing to the 2 E → 4 A 2 transition of Mn 4+ ion. Excitation bands peaking at ∼330, 395, and 480 nm in the range of 220–600 nm indicate that Li 2 Mg 3 SnO 6 :Mn 4+ phosphor can be effectively excited by (near) ultraviolet and blue light-emitting diode chips. The optimal Mn 4+ ion concentration is ∼0.4 mol%. Fluorescence lifetime and quantum efficiency of Li 2 Mg 3 SnO 6 :0.4%Mn 4+ phosphor with excitation 330 nm are ∼266.67 μs and 36.3%, respectively. The luminous mechanism is explained by the Tanabe-Sugano energy level diagram of Mn 4+ in the octahedron. [ABSTRACT FROM AUTHOR]

Novel Ca 0.2 Zr 0.8 O 1.8 :Eu 3+ phosphor is synthesized by high-temperature solid-state reaction method in air. Host Ca 0.2 Zr 0.8 O 1.8 with excitation 310 nm shows deep-blue broadband emission within the range 340–500 nm owing to the Zr 4+ → O 2− transition in [ZrO 8 ] group. Ca 0.2 Zr 0.8 O 1.8 :Eu 3+ phosphor with excitation 263 and 394 nm emits reddish-orange light owing to the 5 D 0 → 7 F J ( J = 1, 2, 3, and 4) transitions of Eu 3+ ion, and that with excitation 310 nm shows a systematically varied hue from deep-blue to reddish-orange by changing Eu 3+ ion concentration. Tunable emission and energy transfer are confirmed via spectral properties. The optimal Eu 3+ concentration is ∼5 mol% in Ca 0.2 Zr 0.8 O 1.8 :Eu 3+ phosphor and the corresponding fluorescence lifetime is ∼1.994 ms. The luminous mechanism is analyzed and explained by the simplified energy level diagrams of [ZrO 8 ] group and Eu 3+ ion in Ca 0.2 Zr 0.8 O 1.8 :Eu 3+ phosphor. [ABSTRACT FROM AUTHOR]

LaAlO:Mn and LaAlO:Mn, Na deep red-emitting phosphors are synthesized by a solid-state reaction method in air. Their crystal structures, lifetimes, and luminescence properties are investigated, respectively. PLE spectrum monitored at 730 nm contains three PLE bands peaking at ~276, 325, and 500 nm within the range 200-550 nm, and PL spectrum with excitation 325 nm exhibits two PL band peaks located at ~703 and 730 nm owing to anti-stokes vibronic sidebands associated with the excited state E of Mn ion and the E → A transition of Mn ion, respectively. The optimal Mn doping concentration is ~0.8 mol%. Lifetime of LaAlO:0.8 %Mn phosphor is ~0.92 ms. Na ion as charge compensator can improve obviously the luminescence properties of LaAlO:Mn phosphor due to the charge compensation. The luminous mechanism of Mn ion is explained by using Tanabe-Sugano diagram of Mn ion in octahedral crystal field. The contents of this paper will be helpful to develop novel Mn-doped materials and improve their luminescence properties. [ABSTRACT FROM AUTHOR]

A series of CaNbO: xSm (0 ≤ x ≤ 10 mol%) and CaNbO : Sm, Na/B phosphors were synthesized by the solid-state reaction method in air. Their crystal structures and luminescence properties were investigated and analysed, respectively. Host CaNbO emitted blue light with excitation 270 nm. CaNbO: xSm phosphors showed a systematically varied hue from blue to white by changing Sm ion concentration from 0 to 10 mol% with excitation of 270 nm and their chromaticity coordinates were the regions from (0.1665, 0.1767) to (0.2484, 0.2260). Luminescence properties of CaNbO : Sm phosphor were tuned and improved significantly by codoping B or Na ions. Energy transfer between Nb $_{\mathbf {2}}\textit {O}_{\mathbf {6}}^{\boldsymbol {2-}}$ group and Sm ion was observed and analysed via luminescence properties. The luminous mechanism was explained by energy level scheme and energy transfer process in CaNbO : Sm phosphor. The strong excitation band peaking at ∼407 nm indicated that the CaNbO : Sm, Na/B phosphor has a potential application in white light-emitting diodes based on near-UV LED chip. [ABSTRACT FROM AUTHOR]

Novel CaWO 4 :Eu 3+ , Mn 2+ red phosphor is synthesized by solid-state reaction method in air. CaWO 4 :Eu 3+ , Mn 2+ phosphor with excitation 268 and 394 nm emits red light with chromaticity coordinates (x = 0.6403, y = 0.3593). The strongest emission bands peaking at ∼615 nm is attributed to 5 D 0 → 7 F 2 of Eu 3+ ion. Strong excitation band peaking at ∼394 nm indicates that the phosphor may be excited by near UV (∼394 nm) chip. Emission intensity of CaWO 4 :Eu 3+ , Mn 2+ phosphor with excitation 268 nm is ∼2 times stronger than that of CaWO 4 :Eu 3+ phosphor owing to energy transfer between Eu 3+ ion and Mn 2+ ion. Energy transfer from WO 4 2 − group and Eu 3+ ion to Mn 2+ ion in CaWO 4 :Eu 3+ , Mn 2+ phosphor may be explained via luminescence properties. Luminous mechanism is analyzed by energy level diagrams of WO 4 2 − group, Mn 2+ and Eu 3+ ion. The paper content is helpful to develop and research other novel phosphors. [ABSTRACT FROM AUTHOR]

A series of SrAl [4−(4 x )/3] O 7 : x Mn 4+ (0≤ x ≤1.4 mol%) and Sr (1−0.06/2) Al [4−(4×0.008)/3] O 7 :0.008Mn 4+ ,0.06R + (R + =Li + , Na + , and K + ) phosphors are synthesized by a conventional solid-state reaction method in air. The PLE bands peaking at~325, 395, and 470 nm and the strongest PL band peaking at~660 nm are assigned to the 4 A 2 → 4 T 1 transition of Mn 4+ ion and O 2− –Mn 4+ change transfer band, 4 A 2 → 2 T 1 , 4 A 2 → 4 T 2 , and 2 E → 4 A 2 transitions, respectively. The optimum Mn 4+ doping concentration is about 0.8 mol%. Li + , Na + , and K + ions used as charge compensator can improve observably the PL intensity of SrAl 4 O 7 :Mn 4+ phosphor with excitation 325 nm. The fluorescence lifetimes of SrAl [4−(4×0.008)/3] O 7 :0.008Mn 4+ and Sr [1−0.06/2] Al [4−(4×0.008)/3] O 7 :0.008Mn 4+ ,0.06 R + (R + =Li + , Na + , and K + ) are 0.958, 0.97, 1.113 and 0.965 ms, respectively. The luminous mechanism is explained by schematic energy level diagram of Mn 4+ ion. These experiment results indicate that SrAl 4 O 7 :Mn 4+ ,R + (R + =Li + , Na + , and K + ) phosphors can be used as red emitting phosphor candidate for white LEDs based on a UV (~325 nm) and near UV (~395 nm) bands of LEDs chip. [ABSTRACT FROM AUTHOR]

A series of SrAl [4−(4 x )/3] O 7 : x Mn 4+ (0≤ x ≤1.4 mol%) and Sr (1−0.06/2) Al [4−(4×0.008)/3] O 7 :0.008Mn 4+ ,0.06R + (R + =Li + , Na + , and K + ) phosphors are synthesized by a conventional solid-state reaction method in air. The PLE bands peaking at~325, 395, and 470 nm and the strongest PL band peaking at~660 nm are assigned to the 4 A 2 → 4 T 1 transition of Mn 4+ ion and O 2− –Mn 4+ change transfer band, 4 A 2 → 2 T 1 , 4 A 2 → 4 T 2 , and 2 E → 4 A 2 transitions, respectively. The optimum Mn 4+ doping concentration is about 0.8 mol%. Li + , Na + , and K + ions used as charge compensator can improve observably the PL intensity of SrAl 4 O 7 :Mn 4+ phosphor with excitation 325 nm. The fluorescence lifetimes of SrAl [4−(4×0.008)/3] O 7 :0.008Mn 4+ and Sr [1−0.06/2] Al [4−(4×0.008)/3] O 7 :0.008Mn 4+ ,0.06 R + (R + =Li + , Na + , and K + ) are 0.958, 0.97, 1.113 and 0.965 ms, respectively. The luminous mechanism is explained by schematic energy level diagram of Mn 4+ ion. These experiment results indicate that SrAl 4 O 7 :Mn 4+ ,R + (R + =Li + , Na + , and K + ) phosphors can be used as red emitting phosphor candidate for white LEDs based on a UV (~325 nm) and near UV (~395 nm) bands of LEDs chip. [ABSTRACT FROM AUTHOR]