Structural and Optical Properties of Zirconia Nanoparticles by Thermal Treatment Synthesis

Hindawi Publishing Corporation Journal of Nanomaterials Volume 2016, Article ID 1913609, 6 pages http://dx.doi.org/10.1155/2016/1913609 Research Article Structural and Optical Properties of Zirconia Nanoparticles by Thermal Treatment Synthesis Aysar S. Keiteb,1,2 Elias Saion,1 Azmi Zakaria,1 and Nayereh Soltani3 1 Department of Physics, Faculty of Science, Universiti Putra Malaysia (UPM), 43400 Serdang, Selangor, Malaysia 2College of Health and Medical Technologies, Baghdad, Iraq 3Young Researchers and Elite Club, Islamic Azad University, Shahr-e-Qods Branch, Tehran, Iran Correspondence should be addressed to Aysar S. Keiteb; [email protected] Received 26 November 2015; Revised 8 May 2016; Accepted 22 May 2016 Academic Editor: Oscar Perales-Perez´ Copyright © 2016 Aysar S. Keiteb et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Zirconium dioxide nanoparticles with monoclinic blended structure were successfully synthesized by thermal treatment method using zirconium (IV) acetate hydroxide as the metal precursor, polyvinylpyrrolidone as the capping agent, and deionized water as a solvent. The chemicals were mixed and stirred to form a homogeneous solution and hereafter directly underwent calcination to attain the pure nanocrystalline powder, which was confirmed by FTIR, EDX, and XRD analyses. The control over the size and optical ∘ properties of nanoparticles was achieved through changing in calcination temperatures from 600 to 900 C. The obtained average particle sizes from XRD spectra and TEM images showed that the particle size increased with increasing calcination temperature. The optical properties which were investigated using a UV-Vis spectrophotometer showed a decrease in the band gap energy with increasing calcination temperature due to the enlargement of the particle size. These results prove that, by eliminating drying process (24 h) in the present thermal treatment method, size-controlled zirconia nanoparticles were conveniently manufactured with a reduction of synthesize time and energy consumption, suitable for large-scale fabrication. 1. Introduction ZrO2 is a wide band gap p-type semiconductor that exhibits abundant oxygen vacancies on its surface. ZrO2 (zirconia) is a material of great technological impor- ZrO2 has three well-defined crystal phases, that is, cubic tance, having good natural color, high strength, transforma- (c-ZrO2), tetragonal (t-ZrO2), and monoclinic (m-ZrO2), tion toughness, high chemical stability, excellent corrosion under normal atmosphere and at different temperatures [8, resisting material, and chemical and microbial resistance 9]. Generally, m-ZrO2 phase is thermodynamically stable [1, 2]. ZrO2 is a wide band gap p-type semiconductor that ∘ up to 1100 C, t-ZrO2 phase exists in the temperature range exhibits abundant oxygen vacancies on its surface. The high ∘ of 1100–2370 C, and the cubic phase is found at higher ionexchangecapacityandredoxactivitiesmakeitusefulin ∘ temperature above 2370 C[10]. catalysis [3]. ZrO2 is also an important dielectric material for potential application as an insulator in transistors in future Several techniques are available for producing zirconia nanoelectric devices [4]. Garcia et al. have highlighted its nanoparticles, such as sol/gel method [11], vapor phase potential to replace SiO2 in advanced metal oxide semicon- method [12], pyrolysis [13], spray pyrolysis [14], hydrolysis ductor (MOS) devices and in optical applications [5]. [15], hydrothermal [16], and microwave plasma [17]. How- ZrO2 nanoparticles have found uses in solid oxide fuel ever, these methods faced many limitation factors such as cells [6] and in nitrogen oxide, oxygen gas sensors [7]. The complicated procedures, high reaction temperature, long fully stabilized ZrO2 nanoparticles are also well suited for reaction time, toxic reagents and by-products use, and high high temperature energy conversion systems, attributed to its cost of production, which made it difficult to prepare zirconia high oxygen ion transport capabilities and long-term stability. nanoparticles on a large-scale production. 2 Journal of Nanomaterials Recently, thermal treatment method has been used in of 100 kV. The average size and size distribution of nanopar- syntheses of several nanomaterials including metals ferrite ticles were determined by Image tool software. The optical nanoparticles [18–21], zinc oxide nanoparticles [22], cad- reflectance spectra of samples were recorded using the UV- mium oxide nanoparticles [23], and thermoluminescence Vis spectrometer (Shimadzu-UV1650PC SHIMADZU), and ∘ nanomaterials [24]. The drying process for 24 h at 80 C the band gap energy was evaluated from the reflectance before undergoing calcination is a common feature in the spectra using the Kubelka-Munk function. All the mentioned thermal treatment synthesis. However, in the synthesis of measuring devices above were calibrated before conducting ZrO2 nanoparticles, a solution containing metal precursor the measurements where applicable. and capping mediator is directly submitted to calcination, thus eliminating the drying process and reducing the prepa- 3. Result and Discussion ration time and the energy consumption. This modified thermal treatment synthesis looks greener than the earlier 3.1. The Role of PVP in Synthesis Process. According to thermal treatment methods for fabrication of metal oxide previous studies [27–29], the use of PVP in nanoparticles nanoparticles such as nanosized ZrO2 powder, a necessity for synthesisisveryimperativeasitplaysfourcrucialroles: large-scale industrial application. The technique is relatively control the growth of nanoparticles, limit the agglomeration environmentally friendly as no toxic material discharges into of nanoparticles, enhance the degree of crystallinity degree of the drainage system. The effect of calcination temperature on particles, and produce uniform particle size distribution. the structural, particle size, and optical properties of ZrO2 In the first step of making initial solution, PVP works nanoparticlesisalsoinvestigatedusingvarioustechniques. asastabilizeroramediatorfordissolvingcomplexmetallic salts through steric and electrostatic stabilization of the amide 2. Experimental groups of the pyrrolidone rings and the methylene groups. By dissolving zirconium acetate in PVP solution, strong ionic bonds between the amide group of polymeric chain and 2.1. Materials. Polyvinylpyrrolidone (PVP MW = 58000 g/ 4+ mol) stock obtained from Sigma Aldrich was used as a metallic ions, Zr . The uniform immobilization of metallic capping agent. Zirconium acetate, [C12H36O24Zr3]withhigh ions in the cavities of the polymer chains tends to form puritystocksuppliedbySigma-AldrichChemistry(MW= nanoparticles with uniform distribution. In the calcination 285.36 g/mol), was used as a metal precursor and deionized step, although the organic matters will be decomposed to water was used as a solvent. All chemicals were used without gasses such as N2,NO,CO,orCO2, trace of carbon residual further purification. that bonded on the surface of nanoparticles, which takes The PVP solution is made by dissolving 3 g ofPVP higher temperatures to decompose as shown by the weight powder in 100 mL of deionized water at a temperature of loss in (Figure 1), can protect them from uncontrolled growth ∘ 70 C and magnetically stirred for 2 h. The metal precursor and agglomeration [21, 28, 29]. of 0.2 mmol was added to the PVP solution and stirred continuously for another 2 h until a semitransparent solution 3.2. Thermal Analysis (TGA/DTG). Thermal analysis of ini- was obtained with no significant precipitation of materials. tial solution allows the optimization of the heat treatment The mixture was directly placed in an alumina crucible for program and shows the suitable temperature at which cal- calcination at different temperatures ranging from 600 to ∘ cination process must take place. The Thermogravimetric 900 C in a retention time of 3 h [25, 26], to decompose the Analysis accompanied with its derivative form (TGA-DTG polymer and to crystallize the metal oxide nanoparticles. curves) was implemented for the initial solution dried at ∘ 30 Canditsthermogramisclearlyillustratedin(Figure1). 2.2. Characterization Procedures. Thermal analysis of initial The TGA curve demonstrates two weight loss steps. The ∘ first insignificant weight loss∼ ( 22%) occurred between ∼30 solution dried at 30 C was investigated by Thermogravimet- ∼ ∘ ric Analysis (TGA) and Derivative Thermogravimetry Anal- and 250 C,whichattributedtothetrappedmoistureand acetate in the sample, respectively, whereas the second one, ysis (DTG) using a Perkin Elmer Thermal Analyzer model ∘ ∘ the drastic weight loss between 400 and 470 C, is due to TGA7/DTA7 in the presence of N2 with 10 C/min heating ∘ the decomposition of organic residues (i.e., PVP). Starting at rate from room temperature to 1000 C to optimize the heat ∘ treatment program. Fourier transform infrared spectroscopy the temperature of 471 C, the remaining material was almost (FTIR) was used to study the chemical composition of sam- pure ZrO2 nanoparticles with some left-out carbonaceous ples using Perkin Elmer Spectrum 1650. Energy dispersive X- product formed as a result of overheated PVP content which is confirmed by FTIR, EDX, and XRD results. The sharp and ray (EDX) measurements were performed under a variable ∼

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