Facile Synthesis Process and Optical Properties of Synthesized Nontoxic Phosphor for Sustainable Environment
Shashank Sharma1* and Sanjay Kumar Dubey2
1Department of Physics, Dr. C. V. Raman University, Kota Bilaspur (Chhattisgarh), India
2Department of Physics, Dr. Radha Bai, Govt. Navin Girls College, Raipur (Chhattisgarh), India
Submission: May 18, 2023; Published: July 28, 2023
*Corresponding author: Dr. Shashank Sharma, Assistant Professor, Department of Physics, Dr. C. V. Raman University, Kota Bilaspur (Chhattisgarh), 495113, India, Email ID: shashanksharma1729@gmail.com
How to cite this article: Shashank S, Sanjay Kumar D. Facile Synthesis Process and Optical Properties of Synthesized Nontoxic Phosphor for Sustainable Environment. Insights Insights Min Sci technol.2023; 4(2): 555632. DOI: 10.19080/IMST.2023.04.555632
Abstract
A variety of inorganic compounds known as silicates has grown to be more popular as a result of their superior chemical resistance and transparency to visible light, which make them suitable for a wide range of uses. They are more expressively researched because to their excellent thermal and chemical stability, abundant, non-toxic, inexpensive price, and strong near-ultraviolet absorption. Ca2MgSi2O7:Eu2+, Dy3+ phosphor was synthesized by high-temperature solid-state reaction technique. This structure is a member of melilite group and revealed tetragonal, Akermanite structure with a space group P¯421m. The excitation spectrum shows a broad absorption band at 200–400nm with 365nm wavelength single broad emission peak situated at 505nm was obtained. The prepared Ca2MgSi2O7:Eu2+, Dy3+ phosphor was characterized using photoluminescence (PL) excitation and emission spectra. Prominent green colour emission was obtained under ultraviolet excitation. The broadband PL emission peaks exhibited maximum intensity of photoluminescence signals centered at 505 nm show efficient emission colour in green region, which is the most sensitive to the human eyes.
Keywords: Ca2MgSi2O7:Eu2+, Dy3+; Tetragonal; Akermanite; Solid-State Reaction; Photoluminescence (PL)
Introduction
Light exhibits remarkable behaviour in the diverse applications of material science and nanotechnology, and as a result, cross-cutting concerns are inevitably growing in importance as the world becomes more networked and dependent on renewable energy in the twenty-first century. One of the most important and fundamental components of the green ecosystem that offers further innovation for human consumption is the new phrase “Material Diversity”. The fact that photoluminescence analysis only needs a minimal amount of the sample (nearly 20mg) and does not require the sample to be in solution form for powdered phosphor materials gives it a similar advantage over other spectroscopic methods. With the use of this technique, materials can be investigated quickly. This method was also used to create Eu2+ doped and Dy3+ cooped di calcium magnesium di silicate phosphors, and the properties of the powder were examined with and without the addition of a flux such H3BO3. It is generally agreed that Eu2+ is the most common emission centre in persistent phosphor hosted by the 4f7→ 4f65d1 transition [1-3]. Matsuzawa et al., it was stated that Eu2+ ions served as electron traps (Eu2+ + e → Eu+) while Dy3+, ions served as hole traps (Dy3+,+ hole → Dy4+). Between the lower energy state (ground) and higher energy state (excited) state of Eu2+ ions, Dy3+, ions serve as deep hole trap levels [4,5]. Silicates are highly transparent to visible light and possess great chemical resistance, they are a desirable class of inorganic materials that are employed in a variety of applications [6]. Because they have good near-UV absorption, high thermal and chemical stability, are inexpensive, and have excellent water resistance [4]. Akermanite phosphors serve their purpose in production because of their excellent physical and chemical stability properties. A calcium magnesium silicate phosphor would be a fantastic by product from the manufacturing of optical devices for the lighting industries [7,8].
In this article, we describe the synthesis of the bright green-emitting calcium magnesium silicate phosphor (Ca2MgSi2O7:Eu2+, Dy3+,) by high-temperature solid-state synthesis method utilizing boric acid (H3BO3) used as flux. Photoluminescence (PL) investigations have employed in order to optical and luminescence properties with excitation and emission being thoroughly discussed of synthesized powder samples.
Experimental Studies
Sample Preparation
In our study, the prepared samples with stoichiometric ratio of Ca2MgSi2O7:Eu2+, Dy3+ were synthesized via conventional hightemperature solid-state synthesis route (shown in Figure 1). Initially, all raw reagents such as CaCO3 (99.99%), MgO (99.99%), SiO2 (99.99%) and H3BO3 (99.99%) of Hi-media (AR grade) as well as rare earth ions Eu2O3 (99.99%) and Dy2O3 (99.99%) were used in present research investigations. Very little amount of boric acid [H3BO3] was used as a flux. Before being transferred to a silica crucible, the precursor chemical reagents were completely crushed in an hour in an agate crusher and pestle. Then the mixture was presintered at 950oC and subsequently fired at 1150oC in high-temperature muffle furnace for 2h in a weak reducing atmosphere with liberation of gaseous products. The weak reducing atmosphere have produced by using activated charcoal [4]. To transform Eu3+ into Eu2+ is the task of decreasing atmosphere. Further grinding into a fine powder was used to produce the finished product. The finished phosphor was produced as a white powder and stored in an airtight container for further characterisation studies including photoluminescence spectra.
The chemical reaction of this process is given as follows:
CaCO3 + MgO + SiO2 → Ca2MgSi2O7 + CO2 (↑) (1)
CaCO3 + MgO + SiO2 + Eu2O3 + Dy2O3 → Ca2MgSi2O37:Eu2+, Dy3+ + CO2 (↑) (2)
Almost any nano- and micro-phosphors’ crystalline materials formation depends to a great extent on fluxes. Any formation proceeds along more rapidly owing to all these fluxes. The final outcome is the synthesis of phosphors with actual chemical compositions. Boric acid (H2BO3), lithium fluoride (LiF), calcium chloride (CaCl2), and other specialized fluxes are utilized in order to enhance crystal structure formation [9].
Sample Characterization
By using the solid-state reaction technique, the Ca2MgSi2O7:Eu2+, Dy3+powder sample was thoroughly prepared. It was presintered at 950°C and then fired at 1150°C in a hightemperature muffle furnace for two hours in a weak reducing atmosphere. The measurement of the Photoluminescence (PL) excitation & emission spectra were carried out using a Spectrofluorophotometer (SHIMADZU, RF-5301PC) with a Xenon lamp as the excitation source.
Results and Discussion
Role of Eu2+ and Dy3+ Ions on the Basis of Ionic Radius
Mellite are a large group of compounds with a basic structural formula M2 A1 B22 O7, [where M= Barium (Ba), Strontium (Sr), Calcium (Ca); A1= Magnesium (Mg), Zinc (Zn), Copper (Cu), Manganese (Mn) and Cobalt (Co); B2 = Germanium (Ge) and Silicon (Si)], have been widely explored as optical materials [9]. Jiang et al. reported that the possible sites for incorporating Eu2+ in Ca2MgSi2O7 lattice are Ca2+ sites, or the Mg2+ sites or the Si4+ sites, Mg2+ (0.58 Å) and Si4+ sites (0.26 Å) are small, but Ca2+ (1.12 Å) is equal to the size of Eu2+ (1.12 Å). So, Eu2+ ions hardly incorporate into tetrahedral [MgO4] and [SiO4] and only incorporate into [CaO8] anions complexes in host [10]. Ca2MgSi2O7:Eu2+, Dy3+ is known as an efficient phosphor with good stability, which also shows green emission with great stability and persistency [4,11].
In host Ca2MgSi2O7 crystal structure, dysprosium (Dy3+) is expected to occupy the calcium cation (Ca2+) site ideally. The reason is that the ionic radius of Dysprosium (Dy3+) 0.97 Å is very near to the ionic radius of divalent calcium cation (Ca2+)1.12 Å but divalent magnesium cation (Mg2+) 0.58 Å and tetravalent silicon cation (Si4+) 0.26 Å are too small for dysprosium [Dy3+] occupation [12]. Dysprosium (Dy3+)substituting calcium cation (Ca2+)will lead to defects with positive charge in the host crystal lattice and should capture electrons, i.e., the most likely defects generated by Dysprosium (Dy3+) ions substitute may be in the form of electronic traps [13].
Most probably the Dysprosium (Dy3+) ions are involved in trapping of electron. The reason behind this result is that when Dysprosium (Dy3+) ions added into the host CMS crystal lattice, then the persistent emission become increase. It is important to note that two Dysprosium (Dy3+) ions can replace three ions of the host. In this way, Dysprosium (Dy3+) ions may facilitate the composition of defects in host lattice that play important role as electron traps, as possible oxygen vacancies [14,15].
Photoluminescence Spectra
The photoluminescence approach has become a primary way in a variety of materials chemistry domains thanks to advancements in nanoscience. When photons are absorbed under the stimulation of external energy, a substance will produce light on its own, a process known as photoluminescence. To examine luminescence characteristics of materials, such as their excitation and emission spectra, photoluminescence is a contactless, nondestructive method [16].
Excitation and Emission spectra
The excitation and emission spectra of Ca2MgSi2O7: Eu2+, Dy3+, phosphor prepared was shown in Figure 2. The broadband emission spectra centered at 505nm (Green region) observed under the ultraviolet excitation of 365 nm correspond to the Eu2+ emission arising due to transitions from sublevels of 4f65d1 configuration to 8S7/2 level of the 4f7 configuration but with Eu2+ occupying different lattice sites. Since the crystal field can greatly affect the 4f65d1 electron states of Eu2+, it suggests that the crystal field is not changed much with the compositional variation [4,17,18]. The emission spectra are identical in shape and the bands differ only in intensities. After stimulation by UV light, ground states of Eu2+ stimulation occurs as a result of electron and hole pairs generation from the ground state 4f to excited 4f5d state. Some free holes transported into the conduction band are captured by the Dy3+ traps [19]. Our results strongly imply that the popular “hole transfer” models.
The broad luminescence of Eu2+ is due to 4f65d1-4f7 transitions. It is known that the bright green emission peaked at 505nm corresponds to the transitions of 4F9/2 → 6H13/2, and this emission belongs to hypersensitive transition with J=2. The prepared Ca2MgSi2O7:Eu2+, Dy3+ phosphor would emit bright light with peak at 505nm.
Measurement of Photoluminescence (PL) Spectra
This optical technique is non-destructive in nature, which is mainly applied to analyze special features, explore about point imperfections or the precise determination of band gap of the sample materials. In the photoluminescence [PL] study, the crystal irradiation primarily included to the image with photons having more energies than the band gap energy of that sample. Such a way, the knowledge obtained from the PL data has been received to be completely unique as a supplement to different semiconductor specialization techniques like XRD and TEM. Additionally, it also gives an idea about the effect of doping concentrations in phosphors. The optical system of the [RF–5301 PC] Spectrofluorophotometer equipment also used for photoluminescence [PL] characterization in the present investigation is shown in Figure 3. In this procedure, the phosphor, used by the equipment, was irradiated through the 150-Watt Xenon lamp.
Working Optical System of Rf-5301 PC Spectro- Fluorophotomete. The optical system of the [RF–5301 PC] Spectrofluorophotometer equipment also utilized for PL characterization in the present research work is illustrated in Figure 4 & Table 1.
Material Diversity and Environmental Protection
During the 21st century, scientific and technological progress have been closely linked to national advancement, and in recent years, this connection has gotten even stronger. In order to understand the chain mechanisms of material analysis, a large area of bio material engineering researches physics, chemistry, and the methods of innovative material modelling. This field applies fundamental ideas to luminescence behaviour. Human resources that placed a higher importance on mental and spiritual purity than on material success. In order to maintain a clean and natural environment, our brand-new, state-of-the-art optical device system, which is made of rare earth minerals, has the ability to absorb and control environmental pollution sources. When linked with business operations, it helps build a balanced industrial framework that has greater potential, better utilises the readily available natural nanomaterial resources, and upholds the planet’s environmental sustainability.
Materials consider the diversity of habitats as well as human society. Rare-earth doped nanophosphors have shown to be a very interesting issue in a number of technological and environmental application sectors. Many applications for white LEDs with phosphor modifications are made possible by their exceptional key properties, including their long operational lifetime, clean energy, higher brilliance, improved luminous efficiency, chemical stability, compactness, and environmental friendliness.
Light sensors are used to get physical information about an object without physical contact or manipulation. Recently, communication has become a part of our daily lives. An abundance of nano sensor materials detects circumstances, and communication keeps the weather updated. One of the most inventive and cutting-edge is silicate-based nanomaterials, and it has been designed to give a quick overview of the potential uses of a fast communication network system.
Using silicate-based nano-sensor optical devices, which are noise-free and noise-free, the transmission of higher frequency, faster, and better transmitted messages has been expedited via this channel. The materials utilised to make electronics with this phosphor are more eco-friendly and energy-efficient. As a result, research and development in the domain of nanostructured silicate-based nanomaterials is extensive and diverse and has been growing rapidly over the past several years on a global scale.
Conclusion
In a summary, biomaterials and biodiversity have the same conservative components. It makes reference to the variety of human existence and the overall energetic exchanges that take place. It is a fundamental part of humanity’s eco-friendly, sustainable behaviour. It plays a number of crucial ecological tasks related to precipitation, climate change, environmental adaptation, and dealing with new pests. From the results presented here, it can be concluded that Ca2MgSi2O7:Eu2+, Dy3+ phosphors were prepared easily by via the solid-state reaction route. The broadband PL emission peaks exhibited maximum intensity of photoluminescence signals centered at 505nm show efficient emission colour in green region, which is the most sensitive to the human eyes. Observed under the ultraviolet excitation of 365nm correspond to the Eu2+ emission arising due to transitions from sublevels of 4f65d1 configuration to 8S7/2 level of the 4f7 configuration but with Eu2+occupying different lattice sites. No emission peaks of Eu3+were observed in the spectra. This suggests that under the reducing environment, all of the Eu3+ ions in the matrix had been converted to Eu2+ ions.
Applications
This synthesized material is Eco-friendly and non-toxic. Moreover, near UV-LED conversion phosphor, medication delivery, cancer therapy, white light emitting phosphor, longlasting phosphor, tissue engineering, bone material, cancer illness detection, image processing of computer science and information technology, etc. are among the advantageous characteristics for applications.
Acknowledgement
Authors express their heartfelt gratitude to institution, who helped the experimental facility to complete this entire research work. Muffle furnace and other experimental research equipment’s facility have provided by the department of physics, Dr. Radha Bai, Govt. Navin Girls College, Raipur (C.G.), India.
Authors Contributions
This work was carried out in collaboration between both authors. Author Dr. Shashank Sharma undertakes the manuscript designed and conducted the entire experiments & characterization studies, collected and analyzed the research data, and prepared the entire manuscript draft as well as supervised the resultsdiscussion. Similarly, author Dr. Sanjay Kumar Dubey has properly checked the spelling mistake, punctuation, grammatical error, conceptualization, writing, review, editing and helped in sample preparation. Both authors read and approved the final manuscript.
Competing Interest of Research Work
In our current research investigations, there are no competing financial interests or any other conflicts of interest.
References
- Blasse G (1968) Fluorescence of Eu2+-Activated Alkaline-Earth Aluminates. Philips Res Reps 23: 201.
- Yamazaki K, Nakabayashi H, Kotera Y, Ueno A (1986) Fluorescence of Eu2+‐activated binary alkaline earth silicate. Journal of the Electrochemical Society 133(3): 657.
- Dubey SK, Sharma S (2020) A Brief Review to Study of Preparation and Photoluminescence (PL) Properties to Finding Possibilities of Divalent Europium Doped Barium Magnesium Silicate Based Phosphors. IJSRED 9: 12.
- Sharma S, Dubey Sk, Diwakar AK (2021) Luminescence investigation on Ca2MgSi2O7:Eu2+, Dy3+ phosphor. International Journal of Materials Science 2(2): 8-15.
- Matsuzawa T, Aoki Y, Takeuchi N, Murayama Y (1996) A new long phosphorescent phosphor with high brightness, SrAl2O4:Eu2+, Dy3+. Journal of the Electrochemical Society 143(8): 2670.
- Lin L, Yin M, Shi C, Zhang W (2008) Luminescence properties of a new red long-lasting phosphor: Mg2SiO4: Dy3+, Mn2+. Journal of Alloys and Compounds 455(1-2): 327-330.
- Sharma S, Dubey SK (2021) The significant properties of silicate based luminescent nanomaterials in various fields of applications: a review. International Journal of Scientific Research in Physics and Applied Sciences 9(4): 37-41.
- Dubey SK, Sharma S, Pandey S, Diwakar AK (2021) Luminescence Characteristics of monoclinic (Ba2MgSi2O7:Dy3+) phosphor. North Asian International Research Journal of Sciences, Engineering & I.T. 7(11): 45-55.
- Jiang L, Chang C, Mao D, Feng C (2003) Concentration quenching of Eu2+ in Ca2MgSi2O7: Eu2+ phosphor. Materials Science and Engineering: B 103(3): 271-275.
- Yen WM, Weber MJ (2004) Inorganic phosphors: compositions, preparation and optical properties. CRC press.
- Shannon RD (1976) Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta crystallographica section A: crystal physics, diffraction, theoretical and general crystallography 32(5): 751-767.
- Jiang L, Chang C, Mao D, Feng C (2004) Luminescent properties of Ca2MgSi2O7 phosphor activated by Eu2+, Dy3+ and Nd3+. Optical Materials 27(1): 51-55.
- Dutczak D, Milbrat A, Katelnikovas A, Meijerink A, Ronda C, et al. (2012) Yellow persistent luminescence of Sr2SiO4:Eu2+, Dy3+. Journal of luminescence 132(9): 2398-2403.
- Sharma S, Dubey SK (2022) Importance of the Color Temperature in Cold White Light Emission of Ca2MgSi2O7:Dy3+ Phosphor. Journal of Applied Chemical Science International 13(4): 80-90.
- Singha A, Dhar P, & Roy A (2005) A nondestructive tool for nanomaterials: Raman and photoluminescence spectroscopy. American journal of physics 73(3): 224-233.
- Shi C, Fu Y, Liu B, Zhang G, Chen Y, et al. (2007) The roles of Eu2+ and Dy3+ in the blue long-lasting phosphor Sr2MgSi2O7: Eu2+, Dy3+. Journal of luminescence 122: 11-13.
- Lin L, Zhonghua ZHA O, Zhang W, Zheng Z, Min YIN (2009) Photo-luminescence properties and thermo-luminescence curve analysis of a new white long-lasting phosphor: Ca2MgSi2O7: Dy3+. Journal of Rare Earths 27(5): 749-752.
- Jia W, Yuan H, Lu L, Liu H, Yen WM (1999) Crystal growth and characterization of Eu2+, Dy3+: SrAl2O4 and Eu2+, Nd3+: CaAl2O4 by the LHPG method. Journal of Crystal Growth 200(1-2): 179-184.
- Ozawa L (2007) Cathodoluminescence and Photoluminescence: Theories and Practical Applications, CRC Press Taylor & Francis Group, Boca Raton.