Abstract:
This study synthesized CeO2-doped ZrO2 nanoparticles using the solid-state reaction, employing varying quantities of 0.05 mol.%, 0.15 mol.%, and 0.25 mol.% CeO2. The structures of CeO2-doped ZrO2 were investigated through XRD, revealing the presence of monoclinic ZrO2 in all samples, while the average size of the crystallite increased as the concentration of CeO2 doping increased. The optical band gap of CeO2-doped ZrO2 was determined using diffuse reflectance spectra, showing that the band gap decreased with increasing doping concentrations. The investigation focused on characterizing parameters such as dielectric constants, dielectric loss, and AC conductivity, emphasizing their frequency dependence at room temperature (RT). The dielectric constant and dielectric loss of Zrlx-CexO2 exhibited a significant drop as the frequency increased (Maxwell-Wagner polarization). Furthermore, the dielectric constant and dielectric loss factor in the lower frequency band exhibited an increase as the cerium content in ZrO2 increased. The incorporation of cerium significantly impacted the optical and electrical characteristics of composite ceramics consisting of CeO2 and ZrO2.
Keywords: Composite particle; Rare earth; Monoclinic; Optical, Dielectric loss.
Сажетак: У ово] cmyouju синтетисане cy наночестице ZrO; допираног CeO; користейи peakyujy y чврстом cmary, користейи различите количине yepujyma (0,05, 0,15 и 0,25 мол.%). Структуре ZrO; допираног CeO; испитиване су рендгенском дифракцитом, omxpueajyhu присуство монклиничног ZrO; y свим узорцима, док ce просечна величина кристалита повейава ca nosehamem концентраци/е допанта. Оптички бенд een je одрейен спектром дифузне рефлекси]е, noxazyjyhu da се ширина nojaca cmareyje ca noseharsem Kkonyenmpayuje donanma. Истраживатье ce фокусирало на Kapakmepusayujy параметара као што cy диелектричне константе, диелектрични губици и проводливост наизменичне струе, наглашава)уйи reuxoey зависност 00 фреквенци/е na coônoj температури. Диелектрична константа и диелектрични губитак Zrix СехО∂ су показали знача/ан пад како ce фреквенци/а повейала (Максвел-Вагнер Вагнер nonapusayuja). Штавише, диелектрична константа и фактор диелектричних губитака у доъем фреквентном onceey nokazyjy пораст како ce повейава садржа] yepujyma y ZrO>. Уградъа yepujyma 3uauajuo je утицала на оптичке и електричне карактеристике композитне керамике Koja ce cacmoju 00 CeO» и ZrO>.
Клъучне речи: uecmuye композита, ретке земле, моноклиничност, | оптика, диелектрични губици.
1. Introduction
Zirconia (ZrO;) nanoparticles possess beneficial physical and chemical qualities, including excellent thermal and chemical stability, high strength and fracture toughness, low thermal conductivity, and strong corrosion resistance [1], along with both acidic and basic properties. Due to these advantages, zirconia materials find wide application in structural materials, thermal barrier coatings, oxygen sensors, fuel cells, catalysts, catalytic supports, and as gate dielectrics in metal-oxide-semiconductor (MOS) devices [2-7]. Under normal atmospheric conditions, pure ZrO, exhibits three distinct polymorphic phases: monoclinic zirconium dioxide (m-ZrO,), tetragonal (t-Zr0>), and cubic (c-Zr0>), with their stability varying with temperature. ZrO, finds extensive utilization across diverse industrial and engineering sectors, including high-strength coatings, catalytic agents, medical prosthetics, cutting tools, synthetic gemstones, and wear-resistant components [8-12]. ZrO, offers promising properties such as a high dielectric constant, low toxicity, low cost, and environmentally friendly nature, making it a desirable material for various applications, especially in nano-scale devices, where increasing the dielectric constant is essential. Doping ZrO; with rare earth oxide materials like CeO; can enhance its dielectric properties (13, 14]. Ceria (CeO) has garnered significant interest for its wide range of applications, such as catalysts, solid electrolytes for fuel cells, and oxygen gas sensors [15]. Combining ZrO; and CeO, is anticipated to yield improved functionalities, including a broader range of light absorption and accelerated separation of electron-hole pairs, leading to significant attention across various domains [16-22].
Cerium (Ce) and its oxides have garnered significant interest across multiple disciplines due to their diverse range of properties, attributed to vacancies in their valence shells, particularly in the 4f and 5d orbitals [23, 24]. CeO, possesses a stable crystalline structure known as cubic fluorite, exhibiting properties such as oxygen storage, ultraviolet light absorption, exceptional thermal stability, electrical conductivity, elevated hardness, and specific chemical reactivity [25-28]. Synthesizing mixed oxides of cerium (Ce) and zirconium (Zr) produces materials with adjustable properties compared to pure CeO; or ZrO», owing to the redesigned lattice's thermal solid stability, oxygen storage, fluidity, and mobility [29, 30]. Understanding the influence of phase and crystal size on composite oxide particles' characteristics is crucial, with various synthesis methods available, including sol-gel, coprecipitation, and solid-state reaction methods. Among these methods, the solid-state reaction approach offers benefits in cost-effectiveness, environmental sustainability, and precision in regulating nanoparticle synthesis. Despite limited literature on materials synthesized using this approach, our research explores the synthesis, characterization, and properties of ceriumdoped zirconium nanocrystals, providing valuable insights into their potential applications.
2. Materials and Experimental Procedures
Zirconium nanoparticles doped with cerium (Ce0O>) (Zrix CexO2, х=0;0.05;0.15;0.25) were synthesized via solid-state reaction using ZrO, and CeO; (particle size: 25 nm). The oxides were meticulously mixed in precise amounts using an agate mortar and pestle to avoid magnetic impurity contamination. The mixture was heated in a tubular furnace at 1000°C for 10 hours, with a heating rate of 5°C per minute. After cooling, a 5% polyvinyl alcohol (PVA) binder was added, followed by regrinding for two hours. A portion of the sample was pelletized under a pressure of 200 MPa to form pellets with a diameter of 10 mm and a thickness of 2 mm. The pellets were sintered at 1100°C for six hours in an alumina crucible within a tubular furnace, following a heating rate of 5°C per minute. Upon cooling to room temperature (RT), the samples were coded as ZC-0, ZC-5, ZC-15, and ZC-25, corresponding to ZrO», Zro.9sCeo.0s02, Zro.ssCeo.1502, and Zro.7sCeo.2502, respectively.
The XRD pattern of nanoparticles composed of ZrO: doped with cerium was obtained using a powder X-ray diffractometer, specifically the Rigaku MiniFlex X-ray diffractometer. The X-ray radiation utilized in the study was generated using CuKa (A=1.54059 A") radiation. The diffraction angle range for data collection was between 20° and 80°, with a scanning speed of 5.0°/min. The surface morphology of CeO»/ ZrO, mixed oxides was evaluated using a scanning electron microscope (SEM), namely the VEGA 3 SBH (TESCAN Brno SRO, Czech Republic). Energy-dispersive X-ray spectroscopy (EDS) was conducted to determine the sample's elemental composition using an EDS system (EDAX-EDS-SDD, EDAX Inc., USA). The Fourier Transform Infrared (FTIR) spectrum of nanoparticles containing ceriumdoped zirconium dioxide was obtained using an Agilent-Cary 630 FTIR Spectrometer, covering a range of 400 to 4000 cm". The optical band gap was determined by recording UVVis diffuse reflectance spectroscopy (DRS) spectra using a PerkinElmer's LAMBDA 365 instrument across the 200 to 1100 nm wavelength range. The dielectric characteristics of all samples were examined using an IM3533-01 LCR Meter within a frequency range of 1 mHz to 200 kHz, maintaining ambient temperature.
3. Results and Discussion
3.1. X-ray diffraction, morphological and chemical composition analysis
The crystal structure, crystallinity, and crystallite size of Zri.Ce,O», (x=0;0.05;0.15;0.25) nanoparticles were determined by generating diffraction patterns, specifically XRD, from the crystalline powder samples. Fig. 1 displays the diffractograms of the mixed oxides (Zri.x CexO>, x=0;0.05;0.15;0.25). The XRD analysis of pure ZrO, and various concentrations of cerium-doped zirconium revealed the presence of monoclinic ZrO>. The diffraction peaks were observed at 20 angles of 28.3°, 31.5°, 34.4°, 35.5°, 38.8°, and 41.1°, corresponding to the Miller Indices (hkl) values (11-1), (111), (002), (200), (120), and (102), respectively. These values matched the JCPDCS Card number 004-7563, with a space group of P121/c 1. In the ZC-5, ZC-15, and ZC-25 samples, distinct CeO, peaks were detected at 20 values of 33.1°, 47.8°, and 56.5°, which correspond to the hk/ values of (200), (220), and (311) respectively. Notably, CeO> has a fluorite cubic structure with the space group Fm-3m [31]. The observed trend in the intensity of the peak at an angle of 26=28.3° shows a reduction as the percentage of cerium doping into ZrO; increases. Conversely, the peaks at angles of 26=33.1°, 47.8%, and 56.5% exhibit an increase in intensity with increasing cerium doping percentage. The crystal characteristics, such as crystallite size, were determined using XRD data by the Debye-Scherrer relation [32]. The average crystallite size of pure ZrO, (ZC-0) was 25.73 nm. Upon introducing cerium doping into ZrO», an increase in the average crystallite size was observed. Introducing CeO> into the ZrO, lattice can lead to dopant segregation, where CeO, prefers to segregate at grain boundaries or interfaces. This segregation can affect the growth kinetics of the grains, leading to larger crystallite sizes. The interplanar spacing, denoted as "d", can be determined using Bragg's formula. Bragg's formula is as follows: 2dsin0 = na [33], where '6' represents the diffraction angle, and 'A' represents the X-ray wavelength. When the concentration of cerium increases in ZrO», the interplanar spacing (d) also increases. Dislocation density is a quantitative measure of the number of dislocations per unit volume in a crystal. Dislocations profoundly affect material characteristics, with an increase in hardness correlating directly with an increase in dislocation density. The dislocation density is indicated by '&' and is determined using the formula 8 = 1/D?, where crystallite size is denoted by 'D'. The microstrain (e) can be calculated by employing the equation € = ß cos0/4. The average crystallite size, average dspacing, dislocation density, and microstrain values of undoped and cerium-doped zirconium dioxide are demonstrated in Table 1.
As depicted in Fig. 2, the surface morphology of pure zirconium and various mole ratios of cerium-doped zirconium composites were examined using SEM. The particles exhibit a high degree of aggregation and irregular shapes. Additionally, an EDS analysis was performed to determine the elemental composition of the Zr xCexO>, (x=0;0.05;0.15;0.25) nanocomposites. Fig. За depicts a sample containing only Zr and O. The EDX spectra of the CeO2/ZrO2 nanocomposites, shown in Figs 3 (b-d), reveal that the only components in the sample are Zr, Ce, and O.
3.2. Fourier-transform infrared spectroscopy (FTIR) and UV-vis absorption spectroscopy
FTIR spectroscopy is a widely recognized and valuable method for identifying and characterizing chemical substances. The nanoparticle sample underwent irradiation, enabling the identification of functional groups and related compounds in the fingerprint region. Additionally, the intensities of their stretching bands were determined. These intensities were graphed against their corresponding wavenumbers in the FTIR spectrum. Fig. 4 displays the FTIR spectrum of the zirconium nanoparticles doped with cerium. The observed peak within the wavenumber range of 450-550 cm"! is attributed to the vibrational mode of O-Ce-O stretching [34]. The presence of zirconia phases was confirmed by the relatively less pronounced peak of Zr-O extending at 435-440 cm" [35].
The diffuse reflectance spectra of Zrix CexO> (x=0, 0.05, 0.15, and 0.25) nanopowder samples were measured at RT within the wavelength range of 200-800 nm. The measured reflectance spectra were converted into the Kubelka-Munk function, F(R), as described in the studies [36, 37]: FR) Where R represents the reflectance value of the sample. The band gap of ZrıxCexO> nanopowders was determined using Tauc's relation and the KubelkaMunk function. Figure 5 depicts the relationship between the squared values of (F(R)hv) and (hv) for several synthesized samples containing varying quantities of cerium-doped zirconium nanoparticles. Straight lines were fitted to the experimental curves to calculate the optical band gap values of the cerium-doped zirconia nanoparticles. These lines were then extended to intersect the (hv) axis. In its pure form, ZrO, powder has a band gap energy of 5.24 electron volts (eV). However, when zirconium nanopowders were doped with cerium at concentrations of 0.05 mol.%, 0.15 mol.%, and 0.25 mol.%, the resulting materials displayed band gap energies of 3.4 eV, 3.3 eV, and 3.2 eV, respectively. An increase in the concentration of cerium in ZrO; results in a decrease in the band gap. Incorporating CeO, dopant atoms introduces additional energy levels within the band gap of ZrO,.These energy levels arise from variations in the electronic configuration of Zr and Ce and serve as intermediary states facilitating electron transitions. The valence band of ZrO, allows for the occupation of energy levels by electrons, which can then transition to the conduction band. This transition requires less energy than a direct transition across the initial band gap of ZrO».
Consequently, ZrO, material reduces its effective band gap by incorporating CeO: dopants. Including dopant levels offers alternate routes for electron excitation, decreasing the energy barrier and diminishing the energy requirement for electron transitions. The observed behavior, band gap narrowing, is widely observed in doped semiconductors.
3.3. Dielectric properties
The dielectric properties, including dielectric constant (g'), loss (e"), and AC conductivity (sac), of both undoped and cerium-doped ZrO, nanoparticles were analyzed across the 2 Hz-200 kHz frequency range at RT using an impedance analyzer. The dielectric constant, denoted as relative permittivity, measures a material's polarization response to an external electric field. Dielectric loss represents the dissipation of electromagnetic energy within the substance, while AC conductivity quantifies its ability to conduct electric current. These properties are affected by factors such as chemical composition and manufacturing technique. Conductivity, or specific conductance, measures a material's ability to conduct current and is influenced by temperature and frequency, remaining independent of the object's shape, size, and mass.
3.3.1. Dielectric constant
The dielectric constant is vital for evaluating high-k materials. In Fig. 6, the relationship between dielectric constant and frequency is shown for pure ZrO, and ZrO»/ CeO, mixed oxides. €' increases at lower frequencies but decreases as frequency rises, attributed to reduced space charge polarization effects. The significant £' at low frequencies is explained by the Maxwell-Wagner model, highlighting the role of grain boundaries in space charge polarization. This behavior aligns with the Debye Relaxation model, particularly regarding orientational polarization. In many dielectric materials, it is observed that the dielectric constant remains constant at higher frequencies. This is on account of the electric dipoles' failure to respond quickly to the rapid changes in the alternating applied electric field [38]. Koop's phenomenological theory states that the conductivity of grain boundaries predominantly influences the dielectric value at lower frequencies. This is because of the heightened effectiveness of grain boundaries in facilitating conductivity at lower frequencies. Consequently, the permittivity exhibits a higher value at lower frequencies and undergoes a drop as the frequency escalates. In Fig. 6, the dielectric constant indicates a rising trend with the increase of CeO, concentration into ZrO, because CeO, possesses a higher atomic number compared to ZrO,. Elements with higher atomic numbers exhibit greater electron cloud polarizability, enabling them to undergo more distortion in their electron clouds when subjected to an externally applied electric field. The increased polarizability can result in a greater dielectric constant.
3.3.2 Dielectric loss
The dielectric properties of high dielectric materials are crucially assessed by considering dielectric loss. This study revealed that dielectric loss (e") decreases as frequency increases across all compounds, plateauing at higher frequencies. Fig. 7 depicts this trend for pure ZrO, and ZrO,/CeO, composites. At low frequencies, dielectric loss is higher, diminishing as frequency rises. Interfacial relaxation and ionic conductivity contribute to this phenomenon, becoming less significant at higher frequencies. CeO, addition increases dielectric loss, particularly at lower frequencies, due to introduced defects affecting charge carriers' behavior and polarization. This frequency-dependent behavior is linked to various polarization mechanisms, with the Maxwell-Wagner effect contributing to higher dielectric loss at lower frequencies [39].
3.3.3 AC Conductivity
Fig. 8 illustrates AC electrical conductivity in Zrix CeO, (x = 0;0.05;0.15;0.25) nanoparticles with respect to frequency. The data reveals a direct relationship between frequency and charge carrier mobility. As frequency rises, conductivity increases, indicating enhanced movement of charge carriers and hopping between sites. Two zones are evident: a frequency-independent zone at low frequency and a frequency-dependent zone at high frequency. Conductivity predominantly increases at higher frequencies due to a hopping process adhering to a power law. ZrıxCexO> (x = 0.05;0.15;0.25) exhibit notably higher conductivity than pure ZrO,, influenced by sintering temperature, crystal structure, defect concentration, and chemical composition. CeO, addition promotes oxygen vacancy formation, facilitating faster ion mobility and thereby enhancing ionic conductivity. This improved mobility, particularly at higher frequencies, contributes to the overall AC conductivity enhancement.
4. Conclusion
The current study successfully synthesized nanoparticles of Zr1-x CexO2) with x=0, 0.05, 0.15, and 0.25 through a solid-state process. The key findings are summarized below:
* XRD analysis reveals that the nanoparticles of Zri.x CexO2 exhibit a monoclinic crystal structure. The size of the crystallite increases proportionally with the concentration of CeO; doping.
* The band gap of pure zirconium is measured at 5.24 eV. With an increase in cerium concentration from 0.05 to 0.25 mol percent in ZrO», the band gap decreases to 3.2 eV.
* Dielectric properties of pure ZrO>, such as the dielectric constant (£') and dielectric loss (e") values, show low values in the low-frequency region. However, doping with CeO, increases these values at lower frequencies, indicating enhanced dielectric qualities. The combination of ZrO, and CeO, mixed oxide ceramic materials holds significant promise for applications in microwave devices, including resonators and filters.
Acknowledgments
The Vice-Chancellor of VIT-AP and the Chancellor of VIT groups are especially appreciated by the authors for granting permission to publish this article. Additionally, acknowledgement is given to the RGEMS project (RGEMS2021016).
ORCID numbers:
М. Naga Sravanthi - https://orcid.org/0000-0003-2683-5877
Jothi Sudagar - https://orcid.org/0000-0002-7670-4843
© 2025 Authors. Published by association for ETRAN Society. This article is an open access article distributed under the terms and conditions of the Creative Commons - Attribution 4.0 International license
5. References
1. Wang, H., Li, J., Liu, K., Xu, G., Zhu, H., Wang, J., Xu, C., Wang, L. and Okulov, A., Microstructural evolution and corrosion resistance property of in-situ Zr-C (B, Si)/Ni-Zr reinforced composite coatings on zirconium alloy by laser cladding, Journal of Materials Research and Technology, 26 (2023) 530-541. DOI: 10.1016/j.jmrt.2023.07.214
2. Tijana Kevkic, Vladica Stojanovic, Vera Petrovié, Dragan Randelovic, Inversion Charge Density of MOS transistor with Generalized Logistic Functions, Science of Sintering, 50 (2018) 225-235. https://doi.org/10.2298/SOS1802225K.
3. Zhang, Q., Li, X., Shen, J., Wu, G., Wang, J. and Chen, L., ZrO, thin films and ZrO>/SiO> optical reflection filters deposited by sol-gel method, Materials Letters, 45(6) (2000) 311-314. https://doi.org/10.1016/S0167-577X(00)00124-5
4. Chen, Q., Chang, Y., Shao, C., Zhang, J., Chen, J., Wang, М. and Long, Y., Effect of grain size on phase transformation and photoluminescence property of the nanocrystalline ZrO, powders prepared by sol-gel method, Journal of Materials Science & Technology, 30(11) (2014) 1103-1107. https://doi.org/10.1016/j.jmst.2014.05.009
5. Purohit, R.D., Saha, $. and Tyagi, A.K., Combustion synthesis of nanocrystalline ZrO, powder: XRD, Raman spectroscopy and TEM studies. Materials Science and Engineering: B, 130(1-3) (2006) 57-60. https://doi.org/10.1016/j.mseb.2006.02.041
6. Dutta, G., Hembram, K.P.S.S., Rao, G.M. and Waghmare, U.V., Effects of O vacancies and С doping on dielectric properties of ZrO»: A first-principles study. Applied Physics Letters, 89(20) (2006) 202904. https://doi.org/10.1063/1.2388146
7. Chraska, T., King, А.Н. and Berndt, C.C., On the size-dependent phase transformation in nanoparticulate zirconia. Materials Science and Engineering: A, 286(1) (2000) 169-178. https://doi.org/10.1016/S0921-5093(00)00625-0
8. Zhang, Q., Shen, J., Wang, J., Wu, С. and Chen, L., Sol-gel derived ZrO,-SiO> highly reflective coatings. International Journal of Inorganic Materials, 2(4) (2000) 319-323. https://doi.org/10.1016/S1466-6049(00)00037-4
9. Wright, P.K. and Evans, A.G., Mechanisms governing the performance of thermal barrier coatings. Current opinion in solid state and Materials Science, 4(3) (1999) 255-265. https://doi.org/10.1016/S1359-0286(99)00024-8
10. Salas, P., De la Rosa-Cruz, E., Diaz-Torres, L.A., Castano, V.M., Melendrez, R. and Barboza-Flores, M.,. Monoclinic ZrO, as a broad spectral response thermoluminescence UV dosemeter. Radiation Measurements, 37(2) (2003) 187-190. https://doi.org/10.1016/S1350-4487(02)00174-9.
11. Kumari, L., Du, G.H., Li, W.Z., Vennila, R.S., Saxena, S.K. and Wang, D.Z., Synthesis, microstructure and optical characterization of zirconium oxide nanostructures. Ceramics International, 35(6) (2009) 2401-2408. https://doi.org/10.1016/j.ceramint.2009.02.007.
12. Karch, J., Birringer, К. and Gleiter, H., Ceramics ductile at low temperature. Nature, 330(6148) (1987) 556-558. https://doi.org/10.1038/330556a0.
13. Babu, C.R., Reddy, N.R.M. and Reddy, K., Synthesis and characterization of high dielectric nano zirconium oxide. Ceramics International, 41(9) (2015) 10675-10679. https://doi.org/10.1016/j.ceramint.2015.04.168.
14. Rashad, M.M. and Baioumy, H.M., Effect of thermal treatment on the crystal structure and morphology of zirconia nanopowders produced by three different routes. Journal of materials processing technology, 195(1-3) (2008) 178-185. https://doi.org/10.1016/j.jmatprotec.2007.04.135.
15. Wang, X., Zhai, B., Yang, M., Han, W. and Shao, X., ZrO,/CeO, nanocomposite: Two step synthesis, microstructure, and visible-light photocatalytic activity. Materials Letters, 112 (2013) 90-93. https://doi.org/10.1016/j.matlet.2013.09.001.
16. Bocanegra-Bernal, M.H. and De La Torre, S.D., Phase transitions in zirconium dioxide and related materials for high performance engineering ceramics. Journal of materials science, 37 (2002) 4947-4971. https://doi.org/10.1023/A:1021099308957.
17. Steele, B.C. and Heinzel, A., Materials for fuel-cell technologies. Nature, 414(6861) (2001) 345-352. https://doi.org/10.1038/35104620.
18. Riegel, J., Neumann, H. and Wiedenmann, H.M., Exhaust gas sensors for automotive emission control. Solid State Ionics, 152 (2002) 783-800. https://doi.org/10.1016/S0167-2738(02)00329-6.
19. Jurado, J.R., Present several items on ceria-based ceramic electrolytes: synthesis, additive effects, reactivity and electrochemical behaviour. Journal of materials science, 36 (2001) 1133-1139. https://doi.org/10.1023/A:1004873623892.
20. Nawrocki, J., Dunlap, C.J., Carr, R.M. and Blackwell, J.A., New materials for biotechnology: Chromatographic stationary phases based on zirconia. Biotechnology progress, 10(6) (1994) 561-573. https://doi.org/10.1021/bp00030a001.
21. Piconi, C. and Maccauro, G., Zirconia as a ceramic biomaterial. Biomaterials, 20(1), (1999) 1-25. https://doi.org/10.1016/S0142-9612(98)00010-6.
22. Li, R., Yabe, S., Yamashita, M., Momose, S., Yoshida, S., Yin, S. and Sato, T., UV-shielding properties of zinc oxide-doped ceria fine powders derived via soft solution chemical routes. Materials Chemistry and Physics, 75(1-3) (2002) 39-44. https://doi.org/10.1016/S0254-0584(02)00027-5.
23. Matijevic, Е. and Hsu, W.P., Preparation and properties of monodispersed colloidal particles of lanthanide compounds: I. Gadolinium, europium, terbium, samarium, and cerium (Ш). Journal of Colloid and Interface Science, 118(2) (1987) 506-523. https://doi.org/10.1016/0021-9797(87)90486-3.
24. Xu, C. and Qu, X., Cerium oxide nanoparticle: a remarkably versatile rare earth nanomaterial for biological applications. NPG Asia materials, 6(3) (2014) е90-е90. https://doi.org/10.1038/am2013.88.
25. Shahin, A.M., Grandjean, F., Long, G.J. and Schuman, T.P., Cerium LIII-edge XAS investigation of the structure of crystalline and amorphous cerium oxides. Chemistry of materials, 17(2) (2005) 315-321. https://doi.org/10.1021/cm0492437.
26. Tsunekawa, S., Sahara, R., Kawazoe, Y. and Kasuya, A., Origin of the blue shift in ultraviolet absorption spectra of nanocrystalline CeO? x particles. Materials transactions, JIM, 41(8) (2000) 1104-1107. https://doi.org/10.2320/matertrans1989.41.1104.
27. Trovarelli, A., De Leitenburg, C., Boaro, M. and Dolcetti, G., The utilization of ceria in industrial catalysis. Catalysis today, 50(2) (1999) 353-367. https://doi.org/10.1016/S0920-5861(98)00515-X.
28. Zhou, F., Zhao, X., Xu, H. and Yuan, C., CeO, spherical crystallites: synthesis, formation mechanism, size control, and electrochemical property study. The Journal of Physical Chemistry C, 111(4), (2007) 1651-1657. https://doi.org/10.1021/jp0660435.
29. Chen, H.I. and Chang, H.Y., Synthesis and characterization of nanocrystalline cerium oxide powders by two-stage non-isothermal precipitation. Solid state communications, 133(9) (2005) 593-598. https://doi.org/10.1016/j.ssc.2004.12.020.
30. Hungria, A.B., Browning, N.D., Emi, R.P., Fernändez-Garcia, M., Conesa, J.C., Pérez-Omil, J.A. and Martinez-Arias, A., The effect of N in Pd-Ni/(Ce, Zr) O,/A1203 catalysts used for stoichiometric CO and NO elimination. Part 1: Nanoscopic characterization of the catalysts. Journal of Catalysis, 235(2) (2005) 251-261. https://doi.org/10.1016/j.jcat.2005.08.011.
31. Malleshappa, J., Nagabhushana, H., Prasad, B.D., Sharma, S.C., Vidya, Y.S. and Anantharaju, K.S., Structural, photoluminescence and thermoluminescence properties of CeO; nanoparticles. Optik, 127(2) (2016) 855-861. https://doi.org/10.1016/j.ijle0.2015.10.114.
32. Panahi-Kalamuei, M., Alizadeh, S., Mousavi-Kamazani, M. and Salavati-Niasari, M., Synthesis and characterization of CeO; nanoparticles via hydrothermal route. Journal of Industrial and Engineering Chemistry, 21 (2015) 1301-1305. https://doi.org/10.1016/j.jiec.2014.05.046.
33. Su, Y., Yang, W., Sun, W., Li, О. and Shang, J.K., Synthesis of mesoporous cerium- zirconium binary oxide nanoadsorbents by a solvothermal process and their effective adsorption of phosphate from water. Chemical Engineering Journal, 268 (2015) 270-279. https://doi.org/10.1016/j.cej.2015.01.070.
34. Prabaharan, D.M.D.M., Sadaiyandi, K., Mahendran, M. and Sagadevan, S., Structural, optical, morphological and dielectric properties of cerium oxide nanoparticles. Materials Research, 19 (2016) 478-482. https://doi.org/10.1590/1980-5373-MR-2015-0698.
35. Jayakumar, S., Ananthapadmanabhan, P.V., Perumal, K., Thiyagarajan, T.K., Mishra, S.C., Su, L.T., Tok, A.LY. and Guo, J., Characterization of nanocrystalline ZrO, synthesized via reactive plasma processing. Materials Science and Engineering: B, 176(12) (2011) 894-899. https://doi.org/10.1016/j.mseb.2011.05.013.
36. Zuas, O., Abimanyu, H. and Wibowo, W., Synthesis and characterization of nanostructured CeO, with dyes adsorption property. Processing and Application of Ceramics, 8(1) (2014) 39-46. https://doi.org/10.2298/PAC1401039Z.
37. King, A., Singh, R., Anand, R., Behera, S.K. and Nayak, B.B., Spectroscopic studies of borohydride-derived cerium-doped zirconia nanoparticles under air and argon annealing conditions. Journal of Nanoparticle Research, 23(8) (2021) 156. https://doi.org/10.1007/s11051-021-05299-x.
38. Kambale, R.C., Shaikh, P.A., Bhosale, C.H., Rajpure, K.Y. and Kolekar, Y.D., Dielectric properties and complex impedance spectroscopy studies of mixed Ni-Co ferrites. Smart materials and structures, 18(8) (2009) 085014. DOI 10.1088/0964-1726/18/8/085014.
39. Soni, B., Makkar, S. and Biswas, S., Effects of surface structure and defect behavior on the magnetic, electrical, and photocatalytic properties of Gd-doped CeO» nanoparticles synthesized by a simple chemical process. Materials Characterization, 174 (2021) 110990. https://doi.org/10.1016/j.matchar.2021.110990.
*) Corresponding author: [email protected]
You have requested "on-the-fly" machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Show full disclaimer
Neither ProQuest nor its licensors make any representations or warranties with respect to the translations. The translations are automatically generated "AS IS" and "AS AVAILABLE" and are not retained in our systems. PROQUEST AND ITS LICENSORS SPECIFICALLY DISCLAIM ANY AND ALL EXPRESS OR IMPLIED WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES FOR AVAILABILITY, ACCURACY, TIMELINESS, COMPLETENESS, NON-INFRINGMENT, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Your use of the translations is subject to all use restrictions contained in your Electronic Products License Agreement and by using the translation functionality you agree to forgo any and all claims against ProQuest or its licensors for your use of the translation functionality and any output derived there from. Hide full disclaimer
© 2025. This work is published under https://creativecommons.org/licenses/by/4.0/ (the "License"). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.
Abstract
This study synthesized CeO2-doped ZrO2 nanoparticles using the solid-state reaction, employing varying quantities of 0.05 mol.%, 0.15 mol.%, and 0.25 mol.% CeO2. The structures of CeO2-doped ZrO2 were investigated through XRD, revealing the presence of monoclinic ZrO2 in all samples, while the average size of the crystallite increased as the concentration of CeO2 doping increased. The optical band gap of CeO2-doped ZrO2 was determined using diffuse reflectance spectra, showing that the band gap decreased with increasing doping concentrations. The investigation focused on characterizing parameters such as dielectric constants, dielectric loss, and AC conductivity, emphasizing their frequency dependence at room temperature (RT). The dielectric constant and dielectric loss of Zrlx-CexO2 exhibited a significant drop as the frequency increased (Maxwell-Wagner polarization). Furthermore, the dielectric constant and dielectric loss factor in the lower frequency band exhibited an increase as the cerium content in ZrO2 increased. The incorporation of cerium significantly impacted the optical and electrical characteristics of composite ceramics consisting of CeO2 and ZrO2.