Synthesis and PL study of Sr3 (VO4 ) 2 :Eu3+ phosphor for W-LED application Текст научной статьи по специальности «Физика»

Physical materials technology

Original article

DOI: https://doi.org/10.18721/JPM.16205

SYNTHESIS AND PL STUDY OF Sr3(VO4)2:Eu3+ PHOSPHOR FOR W-LED APPLICATION P. A. Nagpure , N. D. Kherde , W. S. Barde

Shri Shivaji Science College, Amravati, Maharashtra, India

и nagpurepa@yahoo.co.in

Abstract. In the present paper, a single host phosphor for a white light emitting diode (W-LED) Sr3(VO4)2:Eu3+, prepared by the co-precipitation method and combustion one, has been reported. Formation of the compound was confirmed by studying the X-ray diffraction pattern. The photoluminescence (PL) properties were studied by fluorescence spectrophotometer F-7000. The Sr3(VO4)2:Eu3+ exhibited a broad emission band covering the entire visible region centered at 520 nm wavelength and a sharp peak at 613 nm, when excited by 350 nm. The excitation spectrum at 520 nm emission wavelength was found to be suitable for pc-W-LED application.

Keywords: strontium vanadate, co-precipitation, combustion, X-ray diffraction pattern, photoluminescence spectroscopy, W-LED

For citation: Nagpure P. A., Kherde N. D., Barde W. S., Synthesis and PL study of Sr3(VO4)2:Eu3+ phosphor for W-LED application, St. Petersburg State Polytechnical University Journal. Physics and Mathematics. 16 (2) (2023) 61-67. DOI: https://doi.org/10.18721/ JPM.16205

This is an open access article under the CC BY-NC 4.0 license (https://creativecommons. org/licenses/by-nc/4.0/)

Научная статья УДК 678.046.82

DOI: https://doi.org/10.18721/JPM.16205

СИНТЕЗ И ФОТОЛЮМИНЕСЦЕНТНОЕ ИССЛЕДОВАНИЕ ЛЮМИНОФОРА Sr3(VO4)2:Eu3+ С ЦЕЛЬЮ ПРИМЕНЕНИЯ В БЕЛЫХ СВЕТОИЗЛУЧАЮЩИХ ДИОДАХ П. А. Нагпуре Н. Д. Херде, В. С. Барде

Научный колледж Шри Шиваджи, г. Амравати, штат Махараштра, Индия

и nagpurepa@yahoo.co.in

Аннотация. В статье исследован люминофор Sr3(VO4)2:Eu3+, перспективный для создания белого светоизлучающего диода (W-LED) на основе этого одного соединения. Образцы данного материала были получены двумя способами: соосаждения и сжигания. Образование требуемого вещества было подтверждено рентгенографически. Практически важные свойства объекта изучались методом фотолюминесцентной спектроскопии. В спектрах соединения обнаружены широкая эмиссионная полоса, охватывающая всю видимую область спектра с центром на длине волны 520 нм, а также острый пик на 613 нм. В спектрах возбуждения люминесценции наблюдалась широкая полоса с центром на длине волны 350 нм. Представлена соответствующая диаграмма энергетических уровней. Полученные экспериментальные результаты привели к заключению, что метод соосаждения предпочтителен, а фотолюминесцентные свойства полученного люминофора удобны для создания штучных белых светоизлучающих диодов.

© Nagpure P. A., Kherde N. D., Barde W. S., 2023. Published by Peter the Great St. Petersburg Polytechnic University.

Ключевые слова: ванадат стронция, соосаждение, метод сжигания, фотолюминесценция, белый светоизлучающий диод

Для цитирования: Нагпуре П. А., Херде Н. Д., Барде В. С. Синтез и фотолюминесцентное исследование люминофора Sr3(VO4)2:Eu3+ с целью применения в белых светоизлучающих диодах // Научно-технические ведомости СПбГПУ. Физико-математические науки. 2023. Т. 16. № 2. С. 61-67. DOI: https://doi.org/10.18721/ JPM.16205

Статья открытого доступа, распространяемая по лицензии CC BY-NC 4.0 (https:// creativecommons.org/licenses/by-nc/4.0/)

Introduction

White light emitting diodes (W-LEDs) have been found wide use especially for solid state lighting and backlight of liquid crystal display (LCD), traffic signals. W-LEDs have a number of advantages such as long lifetime and lack of pollutant, higher energy efficiency, compactness and reduced power consumption [1]. In a W-LED, white light can be produced either by combining a blue LED with a yellow phosphor or combining the ultraviolet light emitting diodes (UV-LED) with a blend of blue, green and red phosphors. White light emission resulted from a single-phase phosphor compared to combination of two or three phosphors expected to give high luminous efficiency, because it reduces the probability of multiphosphor reabsorption of emission colors [2].

In recent years, vanadates have been used in many high-technology fields, such as biological materials, electrochemistry, optical lasers, catalysis, etc. [3]. Luminescence materials have been widely studied and used in white light emitting diodes and flat-panel displays (FPDs), such as YVO4:Eu3+, etc. [4]. At ambient pressure orthovanadates exhibit oxygen ionic conductivity and high electronic conductivity, i. e., the migration of electrons between V4- and V5-centers, but electronic conduction is absent in isostructural orthophosphates and orthoarsenates [5]. Vanadates with general formula M3(VO4)2 (M = Ca, Sr, Ba) have been proved to be good candidates for the luminescent hosts, because they have strong absorption band in the UV region and then transfer the energy to rare-earth activator ions efficiently due to good match of energy levels in the wide region and strong interaction between states of [VO4]3- and rare-earth ions. In addition to this, vanadates have the self-activated emitting properties and better chromaticity [6]. [VO4]3- group consists of the central metal vanadium ion coordinated by four oxygen ligands in the tetrahedral symmetry and is known to be an efficient luminescent center with broad band emissions from 400 to more than 700 nm with UV or near-UV light excitation [7]. Vanadium oxides have different complex groups of ortho-, meta- and pyrovanadates. Vanadates generally show a short wavelength of the optical absorption edge. This makes them suitable as hosts to accommodate active rare-earth ions [8]. The ytterbium ions Yb3+ doped with Sr3(VO4)2 provide characteristic near-infrared (NIR) emission in the range of 970 — 1050 nm which are suitable to get rid of the spectral mismatch problem of c-Si solar cells [9].

In the present work, photoluminescence of Sr3(VO4)2:Eu3+ phosphor synthesized by co-precipitation and combustion methods has been studied in the context of its application as W-LED phosphor.

Experimental part

Strontium nitrate Sr(NO3)2 (99.9% A.R.), europium oxide Eu2O3 (99.9% A.R.) and ammonium vanadate NH4VO4 (99.9% A.R.), all from Sigma Aldrich, were use d.

Synthesis. The synthesis of phosphor Sr3x(VO4)2:(Eu3+)x, was attempted using two methods: co-precipitation one and combustion one.

Co-precipitation method. The phosphors Sr3x(VO4)2:(Eu3+)x (x = 0.002, 0.005, 0.010) were synthesized by co-precipitation method (Fig. 1). The precursors Sr(NO3)2 (99.9% A.R.), Eu2O3 (99.9% A.R.) and NH4VO4 (99.9% A.R.) were weighed in proper stoichiometric ratio and used for synthesis of the phosphor. The starting chemicals NH4VO4 (99.9% A.R.) were dissolved in the double distilled water and heated on a hot plate at about 100 °C. The nitric acid HNO3 was added drop by drop in Eu2O3 and a DD water mixture in separate beaker was so as to convert it into

© Нагпуре П. А., Херде Н. Д., Барде В. С., 2023. Издатель: Санкт-Петербургский политехнический университет Петра Великого.

Eu(NO3)3. The hot solution of NH4VO4 then added dropwise to the aqueous transparent mixture of nitrates with constant stirring. The entire homogenous solution was then placed on the hot plate maintained at a temperature of 90 °C for slow evaporation of water. The dried precipitate was finally crushed and heated at 800 °C for 1 hour and 950 °C for 2 hours in order to get white crystalline powder of Sr3x(VO4)2:(Eu3+)x (x = 0.002, 0.005, 0.010).

Add diluteHN03 dropwise and heatedat70°C

Aq.Soln.of3Sr(N03)2xEu203

dropwise and stirr

l_J L_

J-rf N-

Add double distilled water 10ml

Heated at 90°C brown colored powder obtained

Annealed at 800°C for 1hr and 950°C for 2hr and quenched at room temperature

White colorSr3(V04)2 :Eu3+

Fig. 1. Flow chart of synthesis of Sr3x(VO4)2:(Eu3+)x via co-precipitation method

4'2

Combustion method.

The stoichiometric amount of precursors, namely, strontium nitrate urea and Eu„O„ converted to Eu(NO3)3

Sr(NO3)2, ammonium vanadete NH4VO3, urea and Eu2O3 converted to Eu(NO3)3 (x = 0.002, 0.005, 0.010) were taken in a china clay basin and few drops of DD water added to the mixture. This mixture was heated at 90 °C till the precursors dissolved completely, then it was kept into the preheated furnace at 900 °C, and then warmed for 5 min. The self-heat generating redox reaction was completed in 2 min and the fine powder of Sr3(VO4)2:Eu3+ was obtained (Fig. 2). This raw powder was sintered for 2 hours at 950 °C and quenched to room temperature.

Fig. 2. Flow chart of synthesis of Sr3x(VO4)2:(Eu3+)x via combustion method

42

Characterizations. Formation of the required phase of the compound was confirmed by the X-ray diffraction pattern. The photoluminescence (PL) properties were studied using Hitachi (F-7000) fluorescence spectrophotometer.

Results and discussion

X-ray diffraction (XRD) analysis. The formation of Sr (VO4)2 host in the crystalline phase synthesized by both co-precipitation and combustion methods was confirmed by XRD pattern taken from Rigaku miniflex II X-ray diffractometer with scan rate of 2.000°/min and CuA^ (.k = 0.15406 nm) radiation in the range from 10° to 90° (see Fig. 3). The XRD pattern for Sr3(V04), agreed with the ICDD file (01-081-1844) very well.

Si3(V04)3 :En3- -CP

üU*_OJuJ^JJ^

Sd{V04)3î:Eu3-CS

ià

Sr3(V04)2 ICDD-Ol-flSl-844

Fig. 3. X-ray diffraction pattern of Sr3(VO4)2:Eu3+

Photoluminescence characterization. The photoluminescence (PL) emission and excitation spectrum of Sr3(VO4)2:Eu3+ phosphor synthesized by co-precipitation and combustion methods are shown in Fig. 4. For the both cases the nature of emission spectra are almost the same but there is a slight difference in the excitation spectra. The emission spectrum exhibits a green broad band centered at 520 nm which is attributed to 3T 2 ^ XA transition of [VO4]3- group, and with a sharp peak at 613 nm in the red region corresponding to a characteristic 5D0 ^7F2 transition of Eu3+ [6, 10].

The PL emission spectra of the phosphor shows maximum intensity for 0.002 mol doping of Eu when synthesized by the co-precipitation method and for 0.001 mol doping of Eu when synthesized by the combustion one. The overall intensity of PL emission is greater for the phosphor synthesized by the co-precipitation method than that for the phosphor synthesized by the combustion one.

Fig. 5. presents the simplified energy level diagrams of [VO4]3- group and Eu3+ ion and emission transition processes in the Sr3(VO4) 2:Eu3+ phosphor as well.

a)

JOO 400 500

Wav eleu 2 th(nm)

-EU0.002 -EuO.005 -EuO.Ol

„100 iO

W avelen gth(nm)

Fig. 4. Photoluminescence excitation and emission spectra 64 of Sr3_x(VO4)2 : (Eu3+)x synthesized by co-precipitation (a) and combustion (b) methods

2 theta

Fig. 5. The simplified energy level diagrams of [VOJ3- group and Eu3+ ion and emission transition (ET) processes in the Sr3(VO4)2:Eu3+ phosphor

Summary

A series of S^(VO4)2:Eu3+ phosphors were successfully synthesized by co-precipitation and combustion methods. The XRD patterns confirmed the pure crystalline phase of S^VO^. The photoluminescence excitation spectra showed the broad excitation band with maximum at 350 nm. The photoluminescence emission spectra showed the broad band (400 — 650 nm) with a maximum at 520 nm attributed to the 3T} transitions of [VOJ3" group and a sharp peak at

613 nm attributed to the 5D0 ^■1F2 transition of Eu3+. The co-precipitation method was found to be suitable and efficient for synthesis of Sr3(VO4)2:Eu3+.

The photoluminescence spectra of the Sr3(VO4)2:Eu3+ exhibited a potential application of the prepared phosphor in energy-efficient solid-state lighting, optoelectronic devices and organic composite solar cells.

REFERENCES

1. Chung D. N., Hieu D. N., Thao T. T., et al., Synthesis and characterization of Ce-doped Y3Al5O12 (YAG : Ce) nanopowders used for solid-state lighting, J. Nanomater. 2014 (25 May) (2014) 571920.

2. Bajaj N. S., Koparkar K. A., Nagpure P. A., Omanwar S. K., Red and blue emitting borate phosphor excited by near ultraviolet light, J. Optics. 46 (2) (2017) 91—94.

3. Zhang Z., Tang W. J., Energy transfer and tunable luminescence of Na2(Y, Eu)Mg2V3Oi2 phosphors for white LED applications, Mater. Res. Bull. 73 (January) (2016) 351—356.

4. Erdei S., Rodriguez N. M., Ainger F. W., et al., Luminescent characteristics and morphology of Eu3+:YVO4 phosphor powders prepared by HCR and flux techniques, J. Mater. Chem. 8 (1) (1998) 99-103.

5. Grzechnik A., McMillan P. F., High-pressure X-ray diffraction of S^VO^ and Ba3(VO4)2, Physica B. Condens. 252 (4) (1998) 268-273. 3 4 2 3 4 2

6. Cao R., Peng D., Xu H., et al., Synthesis and luminescence properties of S^^VO^^u^ phosphor and emission enhancement by co-doping Li+-ion, Optik. 127 (19) (2016) 7896-7901.

7. Sheetal, Taxak V. B., Khatkar S. P., Synthesis and luminescent properties of M2V2O7 Eu (M = Sr, Ba) nanophosphors, J. Fluoresc. 22 (3) (2012) 891-897.

8. Shinde K. N., Singh R., Vanadate phosphors for energy efficient lighting. Ch. 12, In book: Tiwari A., Valykh S. (Eds.), Advanced Ene^y Materials, John Wiley & Sons, Oxford (UK), 2014.

9. Sawala N. S., Bajaj N. S., Omanwar S. K., Near-infrared quantum cutting in Yb3+ ion doped strontium vanadate, Infrared Phys. Technol. 76 (May) (2016) 271-275.

10. Bedyal A. K., Kumar V., Swart H. C., Charge compensated derived enhanced red emission from Sr3(VO4)2:Eu3+ nanophosphors for white light emitting diodes and flat panel displays, J. Alloys Compd. 709 (30 June) (2017) 362-372.

СПИСОК ЛИТЕРАТУРЫ

1. Chung D. N., Hieu D. N., Thao T. T., Truong V., Dinh N. N. Synthesis and characterization of Ce-doped Y3Al5O12 (YAG : Ce) nanopowders used for solid-state lighting // Journal of Nanomaterials. 2014. Vol. 20145. 25 May. P. 571920 (7 p).

2. Bajaj N. S., Koparkar K. A., Nagpure P. A., Omanwar S. K. Red and blue emitting borate phosphor excited by near ultraviolet light // Journal of Optics. 2017. Vol. 46. No. 2. Pp. 91—94.

3. Zhang Z., Tang W. J. Energy transfer and tunable luminescence of Na2(Y, Eu)Mg2V3O12 phosphors for white LED applications // Materials Research Bulletin. 2016. Vol. 73. January. Pp. 351—356.

4. Erdei S., Rodriguez N. M., Ainger F. W., et al. Luminescent characteristics and morphology of Eu3+:YVO4 phosphor powders prepared by HCR and flux techniques // Journal of Materials Chemistry. 1998. Vol. 8. No. 1. Pp. 99-103.

5. Grzechnik A., McMillan P. F. High-pressure X-ray diffraction of Sr3(VO4)2 and Ba3(VO4)2 // Physica B: Condensed Matter. 1998. Vol. 252. No. 4. Pp. 268-273.

6. Cao R., Peng D., Xu H., Luo Z., Ao H., Guoa S., Fu J. Synthesis and luminescence properties of Sr3(VO4)2:Eu3+ phosphor and emission enhancement by co-doping Li+-ion // Optik. 2016. Vol. 127. No. 19. Pp. 7896-7901.

7. Sheetal, Taxak V. B., Khatkar S. P. Synthesis and luminescent properties of M2V2O?: Eu (M = Sr, Ba) nanophosphors // Journal of Fluorescence. 2012. Vol. 22. No. 3. Pp. 891-897.

8. Shinde K. N., Singh R. Vanadate phosphors for energy efficient lighting. Chapter 12 // Tiwari A., Valykh S. (Eds.). Advanced Energy Materials. Oxford, UK: John Wiley & Sons, 2014. 616 p.

9. Sawala N. S., Bajaj N. S., Omanwar S. K. Near-infrared quantum cutting in Yb3+ ion doped strontium vanadate // Infrared Physics & Technology. 2016. Vol. 76. May. Pp. 271-275.

10. Bedyal A. K., Kumar V., Swart H. C. Charge compensated derived enhanced red emission from Sr3(VO4)2:Eu3+ nanophosphors for white light emitting diodes and flat panel displays // Journal of Alloys and Compounds. 2017. Vol. 709. 30 June. Pp. 362-372.

THE AUTHORS

NAGPURE Pankaj A.

Shri Shivaji Science College, Amravati

Shivaji Nagar, Morshi Road, Amravati, 444603, India

nagpurepa@yahoo.co.in

ORCID: 0000-0001-6767-1907

KHERDE Nivedita D.

Shri Shivaji Science College, Amravati

Shivaji Nagar, Morshi Road, Amravati, 444603, India

niveditaholey@gmail.com

BARDE Waman S.

Shri Shivaji Science College, Amravati

Shivaji Nagar, Morshi Road, Amravati, 444603, India

wamanbarde81@gmail.com

СВЕДЕНИЯ ОБ АВТОРАХ

НАГПУРЕ Панкадж A. — Ph.D., доцент кафедры физики Научного колледжа Шри Шиваджи, г. Амравати, штат Махараштра, Индия.

Shivaji Nagar, Morshi Road, Amravati, 444603, India

nagpurepa@yahoo.co.in

ORCID: 0000-0001-6767-1907

ХЕРДЕ Ниведита Д. — сотрудник кафедры физики Научного колледжа Шри Шиваджи, г. Амравати, штат Махараштра, Индия.

Shivaji Nagar, Morshi Road, Amravati, 444603, India niveditaholey@gmail.com

БАРДЕ Ваман С. — Ph.D., адьюнкт-профессор кафедры физики Научного колледжа Шри Шиваджи, г. Амравати, штат Махараштра, Индия. Shivaji Nagar, Morshi Road, Amravati, 444603, India wamanbarde81@gmail.com

Received 11.10.2022. Approved after reviewing 27.12.2023. Accepted 27.12.2023. Статья поступила в редакцию 11.10.2022. Одобрена после рецензирования 27.12.2023. Принята 27.12.2023.

© Санкт-Петербургский политехнический университет Петра Великого, 2023