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ФИЗИЧЕСКОЕ МАТЕРИАЛОВЕДЕНИЕ
DOI: 10.18721 /JPM.10306 УДК 537.226.33
VISIBLE QUANTUM CUTTING IN GREEN EMITTING BaF2: Gd3+, Tb3+ PHOSPHORS: AN APPROACH TOWARDS MERCURY-FREE LAMPS
S.R. Jaiswal1, N.S. Sawala2, K.A. Koparkar2, P.A. Nagpure1, V.B. Bhatkar1, S.K. Omanwar2
1 Shri Shivaji Science College, Amravati, India 2Sant Gadge Baba Amravati University, Amravati, India
Visible quantum cutting (QC) via down-conversion (DC) has been observed in the green emitting BaF2 co-doped with Gd3+, Tb3+ phosphors synthesized by wet chemical method. Powder X-ray diffraction (XRD) analysis showed structural purity of the synthesized phosphors. The excitation (PLE) and PL spectra in the vacuum ultraviolet (VUV) or UV region were measured with the help of 4B8-VUV spectroscopy experimental station of the Beijing Synchrotron Radiation Facility (BSRF). In the QC process, one VUV-UV photon absorbed cuts into more than one visible photons emitted by Tb3+ through cross relaxation (CR) and direct energy transfer (DET) between Tb3+ and Tb3+ or Tb3+ and Gd3+, depending on the excitation wavelength. From the emission spectra monitored at different wavelength excitation, the two-step energy transfer process was investigated, and theoretically calculated quantum efficiency observed was found to be 148 % and 177 % at the excitation wavelength of 174 nm and 219 nm respectively.
Key words: quantum cutting; inorganic phosphor; cross relaxation; energy transfer; quantum efficiency
Citation: S.R. Jaiswal, N.S. Sawala, K.A. Koparkar, P.A. Nagpure, V.B. Bhatkar, S.K. Omanwar, Visible quantum cutting in green emitting BaF2 : Gd3+, Tb3+ phosphors: an approach towards mercury-free lamps, St. Petersburg Polytechnical State University Journal. Physics and Mathematics. 10 (3) (2017) 64—74. DOI: 10.18721/JPM.10306
ЭФФЕКТ ДАУН-КОНВЕРСИИ В ЛЮМИНОФОРАХ ЗЕЛЕНОГО СВЕЧЕНИЯ BaF2: Gd3+, Tb3+ - ПЕРСПЕКТИВА ИСПОЛЬЗОВАНИЯ В БЕЗРТУТНЫХ ФЛУОРЕСЦЕНТНЫХ ЛАМПАХ
Ш.Р. Джайсвал1, Н.С. Савала2, К.А. Копаркар2, П.А. Нагпуре1,
В.Б. Бхаткар1, Ш.К. Оманвар2
1Научный колледж Шри Шиваджи, г. Амравати, Индия 2Университет Амравати имени Сант Гадж Баба, г. Амравати, Индия
В люминофорах БаБ2 : Gd3+, ТЬ3+ с зеленым свечением, синтезированных мокрым химическим методом, наблюдалось понижение частоты кванта излучения в видимую область через процесс даун-конверсии. Анализ методом порошковой рентгеновской дифракции показал структурную чистоту синтезированных люминофоров. Спектры возбуждения и фотолюминесценции в ультрафиолетовой (УФ) и вакуумной ультрафиолетовой (ВУФ) областях измеряли
на экспериментальной спектроскопической установке синхротронного излучения 4Б8-УиУ (г. Пекин, КНР). В процессе понижения частоты кванта один фотон из ВУФ или УФ области излучения претерпевает конверсию в более, чем один фотон люминесценции в видимой области, и эти фотоны испускаются ионами ТЬ3+ по механизмам кросс-релаксации и прямого энергопереноса между двумя ионами ТЬ3+ либо между ионами ТЬ3+ и Оё3+, что зависит от длины волны возбуждающего излучения. Путем отслеживания спектров испускания при различных длинах волн возбуждающего излучения исследован двухступенчатый процесс переноса энергии. Теоретически рассчитанные максимальные значения наблюдаемого квантового выхода составили 148 и 177 % для длин волн возбуждающего излучения 174 и 219 нм соответственно.
Ключевые слова: понижение частоты кванта; неорганический люминофор; кросс-релаксация; энергоперенос; квантовый выход
Ссылка при цитировании: Джайсвал Ш.Р., Савала Н.С., Копаркар К.А., Нагпуре П.А., Бхаткар В.Б., Оманвар Ш.К. Эффект даун-конверсии в люминофорах зеленого свечения БаБ2 : Оё3+, ТЬ3+ — перспектива использования в безртутных флуоресцентных лампах // Научно-технические ведомости СПБГПУ. Физико-математические науки. 2017. Т. 10. № 3. С. 64-74. БОГ: 10.18721/1РМ.10306
1. Introduction
Luminescent tubes based on phosphors doped with lanthanide ions are presently useful rely on the ultraviolet (UV) excitation originating from a mercury discharge. These luminescent tubes are very popular for domestic and other purpose lighting applications. The main emission line of mercury is positioned at 254 nm. The major drawback of mercury-based fluorescent lamps is toxicity due to mercury and causes serious environmental concerns. In order to overcome these drawbacks the mercury-based discharge lamps are replaced by a xenon-based fluorescent tube. The xenon discharge has emissions in the vacuum ultraviolet (VUV), particularly the Xe resonance emission line (147 nm) and/or the Xe2 molecular emission band (172 nm). The advantage of this xenon discharge is that it requires no start-up time. The phosphors presently worn in luminescent tubes do not absorb the 147 and 172 nm radiation efficiently and also undergo as of degradation upon VUV excitation. Moreover, in the conversion of one VUV photon of the xenon discharge into a visible photon more energy is lost [1].
In order to overcome these difficulties, it is necessary to develop the phosphors which absorb one high-energy VUV photon and split into two or more low energy (visible) photons; the phenomenon is known as quantum cutting (QC). The QC provides a means to obtain two or more photons for each absorbed photon [2 — 5]. Therefore it serves as a DC mechanism with quantum efficiency greater than unity and
it offers the prospect of providing improved energy efficiency in lighting devices [6]. In order to obtain quantum-cutting phosphors with quantum efficiencies exceeding unity, the lanthanide ions are palpable candidates for this purpose due to their energy level structures that afford metastable levels from which quantum-cutting processes are promising.
Shi, et al. [7] reported that the inorganic host matrix BaF2 is a crystal having broad band about 10.9 eV. The BaF2:Re3+ (Ce, Pr, Tb, Eu, Dy) were studied in earlier reports [8 — 10]. The process of energy transfer (ET) and QC in BaF2: Gd3+, Eu3+ can occur by the dopants combination of Gd3+ and Eu3+, in which Gd3+ acts as a sensitizer, and absorbed high energy VUV photon which cuts into two visible photons emitted by two Eu3+ ions which act as activators. Palan, et al. [11, 12] reported terbium doped various phosphor materials.
Motivated from the above survey, here we intended to study the visible QC process under the excitation of VUV or UV radiation in BaF2:Gd3+, Tb3+ phosphors synthesized via wet chemical method followed by reactive atmosphere process (RAP). Belsare, et al. [13] well discussed the RAP in their papers. Triva-lent terbium ions co-doped with Gd3+ ions in the BaF2 host matrix are reported for the first time.
Barium Gd3+, Tb3+
2. Experimental
fluoride (BaF2) co-doped with phosphors was prepared by
wet chemical method followed by reactive atmospheric process. In this method we used metal carbonate like BaCO3 (99.99 % AR) as a precursor. Barium carbonate was taken in the teflon beaker. A small amount of double-distilled water was added into the beaker and stirred it, then hydrofluoric acid (HF) was added in it to get slurry. The slurry was dried by blowing air or heating on a hot plate (80°C). A freshly prepared BaF2 host was obtained. Gd2O3 (99.9% AR) and Tb2(SO4)3-8H2O (99.90 %, AR) were boiled in HNO3 and evaporated to dryness,
so as to convert them into respective nitrates. The aqueous solution of these nitrates was used as a dopant. The 1 mol % of gadolinium nitrate and 1mol % of terbium nitrate were mixed in the host material and dried completely by blowing hot air to obtain dried powder. The dried powder was transferred to a glass tube and about 2.5 wt. % RAP agent was added. In this process, we used ammonium fluoride as a RAP agent. The tube was closed with a tight stopper and slowly heated to 500°C for 2 h. The stopper was removed and the powders were transferred
Fig. 1. Flow chart of BaF2: 1% Gd3+, xTb3+ (0.5% < x < 7.0%) synthesized by wet chemical method
и ■м S
3j
О
U
: x= 7.0% w £ ^ ÎT О 1 es О г: о £1 1 ^ r-j о
Х = 3.0%
Х- 1.0% . i 1 1 . ...
л; =0.5% 11. ...
Frankdicksonite, Ва F2.01-085-1341 1 1 .
1% Gd
of Gd3+
3+
10
20
30
40
Fig. 2. XRD pattern of BaF2: 1% Gd3+, xTb3+ (0.5% < x < 7.0 %) synthesized by wet chemical method
to a graphite crucible pre-heated to a suitable temperature. After heating in the graphite crucible for 1 h the resulting phosphor was rapidly quenched down to room temperature [13]. The complete process involved in the reaction is presented as a flow chart in Fig. 1. The crystal structure of the phosphor powders were characterized by powder X-ray diffraction (XRD) analysis by using Rigaku miniflex II X-ray diffractometer with a scan speed of 2.000°/min and Cu^T (k = 0.15406 nm) radiation in the range from 10° to 80°. The PLE and PL spectra in the VUV region were measured at 4B8-VUV spectroscopy experimental station on beam line of the Beijing Synchrotron Radiation Facility (BSRF), P.R. China. All the measurements were performed at room temperature.
3. Results and discussion
XRD of BaF2 : 1% Gd3+, *Tb3+. The phase purity of BaF2: 1% Gd3+, xTb3+ (0.5% < x < 7.0%) samples were confirmed by XRD pattern as shown in Fig. 2. The XRD pattern of prepared phosphors matched well with ICDD file card No. 01-085-1341. From the XRD pattern, the high intensity peaks were observed at 20 = 24.87, 28.79, 41.17, 48.70, 51.02, 59.6, 65.62 and 67.55 degrees which correspond to (1 1 1), (2 0 0), (2 2 0), (3 1 1), (2 2 2), (4 0 0), (3 3 1) and (4 2 0) diffraction planes respectively.
Photoluminescence properties of BaF2:
, *Tb3+. The concentration quenching as a sensitizer in the BaF2 host matrix was first determined. From Fig. 3 it can be advocated that at 1 mol % of Gd3+ ions in BaF2 the host shows optimum intensity peak at 310 nm under an excitation wavelength of 274 nm [14].
Fig. 4, a shows VUV-UV excitation spectra of photoluminescence (PLE spectra) of BaF2 : 1% Gd 3+, xTb3+ (0.5 % < x < 7.0 %) in the range from 125 to 300 nm. All the excitation spectra are the same except for their intensities. The spectra were obtained 50 60 20, degrees by monitoring at the transition of 5D4 —>7F5 of Tb3+, with an emission wavelength of 543 nm.
The spectra consist of two bands and one small intensity peak. The first broad excitation band ranging from 150 to 190 nm and second excitation band ranging from 200 to 240 nm are centered at 174 and 219 nm, respectively. They are assigned to spin-allowed transitions from the 4/ 8(7F6) to low-spin 4/ 75d states of Tb3+ [15, 16]. The broadening of the absorption band of Tb3+ at 219 nm in the excitation spectrum also supports the fact that the origin of absorption is attributed to 4/ 8 ^ 4/ 7 5d (LS) transition, as described by Wegh, et al. [15] and Lee, et al. [17]. Besides, the broadening of the absorption band is also complicated by the overlapping of the excitation transitions accredited to 8S7/2 ^ 6Gj of Gd3+ and 7F6 ^ 4/7 5d (LS) of Tb3+. The one small intensity peak at 274 and
0.08-
- 0.06-
д 0.04-
ч
0.02-
310 nm
/ Y2
3 \
/ iV\
4 —^—
1 1 1 1 1
306
308
310
312
Wavelenght, nm
314
316
Fig. 3. Photoluminescence emission spectra of BaF2: x Gd3+ under an excitation wavelength of 274 nm; x = 0.5 % (7), 1.0 % (2), 1.5 % (3), 2.0 % (4), 3.0 % (5)
7 6
à tf
£ 5
1
3 4
â 3
A« = 219 nm
3
4-Л
3
|L L2
л U 3
Л
7k21
300 350 400 450 500 550 600 650 300 350 400 450 500 550 600 650
Wavelenght, nm Wavelenght, nm
Fig. 4. VUV-UV PLE spectra monitored by the emission line of Tb3+ at 543 nm (a); PL spectra of the BaF2: 1% Gd3+, xTb3+ (0.5% < x < 7.0%) phosphor excited at 274 nm (b), 219 nm (c) and 174 nm (d), respectively. x = 0.5 % (1), 1.0 % (2), 3.0 % (3), 7.0 % (4)
278 nm are accredited to the 8S7/2 ground state to the 6DT and 6/T states of Gd3+, respectively.
The measured emission spectra of BaF2: 1% Gd3+, xTb3+ (0.5% < x < 7.0%) monitored at 274, 219 and 174 nm are shown in Fig. 4, b, c and d . The emissions could be accredited to 5D3 ^ 7FT (J = 2, 3, 4, 5 and 6) and 5D ^ 1FT ( J = 3, 4, 5 and 6) transitions of
543 nm. The 5D4 emission of Tb3+ increased while the 5D3 emission decreased with an increase in the Tb3+ content, which is due to the cross relaxation between the 5D3 ^ 5D4
transition and 7F
7F transition of Tb3+
6 ' ^0
[18, 19]. The 5D4 emission of Tb3+ increased rapidly with an increase in the concentration of Tb3+. This is due to numerous factors along Tb3+ ions among which the transition 5D4 ^ 7F5 with the cross relaxation between the 5D3 and leads to the green emission at a wavelength of 5D levels since luminescence centers increase
а)
Х«=274шп
70—
20" ю-0-
■5Д
3^7/2 -' г"- 7Fj
Gd3+ Tb34
b)
219 nm
4fSd Ж
▼
II
Tb3+ xb3 +
Tb3+ Gd3+
c)
A„ = 174nm
4fSd
©
Tb3+ Tb3+ Gd3 +
Fig. 5. Energy level diagrams for BaF2: 1% Gd 3+, xTb3+ showing the mechanism for visible quantum cutting and the energy transfer process excited at 274(a), 219(6) and 174 nm(c) , represent cross relaxation and direct energy transfer mechanisms, respectively; 3,4 correspond to green and UV emission lines, respectively
with concentration of Tb3+ ions in the host matrix.
Quantum cutting in BaF2: 1% Gd 3+, *Tb3+.
In the QC process, one VUV-UV photon absorbed by Tb3+ ion "splits" into more than one visible photons emitted by Tb3+ through a cross-relaxation energy transfer (CRET) and a direct energy transfer (DET) between two Tb3+ ions or Tb3+ and Gd3+ ions, depending on the excitation wavelength, was observed in BaF2: 1% Gd3+, Tb3+ samples. Fig. 5 shows three simplified energy level diagrams for Ba(099-x)F2: 1% Gd3+ , xTb3+. No quantum cutting occurs in BaF2: 1% Gd 3+, xTb3+ with excitation of the 8S7/2 ^ 6Ij level of Gd3+ (274 nm) as shown in Fig. 5, a. When Tb3+ ions in the host matrix are excited to their 4/ 75d1 states, the QC process can be realized by two steps: cross relaxation mechanism (step 1 is indicated by number 1 in the circle) and DET (step 2 is indicated by number 2 in the circle) as shown in Fig. 5, b and c. As revealed by the PL spectra shown in Figs. 6, a, b and c, the QC process is proposed to occur firstly through the pumping of Tb3+ and, afterwards, the released energy owing to
4f5d
5D transition was used to pump a
neighboring Tb3+ by cross-relaxation (indicated by lines number 1) that resulted in green emission at 543 nm (indicated by lines 3).
Secondly, in the process of relaxation of Tb3+ from 4/5 d to higher 5DJ levels, the released energy could be directly transferred from Tb3+ ion to a neighboring Gd3+ ion to generate the UV emission at 311 nm (indicated by lines 4) or the excited Tb3+ ion could further relax to the 5D3 4 levels to generate the second green emitting photon (indicated by line 3), in which Tb3+ plays the role of activator by converting a VUV or UV photon into two green-emitting photons [20].
In the second step, i.e. the process of relaxation of Tb3+ from 4/5d to higher 5DJ levels, the released energy utilized to excite Tb3+ion could further relax to the 5D3 4 levels with increasing the Tb3+ ions concentration in the host matrix.
The extra quantum efficiency n corresponding to cross relaxation can be theoretically calculated by the emission spectra, and some essential premises are proposed that,
—>
а)
3
сё
â.
Ж 1
a
Xex= 174nm
hi Лл
300 3S0 400 450 500 550 600 650 300 3S0
Wavelenght, nm
, 0.2 c)
Ч 0.12
St
t i
a 0.08
4S0 500 550
Wavelenght, nm
600 650
S s
ТЪЗ^ j 4>4-»'F, Xex = 274 nm
d 1 = 6 h* V 5Л 3C Î f 1 l\ Л I---- / 5 4 3 V 1лл
300 350 400 450 500 550 600
Wavelenght, nm
Fig. 6. VUV and UV PL spectra of BaF2: 1% Gd3+, 3%Tb3+ upon excitation at 4f s ^ 4f 75d(LS) (a) and f ^ d (LSA) (b) transitions (174 nm (a) and 219 (b) nm) on Tb3+ and at sS7/2 ^ 6// excitation (274 nm) on Gd3+(c)
the VUV absorption of phosphors should not be taken into account and possible nonradiative losses due to energy migration over defects and impurities in samples must be ignored [20]. For calculations of theoretical value of QE involved in the QC processes, in addition to nDT (i.e., 100 %), we have calculated the extra QE equivalent to cross relaxation (nQC) from Tb3+ ion to a neighboring Tb3+ ion through QC with the following equation proposed by Wegh, et al. [15, 21 — 24] and modified by Lee, et al. [17]:
nQc =n + nD^
П =
LCR
PCR + PDT
R(5D4 / rest)
Tb3
- R(5D4 / rest)
Gd3
R(5D4 / rest)Tb3.
+1
Here PCR, PDT represent the probabilities for cross relaxation (CR) and direct energy (DE) transfer mechanisms, respectively; R(5D4/rest) is the ratio of PL intensity of 5D4 to that accredited to 5D3 of Tb3+ and 6P7/2 of Gd3+ where the subscripts indicate the excitation from Tb3+ or Gd3+. If the QE of a phosphor via DET is 100%, from the integrated peak intensity then the cross relaxation efficiency of the phosphor was calculated theoretically.
The CRET efficiency increases with an increase in Tb3+ content in the host matrix and, according to calculations, maximum quantum
efficiency (QE) was calculated to be 148 % and 177% under the excitation wavelength of 174 and 219 nm, respectively, at 3% of Tb3+ ions concentration. The cross-relaxation efficiency decrease at x = 7 % concentration of Tb3+ may be due to a high concentration of defects or impurities in the host matrix [25].
4. Conclusions
The Ba(0 99-x)F2 : 1% Gd 3+, xTb3+ (0.5 % < x < < 7.0 %) phosphors were successfully prepared by the wet chemical method under RAP. Visible quantum cutting through down conversion has been observed in BaF2 : 1% Gd 3+, xTb3+ phosphor. The quantum efficiency of BaF2 : 1% Gd3+, xTb3+ phosphor was calculated and the optimal theoretical quantum efficiency was found to be 148 and 177 % under the excitation of 174 and 219 nm, respectively, for 3 % of Tb3+ ions. From the above investigational
report we conclude that the phosphors BaF2: Gd3+, Tb3+ can be an excellent potential candidate for the applications in Hg-free fluorescent lamps, plasma display panels and 3D PDPs technology.
Acknowledgements
We appreciative to 4B8 VUV spectroscopy beam line scientists of Beijing Synchrotron Radiation Facility (BSRF), P.R. China, for providing that access for recording VUV on beamline 4B8 under dedicated synchrotron mode using remote access mode. One of the authors, S.R. Jaiswal, is thankful to the chairman of FIST-DST project, Department of Physics, Sant Gadge Baba Amravati University, Amravati, for providing necessary facilities, and the authors are also thankful to Dr. G.V. Korpe, Department of Chemistry, Shri Shivaji Science College, Akola, for moral and official supports.
REFERENCES
[1] P.S. Peijzel, A. Meijerink, Visible photon cascade emission from the high energy levels of Er3+, Chem. Phys. Lett. 401 (1) (2005) 241-245.
[2] N.S. Sawala, S.K. Omanwar, Down conversion from ultraviolet to near infrared region in novel Yb3+ doped LiSrVO4 phosphor, J. Alloys Compd. 686 (Nov. 25) (2016) 287-291.
[3] N.S. Sawala, S.K. Omanwar, Spectral downshifting from blue to near infrared region in Ce3+-Nd3+ co-doped YAG phosphor, Infrared Phys. Technol. 77 (July) (2016) 480 -484.
[4] N.S. Sawala, N.S. Bajaj, S.K. Omanwar, Near-infrared quantum cutting in Yb3+ ion doped strontium vanadate, Infrared Phys. Technol. 76 (May) (2016) 271-275.
[5] C.R. Ronda, Phosphors for lamps and displays: an application view, J. Alloys Compd. 225 (1-2) (1993) 534-538.
[6] N.S. Sawala, K.A. Koparkar, N.S. Bajaj, and S.K. Omanwar, Near infrared photoluminescence in La0 98AlO3: 0 02 Ln3+ (Ln = Nd/Yb) for sensitization of c-Si solar. cells, AIP Conf. Proc. 1728 (1) (2016) 020250 1-6.
[7] C.S. Shi, T. Kloiber, G. Zimmerer, Temperature effect of the luminescence band at 300 nm from BaF2 crystals, J. Lumin. 48-49, 2 (Jan.-Feb.) (1991) 597-600.
[8] A.S Grabtchikov, A.N. Kuzmin, V.A. Lisinetskii, G.I Ryabtsev, V.A Orlovich, A.A Demidovich, Stimulated Raman scattering in Nd:KGW laser with diode pumping, J. Alloys Compd. 300-301 (Apr. 12) (2000) 300-302.
[9] N.S. Sawala, S.K. Omanwar, Near infrared DC approach by Bi3+-Yb3+ co-doped YAG phosphor, Res. Chem. Intermed. 43(2) (2016) 693-702.
[10] A.J. Wojtowicz, P. Szupryczynski, W. Drozdowski, Radiative recombination in Ce-, Pr-, and Tb-doped barium fluoride, J. Alloys Compd. 300-301 (Apr.,12)(2000) 199-206.
[11] C. Shi, Z. Xie, J. Deng, Thermoluminescence of BaF2 : RE (Ce, Dy, Eu) crystals, J. Electron Spectrosc. Relat. Phenom. 79 (May) (1996) 87-90.
[12] C.B. Palan, N.S. Bajaj, A. Soni, S.K. Omanwar, A novel KMgPO4 : Tb3+ (KMPT) phosphor for radiation dosimetry, J. Lumin. 176 (Aug.) (2016) 106-111.
[13] C.B. Palan, N.S. Bajaj, A. Soni, M.S. Kulkarni, S.K. Omanwar, Combustion synthesis and preliminary luminescence studies of LiBaPO4 : Tb3+ phosphor, Bulletin of Materials Science. 38 (6) (2015) 1527-1531.
[14] P. Belsare, C. Joshi, S. Moharil, V. Kondawar, P. Muthal, S. Dhopte, Luminescence of Eu2+ in some fluorides prepared by reactive atmosphere processing, J. Alloys Compd. 450 (1) (2008) 468-472.
[15] A.O. Chauhan, A.B. Gawande, S.K. Omanwar, Narrow band UVB emitting phosphor LaPO4: Gd3+ for phototherapy lamp, Optik-Int. J. Light Electron Opt. 127 (16) (2016) 6647-6652.
[16] R. Wegh, E. van Loef, A. Meijerink, Visible quantum cutting via downconversion in LiGdF4: Er3+, Tb3+ upon Er3+ 4fu^4f105d excitation, J.
Lumin. 90 (3-4) (2000) 111-122.
[17] T. Lee, L. Luo, B. Cheng, W. Diau, T. Chen, Investigation of Pr3+ as a sensitizer in quantum-cutting fluoride phosphors, Appl. Phys. Lett. 92 (8) (2008) 081106.
[17] L. Pieterson, M. Reid, G. Burdick, A. Meijerink, 4/^ 4/-1 5d transitions of the light lanthanides: Experiment and theory, Phys. Rev. B. 65 (4) (2002) 45113-16.
[19] Z. Tian, H. Liang, W. Chen, Q. Su, G. Zhang, G. Yang, Efficient emission-tunable VUV phosphors Na2GdF2PO4:Tb3+, Opt. Express. 17 (2) (2009) 956-962.
[20] Y. Li, Y. Chang, Y. Chang, Y. Lin, C. Laing, Luminescence and energy transfer properties of Gd3+ and Tb3+ in LaAlGe2O7, J. Phys. Chem. C. 111 (28) (2007) 10682-10688.
[21] H. Tzenga, B. Chengb, T. Chena, Visible quantum cutting in green-emitting BaGdF5:Tb3+
phosphors via downconversion, J. Lumin. 122—123 (Jan.-Apr.) (2007) 917-920.
[22] R. Wegh, H. Donker, K. Oskam, A. Meijerink, Visible quantum cutting in LiGdF4:Eu3+ through downconversion, Science 283 (5402) (1999) 663-666.
[23] S.R. Jaiswal, N.S. Sawala, P.A. Nagpure, V.B. Bhatkar, S.K. Omanwar, Visible quantum cutting in Tb3+-doped BaGdF5 phosphor for plasma display panel, J. Mater. Sci: Mater. Electron. 28 (3) (2017) 2407-2414.
[24] R. Wegh, H. Donker, K. Oskam, A. Meijerink, Visible quantum cutting in Eu3+-doped gadolinium fluorides via downconversion, J. Lumin. 82 (2) (1999) 93-104.
[25] D. Wang, N. Kodama, Visible quantum cutting through downconversion in GdPO4:Tb3+ and Sr3Gd(PO4)3:Tb3+, J. Solid State Chem. 182 (8) (2009) 2219-2224.
Received 27.04.2017, accepted 26.06.2017.
THE AUTHORS
JAISWAL Shailesh R.
Department of Physics, Shri Shivaji Science College
Shivaji Nagar, Morshi Road, Amravati, Maharastra 444602, India
SAWALA Niraj S.
Department of Physics, Sant Gadge Baba Amravati University Mardi Road, Amravati, Maharastra 444602, India [email protected]
KOPARKAR Kishor A.
Department of Physics, Sant Gadge Baba Amravati University Mardi Road, Amravati, Maharastra 444602, India
NAGPURE Pankaj A.
Department of Physics, Shri Shivaji Science College
Shivaji Nagar, Morshi Road, Amravati, Maharastra 444602, India
BHATKAR Vinod B.
Department of Physics, Shri Shivaji Science College, Amravati Shivaji Nagar, Morshi Road, Amravati, Maharastra 444602, India
OMANWAR Shreeniwas K.
Department of Physics, Sant Gadge Baba Amravati University Mardi Road, Amravati, Maharastra 444602, India [email protected]
СПИСОК ЛИТЕРАТУРЫ
1. Peijzel P.S., Meijerink A. Visible photon cascade emission from the high energy levels of Er3+ // Chem. Phys. Lett. 2005. Vol. 401. No. 1. Pp. 241-245.
2. Sawala N.S., Omanwar S.K. Downconversion
from ultra violet to near infer red region in novel Yb3+ doped LiSrVO4 phosphor // J. Alloys Compd. 2016. Vol. 686. Nov. 25. Pp. 287-291.
3. Sawala N.S., Omanwar S.K. Spectral downshifting from blue to near infer red region in
Ce3+-Nd3+ co-doped YAG phosphor // Infrared Phys. Technol., 2016. Vol. 77. July. Pp. 480 -484.
4. Sawala N.S., Bajaj N.S., Omanwar S.K. Near-infrared quantum cutting in Yb3+ ion doped strontium vanadate // Infrared Phys. Technol. 2016. Vol. 76. May. Pp. 271-275.
5. Ronda C.R. Phosphors for lamps and displays: an applicational view // J. Alloys Compd. 1993. Vol. 225. No. 1-2. Pp. 534 -538.
6. Sawala N.S., Koparkar K.A., Bajaj N.S., Omanwar S.K. Near infrared photoluminescence in La0 98AlO3: 0 02 Ln3+ (Ln = Nd/Yb) for sensitization of c-Si solar cells // AIP Conf. Proc. 2016. Vol. 1728. No. 1. Pp. 020250, 1-6.
7. Shi C.S., Kloiber T., Zimmerer G. Temperature effect of the luminescence band at 300 nm from BaF2 crystals // J. Lumin. 1991. Vol. 48-49. Part 2. Jan.-Feb. Pp. 597-600.
8. Grabtchikov A.S., Kuzmin A.N., Lisinetskii V.A., Ryabtsev G.I., Orlovich V.A., Demidovich A.A. Stimulated Raman scattering in Nd:KGW laser with diode pumping // J. Alloys Compd. 2000. Vol. 300-301. Apr. 12. Pp. 300-302.
9. Sawala N.S., Omanwar S.K. Near infrared DC approach by Bi3+-Yb3+ co-doped YAG phosphor // Res. Chem. Intermed. 2016. Vol. 43. No. 2. Pp. 693-702.
10. Wojtowicz A.J., Szupryczynski P., Drozdowski W. Radiative recombination in Ce-, Pr-, and Tb-doped barium fluoride // J. Alloys Compd. 2000. Vol. 300-301. Apr. 12. Pp. 199-206.
11. Shi C., Xie Z., Deng J. Thermoluminescence of BaF2:RE(Ce, Dy, Eu) crystals // J. Electron Spectros. Relat. Phenom. 1996. Vol. 79. May. Pp. 87-90.
12. Palan C.B., Bajaj N.S., Soni A., Omanwar
S.K. A novel KMgPO4: Tb3+(KMPT) phosphor for radiation dosimetry // J. Lumin. 2016. Vol. 176. Aug. Pp. 106-111.
13. Palan C.B., Bajaj N.S., Soni A., Kulkarni M.S., Omanwar S.K. Combustion synthesis and preliminary luminescence studies of LiBaPO4: Tb3+ phosphor // Bulletin of Materials Science. 2015. Vol. 38. No. 6. Pp. 1527-1531.
14. Belsare P., Joshi C., Moharil S., Kondawar V., Muthal P., Dhopte S. Luminescence of Eu2+ in some fluorides prepared by reactive atmosphere
Статья поступила в редакцию 27.04.2017, принята к публикации 26.06.2017.
processing // J. Alloys Compd. 2008. Vol. 450. No. 1. Pp. 468-472.
15. Chauhan A.O., Gawande A.B., Omanwar S.K. Narrow band UVB emitting phosphor LaPO4: Gd3+ for phototherapy lamp // Optik-Int. J. Light Electron Opt., 2016. Vol. 127. No. 16. Pp. 6647-6652.
16. Wegh R., van Loef E., Meijerink A. Visible quantum cutting via downconversion in LiGdF4 : Er3+, Tb3+ upon Er3+ 4/1 ^ 4/°5d excitation // J. Lumin. 2000. Vol. 90. No. 3-4. Pp. 111-122.
17. Lee T., Luo L., Cheng B., Diau W., Chen T. Investigation of Pr3+ as a sensitizer in quantum-cutting fluoride phosphors // Appl. Phys. Lett. 2008. Vol. 92. No. 8. P. 081106.
18. Pieterson L., Reid M., Burdick G., Meijerink A. 4fn ^ 4fn-1 5d transitions of the light lanthanides: Experiment and theory // Phys. Rev. B. 2002. Vol. 65. No. 4. P. 45113-45116.
19. Tian Z., Liang H.,Chen W., Su Q., Zhang G., Yang G. Efficient emission-tunable VUV phosphors Na2GdF2PO4:Tb3+ // Opt. Express. 2009. Vol. 17. No. 2. Pp. 956-962.
20. Li Y., Chang Y., Chang Y., Lin Y., and Laing C. Luminescence and energy transfer properties of Gd3+ and Tb3+ in LaAlGe2O7 // J. Phys. Chem. C. 2007. Vol. 111. No. 28. Pp. 10682-10688.
21. Tzenga H., Chengb B., Chena T. Visible quantum cutting in green-emitting BaGdF5:Tb3+ phosphors via down conversion // J. Lumin. 2007. Vol. 122-123. Jan. -Apr. Pp. 917-920.
22. Wegh R., Donker H., Oskam K., Meijerink A. Visible quantum cutting in LiGdF4:Eu3+ through down conversion // Science. 1999. Vol. 283. No. 5402. Pp. 663-666.
23. Jaiswal S.R., Sawala N.S., Nagpure P.A., Bhatkar V.B., Omanwar S.K. Visible quantum cutting in Tb3+ doped BaGdF5 phosphor for plasma display panel // J. Mater. Sci.: Mater. Electron. 2017. Vol. 28. No. 3. Pp. 2407-2414.
24. Wegh R., Donker H., Oskam K., Meijerink A. Visible quantum cutting in Eu3+-doped gadolinium fluorides via downconversion // J. Lumin. 1999. Vol. 82. No. 2. Pp. 93-104.
25. Wang D., Kodama N. Visible quantum cutting through down conversion in GdPO4:Tb3+ and Sr3Gd(PO4)3:Tb3+ // J. Solid State Chem. 2009. Vol. 1832. No. 8. Pp. 2219-2224.
СВЕДЕНИЯ ОБ АВТОРАХ
ДЖАИСВАЛ Шайлеш - сотрудник кафедры физики Научного колледжа Шри Шиваджи, г. Амра-вати, Индия.
Shivaji Nagar, Morshi Road, Amravati, Maharastra 444602, India
САВАлА Нираж — сотрудник кафедры физики Университета Амравати имени Сант Гадж Баба, г. Амравати, Индия.
Mardi Road, Amravati, Maharastra 444602, India
КОПАрКАр Кишор — сотрудник кафедры физики Университета Амравати имени Сант Гадж Баба, г. Амравати, Индия.
Mardi Road, Amravati, Maharastra 444602, India
НАГПуРЕ Панкадж — сотрудник кафедры физики Научного колледжа Шри Шиваджи, г. Амравати, Индия.
Shivaji Nagar, Morshi Road, Amravati, Maharastra 444602, India
БАТКАР Винод — сотрудник кафедры физики Научного колледжа Шри Шиваджи, г. Амравати, Индия..
Shivaji Nagar, Morshi Road, Amravati, Maharastra 444602, India
ОМАНВАР Шринивас Керба — заведующий кафедрой физики Университета Амравати имени Сант Гадж Баба, г. Амравати, Индия.
Mardi Road, Amravati, Maharastra 444602, India
© Санкт-Петербургский политехнический университет Петра Великого, 2017
