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Series of NaBa0.97Ce0.03B9O15:xTb3+, ySm3+, zDy3+ are synthesized by the traditional high temperature solid-state method. Ce3+ is used as a sensitizer to improve the spectral properties of Tb3+, Sm3+ and Dy3+ by the way of energy transfer which is proved by the fluorescence decay curves. And the mechanisms of energy transfer from Ce3+ to Tb3+, Sm3+ and Dy3+ are all determined as dipole-dipole interaction. The color of NBB:3%Ce3+, xTb3+, 0.5%Sm3+ can shift from light violet thought white to yellow. And NBB:3%Ce3+, zDy3+ can give out white light and move to green field. Moreover, the thermal stability makes NBB:3%Ce3+, 0.2%Dy3+ be a potential candidate for the self-referencing luminescent thermometry.

Series of Ce3+/Eu2+, Ce3+/Mn2+ and Ce3+/Eu2+/Mn2+ doped Ba3Y(PO4)3 samples were synthesized by a high temperature solid state reaction method. Phase formation, energy transfer, luminescence properties and thermal quenching properties were investigated carefully. The energy transfer from Ce3+ to Eu2+ and Ce3+ to Mn2+ in Ba3Y(PO4)3 were verified and discussed detailed. When Ce3+ and Eu2+ are co-doped, the energy transfer process from Ce3+ to Eu2+ is confirmed with electric dipole-dipole interaction. For Ce3+/Mn2+ co-doped phosphors, the energy transfer process from Ce3+ to Mn2+ is proved with electric dipole-dipole interaction. Besides, due to the existence of defects, the phosphors show excellent thermal stability. For Ce3+/Eu2+/Mn2+ tri-doped Ba3Y(PO4)3, the energy transfer Ce3+→Eu2+ (Mn2+) and Eu2+→Mn2+ are confirmed. The energy transfer priority among Ce3+, Eu2+ and Mn2+ is analyzed in detail basing on the change of emission intensity. The obtained tri-doped phosphors contain red, green and blue component, thus they can emit warm white light basing on the energy transfer. The results show that they may be novel white-light-emitting phosphors for ultraviolet white light emitting diodes.

Luminescence mechanism of self-activated phosphor Ca0.75Sr0.2Mg1.05Si2O6 (CSMS) originating from oxygen vacancy defects has been deeply investigated by regulating synthesis temperature. The results demonstrate that the luminescence comes from three different oxygen defects in the crystal structure. For Ce3+ doped CSMS (ICSD#68180), two concentration quenching phenomena can be observed at x = 0.03 and 0.12 as the result of the formation of new substance CaMgSi2O6 (ICSD#17043), which leads to the actual concentration of Ce3+in CSMS (ICSD#68180) is far less than the doping concentration since part of Ce3+ ions enter CaMgSi2O6 (ICSD#17043). The emission spectra of CSMS:xCe3+ shifts from 388 nm to 405 nm with increasing Ce3+ content, which mainly should be due to the 5d energy center of Ce3+ shifting down and the crystal field split.

Here, using the safety raw materials Li3N, Sr3N2 and Eu2O3 instead of LiAlH4, SrH2 and EuF3 (besides AlN), the nitride phosphor SrLiAl3N4:Eu2+ (SLA:Eu2+) was synthesized in the glove box (O2

Na3Bi(PO4)2:Eu3+/Tb3+/Dy3+/Sm3+ phosphors were synthesized via a high-temperature solid-state reaction method. The X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), diffuse reflection, photoluminescence (PL) and fluorescent decay curves were utilized to characterize the obtained phosphors. Under n-UV excitation, Na3Bi(PO4)2:Eu3+/Tb3+/Dy3+/Sm3+ samples show the characteristic f-f emissions and present red, green, yellow and orange emission, respectively. When Tb3+, Dy3+ and Sm3+ were co-doped into the Na3Bi(PO4)2:Eu3+ phosphors, tunable emission colors can be obtained and can be efficiently adjusted by varying the doping ions and the doping concentration. The energy transfer mechanisms were investigated in detail and demonstrated that there is an efficient energy transfer from Tb3+, Dy3+ and Sm3+ to Eu3+ via a dipole-dipole interaction mechanism. Additional, as the temperature increases from RT to 150 °C, the PL intensity of Tb3+-Eu3+, Dy3+-Eu3+ and Sm3+-Eu3+ co-doped phosphors decreased to 86%, 85% and 88%, respectively, which prove good thermal stability. All the CIE coordinates of as-prepared phosphors are displayed and show abundant colors, making these materials have potential applications for n-UV-excited white-LEDs.

Full-spectrum plant growth light emitting diode (LED) prepared using a variety of phosphors has some problems, such as energy loss and spectral distortion. It is the solution that designing a kind of phosphor, which is the single activated ion doped phosphor with the multiple emission. To achieve this goal, the host Mg2Y2Al2Si2O12 (Abbreviated as: MYASO) was selected from a large number of garnet materials which has the multi-sites, and the Mn2+ was selected as the activated ion which can produce the different emission in the different crystal field. The results show that Mn2+ can produce the green light (536 nm), red light (635 nm) and deep red light (735 nm), which correspond to the Mn2+ substituting for the tetra-coordinated Al3+, the octa-coordinated Mg2+ and the hexa-coordinated Mg2+, respectively, importantly, this phosphor can be efficiently excited by the 456 nm blue light, which matches well with the blue LED chip. Therefore, it may be a great potential application value in the production of plant growth LEDs.

A series of white emitting phosphor of KMgLa (PO4)2:Dy3+ were synthesized via high temperature solid-state method, and the luminescence properties were systematically investigated. Under the 349 nm ultraviolet excitation, KMgLa(PO4)2:Dy3+ shows the 481 nm (blue) and 575 nm (yellow) emission peaks, which are assigned to the 4F9/2–6H15/2 and 4F9/2–6H13/2 transitions of Dy3+. The emission intensities of KMgLa(PO4)2:Dy3+ are influenced by the Dy3+ concentration, and the concentration quenching effect is observed, and the corresponding mechanism is the dipole–dipole (d–d) interaction, and the critical distance is calculated to be 1.136 nm. The CIE chromaticity coordinates of KMgLa(PO4)2:Dy3+ are close to that of standard white light. According to the emission intensity with different temperatures, the sample should have the good thermal stability. The results indicate that KMgLa(PO4)2:Dy3+ may be a potential application to white LEDs.

ZnS coating with oleic acid nano-particles have been successfully synthesized through the oil-phase thermal injection method. As-prepared samples are characterized by powder X-ray diffraction, transmission electron microscopy and spectra analysis. The emission color of ZnS NPs changes from blue to cyan with different ratio of Zn/S. ZnS:xEu3+ NPs with different doping concentrations of Eu3+ ions have different emission intensities and CIE coordination. The emission peaks vary with the change of y value of ZnSeyS1-y NPs, and the chromaticity coordinate transit from green to yellow region. The emission color and mechanism of the luminescent properties of ZnS, ZnS:xEu3+ and ZnSeyS1-y NPs are studied in detail. The results indicate that the thermal mixture injection without toxic is an effective and green method for synthesizing metal sulphitde, and the energy level structure, particle size, photoluminescence of ZnS can be achieved by forming different defect or doping of Eu or Se ions.

A NIR phosphor of the Mn2+, Nd3+, Yb3+ ions doped perovskite-like host LaSrGaO4 is successfully synthesized by high temperature solid phase method, and the energy transfer process about them is analyzed in detail. By measuring the temperature spectra of different samples and calculating the temperature sensitivities, it is found that the temperature sensitivity can be improved by adding Mn2+ and Yb3+ into LaSrGaO4:Nd3+, and that the maximum absolute sensitivity can be 5.64321%/K and that the relative sensitivity can be maintained at 0.474%/K. This NIR luminescent material LaSrGaO4:Mn2+, Nd3+, Yb3+ can be used as the NIR fluorescent temperature sensor for biological detection. In addition, the wide excitation bands of Mn2+, Nd3+ in visible region match well with the solar spectrum (AM 1.5), and the wide emission bands of Nd3+, Yb3+ in near infrared 900–1100 nm region are located in the spectral response curve of c-Si solar cells, so NIR luminescent material LaSrGaO4:Mn2+, Nd3+, Yb3+ may have the potential application in the spectral converter of c-Si solar cells to improve the conversion efficiency.

A series of Na1-zKzBa1-ySryB9O15:Eu2+ were synthesized by the high temperature solid state method. H3BO3 excess makes it easier for Eu2+ to enter Na+ site, and the single-phase "blue + green" double emission band can be observed, which is proved by thermoluminescence and the change of crystal structure. Moreover, there exists an intense energy transfer from the blue-emitting center to the green-emitting center, which is proved by the decay curve. The occupation of Eu2+ can be tuned by the introduction of Sr2+ and K+ in NaBaB9O15. Further, the highly thermal-sensitive property of NaBaB9O15: 1%Eu2+ makes it feasible for its potential application in luminescent ratiometric thermometers with wide temperature range. In addition, the disorder degree of matrix cations increases with the incorporation of K+, which improves the thermal stability.

Ca6Ce2Na2(PO4)6F2 (CCNPF):Mn2+, Tb3+ was synthesized by the high temperature solid state method. There is the obvious energy transfer from Ce3+→Mn2+ and Ce3+→Tb3+, and the transfer efficiencies are 92% and 66%, respectively. And the transfer mechanisms are certified to be the dipole-dipole interaction by the methods of Reisfeld approximation and spectral overlap. CCNPF:0.10Mn2+, 0.10 Tb3+ can produce white light, and the chromaticity coordinate is (0.320,0.254), the CCT is 6503 K and the CRI is up to 87. In addition, the phosphor exhibits good thermal quenching behavior, the emission intensities of Ce3+, Mn2+ and Tb3+ in CCNPF at 423 K are decrease to 78%, 90% and 99% of the values of 298 K, respectively. The results indicate that CCNPF:Mn2+, Tb3+ may be a potential phosphor for white light emitting diodes.

Sm3+, Eu3+, and Sm3+–Eu3+ doped Ca2PO4Cl phosphors are synthesized by a solid-state method. Ca2PO4Cl:Sm3+ can produce red emission under the 400 nm radiation excitation, and the emission peak is located at 601 nm, which is assigned to the 4G5/2→6H7/2 transition of Sm3+. Ca2PO4Cl:Eu3+ can create red emission under the 392 nm radiation excitation, and the strongest peak is located at 620 nm, which is attributed to the 5D0→7F2 transition of Eu3+. The energy transfer from Sm3+ to Eu3+ in Ca2PO4Cl has been validated and the critical distance (Rc) of Sm3+ to Eu3+ in Ca2PO4Cl is calculated to be 1.14 nm. With increasing Eu3+ doping concentration, the energy transfer efficiency (Sm3+→Eu3+) gradually increases to 53.7%. The luminescence property of Ca2PO4Cl:Sm3+, Eu3+ can be tuned by properly tuning the relative ratio of Sm3+–Eu3+, and the emission intensity of Ca2PO4Cl:Eu3+ can be greatly enhanced by codoped Sm3+.

BaZn 2 (PO 4 ) 2 :Sm 3+ phosphor was synthesized by a high temperature solid-state reaction in atmosphere. BaZn 2 (PO 4 ) 2 :Sm 3+ phosphor can be efficiently excited by ultraviolet and blue light, and the emission spectrum consists of three emission peaks at 568, 606 and 660 nm. By increasing the Sm 3+ doped content, the emission intensity of the phosphor can reach the maximum at 0.02 mol Sm 3+ , then the concentration quenching occurs. By introducing the compensator charge R + (R=Li, Na, K) into the BaZn 2 (PO 4 ) 2 :Sm 3+ phosphor, its emission intensity can be enhanced. The Commission International de l'Eclairage (CIE) chromaticity coordinates of Ba 0.96 Zn 2 (PO 4 ) 2 :0.02Sm 3+ , 0.02K + phosphor were ( x =0.623, y =0.361). The results indicate that BaZn 2 (PO 4 ) 2 :Sm 3+ , R + (R=Li, Na, K) may be a promising red phosphor for white light-emitting diodes.

Trivalent dysprosium ions (Dy 3+ ) doped strontium molybdate (SrMoO 4 ) phosphors were synthesized by solid-state reaction and their photoluminescence (PL) properties were investigated. X-ray powder diffraction (XRD) analysis confirmed the formation of SrMoO 4 :Dy 3+ . PL measurements indicated that the phosphor exhibited intense emission at 482, 490 ( 4 F 9/2 → 6 H 15/2 ) and 575 nm ( 4 F 9/2 → 6 H 13/2 ) under UV excitation. The effect of the doping concentration of Dy 3+ in SrMoO 4 :Dy 3+ on the PL was investigated in detail. Na + ion was a good charge compensator for SrMoO 4 :Dy 3+ .

The up-conversion emission properties of Yb3+–Ho3+ co-doped germanium-borate glasses have been investigated with 980 nm excitation. The violet, blue, green and red emission bands at about 350, 485, 544 and 653 nm can be identified, respectively. Experimental results indicated that the relative intensity ratios of the peaks IRed/IGreen increased with increasing B2O3 concentration, which led to changing color of up-conversion emission from green at x=0 to yellow at x=40, to red at x=60. The violet emission at 350 nm was first reported in germanium-borate glass host and up-conversion mechanisms of the emissions were discussed. The Yb3+–Ho3+ co-doped germanium-borate glasses could be an alternative for the generation of violet and primary colors for application in solid-state displays.

LiCaBO3:M (M=Eu3+, Sm3+, Tb3+, Ce3+, Dy3+) phosphors were synthesized by a normal solid-state reaction using CaCO3, H3BO3, Li2CO3, Na2CO3, K2CO3, Eu2O3, Sm2O3, Tb4O7, CeO2 and Dy2O3 as starting materials. The emission and excitation spectra were measured by a SHIMADZU RF-540 UV spectrophotometer. And the results show that these phosphors can be excited effectively by near-ultraviolet light-emitting diodes (UVLED), and emit red, green and blue light. Consequently, these phosphors are promising phosphors for white light-emitting diodes (LEDs). Under the condition of doping charge compensation Li+, Na+ and K+, the luminescence intensities of these phosphors were increased.

Powder phosphor yttrium aluminum garnet (YAG), activated with trivalent cerium (Ce 3+ ) is synthesized by combustion from mixed metal nitrate reactants and urea with ignition temperature of 500–550 °C. After repeated calcinations at a given temperature for 5 h, pure-phase phosphor was obtained. The experiment result shows the appropriate temperature for repeated calcinations is 1000 °C. Luminescent intensity at various quantity of urea is studied in detail and the maximum value shown in the result in fact is 2.5 times larger than the theoretical value. In addition, the characteristics of particles such as crystallinity, morphology and photoluminescence were investigated. There are two peaks in its excited spectrum and the major one is a broad band around 470 nm, which matches the blue emission of GaN LED very well. The emission peak locates at about 532 nm, which can combine the blue light of GaN LED to yield white light.