Niobium-Cobalt co-doped Barium Titanate Dielectric Ceramics for Multilayered Ceramic Capacitors

Özgür, Berkay
Niobium (Nb) and Cobalt (Co) co-doped barium titanate ceramics were prepared to stabilize ferroelectric-tetragonal phase transformation of barium titanate. Preparation of ceramics started with mixing barium titanate, niobium oxide and cobalt oxide powders at predetermined concentrations varying from 1 to 3 at%. The mixing was done at wet conditions using distilled water with alumina balls at 50 rpm for 24 h in a ball mill. Then, the mixtures were compacted into 15 mm diameter and 3 mm thick disc shaped pellets by uniaxial pressing at 200 MPa. After that the discs were sintered at various temperatures ranging from 1250 to 1290 °C for various durations ranging from 30 to 120 min. Sintered pieces were characterized using XRD, SEM, EDS, and DSC characterization techniques. Electrical properties namely dielectric constant, dielectric loss and dielectric constant versus temperature were measured. Experimental results revealed that the co-doping of barium titanate with Nb and Co lead to broadening of dielectric constant peaks and temperature stability. A high dielectric constant of 3258 at 1 kHz was obtained at room temperature, along with +10% and -17% variation over temperature ranging between -30 and +150 ºC. Also, the dramatic change in crystal structure of barium titanate at 10 and 121 ºC was suppressed.


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Citation Formats
B. Özgür, “Niobium-Cobalt co-doped Barium Titanate Dielectric Ceramics for Multilayered Ceramic Capacitors,” M.S. - Master of Science, Middle East Technical University, 2022.