AU2021104320A4 - A nano-phosphor chemical composition and a method for the nano-phosphor synthesis - Google Patents

Abstract

The present disclosure relates to a nano-phosphor chemical composition and a method for the nano-phosphorsynthesis. The chemical composition comprises: EuBa 3B 9018 . The method comprises: mixing Eu2 O3, Y 20 3, BaCO3 , and H3BO3 to form a mixture wherein, adding excess H 3B03 to compensate for B2 03 volatilization in further steps; sintering the mixture to decompose BaCO3 and H3B0 3 slowly; and calcining the mixture with intermediate grindings and wherein, 1% mol excess H3BO3 is added to compensate for B 2 03 volatilization wherein, the mixture is sintered at 600°C for 1 hour and wherein, the mixture is calcined at 950°C for 3 days with intermediate grindings. 9 100¾ 102 addingexcess H BOAtt i mnturto comensate forBOotain io sntercgttiwonirt uretode6co injnrEaCCAan HA 4C.slog; and IV106 cakIionrg tfiem tturew aiinte-reldiate gTk . 108 Figure1I Fig uW re1 2(C

Description

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A NANO-PHOSPHOR CHEMICAL COMPOSITION AND A METHOD FOR THE NANO-PHOSPHOR SYNTHESIS

FIELD OF THE INVENTION The present disclosure relates to a nano-phosphor chemical composition and a method for the nano-phosphor synthesis.

BACKGROUND OF THE INVENTION Alternative lighting sources with substantially reduced energy consumption, great reliability, and environmentally friendly production techniques have recently attracted a lot of attention as a replacement for traditional incandescent and fluorescent lights. Furthermore, they have environmental benefits because their manufacturing processes do not produce greenhouse gas emissions (C02) or cause mercury contamination. There are essentially two ways to create white-light sources by utilizing LEDs. LEDs that produce the three fundamental colors (red, green, and blue) or a combination of complimentary colored light are used. The other makes use of down-converted light from a phosphor and output from either blue or ultraviolet LEDs.

White LEDs, in particular, manufactured by combining a blue or ultraviolet LED with a yellow emitting phosphor, are the most often used method nowadays due to its inexpensive cost, simple fabrication process, and great brightness output. However, because this technology is based on two color mixing and the resulting white-light changes with excitation strength or temperature, it has a low color rendering index. Another flaw in the method is that it lacks red components in its emission spectra, which prevents light from being generated in the red spectral region, and the combination of yellow phosphor and blue-LED generates a high correlated color temperature.

In order to make the existing solutions more efficient there is a need to develop a nano-phosphor chemical composition and a method for the nano-phosphor synthesis.

SUMMARY OF THE INVENTION The present disclosure relates to a nano-phosphor chemical composition and a method for the nano-phosphor synthesis.A modified traditional solid state reaction technique was used to make EuBa 3B 901s. The luminescence parameters measured after UV-visible and infrared stimulation demonstrate the well-known Eu excitation and emission. In all locations covered by the ultraviolet-visible and infrared ranges, the charge transfer excitation band of Eu dominates the excitation spectra. Due to transitions from the Do level to the levels Fj (J=0, 1, 2, 3, 4) of Eu ions, the emission spectra of Eu ions consist mostly of multiple groups of lines in the 400-850nm area (415, 464, 529, 594, 616, 726, 779, and 829 nm).For entirely concentrated EuBa 3 B9 01s, there is no concentration quenching in the dependence between luminescence intensity and Eu concentration. EuBa 3B 901s phosphors are promising for use in displays and optical systems. The synthesised sample has a hexagonal form, as can be seen. The average crystallite size of prepared phosphor is estimated to be around 55nm.

In an embodiment, a nano-phosphor chemical composition comprises: EuBaB3 901s.

In another embodiment, a method 100 for synthesis of EuBa B 3 901s by a solid-state

reaction method comprises the following steps: at step 102, mixing Eu 2 0 3 , Y 2 0 3 , BaCO 3 , and H3 B03 to form a mixture; at step 104, adding excess H 3B0 3 to the mixture to compensate for B2 0 3 volatilization in further steps; at step 106, sintering the mixture to decompose BaCO 3

and H 3 B0 3 slowly; and at step 108, calcining the mixture with intermediate grindings.

To further clarify advantages and features of the present disclosure, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.

BRIEF DESCRIPTION OF FIGURES These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

Figure 1 illustrates a method for synthesis of EuBa 3B 901s by a solid-state reaction method in accordance with an embodiment of the present disclosure.

Figure 2 illustrates (a)EuBa 3B 901s XRD pattern; (b)EuBa 3B 901s FTIR spectra; and(c)full width half maximum (FWHM) of the intense peak position and lattice strain in accordance with an embodiment of the present disclosure.

Figure 3 illustrates (a) EuBa 3B9 01sFEGSEM images; and (b)EuBa 3B 9 01s Photoluminescence emission spectra with different excitation in accordance with an embodiment of the present disclosure.

Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have necessarily been drawn to scale. For example, the flow charts illustrate the method in terms of the most prominent steps involved to help to improve understanding of aspects of the present disclosure. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

DETAILED DESCRIPTION

For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.

Reference throughout this specification to "an aspect", "another aspect" or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by "comprises...a" does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.

Embodiments of the present disclosure will be described below in detail with reference to the accompanying drawings.

Referring to Figure 1 illustrates a method for synthesis of EuBa B 3 901s by a solid

state reaction method in accordance with an embodiment of the present disclosure. The method 100 for synthesis of EuBa 3B 901s by a solid-state reaction method comprises the following steps: at step 102, mixing Eu 2 0 3 , Y 2 0 3 , BaCO3, and H3 B03 to form a mixture; at step 104, adding excess H 3 B0 3 to the mixture to compensate for B2 0 3 volatilization in further steps; at step 106, sintering the mixture to decompose BaCO 3 and H 3B0 3 slowly; and at step 108, calcining the mixture with intermediate grindings.

In an embodiment, the method, wherein, 1% mol excess H 3B03 is added to compensate for B 2 03 volatilization wherein, the mixture is sintered at 600°C for 1 hour and wherein, the mixture is calcined at 950°C for 3 days with intermediate grindings and wherein,

EuBa 3 B901s was synthesized by the solid-state reaction method, which is suitable for a large scale production of phosphors.

Figure 2 illustrates (a)EuBa 3B 901 s XRD pattern; (b)EuBa 3B 9O 1 s FTIR spectra; and(c)full width half maximum (FWHM) of the intense peak position and lattice strain in accordance with an embodiment of the present disclosure.

Figure 2a shows the XRD pattern of EuBa 3B 9 01s. As the particle size decreases, the width of the peak widens. Using the Debye Scherer formula, the particle size was calculated from the full width half maximum (FWHM) of the intense peak. The Debye Scherer formula calculates a crystallite size of 55nm. The FWHM, peak position, and lattice strain of the XRD pattern are shown in Figure 2b.

Figure 2c depicts the infrared (FTIR) spectrum of EuBa3B9018. The band seen in the infrared spectrum is due to symmetric stretching at (Eu-0) is 1025 cm-1, symmetric bending at (0-Ba-0) = 467 cm- 1, and anti symmetric stretching at (Eu-0) is 501-810 cm-1 . The B-0 stretching vibration of tetrahedral B04 units is associated to the absorption band at 1433 cm-1

. The stretching mode of O-H from the water crystallisation in the complex is responsible for the broad band with a peak at ~3432.13 cm-1.

Figure 3 illustrates (a) EuBa 3B 901sFEGSEM images; (b) EuBa 3B 901s Photoluminescence excitation spectra at 400nm excitation; and (c) EuBa 3B 901s Photoluminescence emission spectra with different excitation in accordance with an embodiment of the present disclosure.

Particle morphology was observed by FEGSEM (field emission gun scanning electron microscope), and it showed a hexagonal crystallite structure (Figure 3a).

Figure 3b shows the excitation spectrum at various excitations. Excitation originates from the charge transfer (CT) transition of 0-*Eu. Namely, the electron delocalized from the filled 2p shell of 02-to the partially filled 4p shell of Eu. The intensity of the CT band is much stronger than the lines between 300-850nm due to the f-f transitions of Eu ions.

The emission spectra of EuBa 3B 901s (ex=UV, visible and IR)is shown in Figure 3c. The EuBa 3 B901s samples were found to have the typical Eu luminescence, i.e., the emission of Eu ions in EuBa 3B 901s ranges from 4000nm to 850nm and is composed primarily of various groups of lines. Transitions from the excited state Do to the ground states7 F(J=O, 1, 2, 3, 4) in the 4F6 configuration of Eu ions cause these emission properties. Main lines at roughly ~594nm, attributable to the magnetic dipole transition of 5 D0 -* 7F 1, and main lines at ~616nm, attributed to the 5 D o-* 7F 2transition, dominate the emission spectra (electric dipole transition).According to the Judd-O felt theory, the ratios of the red emission at ~616nm to the orange emission at ~594nm show that the orange emission is prominent and Eu3 + does occupy the inversion symmetry sites in the host lattices. Because the lower-lying charge transfer states skip the higher-lying 5 Di levels during the relaxation process, no emission from the higher levels, such as 5 D 1 ,2 , was identified. In a crystal field with 2J+1 components for Eu, the maximum splitting numbers of transition lines for 5 D o-* 7Fj (J=, 1, 2) are 1 for J=O, 3 for J=1, and 5 for J=2.

The drawings and the forgoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.

Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any component(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or component of any or all the claims.

Claims (10)

WE CLAIM:

1. A nano-phosphor chemical composition, wherein the chemical composition comprises:EuBa 3B 901s

2. The chemical composition as claimed in claim 1, wherein, a crystallite size of EuBa 3 B901s is 55nm and a shape is hexagonal.

3. The chemical composition as claimed in claim 1, wherein, EuBaB 3 901 8 displays a

good photoluminescence response to all emissions ranges from UV-visible to infrared.

4. The chemical composition as claimed in claim 1, wherein, EuBaB3 901s comprises nonlinear optical properties, high transmittance in an ultraviolet (UV) region, and large birefringence.

5. The chemical composition as claimed in claim 1, wherein, borates are doped with rare-earth element (Eu3+) to improve a luminescence properties, wherein, (Eu 3 +)

impurities serve as luminescent centres in a crystal, with an emission wavelength in a range of 300-600 nm.

6. The chemical composition as claimed in claim 1, wherein, EuBa 3B 901s is an efficient material for display devices application for different excitations and optical devices.

7. A method for synthesis of EuBa 3B 901s by a solid-state reaction method, wherein the method comprises:

mixing Eu 2 0 3 , Y 20 3 , BaCO3 , and H3 B0 3 to form a mixture;

adding excess H3 B0 3 to the mixture to compensate for B 2 0 3 volatilization in further steps;

sintering the mixture to decompose BaCO 3 and H 3B0 3 slowly; and

calcining the mixture with intermediate grindings.

8. The method as claimed in claim 7, wherein, 1% mol excess H 3BO 3is added to compensate for B 2 0 3 volatilization.

9. The method as claimed in claim 7, wherein, the mixture is sintered at 600°C for 1 hour and wherein, the mixture is calcined at 950°C for 3 days with intermediate grindings.

10. The method as claimed in claim 7, wherein, EuBa B 3 90 1s was synthesized by the solid

state reaction method, which is suitable for a large-scale production of phosphors.