Combustion Synthesis, Sintering, Characterization, and Properties

Home , Anatase, Calcium titanate

Hindawi Advances in Materials Science and Engineering Volume 2019, Article ID 9639016, 9 pages https://doi.org/10.1155/2019/9639016

Research Article Calcium Titanate from Food Waste: Combustion Synthesis, Sintering, Characterization, and Properties

Siriluk Cherdchom,1 Thitiwat Rattanaphan,1 and Tawat Chanadee 1,2

1Department of Materials Science and Technology, Faculty of Science, Prince of Songkla University (PSU), Hat Yai, Songkhla 90110, &ailand 2Ceramic and Composite Materials Engineering Research Group (CMERG), Center of Excellence in Materials Engineering (CEME), Prince of Songkla University (PSU), Hat Yai, Songkhla 90110, &ailand

Correspondence should be addressed to Tawat Chanadee; [email protected]

Received 31 August 2018; Revised 20 December 2018; Accepted 3 January 2019; Published 12 February 2019

Academic Editor: Andres Sotelo

Copyright © 2019 Siriluk Cherdchom et al. )is 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.

Calcium titanate (CaTiO3) was combustion synthesized from a calcium source of waste duck eggshell, anatase titanium dioxide (A-TiO2), and magnesium (Mg). )e eggshell and A-TiO2 were milled for 30 min in either a high-energy planetary mill or a conventional ball mill. )ese powders were then separately mixed with Mg in a ball mill. After synthesis, the combustion products were leached and then sintered to produce CaTiO3 ceramic. Analytical characterization of the as-leached combustion products revealed that the product of the combustion synthesis of duck eggshell + A-TiO2 that had been high-energy-milled for 30 min before synthesis comprised a single perovskite phase of CaTiO3. )e high-energy milling of the reactant powder had generated a large reactive surface area and induced structural defects, both of which drove the completion of the combustion reaction and the phase conversion of the reactants into the product. A calcium titanate ceramic, fabricated by sintering as-leached powdered combustion product at 1350°C for 180 min, achieved a maximum density of 3.65 g/cm3 and a minimum porosity of 0.54%. )e same fabricated calcium titanate ceramic product also exhibited the highest dielectric constant (∼78) and the lowest dielectric loss (∼0.02), which resulted from the simpliﬁed charge polarization process.

1. Introduction [10–14]. However, soft chemistry methods require complex starting materials and processes, while solid state and )e alkaline earth titanate, calcium titanate (CaTiO3), has mechanoactivated processes consume a lot of energy and attracted attention because it is semiconductive, ferroelec- time. Recently, the advantages of combustion synthesis over tric, and photorefractive. In addition, dielectrics based on other methods have seen it more widely used to synthesize calcium titanate are widely used in different high-frequency several ceramic materials. )e experimental set-up is un- electronic applications such as capacitors, oscillators, filters, complicated, the method is energy-efficient and also has a and resonators for microwave systems [1]. Several ap- short processing time, and a high-temperature furnace and proaches are adopted for the synthesis of calcium titanate large energy input are not required [15]. Moreover, except either by soft chemistry such as sol-gel or by hydrothermal for the necessary elements and metal oxides, waste materials, or solvothermal methods, coprecipitation, or organic- such as those from mining, agriculture, or food consump- inorganic solution [2–5]. High-temperature solid state tion, can be used as reactants because the high-exothermic synthesis of CaTiO3 has been conducted using mixtures of heat of the reaction eliminates the organic and traces in- calcium carbonate (CaCO3), calcium oxide (CaO), and ti- organic materials from the product. tanium dioxide (TiO2) [6–9] and also mechanoactivated )e objective of the present work was to synthesize synthesis has been carried out with various mixtures of calcium titanate (CaTiO3) by combustion synthesis using CaCO3, calcium hydroxide (Ca(OH)2), CaO, and TiO2 powdered duck eggshells and anataste titanium dioxide 2 Advances in Materials Science and Engineering

(A-TiO2) as starting materials and magnesium (Mg) as ∗ fuel. )e duck eggshell and A-TiO2 were mixed together for 30 minutes in either a high-energy planetary mill or a ball mill, and the synthesis products of the two diﬀerent reactant powders were compared. Finally, powdered calcium titanate products from the combustion syntheses were fabricated into monolithic ceramic samples by sintering at 1350°C for 60, 120, and 180 min of holding time. In addition, the various products were characterized (a.u.) Intensity in terms of phase composition, microstructure, and physical, thermal, and electrical properties. ∗ ∗∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗∗ ∗∗ 2. Experimental Procedure ∗ ∗ 20 25 30 35 40 45 50 55 60 65 70 75 80 2.1. Combustion Synthesis of Calcium Titanate Powder. 2θ (°) Duck eggshells, received from Trang province in )ailand, ∗ CaCO3 provided a source of calcium carbonate (CaCO3). XRD analysis in Figure 1 conﬁrmed that the as-received duck Figure 1: XRD pattern of as-received duck eggshell powder used in eggshell was composed entirely of calcium carbonate this work. (CaCO3: ICDD no. 00-005-0586). Anatase titanium dioxide (A-TiO2, 99.5%, <45 μm, Degussa AG) was used as a reactant because an anatase phase is an intermediate state of TiO2, which implies that A-TiO2 may be highly reactive [14]. In addition, magnesium (Mg, 99%, ∼45 μm, Riedel-Detlaen) was used as fuel. )e composition of the starting reaction used in the synthesis of calcium titanate was calculated from stoichiometric ratios and is expressed as follows: 25.4 mm

CaCO3(s) + TiO2(s) + Mg(s) ⟶ CaTiO3(s) + MgO(s) + CO(g) (a) (b) � . ° , Tad 2162 7 C Figure 2: Digital photographs of a typical (a) green pellet of the reactants and (b) as-combusted product. ΔH933.15 � −655.15 kJ/mol (1) time of about 20–30 seconds. Images of typical ignition, Duck eggshells were ground into a friable powder and propagation, relaxation, and cooling down stages of the sieved through a 325 mesh to give particles of 45 μm. Pow- combustion reaction are shown in Figure 3. )e reactant dered duck eggshell and A-TiO2 were high-energy-planetary- compact of ball-milled duck eggshell + A-TiO2/Mg, how- milled (Fritsch GMBH, Pulverisette 6, Germany) with an ever, had to be continually provided with heat from the oxy- Si3N4 vial and ball for 30 min at 400 rpm. )is procedure was acetylene flame because the system could not produce a self- adapted from the work of Palaniandy and Jamil [12]. )e sustained combustion reaction. )e inability of this reactant eggshell and A-TiO2 was also milled in a conventional ball compact to sustain self-propagated combustion was due to mill to obtain an alternative reactant powder for comparison. the low surface area of the duck eggshell + A-TiO2 mixture. )e ball- and high-energy-milled powder mixtures were then Being cooled to room temperature, the as-combusted separately mixed with Mg powder by ball milling for 120 min products (Figure 2(b)) were mechanically pestled into friable using a nylon vial and zirconia (ZrO2) ball. With a hydraulic powders in a ZrO2 mortar. In order to remove the by-products press (Huat Seng, 1939-15T, )ailand), 20 g of a reactant of magnesium oxide (MgO) and magnesium titanate powder mixture were uniaxially pressed at 5 psi into a pre- (MgTiO4), the as-combusted powders were leached using the hardened tooled steel mold to form a cylindrical pellet 2 M HCl solution for 120 min under moderate stirring. )e 25.4 mm in diameter, with a green body density 50–60% of the ratio of powdered product to leaching agent was 10 g :100 mL theoretical density (Figure 2(a)). )e experimental set-up was throughout the experiment. After leaching, the leached product schematically represented in a previous study [16] that used was filtered through filter paper coupled with a pump inlet and an oxy-acetylene flame as the external heat source. washed with deionized (DI) water several times in order to )e magnesiothermic reaction that took place within the adjust pH to 7.0 before final drying at 100°C in an oven. reactant compact of high-energy-milled duck eggshell + A- TiO2/Mg started after a short period of heating and, pre- ceded by a macroscopic combustion front, progressed 2.2. Sintering of Calcium Titanate Ceramic. To study the quickly in gravitational self-propagating mode along the sinterability of the powders obtained from the present entire reactant compact to form a final product in an average combustion method, 1.2 g of the as-prepared calcium Advances in Materials Science and Engineering 3

(a) (b) (c) (d)

Figure 3: Snapshot images illustrating the various stages of combustion reaction within reactant compact of high-energy-milled duck eggshell + A-TiO2/Mg carried out in air. (a) ignition, (b) self-combustion, (c) relaxation, and (d) final product. titanate powders was mixed with 3% polyvinyl alcohol Sintering (PVA) binder and pressed in a hydraulic press (CARVWR, 1350 60, 120, 180 min INC, 4128, USA), using a pressure of about 5 psi, to form a cylindrical pellet 15 mm in diameter. Following the research of Luo et al. [17], the pellet was then sintered at 1350°C for 5°C/min 60, 120, and 180 min of holding time under air atmosphere in a muffle furnace (Lenton, UAF16, USA). )e temperature Debinding 60 min profile of the sintering process is in Figure 4. (°C) Temperature 500 3°C/min

2.3. Characterizations. )e mean particle size of the duck 30 eggshell and A-TiO2 powder obtained by planetary milling and Time (min) ball milling was determined with a laser diffraction particle size Figure analyzer (LPSA, Beckman Coulter, LS 230, USA). To study the 4: Temperature profile of sintering for calcium titanate ceramics. combustion reaction mechanisms in the duck eggshells-TiO2- Mg system, the prepared mixed reactant powders were tested using simultaneous thermal analysis (STA, 449 F3, Jupiter, the water-saturated specimen, and weight in air of the water- Netzsch, Germany) in TG and DSC modes. )e samples were saturated specimen, respectively; and ρwater is the density of ° ° 3 heated from 30 to 1300 C at a rate of 10 C/min in the N2 water (1 g/cm ) [19]. atmosphere. )e morphologies of the as-combusted powder, as-leached powders, and as-sintered calcium titanate ceramics were characterized using scanning electron microscopy (SEM, 2.5. Dielectric Properties. For room temperature dielectric Quanta 400, FEI, USA). X-ray diffraction (XRD, X’ Pert, MPD studies, both flat surfaces of the sintered calcium titanate PHILIPS, the Netherlands) phase identification of all materials ceramic pellet were polished and the thickness controlled was carried at 40 kV, and 30 mA using CuKα radiation at ∼1 mm. Silver (Ag) paste electrodes were applied to the (0.15406 nm). )e average crystallite size was calculated from pellet, which was then dried at 50°C for 24 h. )e pellet was the Debye–Scherrer equation [18]: applied as a disc capacitor in which the sintered product was the dielectric medium. Capacitance was measured 0.9λ D � , (2) using an LCR meter (GW INSTEX, LCR-821, USA) within β cos θ the frequency range of 0 to 200 kHz. )e dielectric con- where D is the crystallite size, λ is X-ray the wavelength, β is stant was calculated according to the following equation the full width at half maximum (FWHM) of the peak in [9]: radians, and θ is Bragg’s angle. C d εr � , (5) ε0A

2.4. Density and Porosity Measurement. )e sintered density where εr is the dielectric constant, C is the equivalent parallel and apparent porosity of the calcium titanate ceramics were capacitance obtained from the data of measurement, d is the measured according to the Archimedes principle and can be thickness of the fabricated ceramic material, A is the calculated using equations (3) and (4), respectively: combined surface electrode area of the electrode discs, and ε0 −12 W is the permittivity of vacuum (8.85 ×10 F/m). )e di- D � 0 × ρ , (3) sintered W − W water electric loss obtained from the value of the dissipation factor 2 1 can be calculated from by the following equation [20]: W − W ε � D × ε , (6) P � 2 0 × 100%, (4) i r W2 − W1 where εi is the dielectric loss, D is the dissipation factor where Dsintered is the sintered density, P is the apparent obtained from data of measurement, and εr is obtained from density; W0,W1,W2 are the dry weight, weight in water of equation (5). 4 Advances in Materials Science and Engineering

3. Results and Discussion ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗∗ (b)

Figure 5 shows the XRD patterns of duck eggshell + A-TiO2 mixed by ball- and high-energy milling. )e diffraction peaks of the high-energy-milled sample have lower intensity and broader bases than the peaks of the ball-milled sample. )e main cause of the difference between the two diffraction patterns was the alteration to the crystal structure of the TiO2 and CaCO3 caused by the more intensive grinding process of the high-energy milling (a.u.) Intensity process. )e reduction of peak intensities implied the formation of a partially amorphous structure in the high- energy-milled powders [12], which was related to the al- (a) teration of long-range lattice periodicity caused by large numbers of dislocations and their related strain fields [21]. 20 25 30 35 40 45 50 55 60 65 70 75 80 However, no phase conversion occurred during the present 2θ (°) high-energy milling process. Also, the particle size of the ∗ CaCO powder mixture was 13.52 μm when high-energy milling 3 A-TiO2 was used, compared with 49.52 when ball milling was used Figure (Table 1). 5: XRD pattern of duck eggshell + A-TiO2 (a) ball-milled for Before the addition of the Mg powder fuel, the thermal 30 min and (b) high-energy-milled for 30 min. properties of the two duck eggshell + A-TiO2 mixtures were studied by TG and DSC techniques. )e TG thermograms Table show that the decomposition of calcium carbonate in both 1: Mean particle size of mixed duck eggshell + A-TiO2 ob- prepared powders occurred in a single step from 600°C tained from different milling processes. onwards (Figures 6(a) and 6(b)). )is step was initiated by Milling condition/time Mean particle size (μm) the release of carbon monoxide (CO) which gave rise to calcium oxide (CaO) [22]. In addition, the mass loss of the Ball-milled for 30 min 49.52 powder obtained from the high-energy milling was higher High-energy-milled for 30 min 13.52 than that of the ball milling, and the loss started and finished at lower temperature ranges as well. )e reactant mixture from 30-minute high-energy milling lost mass swiftly be- 105 ° ° tween about 620 C and 770 C, whereas the mixture from 30- 100 (a) minute ball milling, underwent most of its mass loss between (b) about 650 and 825°C. )is difference is attributable to the 95 larger reactive surface area of the high-energy-milled mix- 90 ture, which increased the thermal decomposition rate of 85 calcium carbonate. Reactant powders milled in both conditions produced 80 Mass (%) Mass large endothermic peaks in the DSC curves between 600 and 75 825°C (Figures 7(a) and 7(b)). )is endothermic reaction 70 was produced by the phase transformation of calcium carbonate to calcium oxide and the emission of carbon 65 monoxide [23], which is consistent with the TG data. After 60 the endothermic peak, an exothermic peak is present at a 50 200 350 500 650 800 950 1100 1250 higher temperature (about 1100°C), and this peak can be Temperature (°C) attributed to the reaction of calcium oxide with titanium Figure dioxide to form calcium titanate [8, 10, 13, 24]. Furthermore, 6: TG curves of duck eggshell + A-TiO2 (a) ball-milled for 30 min and (b) high-energy-milled for 30 min. the endothermic peak of the 30-minute high-energy ball- milled reactant mixture (Figure 7(b)) occurred at a lower temperature and the peak area was smaller than the peak )e diagram of a previous phase conversion between area of the 30-minute ball-milled reactant mixture CaO and TiO2 [8] indicated that the formation of stoi- (Figure 7(a)). )is tendency is regulated by energy accu- chiometric calcium titanate by solid state reaction typically mulation within or at the surface of crystals due to the limit occurred at a temperature above 1450°C after a long heating of fragmentation of particles [21]. )e TG and DSC analyses time. In this work, however, the incorporation of Mg fuel indicate that complete combustion was promoted by high- supported the reaction between the solid powders by re- energy ball-milled duck eggshell + A-TiO2 when Mg fuel was leasing heat from an exothermic reaction at the melting included in the reaction, which is further discussed in the point (660°C). Consequently, the reactants were simulta- next section. neously combusted to completion in a short time. Advances in Materials Science and Engineering 5

Exo

(b) (a) 50 200 350 500 650 800 950 1100 1250 Temperature (°C) 20 25 30 35 40 45 50 55 60 65 70 75 80 Figure 7: DSC measurements of duck eggshell + A-TiO2. (a) ball- 2θ (°) milled for 30 min and (b) high-energy-milled for 30 min. CaTiO3 MgO A-TiO2 MgTiO4 )e XRD patterns of the as-combusted products (ball- Figure 8: XRD patterns of the powder products synthesized in air (a) milled) indicate the presence of calcium titanate (CaTiO3: as-combusted product (ball-milled), (b) as-leached product from ICDD no. 01-074-8732), a by-product of magnesium oxide 30 min high-energy-milled duck eggshell + A-TiO2/Mg, and (c) as- (MgO: ICDD no. 01-089-4248), unreacted anatase titanium leached product from 30 min ball-milled duck eggshell + A-TiO2/Mg. dioxide (A-TiO2: ICDD no. 03-065-5714), and a minor unstable phase of magnesium titanate (MgTiO4: ICDD no. 00-025-1157) (Figure 8(a)). )e XRD pattern of the as- porosity against holding time shows that longer holding time leached product synthesized from ball-milled duck resulted in calcium titanate ceramics of greater sintered eggshell + A-TiO2/Mg (Figure 8(b)) indicates calcium tita- density. Long holding time facilitated tenacious migration of nate coupled with a large amount of unreacted titanium calcium titanate particles and led to closer packing of the dioxide and unstable magnesium titanate, whereas the as- calcium titanate particles. On the other hand, the apparent leached product synthesized from high-energy-milled duck porosity was dramatically reduced by increasing holding eggshell + A-TiO2/Mg (Figure 8(c)) presents calcium titanate time from 60 to 180 min. )is result agrees well with the as a major phase with a small amount of unreacted titanium SEM images in Figures 12(a), 12(c), and 12(e). In addition, dioxide. )e reason why more calcium titanate appears in the SEM micrographs shown in Figures 12(b), 12(d), and Figure 8(c) than Figure 8(b) is that the mechanical activation 12(f) indicate that the microstructure was also dependent on produced by high-energy milling developed more surface the holding time. At a holding time of 60 min, a well-sintered area as well as various sorts of structural defects in the sample could not be obtained. At a holding time of 120 min, reactant powders, which increased the chemical reactivity of a relatively uniform grain size of approximately 2-3 μm the solid compact. could be achieved. However, the grain size increased to Typical SEM images of the combustion product before about 5-6 μm and exhibited abnormal grain growth when leaching (Figure 9(a)) reveal agglomerated particles which the holding time was increased to 180 min. )is occurred included distinct phases, but, in the images taken after the because the longer holding time can enlarge the diffusion leaching out of by-products (Figure 9(b)), the fast growth coefficient and make grain boundary migration easier [18]. time and cooling rate of the combustion reaction appear to )e dielectric constant and dielectric loss of all samples have produced fine particles in a submicron size range. of sintered CaTiO3 ceramic decreased when the frequency XRD patterns of the calcium titanate ceramics sintered was increased (Figures 13(a) and 13(b)). )e reduction in the at 1350°C with different holding times (Figure 10) show dielectric constant with increased frequency can be attrib- that all the calcium titanate ceramic samples had a pe- uted to the lagging of the dipoles in the material, which is a rovskite phase structure (CaTiO3: ICDD no. 01-074-8732) typical Debye-type behavior exhibited by most dielectric with an orthorhombic crystal system (space group: materials [9]. )e available Ti ions on the octahedral sites in Pbnm). However, low amount of secondary phases of calcium titanate were at maximum polarization at low titanium dioxide in an anatase structure (A-TiO2: ICDD frequencies. As the applied frequency increased, the po- no. 03-065-5714) is present. )e increments of holding larized Ti ions could not respond to the changing frequency time from 60 to 180 min slightly increased the average and orientation polarization was arrested. As a result, the crystal size (from 47.40 to 47.94 nm) without changing the dielectric constant and the capacitance were reduced [7, 25]. crystal system. )e highest dielectric constant (∼78) and lowest dielectric )e density and porosity of the sintered calcium titanate loss (∼0.02) at a frequency of 200 kHz occurred in calcium ceramic were approximately dependent on holding time titanate, sintered at 1350°C with a holding time of 180 min. (Figure 11). )e plot of sintered density and apparent )ese results were attributed to the denser structure of the 6 Advances in Materials Science and Engineering

(a) (b)

Figure 9: SEM micrographs of the (a) as-combusted and (b) as-leached product particles.

(a)

20 25 30 35 40 45 50 55 60 65 70 75 80 2θ (°)

CaTiO3 A-TiO2

Figure 10: XRD patterns of calcium titanate ceramic sintered at 1350°C in air with diﬀerent holding times (a) 60, (b) 120, and (c) 180 min.

4.00 40 3.63 3.65 3.50 35.09 35

3.00 30 ) 3 2.50 2.54 25

2.00 20

1.50 15 (%) Porosity Density (g/cm Density 1.00 10

0.50 5 0.54 0.00 0.68 0 60 120 180 Holding time (min)

Figure 11: Eﬀect of holding time on the sintered density and porosity of calcium titanate ceramics sintered at 1350°C in air. Advances in Materials Science and Engineering 7

(a) (b)

(e) (f)

Figure 12: SEM images of the microstructure of calcium titanate ceramics sintered at 1350°C in air represent fracture and top surface with diﬀerent holding times (a, b) 60, (c, d) 120, and (e, f) 180 min.

material and the fewer defects (pores) present in it. )e high dioxide (A-TiO2) and using magnesium (Mg) as fuel. Based density of the sample simpliﬁed the process of charge po- on the experimental results and analysis, the following larization, resulting in a larger dielectric constant [17, 26]. conclusions are presented: )e as-leached product from 30-minute high-energy 4. Conclusions milling of duck eggshell + A-TiO2 showed a single perovskite phase of CaTiO3. )e high-energy milling promoted In the present work, calcium titanate (CaTiO3) was suc- the generation of a large reactive surface area and increased cessfully synthesized by combustion synthesis utilizing duck the structural defects in the reactant powder. )ese physical eggshell, as a source of calcium, mixed with anatase titanium changes drove the combustion reaction to completion in a 8 Advances in Materials Science and Engineering

130 1 120 0.9 110 0.8 100 0.7 90 0.6 r ε i 0.5 80 ε 0.4 70 0.3 60 0.2 50 0.1 40 0 0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 160 180 200 Frequency (kHz) Frequency (kHz)

120 min 120 min 180 min 180 min 60 min 60 min

(a) (b) Figure 13: Variation of dielectric constant εr (a) and dielectric loss εi (b) as a function of frequency with different holding times. self-propagating mode and improved the phase conversion by plasma spray and post-deposition thermal treatment,” of the reactants into the product. Materials Research Bulletin, vol. 72, pp. 123–132, 2015. )e highest density (3.65 g/cm3) and lowest porosity [2] P. K. Mallik, G. Biswal, S. C. Patnaik, and S. K. Senapati, (0.54%) of the fabricated calcium titanate ceramics were “Characterisation of sol-gel synthesis of phase pure CaTiO3 achieved by sintering the as-leached powdered combustion nano powders after drying,” IOP Conference Series: Materials product at 1350°C for 180 min. Science and Engineering, vol. 75, no. 012005, pp. 1–6, 2015. [3] S. Holliday and A. Stanishevsky, “Crystallization of CaTiO by )e densified calcium titanate ceramics sintered at 3 sol-gel synthesis and rapid thermal processing,” Surface and 1350°C for 180 min also exhibited a high dielectric constant Coatings Technology, vol. 188-189, pp. 741–744, 2004. (∼78) with a low dielectric loss (∼0.02) due to the simpli- [4] D. Wang, Z. Guo, Y. Chen, J. Hao, and W. Liu, “In situ fication of the charge polarization process. hydrothermal synthesis of nanolamellate CaTiO3 with con- trollable structures and wettability,” Inorganic Chemistry, Data Availability vol. 46, no. 19, pp. 7707–7709, 2007. [5] W. Dong, G. Zhao, Q. Bao, and X. Gu, “Solvothermal )e data used to support the findings of this study are in- preparation of CaTiO3 prism and CaTi2O4(OH)2 nanosheet cluded within the article. by a facile surfactant-free method,” Materials Science (Medziagotyra)ˇ , vol. 21, no. 4, pp. 583–585, 2015. [6] G. Gralik, C. Zanelli, F. Raupp-Pereira, M. Dondi, Conflicts of Interest J. A. Labrincha, and D. Hotza, “Formation and quantification of calcium titanate with the perovskite structure from alter- )e authors declare that there are no conflicts of interest native sources of titanium,” in Proceedings of 21 Congresso regarding the publication of this paper. Brasileiro de Engenharia e Cienciaˆ dos Materiais, pp. 504–510, Armação de Buzios, RJ, Brazil, October 2014. Acknowledgments [7] M. Sh. Khali and F. F. Hammad, “Influence of Cu addition on the structure and dielectric properties of CaTiO3,” Egyptian )is work was financially supported by Faculty of Science, Journal of Solids, vol. 25, no. 2, pp. 175–183, 2002. Prince of Songkla University, under the revenue budget for [8] G. Gralik, A. )omsen, C. Moraes, F. Raupp-Pereira, and fiscal year 2017. )e authors would like to thank Dr. Sao- D. Hotza, “Processing and characterization of CaTiO3 perovskite ceramics,” Processing and Application of Ceramics, wanee Singsarothai for providing the oxy-acetylene set and vol. 8, no. 2, pp. 53–57, 2014. Assist. Prof. Dr. Pornsuda bomlai for providing the LCR [9] S. J. Mousavi, “)e effect of sintering time on the electrical meter. Sincere thanks and appreciation are extended to Mr. properties of CaTiO3 ceramics,” Digest Journal of Nano- )omas Duncan Coyne for editing and proofreading English materials and Biostructures, vol. 9, no. 3, pp. 1059–1063, 2014. in this article. [10] K. Wieczorek-Ciurowa, P. Dulian, A. Nosal, and J. Domagała, “Effects of reagents’ nature on mechanochemical synthesis of References calcium titanate,” Journal of &ermal Analysis and Calorim- etry, vol. 101, pp. 471–477, 2010. [1] P. Ctibor, J. Kotlan, Z. Pala, J. Sedlacek, Z. Hajkova, and [11] K. H. Park and H. G. Kim, “Improvement of the formation T. M. Grygar, “Calcium titanate (CaTiO3) dielectrics prepared and the thermal properties of CaTiO3 fabricated from a Advances in Materials Science and Engineering 9

CaO-TiO2 mixture by using the mechanochemical method,” Journal of Korean Physical Society, vol. 56, no. 2, pp. 648–652, 2010. [12] S. Palaniandy and N. H. Jamil, “Influence of milling conditions on the mechanochemical synthesis of CaTiO3 nano- particles,” Journal of Alloys and Compounds, vol. 476, no. 1-2, pp. 894–902, 2009. [13] V. Berbenni and A. Marini, “Mechanical activation of calcium titanate formation from CaCO3-TiO2 mixtures,” Journal of Materials Science, vol. 39, no. 16-17, pp. 5279–5282, 2004. [14] G. Mi, Y. Murakami, D. Shindo, and F. Saito, “Mechano- chemical synthesis of CaTiO3 from a CaO-TiO2 mixture and its HR-TEM observation,” Powder Technology, vol. 105, no. 1–3, pp. 162–166, 1999. [15] T. Chanadee, “SHS synthesis of Si-SiC composite powders using Mg and reactants from industrial waste,” Metals and Materials International, vol. 23, no. 6, pp. 1188–1196, 2017. [16] T. Chanadee, “Combustion synthesis of nickel-ferrite mag- netic materials,” International Journal of Self-Propagating High-Temperature Synthesis, vol. 26, no. 1, pp. 40–43, 2017. [17] T. Luo, B. Li, Q. Zhao, and J. Zhou, “Dielectric behavior of low microwave loss unit cell for all dielectric metamaterial,” In- ternational Journal of Antennas and Propagation, vol. 2015, no. 291234, pp. 1–6, 2015. [18] W. Kayaphan and P. Bomlai, “Microstructural and electrical properties of Sn-modified BaTiO3 lead-free ceramics by two- step sintering method,” Advances in Materials Science and Engineering, vol. 2018, Article ID 9048062, 6 pages, 2018. [19] J. Jakic, G. Stefanic, M. Labor, and V. Martinac, “Micro- structural characteristics of low-temperature (1400°C) sintered MgO obtained from seawater,” Science of Sintering, vol. 49, no. 1, pp. 61–71, 2017. [20] K. Omar, M. D. Johan Ooi, and M. M. Hassin, “Investigation on dielectric constant of zinc oxide,” Modern Applied Science, vol. 3, no. 2, pp. 110–116, 2009. [21] T. T. Parlak, F. Apaydin, and K. Yildiz, “Formation of SrTiO3 in mechanically activated SrCO3-TiO2 system,” Journal of &ermal Analysis and Calorimetry, vol. 127, no. 1, pp. 63–69, 2017. [22] F. S. Murakami, P. O. Rodrigues, C. M. T. d. Campos, and M. A. S. Silva, “Physicochemical study of CaCO3 from egg shells,” Cienciaˆ e Tecnologia de Alimentos, vol. 27, no. 7, pp. 658–662, 2007. [23] N. Tangboriboon, R. Kunanuruksapong, and A. Sirivat, “Preparation and properties of calcium oxide from eggshells via calcination,” Materials Science-Poland, vol. 30, no. 4, pp. 313–322, 2012. [24] P. Julphunthong, B. Phengraek, A. Laowanidwatana, and T. Bongkarn, “Low temperature fabrication of dense calcium titanate ceramics via combustion technique,” Integrated Ferroelectrics, vol. 150, no. 1, pp. 107–115, 2014. [25] D. Sandi, A. Supriyanto, A. Jamaluddin, and Y. Iriani, “)e effects of sintering temperature on dielectric constant of barium titanate (BaTiO3),” IOP Conference Series: Materials Science and Engineering, vol. 107, no. 012069, pp. 1–6, 2016. [26] A. Maddu, L. Permatasari, and A. Arif, “Structural and dielectric properties of CaTiO3 synthesized utilizing Duck’s eggshell as a calcium source,” Journal of Ceramic Processing Research, vol. 18, no. 2, pp. 146–150, 2017. NanomaterialsJournal of

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