May 2, 2017 - doped CCTO shows the presence of CuO at Gbs. However, remarkable ..... [22] Z. Yang, L. Zhang, X. Chao, L. Xiong, J. Liu, J. Alloys Comp.
Accepted Manuscript Comparative studies of pure, Sr-doped, Ni-doped and co-doped CaCu3Ti4O12 ceramics: Enhancement of dielectric properties Salam Rhouma, Senda Saîd, Cécile Autret, Sonia De Almeida-Didry, Mohamed El Amrani, Adel Megriche PII:
S0925-8388(17)31636-5
DOI:
10.1016/j.jallcom.2017.05.053
Reference:
JALCOM 41783
To appear in:
Journal of Alloys and Compounds
Received Date: 2 February 2017 Revised Date:
2 May 2017
Accepted Date: 6 May 2017
Please cite this article as: S. Rhouma, S. Saîd, Cé. Autret, S. De Almeida-Didry, M. El Amrani, A. Megriche, Comparative studies of pure, Sr-doped, Ni-doped and co-doped CaCu3Ti4O12 ceramics: Enhancement of dielectric properties, Journal of Alloys and Compounds (2017), doi: 10.1016/ j.jallcom.2017.05.053. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Comparative studies of pure, Sr-doped, Ni-doped and co-doped CaCu3Ti4O12 ceramics: Enhancement of dielectric properties
Salam. Rhoumaa,b, Senda.Saîda , Cécile Autretb, Sonia De Almeida-Didryb, Mohamed El Amranib , Adel
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Megrichea
a)
Université de Tunis El Manar, Faculté des Sciences de Tunis, Unité de Recherche de Chimie Minérale Appliquée (UR11ES18), Campus Universitaire Farhat Hached, 2092, Tunis, Tunisia b)
GREMAN, UMR 7341 CNRS, Université François Rabelais, UFR Sciences et Techniques, Parc de Grandmont, 37200,
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Tours, France
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Abstract
The CaCu3Ti4O12 ceramic, CCTO, remains as the best material due to its high dielectric constant. In this context, Sr-doped CCTO, Ni-doped CCTO and Sr,Ni co-doped CCTO ceramics were prepared by the solid-state reaction method and were sintered at 1100°C for 24 h in order to enhance the geometric microstructure and dielectric properties. X-ray diffraction
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data refined via rietveld method for CaCu3Ti4O12 confirms the formation of single phase. SEM micrographs revealed that the substitution of Sr2+ and/or Ni2+ on Ca and Cu sites respectively increase the grain size of CaCu3Ti4O12 ceramics. Raman scattering measurements shows the presence of TiO2 phase at grain boundaries, which is an important parameter to
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reduce the dielectric loss of samples. It is found that Sr,Ni co-substitution in CCTO leads to the best dielectric measurements at low frequency. The highest grain boundary resistance
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value is also obtained for co-doped CCTO sample in the order of 1.84 106 Ω. This value is 10 times higher than pure CCTO. Meanwhile, the nonlinear coefficient values were improved, whereas, the breakdown electric field and leakage current decreased for all ceramic samples and co-doped CCTO is considered as the best conductive grain and insulating grain boundary.
ACCEPTED MANUSCRIPT 1-Introduction The miniaturization of electronic devices is on a constant development. Many electroceramics with high dielectric constant like the perovskite-based ferroelectric ceramics (e.g., (Pb,La)(Zr,Ti)O3(PLZT)) or the relaxor ferroelectrics (eg., SrBi2Nb2O9 (SBN)) are used to fabricate ceramic dielectric capacitors [1,2]. However, their dielectric constant is closely
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related to the temperature and structural phase transition, which is undesirable for most industrial and electronic applications.
In recent years, an attractive material called CaCu3Ti4O12 (CCTO) has been discovered by Subramanian et al. This compound has been widely studied in view of its giant dielectric
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constant (∼104) in a large temperature [100-400K] and frequency range [102-106Hz] [3,4].
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Many investigations have been performed to find the origin of the giant dielectric constant for CCTO [5,6]. Generally, it is now accepted that the giant dielectric constant is due to the extrinsic effect. The internal barrier layer capacitor (IBLC) model is considered as the most likely mechanism to explain it. This model is associated with an electric semiconducting grains and insulating grain boundaries (Gbs) [7,8]. Thus, the change of the electrical
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properties of grain and Gbs affects drastically the dielectric properties of CCTO ceramic. Unfortunately, this material exhibits a high dielectric loss (tanδ) despite of its high dielectric constant, which is undesirable for most industrial and electronic applications. According to IBLC model, it was demonstrated that low-frequency tanδ is related to the total
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resistance of the bulk ceramics. Moreover, it is strongly linked to the resistance of insulating Gbs (Rgb) as the resistance of grains (Rg) is much smaller than the Rgb [9,10].
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Besides their giant dielectric properties, CCTO can also exhibit nonlinear electrical
Current-Voltage behavior (I-V) [4,11-13] due to the existence of intrinsic potential barriers at Gbs, i.e., Schottky barriers [4,7].
The researchers paid more attention to improve the dielectric properties of CCTO via several ways. Among them, doping is an efficient method. Many cations have been introduced into CCTO, but some of them led to increase the dielectric constant as well as the dielectric loss (eg,. Na2+ [14] and Mo6+ [15]). It was also reported that doping of CCTO with Ni2+ doping ions is widely investigated [16-18], and increases considerably the dielectric constant whereas the dielectric losses are much higher. Despite the dielectric losses decrease,
ACCEPTED MANUSCRIPT it stills much higher than 0.1 as mentioned [18]. On the other hand, many studies showed the important effect of Sr2+ doping ions on Ca-site, promoting the dielectric properties (increased the dielectric constant and decrease the dielectric losses) as well as the frequency stability [19-22]. It is expected that the addition of Sr doping ions in Ni-doped CCTO may decrease the dielectric losses and also increase the frequency stability of both dielectric properties.
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The aim of this work is to compare both of Sr-doped CCTO, Ca0.9Sr0.1Cu3Ti4O12 (CSCTO) and Ni-doped CCTO, CaCu2.9Ni0.1Ti4O12 (CCNTO) with those obtained by Sr2+ and Ni2+ co-doping ions CCTO, Ca0.9Sr0.1Cu2.9Ni0.1Ti4O12 (CSCNTO). In this paper, the effect of Sr and/or Ni doping ions on the microstructure, dielectric properties and non-linear current-
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Voltage of CCTO ceramics has been investigated.
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2-Experimental
Ca1-xSrxCu3-yNiyTi4O12 (x=y=0; x=0.1, y=0; x=0, y=0.1 and x=0.1, y=0.1) ceramics were synthesized by solid state reaction method. CaCO3 (99.9% purity), CuO (99.9% purity), TiO2 (99.9% purity), SrCO3 (99.9% purity) and NiO (99.9% purity) were used as starting raw materials. A stoichiometric mixture of the starting materials was weighted and mixed first by mortar-pestle and after by ball-milled in ethanol for 6 h using zirconia ball. The mixture were
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dried in the oven, placed in alumina crucibles and calcined in air at 1000°C for 24 h. The calcined powder was ground again, and pressed into disks of 10 mm in diameter and 2 mm in thickness. Finally, these pellets were sintered at 1100°C for 24h.
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X-ray diffraction (XRD) data was used in order to study the crystalline structure of the sintered samples employing a D8 Bruker with CuKα radiation (λ=1.540 Ǻ). The diffraction
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patterns were recorded in 2θ range of 20 – 80 ° with a step size of 0.02°, and a step time of 12s. The X-ray diffraction data was analyzed via Rietveld crystal structure refinement software (FULLPROF). The microstructures of the fractured surfaces were performed by Scanning Electron Microscopy (SEM) Hitachi 4160-F. All the SEM images were acquired under secondary electron imaging mode (accelerating voltage = 10 kV). Raman spectra were recorded with a Renishaw inVia Reflex Raman Microscope. Experiments were conducted in micro-Raman mode at room temperature by using 514 nm as exciting wavelength. Before the dielectric measurements, the pellets were polished and painted with silver paste in order to build the capacitor electrodes. Then impedance analyzer (Agilent 4294A) was used in the frequency range from 102 Hz to 10 MHz at room temperature in order to measure the
ACCEPTED MANUSCRIPT dielectric properties and the current–voltage measurements were carried out by an Agilent B2911A unit.
3-Result and discussion
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The simulated patterns of un-doped CCTO are shown in fig. 1. Its structure was refined by X-ray diffractometer data at room temperature revealing a single phase. The fit confirms the structure of cubic symmetry Im3. The refined lattice parameter was determined as a= 7.3945Å confirming the result reported by Subramanian et al. [3], and the unit cell
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V=404.329 Å3. The values of reliability factors Rwp, Rbragg and χ2 were found 3.17, 2.14, and
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6.97 respectively.
X-ray patterns of Ca1-xSrxCu3-yNiyTi4O12 (x=y=0; x=0.1, y=0; x=0, y=0.1 and x=0.1, y=0.1) ceramics are shown in Fig.2. These diagrams show that all diffraction peaks of CCTO appeared in all ceramic samples indicating the formation of single CCTO phase. Lattice parameter (a) values summarized in Table 1 changed slightly for doped ceramic samples and
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shifts the principal peak of CCTO in the vicinity of 2θ from 33.5° to 34.5°. The Sr2+ doping ions on Ca-site causes a shift towards small angles due to the larger radius of Sr2+ (1.12Ǻ), while the peaks of CCTO doped with nickel on Cu-site shift to high angles because of the
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smaller radius of Ni2+(0.64Å).
Fig. 3 shows the SEM images of Ca1-xSrxCu3-yNiyTi4O12 (x=0, y=0; x=0.1, y=0; x=0,
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x=0.1 and x=0.1, y=0.1) ceramics at the same magnification. The average grain size of CCTO, CSCTO, CCNTO and CSCNTO ceramics (estimated by a line intercept method) and the relative bulk density (calculated by measuring mass and (diameter/thickness) of pellets) are listed in Table 1. The un-doped CCTO reveals a homogenous microstructure constituted by small cubic grains. A huge change in the microstructure was observed for the Sr and/or Ni doping samples which present a bimodal distribution grains. It can be obviously seen that the addition of Ni2+ induces a further increase in grain growth (fig. 2 (b) and (c)). Moreover, the Table 1 revealed a dense ceramics with a relative density around (91-94 %) for all samples. Both of Sr2+ and Ni2+ doping ions lead to increase the density of Ca1-xSrxCu3-yNiyTi4O12 ceramics and minimize the presence of porosity. Furthermore, a remarkable increase in grain size was observed for co-doped CCTO (fig.2 (d)) surrounded by small ones. Otherwise, it can
ACCEPTED MANUSCRIPT be noticed that the sintering at 1100°C for a long time (24h) helps also to decrease the porosity and to increase the relative density. According to previous studies, the grain growth of Sr-Ni-co-doped CCTO is similar to that observed in Sr doped CCTO [22], Ni-doped CCTO [23], Ga doped CCTO [24], CCTO–MgO composites [25] and Mo doped CCTO ceramics [15]. In conclusion, these results revealed that both of Sr2+ and Ni2+ doping ions have a good
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influence to promote both of the relative density and the grain growth rates of CCTO ceramics.
In order to explain the origin of grain growth, the determination of grain and Gbs composition
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is important. In this case, Raman spectra measurements were carried out. The modes of Raman for CCTO are observed at 444 cm-1, 510 cm-1 and 576 cm-1 as reported in the literature
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[26,27]. Fig. 4(a) confirms the presence of CCTO phase in grains for all ceramic samples. Previous works have reported the presence of CuO at Gbs [15, 24]. In our case, only undoped CCTO shows the presence of CuO at Gbs. However, remarkable peaks relative to TiO2 phase were observed in the grain boundaries of CSCTO and CSCNTO ceramics (Fig 4(b))[28]. These results are in contradiction with XRD data where no secondary phases were detected in un-doped and doped CCTO ceramic samples. This is can be explained by the
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resolution limit of the XRD technique. This phenomenon was mentioned by De AlmeidaDidry et al. [29], wherein, they reported the importance of the TiO2 phase on the sample’s resistivity and breakdown voltage. TiO2, CuO, and CCTO peaks appeared for all samples at
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the Gbs. The presence of this CCTO phase can be explained by the large spot size of the laser which is difficult to distinguish between grain and Gbs. As described in previous researches, the grain growth of CCTO is more related to the presence of liquid phase based on Cu-rich
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phase [30-31]. Therefore, the grain growth may be related to the presence of a few quantity of Cu reacted with TiO2 forming eutectic CuO-TiO2 phase and leading after to grain boundary mobility. This is can be the major factor to increase the grain growth.
Fig. 5(a-b) illustrates the frequency dependence of the relative permittivity (ɛ’) and dielectric loss (tanδ) of the ceramic samples at room temperature within the frequency range from 102Hz to 107 Hz. As seen in fig 5(a), the ɛ’ increases for all the doped ceramic samples, indicating that Sr2+ and Ni2+ doping ions have a good influence. It was observed that the ɛ’ is better for Ni-doped sample (CCNTO) than for Sr-doped (CSCTO) one, whereas, the
ACCEPTED MANUSCRIPT frequency stability is enhanced for CSCTO sample, which is consistent with previous works [19-22]. Moreover, the dielectric measurements highlight that the simultaneous addition of Sr2+and Ni2+ doping ions on CCTO (CSCNTO) leads to increase both ɛ’ and frequency stability. The CSCNTO sample shows the highest ɛ’ value. On the other hand, SEM analyses clearly indicate that there is a remarkable difference of grain growth of ceramic samples and
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Table 1 reveals that ɛ’ values of ceramic samples increase as the grain size increases (fig.3 and Table 1). This confirms a relationship between the ɛ’ and the mean grain size of CCTO [7,3138]. By referring to the internal barrier layer capacitor (IBLC) model, the ɛ’ of CCTO ceramics can be expressed as εr ~ ε (A/t ) where εr , , A and tgb are the effective
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dielectric constant, dielectric constant of the grain boundary (GBs), the average grain size, and the thickness of GBs, respectively. Besides, densification of CCTO samples can contribute to the value of dielectric constant, while the presence of porosities in CCTO can
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reduce the dielectric constant of the sample [39-41]. In our results, Sr and Ni doping ions incorporated in the lattice of CCTO and led after to increase the relative densities and minimize the presence of porosities. As seen in Table 1, there is a big difference of the density values between the un-doped CCTO and co-doped CCTO as well for the permittivity values.
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So, it can be noticed that there is a relationship between relative density and permittivity.
Frequency dependence of tan δ is plotted in fig. 5(b). For doped CCTO ceramic samples, tan δ is reduced at low frequency followed by a sharp rise at high frequency. This strong increase could be attributed to the Debye relaxations seen at higher frequency [42]. The
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tan δ of ceramic samples can be related to the structural defect (such as pores, metal valence change and oxygen vacancies) [43] and then can be sensitive to the densification. According
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to Table 1, the co-doped CCTO showed the highest density value and the lower porosity leading to decrease the tan δ at low frequency. Moreover, presence of TiO2 phase at grain boundaries has also a good effect in reducing dielectric losses and increasing the grain boundary resistance [44,45]. Based on these results, the CSCNTO is considered as the best material due to its remarkable dielectric properties at low frequency.
In order to elucidate the effect of Sr2+ and Ni2+ doping ions on tan δ values, the electrical properties inside the grains and Gbs were analyzed for all ceramic samples. Fig. 6 shows the impedance complex plane of all ceramic samples at room temperature over a wide frequency range. According to IBLC model, the complex impedance can be described by an
ACCEPTED MANUSCRIPT equivalent circuit, which consists of two parallel resistor-capacitor (RC) elements connected in series [46]. One RC element represents the resistance R and capacitance C values of semiconducting grains (Rg, Cg) and the other one corresponds to insulating grain boundary region (Rgb, Cgb). It is known that the resistance of Gbs can be obtained at low frequency from the diameter of a large semicircular arc on the impedance complex plane plot [7,46] and
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varies as tan(δ) ~1/ω RgbCp(1), where Rgb represents the resistance of insulating Gbs, ω is the angular frequency and Cp is the capacitance of the sample proportional to the value of dielectric constant ɛ. The resistance of grains can be estimated at high frequency from the nanozero intercept on the Z’ axis [7,45]. Additionally, the geometric properties (grain and
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Gbs) are also considered as an important key to determine the electrical properties. Generally, the increase in Rgb is more related to the enhancement of Gbs density and therefore to the reduction of mean grain size [47]. Resistance values of grain and Gbs for all ceramic samples
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are listed in Table 2. As seen in the fig.6 (a), the Rgb value increased in both single and codoped ceramic samples although the grain size was increased (reduction of Gbs density). The geometric properties cannot explain the difference in Rgb values between the un-doped and doped CCTO. The co-doped CCTO shows the highest Rgb value, indicating that Rgb is strongly affected by simultaneous addition of Sr2+ and Ni2+ doping ions. According to the formula (1), the tan δ value at low frequency should be inversely proportional to Rgb. Fig.6(c)
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revealed that the tan δ decreased as Rgb increased (formula (1)), with the adding of Sr and Ni doping ions. Besides, presence of secondary phase at grain boundaries plays an important role in increasing the Rgb, whilst reducing dielectric losses [48]. Subsequently, the increase of Rgb
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could be attributed to the segregation of TiO2 phase at grain boundary as pointed out in Raman measurements. This phenomenon has also been observed by Y.Lin et al. in TiO2 rich CaCu3Ti4O12 ceramics [44]. Both effects (Sr/ Ni doping ions and TiO2 phase) can explain the
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increase of Rgb. As shown in fig.7 (a) and Rg data in Table 2, it can be noted that Rg values is almost negligible compared to those found for Rgb. These results revealed that tan δ and resistance are directly related to the Gbs, with little effect due to grains [38]. Thus, the Gbs behave like an insulating grain and the grains as semiconducting in CCTO ceramics. Based on above results, Sr2+ and Ni2+ doping ions and also TiO2 phase have a significant influence on the intrinsic properties of grain and Gbs and these latter can lead to increase the permittivity (IBLC model) more than the grains. The measurements of the current density vs electric field (J-E) are shown in Fig.7. A nonlinear relationship between J and E are observed for all ceramic samples. The Table 2
ACCEPTED MANUSCRIPT summarized the breakdown electric field values obtained at 1 mA.cm-2 and the nonlinear coefficient values calculated by α=1/[log(U1mA/U0.1mA)], where U1mA and U0.1mA are the voltage corresponding to the electric field in volt per millimeter when the dc current is 1mA and 0.1mA to flow through the ceramic samples, respectively [49]. It can be seen that α increased for doped ceramic samples, and was more improved by simultaneous addition of
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Sr2+ and Ni2+ doping ions, while the breakdown electric field and leakage current values decreased. According to N. Daneu et al., the breakdown electric field can be controlled by the grain size of CCTO and especially by the density of Gbs [50]. In fact, the increase of breakdown electric field is related to the presence of smaller grain. SEM results show big
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grains with no clear grain boundaries. Thus the decrease of breakdown electric field may be related to the increase of grain size. On the other hand, the increase of α can be attributed to the formation of Shottky barriers at the Gbs [51,52]. As reported in [29,43] the breakdown
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electric field value increased in TiO2-rich CCTO ceramics. Therefore, the effect of TiO2 phase is neglected. So, Sr2+ and Ni2+ doping ions are strongly suspected to be the origin of the nonlinear enhancement, which have a significant impact to improve the barrier height. We can conclude that co-doping CCTO has the best conductive grain and the best insulating grain
4-Conclusion
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boundary.
In summary, Ca1-xSrxCu3-yTi4O12 (x=y=0; x=0.1, y=0; x=0, y=0.1 and x=0.1, y=0.1)
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were successfully prepared by solid-state reaction method. Their phase structure, microstructure, dielectric properties, complex impedances and nonlinear J-E characteristics
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were investigated. XRD analysis confirmed the formation of single phase for all ceramics samples sintered at 1100°C for 24 h. Addition of Sr and Ni doping ions on CCTO cause a significant increase in the mean grain size. TiO2 phase was found at grain boundaries detected by Raman scattering, which has a good influence on the dielectric loss. The best overall properties were successfully obtained for Sr,Ni co-doped CCTO, which this sample shows the highest ɛ’ and Rgb value and also the lowest tanδ value. According to these properties, the Sr,Ni co-doped CCTO ceramic is considered as the best material for industrial applications.
ACCEPTED MANUSCRIPT References: [1] W. Geng, Y. Liu, X. Lou, F. Zhang, Q. Liu, B. Dkhil, M. Zhang, X. Ren, H. He, A. Jiang, Ceram. Int. 41 (2015) 289-295.
[2] H. Naceur, A. Megriche, M. Maaoui, J. Alloys Comp. 546 (2013) 145–150.
Solid State Commun. 115 (2000) 217-274.
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[3] A.P. Ramirez, M.A. Subramanian, M. Gardel, G. Blumberg, D. Li, T. Vogt, S.M. Shapiro,
[4] S.Y. Chung, I.D. Kim, S.J.L. Kang, Nat Mater. 3 (2004) 774-778.
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[5] A.P. Litvinchuk, C.L. Chen, N. Kolev, V.N. Popov, V.G. Hadjiev, M.N. Lliev, R.P.Bontchev, A.J. Jacobson, Phys. Status Solidi A. 195 (2003) 453–458.
B. 66 (2002) 52104–52105.
M AN U
[6] P. Lunkenheimer, V. Bobnar, A.V. Pronin, A.I. Ritus, A.A. Volkov, A. Loidi, Phys.Rev.
[7] T.B. Adams, D.C. Sinclair, A.R. West, Phys. Rev. B. 73 (2006) 094124. [8] D.C. Sinclair, T.B. Adams, F.D. Morrison, A.R. West, Appl. Phys. Lett. 80 (2002) 21532155.
[9] T.B. Adams, D.C. Sinclair, A. West, J. Am. Ceram.Soc.89 (2006) 3129-3135.
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[10] R. Schmidt, M.C. Stennet, N.C. Hyatt, J. Pokorny, J. Prado-Gonjal, M. Li, D.C. Sinclair, J. Eur.Ceram. Soc 32 (2012) 3313-3323.
(2012) 795-801.
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[11] P. Thongbai, B. Putasaeng, T. Yamwong , S. Maensiri, J. Mater. Sci .Mater .Electron 23.
[12] Q. Zhang, T. Li, Z. Chen, R. Xue, Y. Wang, Mater. Sci. Eng., B. 177 ( 2012) 168-172.
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[13] T. Li, R. Xue, J. Hao, Y. Xue, Z. Chen, J Alloys Compd. 509(2011) 1025-1028. [14] P. Thongbai, K. Meeporn, T. Yamwong, S. Maensiri, Mater. Lett. 106 (2013)129–132. [15] P. Thongbai, B. Putasaeng, T. Yamwong, V. Amornkitbamrung, S. Maensiri, J. Alloys Comp. 582 (2014) 747–753. [16] C.H. Zhang, K. Zhang, H.X. Xu, Q. Song, Y.T. Yang, R.H. Yu, D. Xu, X.N. Cheng, Trans. Nonferrous Met. Soc. China. 22 (2012) 127-132. [17] A.K. Raia, K.D. Mandala, D. Kumarb, O. Parkashb, J. Alloys Comp. 491 (2010) 507– 512].
ACCEPTED MANUSCRIPT [18] T. Li, J. Chen, D. Liu, Z. Zhang, Z. Chen, Z. Li, X. Cao, B. Wang, Ceram Int. 40 (2014) 9061–9067. [19] T. Li, D. Liu, H. Dai , H. Xiang, Z. Chen, H. He, Z. Chen, J. Alloys Comp. 599 (2014) 145–149. [20] W. Li, S.Y. Qiu, N. Chen, B.F. Liu, G.P. Du, Physica B. 405 (2010) 1193–1196.
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[21] H. Xue, X. Guan, R.Yu, Z. Xiong, J. Alloys Comp. 482 (2009) L14–L17. [22] Z. Yang, L. Zhang, X. Chao, L. Xiong, J. Liu, J. Alloys Comp. 509 (2011) 8716– 8719. [23] S. Senda, S. Rhouma, E. Torkani, A. Megriche, C. Autret, J. Alloys Comp. 698 (2017) 152-158.
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[24] J. Jumpatama, B. Putasaengb, T. Yamwongb, P. Thongbaia, S. Maensirie, Ceram. Int. 39 (2013) 1057–1064.
[25] A. Nautiyal, C. Autret, C. Honstettre, S. De Almeida-Didry, M. El Amrani, S. Roger,B.
M AN U
Negulescu, A. Ruyter, J. Eur.Ceram. Soc. 36 (2016) 1391-1398.
[26] N. Kolev, R.P Bontchev, A.J. Jacobson, V.N. Popov, V.G Hadjiev, AP Litvinchuk, MN Iliev, Phys Rev.B. 66 (2002) 132102.
[27] A.F.L. Almeida, P.B.A. Fechine, M.P.F. Graca, M.A. Valente, A.S.B. Sombra, J. Mater. Sci.-Mater. Electron. 20 (2009) 163-170.
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[28] T. Ohsaka, F. Izumi, Y. Fujiki, J. Raman spectrosc. 7 (1978) 321-324. [29] S. De Almeida-Didry, C. Autret, C. Honstettre, A. Lucas, M. Zaghrioui, F. Pacreau, F. Gervais, Solid State Sci. 61 (2016) 102-105.
[30] M.A. Sulaimain, S.D. Hutagalung, M.F. Ain, Z.A. Ahmad, J. Alloys Comp. 493 (2010)
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486-492.
[31] P. Thongbai, J. Jumpatam, T. Yamwong, S. Maensiri, J. Eur. Soc. 32 (2012) 2423-2430.
2263.
AC C
[32] P. Thongbai, B. Putasaeng, T. Yamwong, S. Maensiri, Mater. Res. Bull. 47 (2012) 2257-
[33] L. Ni, X.M. Chen, X.Q. Liu, Mater. Chem. Phys. 124 (2010) 982-986. [34] B.A. Bender, M.J. Pan, Mater. Sci. Eng., B. 117 (2005) 339-347. [35] L. Liu, H. Fan, P. Fang, X. Chen, Mater. Res. Bull. 43 (2008) 1800. [36] J. Jumpatam, B. Putasaeng, T. Yamwong, P. Thongbai, S. Maensiri, Ceram. Int. 39 (2013) 1057-1064. [37] F. Amaral, M.A. Valente, L.C. Costa, J. Non-Cryst. Solids. 356 (2010) 822-827. [38] S. De Almeida-Didry, C. Autret, A. Lucas, C. Honstettre, F. Pacreau, F. Gervais, J. Eur.Ceram. Soc. 34 (2014) 3649–3654.
ACCEPTED MANUSCRIPT [39] R. Xue, Z. Chen, H. Dai, D. Liu, T. Li, G.Zhao, Mater. Res. Bull.66 (2015) 254–261. [40] M. F. Ab Rahman, S. D. Hutagalung, Z. A. Ahmad, M. F. Ain, J. King .Saud .Univ.Sci. 28 (2016) 240-245. [41] M.H. WANG, B. ZHANG, F.ZHOU, J. Electron.Mater. 43(2014) 2607-2613. [42] C.H. Mu, P.Liu, Y.He, J.P. Zhou, H.W. Zhang, J. Alloys Comp. 471 (2009) 137–141.
Varela, J. Phys. D. Appl. Phys. 42 (2009) 055404.
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[43] P.R. Bueno, R. Tararan, R. Parra, E. Joanni, M.A. Ramirez, W.C. Ribeiro, E. Longo, J.
[44] Y.-H. Lin, J. Cai, M. Li, C.-W. Nan, J. He, Appl. Phys. Lett. 88 (17) (2006) 172902. [45] Y.-H. Lin, J. Cai, M. Li, C.-W. Nan, J. He, J. Appl. Phys. 103 (2008) 074111.
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[46] D.C. Sinclair, T.B. Adams, F.D. Morrison, A.R. West, Appl. Phys. Lett. 80 (2002) 2153. [47] P.Thongbai, T.Yamwong, S.Maensiri, Microelectron. Eng. 108 (2013) 177–181.
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[48] E.A. Patterson, S. Kwon, C.C. Huang, D.P. Cann, Appl. Phys. Lett. 87 (2005) 182911. [49] J. Y. Li, X.T. Zhao, S.T. Li, M.A. Alim, J. Appl. Phys. 108 (2010) 104104. [50] N. Daneu, S. Bernik, A. Recnik, J. Phys. Conf. 326 (2011) 012003. [51] M.A. Ramirez, P.R. Bueno, J.A. Varela, E. Longo. Appl. Phys.Lett. 89 (2006) 212102.
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[52] D. L. Sun, A.Y. Wu, S.T. Yin, J. Am.ceram.Soc.91 (2008) 169.
ACCEPTED MANUSCRIPT Fig.1. Profile fits for the Rietveld refinement of CCTO. Fig.2. X-Ray powder diffraction patterns of Ca1-xSrxCu3-yNiyTi4O12 (x=y=0, x=0.1, y=0; x=0, y=0.1 and x=y=0.1) samples sintered at 1100°C for 24 h. Fig.3. (a-d) SEM images of surface morphologies of CCTO, CSCTO, CCNTO and CSCNTO
Fig.4. Raman Spectra (a) on grains and on grain boundaries (b).
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ceramics samples. (e,f) EDS images of CSCTO and CCNTO samples.
Fig.5.Variation of dielectric constant ɛr (a) and dielectric loss (tanδ) (b) with frequency at
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Fig.6. (a) Impedance complex plane plot (z*) at 25°C for CCTO, CSCTO, CCNTO and CSCNTO ceramic samples (b) shows an expanded view of the high frequency data close to
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Fig.7. Nonlinear current-voltage behavior of Ca1-xSrxCu3-yNiyTi4O12 (x=y=0, x=0.1, y=0; x=0,
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ACCEPTED MANUSCRIPT Table 1 XRD patterns, εr and tan (δ) of pure CCTO, CSCTO, CCNTO and CSCNTO ceramics. Crystal system
Density
Average grain
Lattice
size (µm)
parameter (Ǻ)
εr at 1 KHz
tan(δ) at 1 KHz
Cubic
90.98
8.540
7.3945
15.800
0.14
CSCTO
Cubic
91.96
15.55
7.3970
29,660
0.084
CCNTO
Cubic
93.74
26.34
7.3915
42,370
0.069
CSCNTO
Cubic
94.30
35.50
7.3958
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44,410
0.070
ACCEPTED MANUSCRIPT Table 2 Resistance of grains (Rgrain) and grain boundaries (Rgrain b), Nonlinear coefficient (α), Breakdown electric field and Leakage current of Ca1-xSrxCu3-yNiyTi4O12 (x=y=0; x=0.1, y=0; x=0, y=0.1 and x=0.1, y=0.1) ceramics sintered at 1100°C for 24h. Samples
Rgrain(Ω)
Rgrain b(Ω)
α
Breakdown electric
CCTO
14.3
2.39 105
3.33
CSCTO
7.1
1.19 106
5.88
29
1.05 10
6
8.33
1.84 10
6
11.62
field (KV.Cm )
current(µA.cm-2)
1
300
0.6
200
0.58
130
0.31
100
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Leakage
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Highlights
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Structure of ceramic samples is remained Cubic. The grain size was increased by adding Sr2+ and Ni2+ doping ions. TiO2 phase revealed by Raman scattering in CCTO grain boundaries. (Sr,Ni) co-doped CCTO revealed the best dielectric properties at low frequency.
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• • • •
