Browsing by Author "K.D. Mandal"

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Chemistry of organic eutectics and 1:1 addition compound: p-phenylenediamine-catechol system
(1989) U.S. Rai; K.D. Mandal
The phase diagram of the p-phenylenediamine-catechol system, determined by the thaw-melt method, shows the formation of a 1:1 molecular compound and two eutectics. The linear velocities of crystallization of the pure components, the eutectics and the addition compound, determined by measuring the rate of movement of the growth front in a capillary, suggest that crystallization data obey the Hillig-Turnbull equation v = u(ΔT)n. where u and n are constants and ΔT is the undercooling. Experimental values of the heats of fusion and the entropy of fusion and calculated excess thermodynamic functions were considered and the results were explained on the basis of cluster formation in the eutectic melt. X-ray diffraction data of the pure components, the eutectics and the addition com- pound infer that these eutectics are not simply a mechanical mixture of the two components; preferential ordering of atomic planes occurs during their formation. The IR studies carried out on this system suggest intermolecular hydrogen bonding between the two components which form the molecular compound. © 1989.
Comparative Dielectric and Ferroelectric Characteristics of Bi0.5Na0.5TiO3, CaCu3Ti4O12, and 0.5Bi0.5Na0.5TiO3–0.5CaCu3Ti4O12 Electroceramics
(Springer New York LLC, 2016) Laxman Singh; Shiva Sundar Yadava; Byung Cheol Sin; Uma Shanker Rai; K.D. Mandal; Youngil Lee
Abstract: The dielectric and ferroelectric characteristics of Bi0.5Na0.5TiO3 (BNT), CaCu3Ti4O12 (CCTO), and 0.5Bi0.5Na0.5TiO3–0.5CaCu3Ti4O12 (BNT/CCTO) ceramics are compared. X-ray diffraction patterns confirmed the formation of single phase of all the ceramics after sintering at 950°C for 15 h. Scanning electron microscopy images of the sintered ceramics reveal average grain sizes in the range from 200 nm to 2.5 μm. Energy-dispersive x-ray mapping and x-ray photoelectron spectroscopy show the presence of the elements Bi, Na, Ca, Cu, Ti, and O with uniform distribution in the ceramics. BNT/CCTO exhibits high dielectric constant (εr ∼ 6.9 × 104) compared with BNT (εr ∼ 0.13 × 104) and CCTO (εr ∼ 1.68 × 104) ceramics at 1 kHz and 503 K. The high dielectric constant of BNT/CCTO compared with BNT and CCTO is associated with a major contribution from grain boundaries, as confirmed by impedance and modulus analyses. The P–E hysteresis loop of all the ceramics measured at room temperature and 50°C exhibited typical ferroelectric nature. The remanent polarization (Pr) of BNT (1.58 μC/cm2) and CCTO (0.654 μC/cm2) ceramics are higher than that of BNT/CCTO (0.267 μC/cm2) ceramic. Graphical Abstract: [Figure not available: see fulltext.] © 2016, The Minerals, Metals & Materials Society.
Dielectric and ac impedance studies of nanostructured CaCu 3Ti3.90Ce0.10O12 electro-ceramic synthesized by citrate-gel route
(2013) K.D. Mandal; Laxman Singh; Sunita Sharma; U.S. Rai; M.M. Singh
Effect of doping at Ti4+ site by Ce3+ has been examined in CaCu3Ti3.90Ce0.10O12 synthesized by citrate-gel route. DTA/TG analysis of dry powder gives pre-information about formation of final product around 850 C. X ray diffraction analysis confirmed the formation of CaCu3Ti3.90Ce 0.10O12 phase of the ceramic sintered at 950 C for 12 h. Microstructure has been studied using scanning electron microscopy and confirmed the average grain size found in nano range 200-400 nm in system CaCu 3Ti3.90Ce0.10O12.The nature of relaxation behavior of ceramic was also rationalized by using the impedance and modulus spectroscopy. The bulk conductivity indicates an Arrhenius-type thermally activated process. The ac conductivity spectrum obeyed the Jonscher power law. The complex impedance diagrams of the ceramic exhibited a significant contribution from the grains, grain boundaries and electrode. The activation energies calculated from the grain-boundary relaxation time constant was found to be 0.49 eV which confirmed the Maxwell-Wagner type of relaxation present in the ceramic. © 2013 Springer Science+Business Media New York.
Dielectric and electrical properties measurement of BCTO and Co & V-doped BCTO synthesized via semi-wet route method
(Springer, 2023) Anup Kumar; Vinod Kumar; Manish Kumar Verma; Vishnu Shankar Rai; Dinesh Prajapati; Biswajit Jena; Dipendra Kumar Verma; Poonam Kumari; D. Tiwary; K.D. Mandal
Bi2/3Cu3Ti4O12 (BCTO) and Bi2/3Cu3Ti3.95Co0.025V0.025O12 (BCTCVO) Ceramic was synthesized by using a cost-effective novel semi-wet route method. The phase formation was confirmed by XRD analysis with traces of TiO2 and CuO phases of BCTO and BCTCVO ceramic. The average crystallite sizes of BCTO and BCTCVO ceramic were found to be 40.49 and 39.72 nm, respectively. XPS studies confirm the oxidation state of each elements in appropriate oxidation state. Elemental analysis was performed by EDS. It was observed that the maximum dielectric constant values of BCTO and BCTCVO ceramic were 3372 and 1663 at 523 K and at 1 kHz. The value of dielectric constant was observed very low at higher frequency. Tangent loss values of BCTO and BCTCVO ceramic were found 3.67 and 2.39 at 523 K and 1 kHz, respectively. © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Dielectric and Electrical sensing behavior of undoped and doped complex perovskite oxide
(SPIE, 2023) Vishnu Shankar Rai; Shrikrishna Dutta Verma; Anup Kuma; K.D. Mandal; Meghan Brandt; N.B. Singh
CuY2Ti4O12 (CYTO) crystalline ceramic was successfully prepared through semi-wet route. The phase formation of CYTO ceramic was confirmed by powder X-ray diffraction studies with minor secondary phases formation of Y2O3 and Cu2Ti2O5. In the higher frequency section, the dielectric permittivity and tangent loss are temperature independent, whereas in the lower frequency section, these properties are temperature dependent. The dielectric constant of CYTO was determined as 1.2 x 104 at 100 Hz and 500 K. The dielectric loss of CYTO ceramic was found 0.75 at 10 kHz and 423 K. The dielectric constant and tangent loss both reduce with rising frequency in the lower frequency regions, while these are almost constant in the higher frequency regions. Impedance properties were used to check the grain and grain boundary phenomena in this ceramic. The presence of temperature dependent Maxwell-Wagner type relaxation was established by Impedance investigation of CYTO ceramic. © 2023 SPIE.
Dielectric behavior of CaCu3Ti4O12 electro-ceramic doped with La, Mn and Ni synthesized by modified citrate-gel route
(Tsinghua University, 2013) Laxman Singh; U.S. Rai; Alok Kumar Rai; K.D. Mandal
The effect of La3+, Mn2+ and Ni2+ doped calcium copper titanate, CaCu3Ti4O12 (CCTO), at higher concentrations (CR1 and CR2 with 5 mol% and 10 mol%, respectively), has been examined by semi-wet route at relatively lower temperature. This semi-wet route employs citrate-nitrate gel chemical method using TiO2 solid powders. X-ray diffraction (XRD) analysis confirms the formation of single phase in the doped samples sintered at 900 °C for 8 h. Scanning electron micrographs (SEM) show that the average grain size for CR2 is larger than that of CR1 composition. The energy dispersive X-ray spectroscopy (EDX) is used to study the percentage compositions of different ions present in both ceramics. Dielectric constant (ɛr) and dielectric loss (tanδ) values of CR1 are comparatively higher than those of CR2 ceramic at all measured frequencies and temperatures. The nature of temperature-dependent relaxation behavior of the ceramics is also studied by impedance, modulus spectroscopic analysis and confirms Maxwell-Wagner relaxation. © 2013, The Author(s).
Dielectric properties of CaCu3-xMgxTi4O12 (x=0.20 and 0.50) material synthesized by the semi-wet route for energy storage capacitor
(SPIE, 2019) Laxman Singh; U.S. Rai; N.B. Singh; Y. Lee; D.K. Mahato; Divyanshu Bhardwaj; K.D. Mandal
Dielectric properties of high percentage Mg doped CaCu3Ti4O12, CaCu3-xMgxTi4O12 (x=0.20 and 0.50) ceramics carried out. They were synthesized by the semi-wet route using a solution based citrate-nitrate method along with inexpensive solid TiO2 powder. X-ray diffraction analysis reveals that the ceramics form single phase when sintered at 950 °C for 12h. SEM analyses show the smooth surfaces of grains with a spherical appearance. The grains of CCMTO2 and CCMTO5 ceramics were found to be in the size range of 1-5 μm and 1-3 μm, respectively. Dielectric studies show that the CCMTO2 ceramic has higher value of dielectric constant and lower dielectric loss in comparison to that of CCMTO5. © 2019 SPIE. Downloading of the abstract is permitted for personal use only.
Dielectric properties of zinc doped nanocrystalline calcium copper titanate synthesized by different approach
(2013) Laxman Singh; U.S. Rai; K.D. Mandal
Zinc doped calcium copper titanate, CaCu2.90Zn 0.10Ti4O12 (CCZTO), nanocrystalline electro-ceramics synthesized by solution-wet route (SR) as well as semi-wet route using citric acid (SWR1) and glycine (SWR2) separately, were characterized by TGA/DTA, XRD, TEM, SEM and EDX techniques. The crystallite sizes of the ceramics obtained by XRD were found to be in the range of 45-90 nm is in good agreement with those observed by TEM analysis. The grain sizes for the ceramics SWR1, SWR2 and SR observed by SEM were found in the range of 10-15 μm, 1-4 μm, and 2-4 μm, respectively. Thermal studies show that the single phase CCZTO ceramic was formed in single step combustion reaction in SWR2 while in the case of SWR1 and SR were obtained in multistep reactions. SWR2 route shows more effective solid state reaction for the formation of nanocrystalline CCZTO single phase at much lower sintering temperature. SWR1 ceramic exhibits higher dielectric constant (εr ∼ 4317) than SWR2 and SR ceramics at room temperature. © 2013 Elsevier Ltd.
Dielectric, modulus and impedance spectroscopic studies of nanostructured CaCu2.70Mg0.30Ti4O12 electro-ceramic synthesized by modified sol-gel route
(2013) L. Singh; U.S. Rai; K.D. Mandal
Effect of doping of Mg2+ at Cu2+ site has been examined in CaCu3Ti4O12. CaCu 2.70Mg.30Ti4O12 was synthesized by semi- wet chemical method, for the first time, using solid TiO2 and metal nitrate solutions. XRD analysis confirmed the formation of single-phase material, and the structure does not change on doping of Mg and it remains cubic similar to CaCu3Ti4O12 (CCTO). The average particle size in sintered powder of the ceramic obtained from XRD and Transmission electron microscopy (TEM) was found 59 ± 05 and 90 ± 25 nm, respectively. SEM image shows the presence of bimodal grains while EDX analysis confirmed copper oxide rich phase a grain boundary. We found exceptionally very high dielectric constant 86,084 at 500 K on partially substituted Mg2+ at Cu-site in CCTO ceramic at 1 kHz. The nature of relaxation behavior of the ceramic was also rationalized by impedance and modulus spectroscopic analysis. Modulus spectroscopic studies confirmed the Maxwell-Wagner relaxation arising due to the interfaces between grain and grain boundary. © 2012 Elsevier B.V. All rights reserved.
Effect of processing routes on microstructure, electrical and dielectric behavior of Mg-doped CaCu3Ti4O12 electro-ceramic
(2013) Laxman Singh; U.S. Rai; K.D. Mandal; Alok Kumar Rai
In the present communication, data on magnesium-doped calcium copper titanate CaCu2.90Mg0.10Ti4O12 (CCMTO) electro-ceramic, synthesized by the semi-wet route (SWR), ball-milled route (BMR) and solid-state route (SSR), is characterized by TG-DTA, XRD, SEM, EDX and TEM techniques. XRD confirmed the formation of single phase in CCMTO ceramic. The CuO phase present at grain boundaries in SWR ceramic was shown by the SEM micrograph, which was verified by EDX. The TEM image of SWR ceramic shows nanocrystalline particles in the range 80±20 nm. The value of the dielectric constant of SWR (ε r ∼20091) ceramic is higher than those of BMR and SSR (ε r ∼1247) ceramics at 1 kHz at 450 K. A dielectric relaxation has been observed in the frequency range 100 Hz-100 kHz. The high-temperature dielectric dispersion shows one large low-frequency response and two Debye-type relaxations. The impedance and modulus studies show the highest grain-boundary resistance for BMR ceramic. © 2012 Springer-Verlag Berlin Heidelberg.
Effect of site selection on dielectric properties of Fe doped CaCu 3Ti4O12 electro-ceramic synthesized by citrate nitrate gel route
(Scientific Publishers, 2014) L. Singh; K.D. Mandal; U.S. Rai; A.K. Rai
The effect of doping of Fe at Cu2+ and Ti4+ sites in calcium copper titanate, CaCu3Ti4O12, has been examined. The compositions CaCu3-xFexTi4O 12 (CCFTO) and CaCu3Ti4-xFexO 12 (CCTFO), (x = 0.10) have been synthesized by citrate nitrate gel route. XRD analysis confirms the formation of single- phase ceramics on sintering at 900°C for 8 h. Structure of CaCu3Ti 4O12 does not change on doping with iron on Cu-site or Ti-site and it remains cubic. Surface morphology indicates that the average grain size is in range of 30-90 μm and 5-7 μm for systems CCFTO and CCTFO, respectively. EDX studies confirm the presence of Ca2+, Cu 2+, Ti4+ and Fe3+ ions as per stoichiometry of ceramics. The grain resistance of CCTFO is higher than that of CCFTO. Values of dielectric constant (εr) and dielectric loss (tanδ) of CCTFO are higher than those of CCFTO ceramic at all measured frequencies and temperatures. © 2014 Indian Association for the Cultivation of Science.
Evolution of microstructure, dielectric, and electrical properties of Nd-doped BCTO synthesized via semi-wet route
(Springer Science and Business Media B.V., 2024) Dinesh Prajapati; Vishnu Shankar Rai; Biswajit Jena; Harish Verma; Atendra Kumar; N.B. Singh; K.D. Mandal
The Bi(2/3)-xNdxCu3Ti4O12 (BNCTO) ceramic with few selected concentrations (x = 0.05, 0.10, and 0.20) was fabricated through semi-wet route. The structural properties of synthesized compounds were examined using X-ray diffraction, followed by Rietveld refinement with a space group of Im-3. The crystallite size observed from X-ray diffraction was found in decreasing order with an increase in dopant concentration of Nd3+ ions in to BCTO ceramic. Scanning electron microscopy (SEM), energy-dispersive spectra (EDS), atomic force microscope (AFM), and X-photoelectron spectroscopy (XPS) were used to study the surface morphology, elemental compositions, surface roughness, and electronic state, respectively. Surprisingly, Nd doping can result in an exceptionally low dielectric loss (tan δ), with a minimum value of 0.05 at 1 kHz and 303 K for BNCTO-0.2. These findings show that Nd doping is more favorable to dielectric characteristics, introducing increased grain boundary resistance, activation energy, and lower conductivity. © The Author(s), under exclusive licence to Springer Nature B.V. 2024.
Influence of Zn doping on microstructures and dielectric properties in CaCu 3Ti 4O 12 ceramic synthesised by semiwet route
(2012) L. Singh; U.S. Rai; K.D. Mandal
A single phase of calcium copper titanate [CaCu 3Ti 4O 12 (CCTO)] was produced at lower temperature and shorter calcination time via a novel semiwet route. Undoped CCTO and zinc doped CaCu 3-xZn xTi 4O 12 samples with x=0·10, 0·20 and 0·30 were prepared by this method for the first time using solid TiO 2 powder in metal nitrate solutions. The CaCu 3-xZn xTi 4O 12 ceramics were characterised by thermogravimetric/differential thermal analysis, X-ray diffraction, SEM and EDX techniques. The SEM images of the sintered CaCu 3-xZn xTi 4O 12 ceramics showed average grain size in the ranges of 2-6, 8-13, 12-16 and 14-20 μm for x=0·00, 0·10, 0·20 and 0·30 respectively. Energy dispersive X-ray spectroscopy studies confirm the purity of parent and Zn doped CCTO ceramics. At room temperature, the dielectric constants of Zn doped CCTO are always higher than pure CCTO. CaCu 3-xZn xTi 4O 12 (x=0·20) ceramic has the maximum value of ε r≈4347 along with the minimum value of tan δ≈0·14 at 1 kHz. © 2012 Institute of Materials, Minerals and Mining.
Low temperature processing of dielectric perovskites for energy storage
(SPIE, 2016) N.B. Singh; Ben Schreib; Michael Devilbiss; Julian Loiacono; Bradley Arnold; Fow-Sen Choa; K.D. Mandal
Since the report of high dielectric value was published for the calcium copper titanate of the stoichiometry CaCu3Ti4O12 (CCTO), several of its analogs such as Yittrium copper titanate Y2/3Cu3Ti4O12 (YCTO), Pr2/3Cu3Ti4O12 (PCTO) and several other compounds have been studied extensively. Most of these materials have demonstrated very high dielectric constants. However, the roadblock is their low resistivity. To overcome this problem, several approaches have been considered, including doping and substitution. In order to solve this problem, we have synthesized the stoichiometric composition and used low temperature processing to grow grains of La2/3Cu3Ti4O12 (LCTO) stoichiometric compound. LCTO with excess copper oxide was also prepared to determine its effect on the morphology and dielectric constant of the stoichiometric LCTO compound. In spite of the low melting point of copper oxide, we observed that excess copper oxide did not show any faster grain growth. Also, the dielectric constant of LCTO was lower than CCTO and unlike CCTO, LCTO showed significant changes as the function of frequency. The measured resistivity was slightly higher than CCTO. © 2016 SPIE.
Morphological evolution and transition at nanoscale in BSTO ceramic materials
(Taylor and Francis Ltd., 2023) N.B. Singh; Ching Hua Su; Fow-Sen Choa; Bradley Arnold; Brian Cullum; K.D. Mandal
Considerable efforts have been devoted since the past three decades for the development of low cost ferroelectric and clean energy storage multifunctional materials. Modification in design and production of a low cost material with well proven process provides pathway for high energy density dielectric energy storage. We studied fluorine doped a commercially well-established material system barium strontium titanate with two different concentrations of dopants and studied the morphological transition and its effect on properties. It was observed that sample with higher concentration transitioned much faster into glassy state, followed by growth of fibers which turned into a self-arranged bird nest type shape. The sample with lower concentration changed slowly into glassy state and only few fibers were farmed. Dielectric was highly dependent on processing methods and shows variation with crystallinity of material, temperature, and cooling conditions during processing. In the higher concentration range, we observed nano-scale interface breakdown very similar to that of solid-liquid interface breakdown during crystal growth. © 2023 Taylor & Francis Group, LLC.
Phase Evolution, Dielectric, and Electric Behavior of Sm-Doped BCTO Ceramic Fabricated by Semi-Wet Method
(John Wiley and Sons Inc, 2024) Dinesh Prajapati; Vishnu Shankar Rai; Atendra Kumar; N.B. Singh; Harish Verma; Shail Upadhyay; K.D. Mandal
Bi(2/3)-xSmxCu3Ti4O12 (BSCTO x = 0.05, 0.10, and 0.20) ceramics are synthesized using semi-wet technique and an extensive investigation into their structural, morphological, and elemental properties, alongside dielectric and impedance behaviors, is meticulously carried out. X-ray powder diffraction analysis unequivocally confirmed the formation of a monophasic BCTO cubic phase without any discernible secondary phases. and the crystallite size of the BSCTO ceramic, obtained by X-ray diffraction using Debye Scherrer formula, range from 62 to 81 nm. Rietveld analysis reveals that ceramics have a body centered cubic structure with space group Im-3. The Scanning electron microscope image displays the dense microstructure of the ceramics, while EDX analysis unveils the elemental composition of resulting products. Doping with Sm3+ induced a notable reduction in grain size, as observed through Scanning electron microscope and Atomic Force Microscope analyses, indicating Sm3+ hindered grain growth during sintering, potentially resulting in reduced dielectric constant (ε′). Dielectric constant and dielectric loss of the composition (x = 0.2) are found to be (Formula presented.) 152 and 0.04, respectively at room temperature (1 kHz). Impedance characteristics revealed a substantial increase in grain boundary resistance, leading to improved dielectric loss. The AC conductivity of BSCTO ceramics exhibited a frequency-dependent increase satisfying to Johncher's power law. © 2024 Wiley-VCH GmbH.
Preparation and characterization of nanostructured CaCu2.90Zn0.10Ti4O12 ceramic
(InTech Europe, 2011) Laxman Singh; U.S. Rai; K.D. Mandal
Nanostructure CaCu2.90Zn0.10Ti4O12 (CCZTO) electronic ceramic was synthesized by semi-wet route. The objective of this route is to enable the calcination and sintering processes to go for completion in shorter time and at lower temperature.The samples were characterized by XRD, TEM, SEM and EDX analyses. The crystallite size of the CCZTO ceramic, obtained by XRD using Debye Scherrer formula, range from 38-74nm which is in good agreement with the particle size observed by TEM analysis. It was observed clearly that the grain size significantly increased with an increase in sintering duration. Dielectric measurements were carried out by LCR meter in the temperature range, 300-500K, at few selected frequencies. It was also observed that the dielectric constant and dielectric loss of CCZTO are temperature independent in higher frequency whereas temperature dependent in low frequency region. The ceramics exhibit high dielectric constant of 1.35 × 104 at 1 kHz.
Progress in the growth of CaCu3Ti4O12 and related functional dielectric perovskites
(Elsevier Ltd, 2014) Laxman Singh; U.S. Rai; K.D. Mandal; N.B. Singh
Calcium copper titanate, CaCu3Ti4O12, (CCTO), a potential electro-ceramic is a member of a very important perovskite family and has been found to a show dielectric constant of the order of 10 4-105. It has a remarkable ability to undergo a series of cationic exchange reactions resulting in corresponding isomorphs. In the past decade there has been immense activity in the search of an isomorph of CCTO with high dielectric constant and low loss which enables its use as capacitor material for the storage of energy and miniaturization of electronic based equipment. Despite intensive research in the area there is no source of any literature that gives all the possible relevant information regarding various synthetic methods, characterizations, effect of sintering parameters (temperature, duration, and atmosphere). This review article is an effort to review the synthesis, grain growth, morphological evolution, effect of impurities, substitution and interface anisotropy on the dielectric constant, resistivity and other materials parameters. © 2014 Elsevier Ltd. All rights reserved.
Rationalization of dielectric properties of nano-sized iron doped yttrium copper titanate using impedance and modulus studies
(Elsevier Ltd, 2015) S. Sharma; M.M. Singh; U.S. Rai; K.D. Mandal
Iron doped Yttrium Copper Titanate nano-ceramic with composition, Y2/3Cu3Ti3.90Fe0.10O12 (YCTFO) was prepared by semi-wet route. It displays all normal XRD peaks of Y2/3Cu3Ti4O12 (YCTO) along with a few secondary peaks of CuO. Stoichiometric purity of the composition was ascertained by EDX spectral analysis. The distribution of bimodal spherical grains confirms 0.5-1.5 μm size limit along with a few irregular shaped large grains with size 1.5-2.8 μm. The impacts of acceptor type of hetero-valent substitution of Ti4+ by Fe3+ in Y2/3Cu3Ti4O12 (YCTO) were reflected as decrease in grain size and broadening of εr-T peak with simultaneous decrease in εr value. The presence of temperature dependent relaxation was also rationalized by impedance and modulus spectroscopic studies which confirm ferroelectric to paraelectric phase transition at 348 K. © 2015 Published by Elsevier Ltd.
Sintering effects on dielectric properties of Zn-doped CaCu3Ti4O12 ceramic synthesized by modified sol-gel route
(Kluwer Academic Publishers, 2013) Laxman Singh; U.S. Rai; Alok Kumar Rai; K.D. Mandal
CaCu2. 90Zn0. 10Ti4O12 ceramic was synthesized by a novel semi-wet route and calcined at 800°C in air for 8 h. The obtained powder was divided into three parts and sintered in air at 950°C for 6 h, 8 h, and 12 h, separately. XRD results confirmed the single phase formation of all the sintered samples with similar cubic structure of CaCu3Ti4O12 (CCTO). Scanning electron micrographs of the CaCu2. 9Zn0. 1Ti4O12 ceramic sintered for 6 h shows bimodal grain size distribution. Increasing the sintering time significantly promotes the grain growth and microstructural densification. The sintering duration was found to have tremendous influence on microstructure and dielectric properties of CaCu2. 90Zn0. 10Ti4O12 ceramic. The CaCu2. 9Zn0. 1Ti4O12 ceramic sintered for 12 h exhibited high dielectric constant εr ~ 5971 at 1 kHz and room temperature. It is found that εr is independent at high frequency and weakly dependent on temperature. © 2013 The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.