Open AccessImproved dielectric properties of Na1/2Y1/2Cu3Ti4O12 ceramics synthesized by ball-milling and reactive sintering
Author(s) -
H. Mahfoz-Kotb,
M. S. Ahmad,
Adil Alshoaibi,
Hassan A. Khater,
Abdullah Aljaafari
Publication year - 2020
Publication title -
materials research express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.383
H-Index - 35
ISSN - 2053-1591
DOI - 10.1088/2053-1591/ab73fb
Subject(s) - materials science , dielectric , ceramic , ball mill , sintering , analytical chemistry (journal) , activation energy , grain size , atmospheric temperature range , grain boundary , mineralogy , microstructure , composite material , chemistry , physics , optoelectronics , chromatography , meteorology
Na 1/2 Y 1/2 Cu 3 Ti 4 O 12 (NYCTO) ceramics with giant dielectric constant ( ε ′) were synthesized by simple reactive sintering. NYCTO nanopowder was first synthesized using high energy ball-mill. Then the pelletized powder was sintered in air at temperatures in the range 975 °C to 1050 °C for 10–20 h. The obtained ceramics showed pure CaCu 3 Ti 4 O 12 (CCTO)-like cubic phase as revealed by x-ray diffraction measurements. Field effect-SEM observations showed that the grain size increases from 2 μ m to 5 μ m with increasing sintering temperature. NYCTO samples sintered at temperatures higher than 975 °C showed giant dielectric constant (10 3 –10 4 ) over most of the frequency range. The minimum dielectric loss (tan δ ) of ∼0.055 at 300 K has been approved for the ceramic sample sintered at 1050 °C. Impedance and modulus spectra of the current samples showed two relaxations related to semiconductor (grain) and high resistance (grain-boundaries) elements. The activation energy for conduction located in the range 0.1–0.5 eV highlighted the role of single ionized oxygen vacancies in the dielectric properties of the investigated NYCTO ceramics.