Share This Article:

Structural and Optical Properties of Cu2+ + Ce3+ Co-Doped ZnO by Solution Combustion Method

Abstract Full-Text HTML XML Download Download as PDF (Size:2669KB) PP. 300-309
DOI: 10.4236/wjcmp.2016.64029    1,064 Downloads   1,613 Views   Citations

ABSTRACT

In this work, ZnO, Ce3+ doped ZnO (ZnO/Ce3+) and Cu2+ + Ce3+ co-doped ZnO (ZnO/Cu2+ + Ce3+ ) solid solutions powders were synthesized by a solution combustion method maintaining the Ce3+ ion concentration constant in 3%Wt while the Cu2+ ion concentration was varied in 1, 2, 3, 10 and 20%Wt. After its synthesis, all the samples were annealed at 900?C by 24 h. The ZnO, ZnO/Ce3+ and ZnO/Cu2+ + Ce3+ powders were structurally characterized using X-ray diffraction (XRD) technique, and the XRD patterns showed that for pure ZnO, Cu2+ undoped ZnO/Ce3+ and ZnO/Ce3+ doped with the Cu2+ ion, the three samples exhibited the hexagonal wurtzite ZnO crystalline structure. However, the morphology and particle size of both samples were observed by means of a scanning electron microscopy (SEM); from SEM image, it is observed that the crystallites of both samples are agglomerated forming bigger amorphous particles with an approximate average size of 1 μm. In addition, the photoluminescence of the ZnO, Ce3+ doped ZnO and Cu2+ + Ce3+ doped ZnO samples was measurement under an illumination of 209 nm wavelength (UV region): for the ZnO/Ce3+ sample, your emission spectrum is in the visible region from blue color until red color; the UV band of the ZnO is suppressed. The multicolor emission visible is attributed to the Ce3+ ion photoluminescence, while for the ZnO/Cu2+ + Ce3+, its emission PL spectrum is quenching by the Cu2+ ion, present in the ZnO crystalline.

1. Introduction

Between the II-VI semiconductors compounds, the Zinc oxide (ZnO) by its extraordinary properties such as exhibiting an high energy band gap of 3.37 eV and an exciton binding energy of 60 meV [1] [2] , has been converted in a strategic material for basic science investigation and technological applications [3] [4] [5] , such as in the fabrication of solar cells [6] , electro-optical devices [7] , gas sensors [8] , catalyst [9] , piezoelectric device [10] , paramagnetic materials [11] [12] [13] , etc. In the scientific literature, there are various synthesis methods to obtain undoped and doped ZnO with various dopants types, for example: rare heart, metals, lanthanides, etc. [14] , such synthesis methods include: electrodeposition [15] , evaporation [16] , vapor-liquid-solid (VLS) growth [17] , metal organic catalyst assisted vapor-phase epitaxy [18] , aqueous thermal decomposition [19] , microwave activated chemical bath deposition (MW-CBD) [20] , chemical bath deposition (CBD) [21] , surfactant-assisted hydrothermal method [22] , solution combustion [23] etc. Of the before methods, solution combustion presents some advantages because it is very fast, less expensive; it has an easier composition control, and coating can be deposited on large area etc. Lanthanide doped ZnO semiconductor nanoparticles have important technological properties: they have been used to make efficient photoluminescent materials when lanthanide ions are intercalated into ZnO crystal lattice, by means of an energy transfer process from the ZnO lattice to the Ce3+ ions to produce internal transitions atomic in the lanthanide ions. Between the lanthanide ions family members, the cerium ion (Ce) is the most emblematic according to the studies realized by various researchers [24] [25] [26] [27] , from its results the authors show that the Ce3+ doped ZnO can present anomalous emission from the UV until red color region; this multiple emission is studied in the present work. As a complement for the present work, it is necessary to mention that the doping of the ZnO matrix with Cu2+ ions leads to sum or produce changes that improve the ZnO properties such as: band gap tailored, magnetic, electrical and optical. It can also produce passivation of defects and surfaces, as p-type dopant in the original n-type ZnO semiconductor. However, actually it is well known that due to the co-doping between the Cu2+ and Eu3+ ions in co-doped glasses matrix, the Cu2+ ion can quench the Eu3+ photoluminescence [28] [29] [30] [31] , recently. S. Lopez-Romero et al. experimentally demonstrated that such quenching also can occur in solid ZnO semiconductor, this quenching effect can be used to tune between ultra-violet and visible PL emission in devises photoluminescent. In this study, ZnO/Ce3+ and co-doped ZnO/Cu2+ + Ce3+ solid solutions powders have been synthesized by solution combustion method as a function of the Cu2+ ion concentration in %Wt. maintaining the Ce3+ ion concentration constant at a value of 3%Wt. for both compounds Cu2+ undoped and doped. Finally the samples were annealing at 900˚C by 24 h. In addition, the influence of the Cu2+ ion on the morphology, structure and photoluminescence of the compounds is analyzed.

2. Experimental Details

The experimental method of synthesis solution combustion basically consist in carry out a oxidation-reduction (REDOX) chemical reaction between an oxidizer agent and a fuel, such reaction is highly exothermic (1200˚C) [22] and generally to produce oxides metallic, water vapor, carbon dioxide and nitrogen molecular. We used zinc nitrate hexa- hydrate (Zn(NO3)2∙6H2O) as oxidizer agent and urea (NH2CONH2) as fuel, the REDOX reaction between them is:

(1)

Complementary information about how the Equation (1) was obtained can be seen in reference [22] . Using the Equation (1) intrinsic ZnO, Ce3+ doped ZnO and Cu2+ + Ce3+ co-doped ZnO were synthesized and after annealing at 900˚C by 24 h, the source of the dopants Cu2+ and Ce3+ were CuCl2 and Ce2O3. The Ce3+ ion concentration was fixed at 3%Wt, while the Cu2+ ion concentration takes the values of 0, 1, 2, 3, 10 and 20%Wt. The ZnO/Ce3+ and ZnO/Cu2+ + Ce3+ samples thus obtained were structurally characterized by x-ray diffraction (XRD) technique using a Philips PW 1800 diffractometer with CuKα radiation (1.5406 Å), the morphology of the samples was recorded using a scanning electron microscopy SEM JEOL JSM 840.), the properties photoluminescent (PL) of the ZnO/Ce3+ and ZnO/Cu2+ + Eu3+ samples was studied by means of a spectrofluorometer FluoroMax-P that uses a xenon lampas excitation source, the wavelength excitation was of 209 nm.

3. Results and Discussion

3.1. Structural Characterization

Figure 1 shows the XRD patterns of the as prepared samples of ZnO, ZnO/Ce3+ and ZnO/Cu2+ + Ce3+ as a function of the Cu2+ ion concentration with the Ce3+ ion concentration fixed in 3%wt. From the diffractograms can be see that all the diffraction peaks can be indexed to the hexagonal wurtzite ZnO structure (JCPDS CARD #89-(102)), no change of the peaks toward lesser angles was observed, however in Figure 2 can be observed the XRD pattern of the ZnO joint to two diffraction peaks at 28.4˚ and 32.5˚: the first is assigned to the Ce2O3 phase and the second to the CuO compound. Also is observed that the diffraction peaks are very sharp indicating good crystallization of the products.

3.2. Morphology Study

Figures 3(a)-(d) are the SEM images of the ZnO/Cu2+ + Ce3+ samples with Cu2+ ion concentration of 0, 3, 10 and 20%wt respectively, it is observed that for low Cu2+ ion concentration the ZnO nanocrystals have nanoplate form and are agglutinated in amorphous geometry with bigger sizes of about 0.75 μm side and 1 μm large, while in the sample doped with 20%Wt the nanocrystals present ovoid form and are agglomerated in particles measuring up to 2.5 μm side and 3 μm large.

3.3. Photoluminescence Study

3.3.1. ZnO and ZnO/Ce3+ Photoluminescence

Figure 4(a) and Figure 4(b) show the photoluminescence PL spectra of the pristine ZnO and of the Ce3+ doped ZnO nanocrystals respectively excited by a wavelength radiation of 209 nm at room temperature. The PL spectra exhibited by the ZnO is typical of the pure ZnO: present a strong UV band peaking about 395 nm and a little broad green band centered about 460 nm. The UV emission band is due to excitonic recombination corresponding to the near band edge emission of the ZnO. The green emission band is attributed to deep-level or trap-state emission. Effectively, actually various mechanism have been proposed to understand the origin of the visible light of the ZnO which involve oxygen vacancies with various oxidation state: the single ionized oxygen vacancy, and the doubly ionized oxygen vacancy. Finally Vanheused et al. [31] found that only the singly ionized oxygen vacancies can emit green light in the ZnO. For the Cu2+ undoped ZnO/Ce3+ samples doped with 3%wt (see Figure 4(b)) and illuminated

Figure 1. XRD pattern of ZnO, Ce3+ doped ZnO and Cu2+ + Ce3+ co-doped ZnO as a function of the Cu2+ ion concentration.

Figure 2. XRD patterns of ZnO, Ce2O3 and CuO compounds.

(a) ZnO/Ce (b) ZnO/Ce + 3% Cu2+(c) ZnO/Ce + 10% Cu2+ (d) ZnO/Ce + 20% Cu2+

Figure 3. SEM images of the (a) Ce3+ doped ZnO, (b) Ce3+ co-doped ZnO with 3%Wt of Cu2+, (c) Cu2+ + Ce3+ co-doped ZnO with 10% Cu2+, (d) Cu2+ + Ce3+ co-doped ZnO with 20% Cu2+.

with 209 nm wavelength. The emission spectra now present bands at 418 nm and 432 nm belong to the blue color, the peak centered about 452 nm correspond to purple color, the bands centered at 468 nm and 480 nm belong to the green region, the peak at 496 is green color, the band centered at 541 nm is yellow color, the peak at 648 nm is orange color, and the band at 687 nm is red color. This multicolor PL emission spectra is possible because when any matrix is doped with the Ce ion this attain two oxidation states namely the Ce3+ and Ce4+, consequently f-d transitions occur by effects field in the ZnO matrix and 5 d state of the Ce3+ is splitting in two states: Eg and T2g attributed to the new intern electronic ambient of the Ce3+ ion in the ZnO matrix [23] . It is important note the quenching of the UV band emission of the ZnO at 395 nm sowed by the pure ZnO sample. This quenching effect is caused by defects on the ZnO surface generated by organic residues of the fuel (more studies are necessary with this tem).

3.3.2. Ce3+ Photoluminescence Quenching by the Cu2+ Ion

Figure 5 represent the excitation spectrum applied to a ZnO/Cu2+ + Ce3+ sample doped with 1%Wt of the Cu2+ ion, from the wavelength scale of the spectrum can be see clearly that for the excitation wavelength of 209 nm no PL emission of the ZnO/Ce3+ + Cu2+ sample was observed, only until a excitation wavelength of 378nm can be see a new emission spectrum of the Ce43+ ion. The suppressing of the Ce3+ is due to that the Cu2+ ion quenching the Ce3+ photoluminescence [28] [29] [30] . This same quenching effect also occur in glass matrix doped with the europium and copper ions [29] : the authors

(a)(b)

Figure 4. (a) Photoluminescence spectra of pure ZnO; (b) Photoluminescence spectra of Ce3+ doped ZnO. Doped with 3% of Ce3+ concentration.

Figure 5. Excitation spectrum used to illuminate the ZnO/Cu2+ + Ce3+ sample doped with 1%Wt. of the Cu 2+ ion.

explain the quenching effect by the occurrence of an overlap between Eu3+ emission band and a Cu2+ absorption band. In our case, we suppose that this quenching effect is due to an overlap between Ce3+ emission band and a Cu2+ absorption band. The Ce3+ PL quenching occur for all Cu2+ ion concentration. (More studies are necessary in this tem).

4. Conclusion

In this work, ZnO, Ce3+ doped ZnO and Ce3+ + Cu2+ co-doped ZnO were synthesized by a solution combustion method maintaining the Ce3+ ion concentration constant and changing the Cu2+ ion concentration. The ZnO resultant crystalline structure was the hexagonal wurtzite structure for the three samples types. From PL studies, it is found that the UV band of 395 nm in the pure ZnO is suppressed in the Ce3+ doped ZnO and the PL emission spectrum of the Ce3+ + Cu2+ co-doped ZnO samples also was quenching by the Cu2+ ion.

Acknowledgements

The authors wish to thank to Dr. Ciro Falcony (IPN), Adriana Tejeda (IIM) for the XRD measurements, to Omar Novelo Peralta (IIM) for his SEM study, to M.A. Canseco Martinez and Lázaro Huerta (IIM) for their chemical analysis.

Conflicts of Interest

The authors declare no conflicts of interest.

Cite this paper

López-Romero, S. , Jiménez, M. and García-Hipólito, M. (2016) Structural and Optical Properties of Cu2+ + Ce3+ Co-Doped ZnO by Solution Combustion Method. World Journal of Condensed Matter Physics, 6, 300-309. doi: 10.4236/wjcmp.2016.64029.

References

[1] Klingshirn, C. (2007) ZnO: From Basics towards Applications. Physica Status Solidi (b), 244, 3027-3073.
http://dx.doi.org/10.1002/pssb.200743072
[2] Sharma, S.K., Pitale, S.S., Manzar Malik, M., Dubey, R.N., Qureshi, M.S. and Ojha, S. (2010) Influence of Fuel/Oxidizer Ratio on Lattice Parameters and Morphology of Combustion Synthesized ZnO Powders. Physica B: Condensed Matter, 405, 866-874.
http://dx.doi.org/10.1016/j.physb.2009.10.005
[3] Sharma, S.K., Pitale, S.K., Manzar Malik, M., Dubey, R.N., Qureshi, M.S. and Lumin, J. (2009) Luminescence Studies on the Blue-Green Emitting Sr4Al14O25:Ce3+ Phosphor Synthesized through Solution Combustion Route. Journal of Luminescence, 129, 140-147.
http://dx.doi.org/10.1016/j.jlumin.2008.09.002
[4] Leea, J.-B., Leea, H.-J., Seob, S.-H. and Parka, J.-S. (2001) Characterization of Undoped and Cu-Doped ZnO Films for Surface Acoustic Wave Applications. Thin Solid Films, 398-399, 641-646.
http://dx.doi.org/10.1016/S0040-6090(01)01332-3
[5] Qi, J., Gao, D.Q., Zhang, L. and Yang, Y.H. (2010) Room-Temperature Ferromagnetism of the Amorphous Cu-Doped ZnO Thin Films. Applied Surface Science, 256, 2507-2508.
http://dx.doi.org/10.1016/j.apsusc.2009.10.096
[6] Wei, H.M., Gong, H.B., Wang, Y.Z., Hu, X.L., Chen, L., Xu, H.Y., Liu, P. and Cao, B.Q. (2011) Three Kinds of Cu2O/ZnO Heterostructure Solar Cells Fabricated with Electrochemical Deposition and Their Structure-Related Photovoltaic Properties. CrystEngComm, 13, 6065-6070.
http://dx.doi.org/10.1039/c1ce05540b
[7] Kundu, T.K., Karak, N., Barik, P. and Saha, S. (2011) Optical Properties of ZnO Nanoparticles Prepared by Chemical Method Using Poly (VinylAlcohol ) (PVA) as Capping Agent International Journal of Soft Computing and Engineering (IJSCE), 1, 2231-2307,
[8] Ge, C.Q. and Xie, C.S. (2007) Preparation and Gas-Sensing Properties of Ce-Doped ZnO Thin-Film Sensors by Dip-Coating. Materials Science and Engineering: B, 137, 53-58.
http://dx.doi.org/10.1016/j.mseb.2006.10.006
[9] Anandana, S. and Miyauchi, S. (2011) Ce-Doped ZnO (CexZn1?xO) Becomes an Efficient Visible-Light-Sensitive Photocatalyst by Co-Catalyst (Cu2+) Grafting. Physical Chemistry Chemical Physics, 13, 14937-14945.
http://dx.doi.org/10.1039/c1cp21514k
[10] Ahn, C.-W., Nahm, S., Ryu, J., Uchino, K., Yoon, S.-J., Jung, S.-J. and Song, J.-S. (2004) Effects of CuO and ZnO Additives on Sintering Temperature and Piezoelectric Properties of 0.41 Pb(Ni1/3Nb2/3)O3 – 0.36 PbTiO3 – 0.23 PbZrO3 Ceramics. Japanese Journal of Applied Physics, 43, No. 1
[11] Morinaga, Y., Sakuragi, K., Fujimura, K. and Ito, T. (1997) Effect of Ce Doping on the Growth of ZnO Thin Films. Journal of Crystal Growth, 174, 691-695.
http://dx.doi.org/10.1016/S0022-0248(97)00045-6
[12] Sinhaa, N., Raya, G. and Bhandaria, S. (2014) Synthesis and Enhanced Properties of Cerium Doped ZnO Nanorods. Ceramics International, 40, 12337-12342.
http://dx.doi.org/10.1016/j.ceramint.2014.04.079
[13] Shukla, S., Agorku, E., Mittal, H. and Mishra, A. (2013) Synthesis, Characterization and Photoluminescence Properties of Ce3+ Doped ZnO-Nanophosphors. Chemical Papers, 68, 217-222.
http://dx.doi.org/10.2478/s11696-013-0442-5
[14] Sofiania, Z., Derkowskab, B., Dalasińskib, P. and Wojdy?ab, M. (2006) Optical Properties of ZnO and ZnO:Ce Layers Grown by Spray Pyrolysis. Optics Communications, 267, 433-439.
http://dx.doi.org/10.1016/j.optcom.2006.06.049
[15] Varughese, G., Jithin, P.W. and Usha, K.T. (2015) Determination of Optical Band Gap Energy of Wurtzite ZnO:Ce Nanocrystallites. Physical Science International Journal, 5, 146- 154.
http://dx.doi.org/10.9734/PSIJ/2015/14151
[16] Koaoa, L.F., Dejenea, F.B. and Swartb, H.C. (2013) The Effect of Ce3+ on Structure, Morphology and Optical Properties of Flower-Like ZnO Synthesized Using the Chemical Bath Method. Journal of Luminescence, 143, 463-468.
http://dx.doi.org/10.1016/j.jlumin.2013.05.045
[17] Yousefia, M., Amirib, M. and Azimiradc, R. (2011) Enhanced Photoelectrochemical Activity of Ce Doped ZnO Nanocomposite Thin Films under Visible Light. Journal of Electroanalytical Chemistry, 661, 106-112.
http://dx.doi.org/10.1016/j.jelechem.2011.07.022
[18] Pandey, P., Kurchania, R. and Haque, F.Z. (2015) Structural, Diffused Reflectance and Photoluminescence Study of Cerium Doped ZnO Nanoparticles Synthesized through Simple Sol-Gel Method. Optik-International Journal for Light and Electron Optics, 126, 3310- 3315.
http://dx.doi.org/10.1016/j.ijleo.2015.06.026
[19] Karunakaran, C., Gomathisankar, P. and Manikandan, G. (2010) Preparation and Characterization of Antimicrobial Ce-Doped ZnO Nanoparticles for Photocatalytic Detoxification of Cyanide Materials. Chemistry and Physics, 123, 585-594.
http://dx.doi.org/10.1016/j.matchemphys.2010.05.019
[20] Samadia, M., Ziraka, M. and Naserib, A. (2016) Recent Progress on Doped ZnO Nanostructures for Visible-Light Photocatalysis. Thin Solid Films, 605, 2-19
http://dx.doi.org/10.1016/j.tsf.2015.12.064
[21] Koaoa, L.F., F.B. Dejenea, F.B. and Tsegaa, M. (2016) Annealed Ce3+-Doped ZnO Flower- Like Morphology Synthesized by Chemical Bath Deposition Method. Physica B: Condensed Matter, 480, 53-57.
http://dx.doi.org/10.1016/j.physb.2015.09.010
[22] Patil, K.C., Hegde, M.S., Tanu, R. and Aruna, S.T. (2008) Chemistry of Nanocrystalline Oxide Materials. Combustion Synthesis, Properties and Applications. World Scientific, 52- 58.
[23] George, A. and Sharma, S.K. (2011) Detailed of X-Ray Diffraction and Photoluminescence Studies of Ce Dopes ZnO Nanocrystals. Journal of Alloys and Compounds, 509, 5942-5946.
http://dx.doi.org/10.1016/j.jallcom.2011.03.017
[24] Ge, C., Xie, C. and Cai, S. (2007) Preparation and Gas-Sensing Properties of Ce-Doped ZnO Thin-Film Sensors by Dip-Coating. Materials Science and Engineering: B, 137, 53-58.
http://dx.doi.org/10.1016/j.mseb.2006.10.006
[25] Li, F., Yan, B., Zhang, J., Jiang, A.X., Shao, C.H., Kong, X.J. and Wang, X. (2007) Study on Desulfurization Efficiency and Products of Ce-Doped Nanosized ZnO Desulfurizer at Ambient Temperature. Journal of Rare Earths, 25, 306-310.
http://dx.doi.org/10.1016/S1002-0721(07)60427-X
[26] Yang, J., Gao, M., Yang, L., Zhang, Y., Lang, J., Wang, D., Wang, Y., Liu, H. and Fan, H. (2008) Low-Temperature Growth and Optical Properties of Ce-Doped ZnO Nanorods. Applied Surface Science, 255, 2646-2650.
http://dx.doi.org/10.1016/j.apsusc.2008.08.001
[27] Iqbal, J., Liu, X., Zhu, H., Wu, Z.B., Zhang, Y., Yu, D., Yu, R. and Yu, R. (2009) Raman and Highly Ultraviolet Red-Shifted near Band-Edge Properties of LaCe-Co-Doped ZnO Nanoparticles. Acta Materialia, 57, 4790-4796.
http://dx.doi.org/10.1016/j.actamat.2009.06.056
[28] López-Romero, S., Quiroz Jiménez, M.J. and García-Hipólito M. () Quenching Photoluminescence of Eu(III) by Cu(II) in ZnO:Eu3+ + Cu2+ Compounds by Solution Combustion Method. World Journal of Condensed Matter Physics, 6, 269-275.
http://dx.doi.org/10.4236/wjcmp.2016.63025
[29] Jiménez, J.A. (2015) Photoluminescence of Eu3?-Doped Glasses with Cu2? Impurities. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 145, 482-486.
http://dx.doi.org/10.1016/j.saa.2015.03.047
[30] Batyaev, I.M. and Tinus, A.M. (1998) Transport of Electronic Excitation Energy in Solid- State Glassy Phosphors Activated with Europium (III) and Copper (II). Technical Physics Letters, 24, 26-27.
http://dx.doi.org/10.1134/1.1261979
[31] Vanheusden, K., Seager, C.H., Warren, W.L., Tallent, D.R., Voigt, J.A. and Gnade, B.E. (1966) Mechanisms behind Green Photoluminescence in ZnO Phosphor Powders. Journal of Applied Physics, 79, 7983.
http://dx.doi.org/10.1063/1.362349

  
comments powered by Disqus

Copyright © 2019 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.