Available free online at www.medjchem.com Mediterranean Journal of Chemistry 2019, 8(3), 234-244 *Corresponding author: Nasr Hadi Received February 7, 2019 E-mail adresse: nassarmabbed@hotmail.com Accepted March 25, 2019 DOI: http://dx.doi.org/10.13171/mjc8319052011nh Published May 20, 2019 The effects of calcination and doping on structural and dielectric properties of CaCu 3-x Co x Ti 4 O 12 ceramic Nasr Hadi 1,* , Abdi Farid 1 , Tajdine Lamcharfi 1 , Nor-Said Echtoui 1 , Ahmed Harrach 2 , Mohammed Zouhairi 2 and Fatima Zahra Ahjyaje 3 1 Laboratory of Signals, Systems and Components, USMBA. FST Fez, B.P. 2202, Morocco 2 Laboratory of Condensed Matter Chemistry, USMBA.FST-Fes, B.P. 2202, Morocco 3 Laboratory of Materials Natural Substances, Environment and Modeling, LMSNEM, USMBA. FP-Taza. Morocco Abstract: The influences of calcination temperature and doping with cobalt in A–site on structural and dielectric properties of CaCu 3-x Co x Ti 4 O 12 (CCCxTO, x = 0.00, 0.02 and 0.10) ceramics sintered at 1050 0 C for 8h were investigated. The ceramic samples are prepared by the conventional solid-state method using high purity oxide powders, and they are calcined at 850 °C, 950 °C and 1050 0 C for 4h. The X-ray diffraction (XRD) analysis of pure and doped CCTO samples calcined at 950 °C and 1050 0 C showed no traces of any other secondary phases, while impurity phases alongside CCTO phase in the x=0.00 sample calcined at 850 0 C was observed. Scanning electron microscopy (SEM) investigation showed an increase in grain size with increasing of Co content and calcining temperature. Dielectric measurements indicated that the dielectric constant of the pure CCTO calcined at 1050 0 C/4h has a low value in the frequency range of 1kHz up to 1MHz, whereas the substitution of Co up to x = 0.10 into CCTO caused a huge increase in the dielectric constant value of the calcined samples which is equal to 153419 and 18957 at 950 ° C and 1050 0 C respectively. The complex impedance analysis of all samples shows a decrease in resistance with an increasing temperature, which suggests a semiconductor nature of the samples. Keywords: Ceramic, CCTO, Dielectric properties, Doping; Cobalt; CaCu 3-x Co x Ti 4 O 12 ; calcination temperature. Introduction There are a great number of applications for ceramic materials due to their giant relative permittivity, electrically insulating and electrical conducting properties. Nowadays, advanced ceramics became the key to success for the development of integrated circuits in microelectronic 1,2 . Calcium copper titanate (CaCu 3 Ti 4 O 12 )(CCTO) is well known for the treatment of radioactive wastes since these properties form a vast number of solid solutions with rare earth metals 3,6 . CaCu 3 Ti 4 O 12 based dielectric ceramics have been extensively investigated for their microwave dielectric properties 6 . CCTO exhibits a combination of high permittivity and modest dielectric loss. It has been extensively investigated for their temperature independent dielectric permittivity without a ferroelectric transition over a large temperature range 1,7-9 . These investigations concern the origin of the huge dielectric permittivity. Numerous theoretical 10-12 and experimental 13-16 attempts have been made to understand the extraordinarily high value of the dielectric permittivity. Extrinsic and intrinsic origin, and the internal barrier layer capacitor model has been proposed to account for such high  r 14-16 . Other interesting features observed in CaCu 3 Ti 4 O 12 are the strong nonlinear I-V characteristics ascribed to the intrinsic electrostatic barrier at the grain boundary 17,19 and optical responses 11,12 . All these properties are controlled by the chemistry of the ceramics. Hence, CaCu 3 Ti 4 O 12 ceramics were synthesized by different methods and chemically modified by doping to tune the microstructure, grain size, boundary and surfaces, which are the dominant factor to determine the dielectric properties of CCTO 14-23 . This paper aims to study the effects of calcination temperature and to dope with Cobalt on A–site (Cu- site) on the microstructure, electrical and dielectric properties of CaCu 3-x Co x Ti 4 O 12 , (CCC x TO). For this purpose, three sets of CCC x TO (x = 0.00, 0.02 and 0.10) specimens have been prepared at different temperatures of calcination and characterized by XRD, SEM and dielectric measurements.