Next Article in Journal
Syngas Production Improvement of Sugarcane Bagasse Conversion Using an Electromagnetic Modified Vacuum Pyrolysis Reactor
Previous Article in Journal
Fluid–Solid Coupling Model and Simulation of Gas-Bearing Coal for Energy Security and Sustainability
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Processes
Volume 8
Issue 2
10.3390/pr8020253
processes-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Synthesis and Research of Rare Earth Nanocrystal Luminescent Properties for Security Labels Using the Electrohydrodynamic Printing Technique

by
Chinh Dung Trinh
1,2,3,*,†,
Thuan Van Doan
4,†,
Phuong Hau Thi Pham
1,2,
Dung My Thi Dang
1,2,
Pham Van Quan
5 and
Chien Mau Dang
1,2,*
1
Institute for Nanotechnology, Ho Chi Minh City 700000, Vietnam
2
Vietnam National University, Ho Chi Minh City 700000, Vietnam
3
The University of Science, Vietnam National University, Ho Chi Minh City 700000, Vietnam
4
NTT Institute of High Technology, Nguyen Tat Thanh University, Ho Chi Minh City 700000, Vietnam
5
Hue Industry College 70 Nguyen Hue, Hue City 530000, Vietnam
*
Authors to whom correspondence should be addressed.
†
These authors contributed equally.
Processes 2020, 8(2), 253; https://doi.org/10.3390/pr8020253
Submission received: 1 October 2019 / Revised: 29 December 2019 / Accepted: 6 January 2020 / Published: 24 February 2020
(This article belongs to the Section Materials Processes)
Browse Figures
Versions Notes

Abstract

:
YVO4:Eu3+ nanoparticles were successfully synthesized by two methods, namely the sonochemical method and hydrothermal method. The X-ray diffraction (XRD) patterns showed the tetragonal phase of YVO4 (JCPDS 17-0341) was indexed in the diffraction peaks of all samples. The samples synthesized by the sonochemical method had a highly crystalline structure (X-ray diffraction results) and luminescence intensity (photoluminescence results) than those synthesized by the hydrothermal method. According to the results of field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM), the average size of YVO4:Eu3+ nanoparticles was around 25–30 nm for the sonochemical method and 15–20 nm for the hydrothermal method. YVO4:Eu3+ nanoparticles in the case of the sonochemical method had a better crystalline structure and stronger emissivity at 618 nm. The Eu3+ ions’ average lifetime in YVO4:Eu3+ at 618 nm emission under 275 nm excitation were at 0.955 ms for the sonochemical method and 0.723 ms for the hydrothermal method. The security ink for inkjet devices contained YVO4:Eu3+ nanoparticles, the binding agent as polyethylene oxide or ethyl cellulose and other necessary solvents. The device used for security label printing was an inkjet printer with an electrohydrodynamic printing technique (EHD). In the 3D optical profilometer results, the width of the printed line was ~97–167 µm and the thickness at ~9.1–9.6 µm. The printed security label obtained a well-marked shape, with a size at 1.98 × 1.98 mm.

1. Introduction

Recently, researchers have paid attention to an inkjet technique in order to produce spare parts, such as electric circuits and bio-sensors [1,2,3,4]. This technique possesses the advantages of reducing steps in preparation and the printing ability in many different substrates, such as conductive, non-conductive, solid or flexible substrates. Besides research on the printing procedure, the most important issue is the preparation of an appropriate ink for a particular application. For that reason, security ink made of rare earth nanoparticles is a current focus as it has a wide application. In 2012, Meruga et al. [5] researched security ink from rare earth nanoparticles using β-NaYF4-doped Yb3+/Er3+ and Yb3+/Tm3+ in order to print a security QR code on a paper substrate and PET by Optomec direct-write aerosol jetting. In this research, the thickness of the QR sample printed on the paper substrate was in micrometer and the width in centimeter. A publication by Gupta et al. in 2010 also researched security ink from a rare earth nanoparticle, this time Y2O3-doped Eu3+ (Y2O3:Eu3+), but the printing method was by screen printing devices with a large-size security label, not by inkjet devices [6]. Our research goal is to study the security inkjet technique to enhance its security ability. The utilization of inkjet technology and security ink are emerging in high-security labels for printing money, visas, certificates and military products. There were two keys for the high security requirement: a small delicacy size (related to the printing technique) and strong luminescent intensity of the printed label under UV irradiation (related to optical emissivity of YVO4:Eu3+ nanoparticles in the ink). The luminescent intensity of YVO4:Eu3+ nanoparticles was attributed by many parameters, such as particles size and crystallinity, doped yield of Eu3+ ions into YVO4, etc. A producible method need optimum synergy of these parameters [7,8,9].
In this report, two methods, namely the sonochemical and hydrothermal methods, were experimented with for the YVO4:Eu3+ synthesis. According to a published work, a doped ratio at 5 mol % is the most appropriate ratio for luminescent intensity [9,10,11,12,13,14], which was also our doped ratio of the Eu3+ ion. YVO4:Eu3+ nanoparticles in the sonochemical method resulted the strongest luminescent intensity, which was used as red phosphor secured ink. Two types of security ink were prepared with different binding agents and solvent ingredients, and lead to different surface tensions. Using the electrohydrodynamic printing technique (EHD) inkjet printer, the line of the security label had width at ~97–167 µm and thickness at ~3–5 µm. The security labels were printed with various nanoparticle sizes, but the specific size was at 1.98 × 1.98 mm and the minimum distance between the two droplets was controlled at 0.05 µm.

2. Experimental

2.1. Material

Y (NO3)3.6H2O (99.8%, Aldrich, St. Louis, MO, USA), Eu (NO3)3·5H2O (99.9%, Aldrich, St. Louis, MO, USA) and Na3VO4 (99.98%, Aldrich, St. Louis, MO, USA) were used right after being unpacked as initial materials. NaOH (99%, Merck, Darmstadt, Germany) was used to control pH.
Poly (ethylene oxide)-PEO 100.000 (Aldrich, St. Louis, MO, USA), chloroform (99.5%, Aldrich, St. Louis, MO, USA), ethyl cellulose (Aldrich, St. Louis, MO, USA), α-terpinoel (99%, Aldrich, St. Louis, MO, USA), isopropanol (99.5%, Aldrich, St. Louis, MO, USA) and deionized water were binding agents and solvents used in the synthesis of the security ink.

2.2. Synthesis of YVO4:Eu3+ Nanoparticles

YVO4:Eu3+ nanoparticles were synthesized by the wet chemical method. Solution A was prepared by dissolving 0.88 g of Y(NO3)3·6H2O (2.3 mmol) and 0.05g of Eu(NO3)3·5H2O (0.12 mmol) into 15 mL deionized water (Eu3+ doping molar concentration was 5%) for 15 min under stirring. Solution B was formed by dissolving 0.44 g of Na3VO4 (2.4 mmol) in 15 mL deionized water. Next, solution A and solution B were dropwise mixed until a white precipitation formed in the solution. The pH value of the solution was adjusted to 12 by adding 5M of NaOH. The mixture was then heated by two methods:
  • The sonochemical method: The mixture was ultrasonicated in 10 min, at a frequency of 20 kHz (Ultrasonic Liquid Processors VCX 750) made by Sonics & Materials (Newtown, CT, USA).
  • The hydrothermal method: The mixture was poured in Teflon sealed tightly and placed in the autoclave oven at 200 °C for one hour.

2.3. Preparation of Security Inkjet Ink

Two kinds of security inkjet inks using YVO4:Eu3+ nanoparticles were prepared by mixing YVO4:Eu3+ nanoparticles with a binding agent and solvents in the appropriate ratio (Table 1).

2.4. Security Printing

The test patterns were printed on a glass substrate by a commercial printer (PS JET 300V, Printing Solution, Seoul, Korea) using the electrohydrodynamic (EHD) inkjet technique.

2.5. Characterization

The synthesized YVO4:Eu3+ nanoparticles samples were studied by field emission scanning electron microscopy (SU8010, Hitachi, Tokyo, Japan) and transmission electron microscopy (TEM, JEOL, Tokyo, Japan). The crystalline structure and doping of YVO4:Eu3+ has been analyzed by X-ray diffraction spectroscopy and Raman spectroscopy. The excitation and emission spectra were recorded at room temperature through a Hitachi F-4500 spectrofluorometer (Hitachi, Tokyo, Japan). The luminescence time decay was measured by a DeltaflexTM (Horiba, Kyoto, Japan) with a 275 nm SpectraLED excitation source.
The surface tension of the security ink was analyzed by optical contact angle and the surface tension meter KSV CAM 101 (KSV Instruments, Monroe, CT, USA). The viscosity of the security ink was analyzed by a m-VROC™ VISCOMETER (RheoSense, San Ramon, CA, USA). The printed samples were analyzed by a 3D optical profilometer (Sensofar Metrology, Barcelona, Spain) and UV 20 W mercury lamps of 254 nm (Germicidal lamp, Sankyo Denki Co., Kanagawa, Japan). The ink droplet which jetted out of the printer was imaged by high-speed camera (FASTCAM SA-Z, Photron, Tokyo, Japan).

3. Results and Discussion

The purpose of this study is to provide a synthesis of strong luminescent intensity YVO4:Eu3+ nanoparticles for application in security ink as a luminescent substance. Many factors may affect the light emission of YVO4:Eu3+ nanoparticles (related to the light-emitting mechanism), such as the doping ratio of Eu3+ ions, the particle crystalline growth and the nanoparticle size. With the same chemical components and ratio (the doping concentration of Eu3+ was 5 mol %), the different correspondences of YVO4:Eu3+ nanoparticles that were found were due to the two synthesis methods, sonochemical or hydrothermal.
According to Figure 1a–c, there is an appearance of sphere morphology in YVO4:Eu3+ nanoparticles from the hydrothermal method, whereas no sphere was found in the sonochemical method. The YVO4:Eu3+ nanoparticle size of both the sonochemical and hydrothermal methods is mainly at 25–30 nm and 15–20 nm, respectively. The YVO4:Eu3+ nanoparticles size synthesized by two methods is suitable for the preparation of security ink. Figure 1d shows the XRD patterns of the YVO4:Eu3+ nanoparticle crystalline prepared by the two different methods. YVO4 tetragonal phase (JCPDS, No. 17-0341) represented by all the diffraction peaks confirmed the existence of a crystalline structure in all nanoparticles [15,16,17,18,19,20]. The presence of additional peaks indicated that the Eu3+ ions have been successfully built into the YVO4 host lattice. However, the peaks in the sonochemical method have a clear appearance with higher YVO4:Eu3+ nanoparticle crystallinity than when using the hydrothermal method.
Figure 2 shows the energy dispersive X-ray (EDX) spectra of YVO4:Eu3+ nanoparticles synthesized by the sonochemical and hydrothermal methods. According to the EDX spectrum in the two samples of YVO4:Eu3+ nanoparticles, there exists yttrium (Y), oxygen (O), vanadium (V) and europium (Eu) elements, indicating that Eu3+ ions were doped into the YVO4 nano-crystals.
Figure 3a shows the Raman spectra of undoped and Eu-doped YVO4 nanoparticles synthesized at different methods. The undoped YVO4 sample is synthesized by the hydrothermal method with the same chemical ratio as two doped samples. The YVO4 crystal in the tetragonal structure is attributed to the point group of D4h. The vibration appearance of complex VO43− and Y3+ ions in YVO4 unit cells produce the lowest vibrational frequency at 164 cm−1 as external modes of Raman spectra [15]. The six Raman modes of these crystals were at 260, 379, 488, 813, 839 and 893 cm−1 (internal modes) [15,16]. There is a red shift of 388 cm−1 belonging to the undoped YVO4 to the weaker wavelength at 379 cm−1 (Figure 3b). Furthermore, the intensity ratio difference between the two typical modes is at 839 and 893 cm−1 (Figure 3c), presenting a significant change between doped and undoped samples. The doping frequently causes the expansion or contraction of the crystal lattice depending on the difference between the ionic radius of the dopant and host cations. The replacement of Y3+ ions by relatively larger Eu3+ ions causes a stretching of the host lattice which can decrease the phonon energies causing a shift of the Raman modes [7,11,13,17]. The result of Raman spectra shows that the lattice vibration of the YVO4 structure is altered due to the occupancy of the Eu ions at Y3+ sites in the YVO4 host lattice.
Figure 4a shows the YVO4:Eu3+ luminescence mechanism. There are three major steps in the excitation and emission process of YVO4:Eu3+ under UV radiation. First, the absorption of UV radiation by VO43− groups. Second, the migration of thermal activated energy (comes from the UV excitation source) through the vanadate sub-lattice, causing the transferring of excited energy to Eu3+ ions. Last, the appearance of strong red emissions due to the de-excitation process of excited Eu3+ ions [11,13,18,21,22,23].
Figure 4b shows the correspondence of the excited photoluminescence (PLE) spectra of the 618 nm emissions to Eu3+: 5D0→7F2 transition of theYVO4: Eu3+ nanoparticles. There is an intensive broadband consistence, ranging from 260 to 350 nm, which occurred in all excited spectra. The origin of the broadband is supposed by O2−–V5+ within the VO43− group charge transfer. There is the respective attribution of several weak narrow bands in the range of 350–550 nm to the f–f transitions within the 4f6 configuration of the Eu3+ ions. The Eu3+ f–f transitions have a weak absorption intensity in comparison to that of the VO43− groups, indicating that the Eu3+ ions excitation is mainly created by the VO43− groups, and energy transfer from the VO43− groups to Eu3+ions [18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40].
In Figure 4c, the specific peaks appear at 590, 618, 645 and 690 nm as a result of the 5D0→7F1 (magnetic-dipole transition), 5D0→7F2 (electric-dipole transition), 5D0→7F3 and 5D0→7F4 (excited optical source at approximately 275 nm) transfer. The main emission is at 618 nm by strongest emissivity 5D0→7F2. In this research, the red emission of YVO4:Eu3+ nanoparticles was analyzed (peak at 618 nm). At 618 nm, the luminescent intensity of the sample synthesized by the sonochemical method is stronger than the one using the hydrothermal method. This is again confirmed with the XRD patterns above. In the sonochemical method, particles have a better crystallinity due to a high local temperature and pressure during the growing. The result in Figure 4c also indicates the occupying of Eu3+ ions in the asymmetry inversion center instead of Y3+ in both methods.
In Figure 5, the room-temperature luminescence decay curves of the 5D0→7F2 transition of Eu3+ are presented for the samples synthesized in both methods. The excitation wavelength is fixed at 275 nm. The common factors that affect to the decay kinetics behavior are the number of different luminescent centers, defects, energy transfer and host impurities [41]. The raw recorded data for the decay curves of all samples are well-fitted by a double-exponential function, descripted as below:
I = A1exp(−t/τ1) + A2exp(−t/τ2)
where I is the luminescence intensity at time t. A1, A2 are the fitting parameter and τ is the decay lifetime, respectively. The Eu3+ ions’ average lifetime in the samples synthesized by sonochemical and hydrothermal methods at 618 nm emission under 275 nm excitation are 0.955 and 0.723 ms. The average lifetime increases for the sonochemical method sample. The non-radiative transition by the surface defects and/or crystallinity rate causes the appearance of a decay lifetime difference [8]. The surface effect has a great impact on the properties of the material at the nanometer size. In the nanocrystal, the defects of the lattice commonly appear on the surface. The surface defects cause the decreasing of lifetime and luminescent intensity. With sonochemical method, YVO4:Eu3+ nanoparticles have better crystallization due to a high local temperature and pressure, and the lower surface effect. Furthermore, decay time is measured in both radiative and nonradiative transmission. The radiative decay component is depended on the number of light-emitting activator ions in the nanoparticles [19]. The Eu3+-doped ions in the host lattice are light emitting activators, showing the better Eu3+ ion occupancy to Y3+ sites in the sample when synthesized by the sonochemical method compared to the hydrothermal method.
Due to the stronger luminescent intensity and more compatible nanoparticle size, YVO4:Eu3+ nanoparticles synthesized by the sonochemical method are primarily used in the preparation of security ink. Two type of printing ink are prepared with same mass ratio of YVO4:Eu3+ nanoparticles powder but different solvent ingredients. The ingredients of printing ink are shown in Table 1.
The viscosity and surface tension of printing ink are very important in the preparation of patterns using the inkjet technique due to the huge influence in spraying ink out of a head nozzle [42,43]. The analyzed and calculated parameters of ink I and II are presented in Table 2. All these parameters are analyzed under room temperature. Figure 6 presents the diagram of analyzed surface tension of ink I and ink II. Ink I’s surface tension is ~46–47 mN/m, whereas ink II’s is ~38–40 mN/m. The average viscosity of ink I and ink II, in turn, is ~119 and 108 cP (Table 2). The parameters of the prepared inks are in good working range of the inkjet device. The pattern is printed onto a glass substrate by a commercial printer PS JET 300V operated by the electrohydrodynamic (EHD) inkjet technique.
Figure 7 shows the mechanism of EHD technology. The application of electrohydrodynamic inkjet technique with positive pressure and high-voltage in the nozzle is to spray a fine droplet or thin line [44,45]. The EHD technique usage in pattern preparation required the adjustment of many parameters in the printing devices. This is an important step which the direction of the inkjet are performed. The parameter for the printing device has been adjusted after many experiments and established the standard parameter, showed in Table 3.
These parameters are used to print both ink I and ink II. The diameter of the printhead nozzle is one of the most important factors influencing the size of ink droplet when contacting to substrate (related to printed patterns size and sharpness). The smaller the printhead nozzle, the smaller the droplet size.
Figure 8 shows the picture of an ink droplet jetted onto a glass substrate, using ink II (Figure 8a) and ink I (Figure 8b). The process of an ink droplet jetted onto the glass substrate is shown in three continuous pictures taken by high speed camera with frame rate set at 1000 frames per second. According to the frame rate, the time for an ink droplet to be jetted onto the substrate (from start to finish) is around 0.002 s. With a diameter of the print head at ~15 µm, the droplet size on the substrate is at ~10 µm with ink II and ~2 µm with ink I. The surface tension difference between ink I and ink II causes this phenomenon (with the same viscosity, the surface tension of ink I being higher than ink II). Due to the characteristic differences, each security ink can be applied for separate security label printings.
The purpose of this process is to adjust the printing parameters by observing the ink jetting out of the printhead. In Figure 9a,b, the width of lines printed by ink I was ~97–115 µm and by ink II ~135–167 µm. All lines are sharp and seamless. Figure 9c,d show a clear appearance of security labels with an actual diameter at 1.98 mm × 1.98 mm (printed by ink I). The printed security label size may vary depending on the label shape. With this result, there is a possibility to print labels of a few hundred micrometers in size (by both ink I and ink II). Downsizing the label may increase the security ability. The continuous improving of the ink and the printing process is contributed to the printing ability on different types of substrate with higher sharpness and a few micrometers size.
Figure 10 shows the height–width diagram of lines printed by ink I and II. The size of the lines printed by ink I is smaller than those printed by ink II, conforming with the results shown in Figure 8. The thicknesses of the labels are, respectively, ~10.8 and 13.5 µm and the widths are ~110 µm and 145 µm. Figure 10b presents the image of a label printed in different sizes on a glass substrate under daylight and UV lamp. The labels are nearly transparent under daylight and have a red color luminescence under a UV lamp with a wavelength of 254 nm. The line appearance is clear, sharp, seamless and does not overlap one another at small distances.

4. Conclusions

YVO4:Eu3+ nanoparticles were synthesized by sonochemical and hydrothermal methods. According to the analysis results, YVO4:Eu3+ nanoparticles were crystallized in the tetragonal structure and exhibited the strongest luminescence at a wavelength of 618 nm due to the 5D0→7F2 transition. The Eu3+ ions’ average lifetime in the samples synthesized by sonochemical and hydrothermal methods at 618 nm emission under 275 nm excitation were 0.955 and 0.723 ms. The sonochemical method created the high local temperature, which had a positive effect on the YVO4:Eu3+ nanoparticles crystalline formation and Eu3+ ions into the Y3+ doping position. Thus, YVO4:Eu3+ nanoparticles synthesized by the sonochemical method possessed a higher crystallinity and better luminescence intensity. The TEM and FE-SEM results showed the average size of the YVO4:Eu3+ nanoparticles was about 23–30 nm under the sonochemical method and about 15–20 nm under the hydrothermal method.
YVO4:Eu3+ nanoparticles synthesized by the sonochemical method had a higher luminescent intensity and compatible particle size, which might be used as red phosphor in security ink. The security labels were printed by inkjet printers using the electrohydrodynamic printing technique. The widths of the printed line were ~97–167 µm and ~3–5 µm were the thicknesses. The properties of the printed security labels (the size at 1.98 mm × 1.98 mm) were a well-sharp shape, daylight invisibility and red emission under UV mercury lamps (wavelength ~254 nm). The high-security labels require a small size, shape sharpness and high luminescence. The minimum controllable diameter of an ink droplet on a glass substrate was ~2 µm, a good base for printed security labels with high sharpness and micrometer size in the future.

Author Contributions

C.D.T. and D.M.T.D. designed the experiments with technical contributions from C.M.D.; C.D.T., T.V.D. and P.H.T.P. performed the experiments and analyzed the data; C.D.T., P.V.Q. and C.M.D. wrote the paper. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by Ministry of Science and Technology of Vietnam under the grant number 03/2019/HĐ-SPĐP.

Acknowledgments

The authors highly appreciate the financial support of Ministry of Science and Technology of Vietnam under the grant number 03/2019/HĐ-SPĐP.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Bidoki, M.S.; Lewis, M.D.; Clark, M. Ink-jet fabrication of electronic components. J. Micromech. Microeng. 2007, 17, 967–974. [Google Scholar] [CrossRef]
  2. Park, K.B.; Kim, D.; Jeong, S. Direct writing of copper conductive patterns by ink-jet printing. Thin Solid Film. 2007, 515, 7706–7711. [Google Scholar] [CrossRef]
  3. Apilux, A.; Ukita, Y.; Chikae, M.; Chailapakul, O.; Takamura, Y. Development of automated paper-based devices for sequential multistep sandwich enzyme-linked immunosorbent assays using inkjet printing. Lab Chip 2013, 13, 126–135. [Google Scholar] [CrossRef] [PubMed]
  4. Dang, M.C.; Dang, T.M.D.; Fribourg-Blanc, E. Inkjet printing technology and conductive inks synthesis for microfabrication techniques. Adv. Nat. Sci. 2013, 4, 15009–15016. [Google Scholar] [CrossRef]
  5. Meruga, M.J.; Cross, M.W.; May, S.P.; Luu, A.Q.; Crawford, A.G.; Kellar, J.J. Security printing of covert quick response codes using upconverting nanoparticle inks. Nanotechnology 2012, 23, 395201–395210. [Google Scholar] [CrossRef] [PubMed]
  6. Gupta, K.B.; Haranath, D.; Saini, S.; Singh, N.V.; Shanker, V. Synthesis and characterization of ultra-fine Y2O3: Eu3+ nanophosphors for luminescent security ink applications. Nanotechnology 2010, 21, 055607–055615. [Google Scholar] [CrossRef]
  7. Georgescu, S.; Cotoi, E.; Voiculescu, M.A.; Toma, O. Effects of particle size on the luminescence of YVO4:Eu nanocrystals. Rom. Rep. Phys. 2008, 60, 947–955. [Google Scholar]
  8. Shao, B.; Zhao, Q.; Guo, N.; Jia, Y.; Lv, W.; Jiao, M.; Lü, W.; You, H. Monodisperse YVO4:Eu3+ submicrocrystals: Controlled synthesis and luminescence properties. CrystEngComm 2013, 15, 5776–5783. [Google Scholar] [CrossRef]
  9. Bao, A.; Lai, H.; Yang, Y.; Liu, Z.; Tao, C.; Yang, H. Luminescent properties of YVO4:Eu/SiO2 core–shell composite particles. J. Nanopart. Res. 2010, 12, 635–643. [Google Scholar] [CrossRef]
  10. He, F.; Yang, P.; Niu, N.; Wang, W.; Gai, S.; Wang, D.; Lin, J. Hydrothermal synthesis and luminescent properties of YVO4: Ln3+ (Ln = Eu, Dy, and Sm) microspheres. J. Colloid Interface Sci. 2010, 343, 71–78. [Google Scholar] [CrossRef]
  11. Riwotzki, K.; Haase, M. Wet-chemical synthesis of doped colloidal nanoparticles: YVO4:Ln (Ln = Eu, Sm, Dy). J. Phys. Chem. B 1998, 102, 10129–10135. [Google Scholar] [CrossRef]
  12. Wang, H.H.; Odawara, O.; Wada, H. Facile and chemically pure preparation of YVO4:Eu3+ colloid with novel nanostructure via laser ablation in water. Sci. Rep. 2016, 6, 20507–20515. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  13. Georgescu, S.; Cotoi, E.; Voiculescu, M.A.; Toma, O.; Matei, C. Reflectance spectra of YVO4: Eu3+ phosphors synthesized by direct precipitation. Rom. J. Phys. 2010, 55, 750–757. [Google Scholar]
  14. Zhang, Y.; Xu, J.; Cui, Q.; Yang, B. Eu3+-doped Bi4Si3O12 red phosphor for solid state lighting: Microwave synthesis, characterization, photoluminescence properties and thermal quenching mechanisms. Sci. Rep. 2017, 7, 42464–42476. [Google Scholar] [CrossRef] [Green Version]
  15. Qiao, Y.B.; Liu, X.F.; Zhang, Q.; Chen, D.P.; Wang, Y.W.; Ma, W.B. Synthesis and luminescence properties of YVO4:Eu nanocrystals grown in nanoporous glass. Mater. Lett. 2010, 64, 1306–1308. [Google Scholar]
  16. Zhang, S.; Liang, Y.; Gao, Y.X.; Liu, T.H. Hydrothermal synthesis and microstructural, optical properties characterization of YVO4 phosphor powder. Acta Phys. Pol. A 2014, 125, 105–110. [Google Scholar] [CrossRef]
  17. Kumar, Y.; Pal, M.; Herrera, M.; Mathew, X. Effect of Eu ion incorporation on the emission behavior of Y2O3 nanophosphors: A detailed study of structural and optical properties. Opt. Mater. 2016, 60, 159–168. [Google Scholar] [CrossRef]
  18. Young, S.C.; Young, D.H. Photoluminescence properties of YVO4:Eu nanophosphors prepared by the hydrothermal reaction. Bull. Korean Chem. Soc. 2010, 31, 2368–2370. [Google Scholar]
  19. Kumar, V.; Khan, F.A.; Chawla, S. Intense red-emitting multi-rare-earth doped nanoparticles of YVO4 for spectrum conversion towards improved energy harvesting by solar cells. J. Phys. D 2013, 46, 365101–365108. [Google Scholar] [CrossRef]
  20. Young, S.C.; Young, D.H. Preparation of transparent red-emitting YVO4:Eu nanophosphor suspensions. Bull. Korean Chem. Soc. 2011, 32, 335–337. [Google Scholar]
  21. Natacha, D.; Chrystel, A.; Franck, P.; David, P.; Bruno, V.; Karine, V.; Denis, A.; Clément, S. New synthesis strategies for luminescent YVO4:Eu and EuVO4 nanoparticles with H2O2 selective sensing properties. Chem. Mater. 2015, 27, 5198–5205. [Google Scholar]
  22. Li, H.Y.; Zang, F.G.; Ma, J. Synthesis and luminescence properties of YVO4:Eu3+ nanocrystals by a Sol-Gel method. Adv. Mater. Res. 2013, 634, 2268–2271. [Google Scholar] [CrossRef]
  23. Huignard, A.; Buissette, V.; Laurent, G.; Gacoin, T.; Boilot, P.J. Synthesis and characterizations of YVO4:Eu colloids. Chem. Mater. 2002, 14, 2264–2269. [Google Scholar] [CrossRef]
  24. Van Uitert, L.G. Characterization of energy transfer interactions between rare earth ions. J. Electrochem. Soc. 1967, 114, 1048–1053. [Google Scholar] [CrossRef]
  25. Struck, C.W.; Fonger, W.H. Quantum-mechanical treatment of Eu3+ 4f→4f and 4f? charge-transfer-state transitions in Y2O2S and La2O2S. J. Chem. Phys. 1976, 64, 1784–1790. [Google Scholar] [CrossRef]
  26. Nicholas, V.J. Origin of the luminescence in natural Zircon. Nature 1967, 215, 1476. [Google Scholar] [CrossRef]
  27. Dong, H.; Kuzmanoski, A.; Wehner, T.; Müller-Buschbaum, K.; Feldmann, C. Microwave-assisted polyol synthesis of water dispersible red-emitting Eu3+-modified carbon dots. Materials 2017, 10, 25. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  28. Steudel, F.; Johnson, A.J.; Johnson, E.C.; Schweizer, S. Characterization of Luminescent Materials with Eu Mössbauer Spectroscopy. Materials 2018, 11, 828. [Google Scholar] [CrossRef] [Green Version]
  29. Blasse, G.; Grabmaier, B.C. Luminescent Materials; Springer: Berlin/Heidelberg, Germany, 1994. [Google Scholar]
  30. Schweizer, S.; Hobbs, L.W.; Secu, M.; Spaeth, J.M.; Edgar, A.; Williams, G.V.M. Photostimulated luminescence in Eu-doped fluorochlorozirconate glass ceramics. Appl. Phys. Lett. 2003, 83, 449. [Google Scholar] [CrossRef]
  31. Aitasalo, T.; Deren, P.; Hölsä, J.; Jungner, H.; Krupa, J.C.; Lastusaari, M.; Legendziewicz, J.; Niittykoski, J.; Strek, W. Persistent luminescence phenomena in materials doped with rare earth ions. J. Solid State Chem. 2003, 171, 114–122. [Google Scholar] [CrossRef]
  32. Ten Kate, O.M.; Vranken, T.; van der Kolk, E.; Jansen, A.P.; Hintzen, H.T. Optical properties of Eu2+/Eu3+ mixed valence, silicon nitride based materials. J. Solid State Chem. 2014, 213, 126–131. [Google Scholar] [CrossRef]
  33. Van Dijk, J.M.F.; Schuurmans, M.F.H. On the nonradiative and radiative decay rates and a modified exponential energy gap law for 4f–4f transitions in rare earth ions. J. Chem. Phys. 1983, 78, 5317. [Google Scholar] [CrossRef]
  34. Shionoya, S.; Yen, W.M.; Yamamoto, H. (Eds.) Phosphor Handbook; CRC Press: Boca Raton, FL, USA, 2006. [Google Scholar]
  35. Samanta, T.; Hazra, C.; Mahalingam, V. C-dot sensitized Eu3+ luminescence from Eu3+-doped LaF3-C dot nanocomposites. New J. Chem. 2016, 39, 106–109. [Google Scholar] [CrossRef]
  36. Kumar, A.; Rai, D.K.; Rai, S.B. Optical studies of Eu3+ ions doped in tellurite glass. Spectrochim. Acta Part A 2002, 58, 2115–2125. [Google Scholar] [CrossRef]
  37. Kemere, M.; Sperga, J.; Rogulis, U.; Krieke, G.; Grube, J. Luminescence properties of Eu, RE3+ (RE = Dy, Sm, Tb) co-doped oxyfluoride glasses and glass–ceramics. J. Lumin. 2017, 181, 25–30. [Google Scholar] [CrossRef]
  38. Moos, H.W. Spectroscopic relaxation processes of rare earth ions in crystals. J. Lumin. 1970, 1, 106–121. [Google Scholar] [CrossRef]
  39. Binnemans, K. Interpretation of europium(iii) spectra. Coord. Chem. Rev. 2015, 295, 1–45. [Google Scholar] [CrossRef] [Green Version]
  40. Zollfrank, C.; Scheel, H.; Brungs, S.; Greil, P. Europium(III) orthophosphates: Synthesis, characterization, and optical properties. Cryst. Growth Des. 2008, 8, 766–770. [Google Scholar] [CrossRef]
  41. Pu, Y.; Tang, K.; Zhu, C.D. Synthesis and luminescence properties of (Y, Gd)(P, V)O4:Eu3+, Bi3+ red nano-phosphors with enhanced photoluminescence by Bi3+, Gd3+ doping. Nano-Micro Lett. 2013, 5, 117–123. [Google Scholar] [CrossRef]
  42. Dybowska-Sarapuk, L.; Kielbasinski, K.; Arazna, A.; Futera, K.; Skalski, A.; Janczak, D.; Sloma, M.; Jakubowska, M. Efficient inkjet printing of graphene-based elements: Influence of dispersing agent on ink viscosity. Nanomaterials 2018, 8, 602. [Google Scholar] [CrossRef] [Green Version]
  43. Huang, L.; Huang, Y.; Liang, J.; Wan, X.; Chen, Y. Graphene-based conducting inks for direct inkjet printing of flexible conductive patterns and their applications in electric circuits and chemical sensors. Nano Res. 2011, 4, 675–684. [Google Scholar] [CrossRef]
  44. Cui, Z.; Han, Y.; Huang, Q.; Dong, J.; Zhu, Y. Electrohydrodynamic printing of silver nanowires for flexible and stretchable electronics. Nanoscale 2018, 10, 6806–6811. [Google Scholar] [CrossRef] [PubMed]
  45. Samuel, H.K.; Heuiseok, K.; Kyungtae, K.; Sang, H.L.; Kwan, H.C.; Jun, Y.H. Effect of meniscus damping ratio on drop-on-demand electrohydrodynamic jetting. Appl. Sci. 2018, 8, 164–172. [Google Scholar]
Processes 08 00253 g001a 550Processes 08 00253 g001b 550
Figure 1. FE-SEM micrographs of YVO4:Eu3+ nanoparticles synthesized by the sonochemical (a) and hydrothermal (b) methods. TEM micrographs of YVO4:Eu3+ nanoparticles synthesized by the sonochemical method (c). XRD patterns of YVO4:Eu3+ nanoparticles synthesized by different methods (d).
Figure 1. FE-SEM micrographs of YVO4:Eu3+ nanoparticles synthesized by the sonochemical (a) and hydrothermal (b) methods. TEM micrographs of YVO4:Eu3+ nanoparticles synthesized by the sonochemical method (c). XRD patterns of YVO4:Eu3+ nanoparticles synthesized by different methods (d).
Processes 08 00253 g001aProcesses 08 00253 g001b
Processes 08 00253 g002 550
Figure 2. EDX spectra of YVO4:Eu3+ nanoparticles synthesized by sonochemical and hydrothermal methods.
Figure 2. EDX spectra of YVO4:Eu3+ nanoparticles synthesized by sonochemical and hydrothermal methods.
Processes 08 00253 g002
Processes 08 00253 g003a 550Processes 08 00253 g003b 550
Figure 3. Raman spectra of undoped and Eu-doped YVO4 nanoparticles synthesized by the sonochemical and hydrothermal methods (a). The Raman active mode shift at 388 cm−1 for undoped and Eu-doped YVO4 nanoparticles (b). The Raman peak intensity ratio diagram at 839 and 893 cm−1 (c).
Figure 3. Raman spectra of undoped and Eu-doped YVO4 nanoparticles synthesized by the sonochemical and hydrothermal methods (a). The Raman active mode shift at 388 cm−1 for undoped and Eu-doped YVO4 nanoparticles (b). The Raman peak intensity ratio diagram at 839 and 893 cm−1 (c).
Processes 08 00253 g003aProcesses 08 00253 g003b
Processes 08 00253 g004a 550Processes 08 00253 g004b 550
Figure 4. Energy levels and transitions scheme of Eu3+, vertical arrows: absorption and emission transitions (a). Photoluminescence excitation (PLE) spectra (b) and photoluminescence emission (PL) spectra of samples with different methods (c).
Figure 4. Energy levels and transitions scheme of Eu3+, vertical arrows: absorption and emission transitions (a). Photoluminescence excitation (PLE) spectra (b) and photoluminescence emission (PL) spectra of samples with different methods (c).
Processes 08 00253 g004aProcesses 08 00253 g004b
Processes 08 00253 g005 550
Figure 5. The luminescence decay curves for the 5D0 excited state of Eu3+ under 275 nm excitation for YVO4:Eu3+ samples synthesized with different methods.
Figure 5. The luminescence decay curves for the 5D0 excited state of Eu3+ under 275 nm excitation for YVO4:Eu3+ samples synthesized with different methods.
Processes 08 00253 g005
Processes 08 00253 g006 550
Figure 6. The diagram of analyzed ink surface tension.
Figure 6. The diagram of analyzed ink surface tension.
Processes 08 00253 g006
Processes 08 00253 g007 550
Figure 7. Schematic of the electrohydrodynamic (EHD) technology mechanism.
Figure 7. Schematic of the electrohydrodynamic (EHD) technology mechanism.
Processes 08 00253 g007
Processes 08 00253 g008 550
Figure 8. Image taken by high speed camera of an ink droplet jetted onto a glass substrate, performing of ink II (a) and ink I (b).
Figure 8. Image taken by high speed camera of an ink droplet jetted onto a glass substrate, performing of ink II (a) and ink I (b).
Processes 08 00253 g008
Processes 08 00253 g009 550
Figure 9. The micrographs from a 3D optical profilometer of a security label’s lines printed by ink I (a) and ink II (b). The micrograph of the security label printed by ink I (c,d)
Figure 9. The micrographs from a 3D optical profilometer of a security label’s lines printed by ink I (a) and ink II (b). The micrograph of the security label printed by ink I (c,d)
Processes 08 00253 g009
Processes 08 00253 g010 550
Figure 10. The height–width diagram of the printed lines by ink I and II taken by a Sensofar Metrology 3D Optical Profilometer (a). The image of a label under daylight and UV lamp (b).
Figure 10. The height–width diagram of the printed lines by ink I and II taken by a Sensofar Metrology 3D Optical Profilometer (a). The image of a label under daylight and UV lamp (b).
Processes 08 00253 g010
Table
Table 1. The ingredient components of the printing inks.
Table 1. The ingredient components of the printing inks.
YVO4:Eu3+ Powder (wt %)Polyethylene Oxide (wt %)Chloroform (wt %)Deionized Water (wt %)Ethyl Cellulose (wt %)α-Terpinoel (wt %)Isopropanol (wt %)
Ink I8492320000
Ink II80006924
Table
Table 2. The printing parameters of inks I and II.
Table 2. The printing parameters of inks I and II.
Viscosity (cP)Surface Tension (mN/m)Density (g/cm3)
Ink I11946.31.15
Ink II10838.21.32
Table
Table 3. The parameter conditions of printing.
Table 3. The parameter conditions of printing.
Pressure (kPa)DC Volt (V)AC Volt (V)Frequency (Hz)Distance between Printhead and Substrate (µm)
11–15500–550700–900500100–150

Share and Cite

MDPI and ACS Style

Trinh, C.D.; Doan, T.V.; Thi Pham, P.H.; Thi Dang, D.M.; Quan, P.V.; Dang, C.M. Synthesis and Research of Rare Earth Nanocrystal Luminescent Properties for Security Labels Using the Electrohydrodynamic Printing Technique. Processes 2020, 8, 253. https://doi.org/10.3390/pr8020253

AMA Style

Trinh CD, Doan TV, Thi Pham PH, Thi Dang DM, Quan PV, Dang CM. Synthesis and Research of Rare Earth Nanocrystal Luminescent Properties for Security Labels Using the Electrohydrodynamic Printing Technique. Processes. 2020; 8(2):253. https://doi.org/10.3390/pr8020253

Chicago/Turabian Style

Trinh, Chinh Dung, Thuan Van Doan, Phuong Hau Thi Pham, Dung My Thi Dang, Pham Van Quan, and Chien Mau Dang. 2020. "Synthesis and Research of Rare Earth Nanocrystal Luminescent Properties for Security Labels Using the Electrohydrodynamic Printing Technique" Processes 8, no. 2: 253. https://doi.org/10.3390/pr8020253

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop