Synthesis and photoluminescence spectroscopy of BaGeF6:Mn4+ red phosphor

Sekiguchi, Daisuke; Adachi, Sadao

doi:10.1016/j.optmat.2015.01.039

Cited by 75 publications

(47 citation statements)

References 36 publications

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“…Rb 2 TiF 6 :Mn 4+ phosphors, respectively. These values fall in the range of the ever-reported Mn 4+ -activated hexafluorometallate values of ∼3−9 ms at 300 K. 2,6,13,[24][25][26][27][28][29][30][31][32][33] Temperature dependence of PL spectra.-For practical application of the red-emitting phosphors in solid-state lighting system, temperature dependence of the luminescence intensity is very important. Therefore, we measured the PL spectra for the Rb 2 SiF 6 :Mn 4+ and Rb 2 TiF 6 :Mn 4+ phosphors at temperatures between T = 20 and 500 K. Figure 6 shows the results of these measurements.…”

Section: Resultsmentioning

confidence: 92%

Editors' Choice—Rb₂SiF₆:Mn⁴⁺and Rb₂TiF₆:Mn⁴⁺Red-Emitting Phosphors

Sakurai

Nakamura

Adachi

2016

ECS J. Solid State Sci. Technol.

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Rb-based hexafluoride red-emitting phosphors, Rb 2 SiF 6 :Mn 4+ and Rb 2 TiF 6 :Mn 4+ , were synthesized by the coprecipitation method. Optical microscopy observation, X-ray diffraction (XRD) measurement, photoluminescence (PL) analysis, PL excitation (PLE) spectroscopy, and luminescence decay characteristics measurements were used to study the structural and optical properties of the phosphors. The photographs of the bulk samples showed clear crystallographic habits originating from the cubic and trigonal symmetries of the Rb 2 SiF 6 and Rb 2 TiF 6 hosts, respectively, in agreement with the XRD results. The phosphors exhibited an intense narrow-band Mn 4+ ( 2 E g → 4 A 2g ) red emission with internal quantum efficiencies higher than 90% upon blue light excitation. The Franck−Condon analysis of the PLE data yielded the Mn 4+ intra-d-shell transitions to occur at ∼2.47 eV (∼2.34 eV) for the 4 A 2g → 4 T 2g transition and at ∼2.86 eV (∼2.83 eV) for the 4 A 2g → 4 T 1g transition in the Rb 2 SiF 6 :Mn 4+ (Rb 2 TiF 6 :Mn 4+ ) phosphor. Temperature dependence of the PL spectra from T = 20 to 500 K gave the quenching temperature values (T q 's) at which the PL intensity has fallen to half its maximum value to be T q ∼ 490 and ∼450 K for Rb 2 SiF 6 :Mn 4+ . To the best of our knowledge, only one paper has been published on Rb 2 TiF 6 reporting that it crystallizes in the trigonal structure with a = 0.5892 nm and a = 0.4795 nm. Our synthesized phosphors were examined by the X-ray diffraction (XRD) measurement, PL, PLE, and PL decay curve measurements. Temperature dependence of the PL properties was also examined from T = 20 to 500 K in 10-K increments. Efficient sharp red emissions with internal quantum efficiencies larger than 90% were observed from our phosphors that may promise improving a color rendering index of the conventional white-LED lamps.z E-mail: tnakamura@gunma-u.ac.jp; adachi@gunma-u.ac.jp ExperimentalThe rubidium hexafluorometallate phosphors were grown by the coprecipitation method. First, XO 2 (X = Si, Ti) and Rb 2 CO 3 in molar ratio of 1 : 1 were dissolved in an HF solution. Then, KMnO 4 powder was added in the HF solution at 300 K. This mixed solution was left in dark for a few days and resulted in a large single-crystalline phosphor growth (see Fig. 2 below). The resultant bulk single-crystalline phosphors were paper-filtered and dried in room ambient. They were grained in an agate mortar and then used for various measurements.The crystal structures of the synthesized phosphors were examined by performing an XRD analysis using a SmartLab X-ray diffractometer (Rigaku) with Cu Kα radiation at λ = 0.1542 nm. PL measurements were carried out using a single monochromator equipped with a charge-coupled device (Princeton Instruments PIXIS 100) in a CryoMini cryostat (Iwatani Industrial Gases) and a stainless cryostat (Technolo Kogyo) at T = 20 − 500 K in increments of 10 K. A He−Cd laser at λ ex = 325 nm (Kimmon IK3302R-E) was used as the excitation light source.PLE measurements were performed at 300 K...

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Section: Resultsmentioning

confidence: 92%

Editors' Choice—Rb₂SiF₆:Mn⁴⁺and Rb₂TiF₆:Mn⁴⁺Red-Emitting Phosphors

Sakurai

Nakamura

Adachi

2016

ECS J. Solid State Sci. Technol.

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“…No such degradation phenomenon has been previously observed in any other phosphor or luminescent material. The A II B IV F 6 -type ''unhydrate'' phosphors, such as BaSiF 6 :Mn 4+ , BaGeF 6 :Mn 4+ , and BaTiF 6 :Mn 4+ , did not show any light-induced degradation phenomenon [15][16][17]. Of course, no degradation was observed in the dialkaline hexafluorometallate red phosphors (K 2 SiF 6 :Mn 4+ , K 2 TiF 6 :Mn 4+ , etc.).…”

Section: Degradation By Laser Beam Irradiationmentioning

confidence: 91%

“…Recently, we synthesized some hexafluorometallate red phosphors in a family of A I 2 BF 6 :Mn 4+ or A II BF 6 :Mn 4+ (A I = K, Na, Cs, NH 4 ; A II = Zn, Ba; B = Si, Ge, Sn, Ti) and reported their phosphor properties in detail [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. These phosphors exhibit efficient red emission under blue or UV excitation and may thus meet efficacy and color-quality targets for future white-LED devices.…”

Section: Introductionmentioning

confidence: 99%

Photo-induced degradation and thermal decomposition in ZnSnF6·6H2O:Mn4+ red-emitting phosphor

Hoshino

Adachi

2015

Optical Materials

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“…BaGeF 6 is one such complex uoride, whose PL characteristics are exclusively reported as a red-light emitting phosphor for warm white LED devices when doped with Mn 4+ ions in the recent years. 13,23,24 The PL emission properties of Mn 4+ doped BaGeF 6 red phosphors are analogous to the complex uorides with the formula BaXF 6 (X ¼ Si, Ti, Sn, etc.). [12][13][14][15] A warm white LED with a lower corrected color temperature (CCT ¼ 4766 K) and higher color rendering index (R a ¼ 86.3) can be obtained by combining blue GaN chip with a mixture of BaGeF 6 :Mn 4+ red phosphor and commercial YAG:Ce 3+ yellow phosphor.…”

Section: Introductionmentioning

confidence: 99%

“…13,23,24 The PL emission properties of Mn 4+ doped BaGeF 6 red phosphors are analogous to the complex uorides with the formula BaXF 6 (X ¼ Si, Ti, Sn, etc.). [12][13][14][15] A warm white LED with a lower corrected color temperature (CCT ¼ 4766 K) and higher color rendering index (R a ¼ 86.3) can be obtained by combining blue GaN chip with a mixture of BaGeF 6 :Mn 4+ red phosphor and commercial YAG:Ce 3+ yellow phosphor. 24 Also, BaGeF 6 :Mn 4+ red phosphor exhibit good thermal stability as the phosphor can retain 42.5% of the luminescence intensity at 448 K with respect to room temperature.…”

Section: Introductionmentioning

confidence: 99%