The effect of SiO_2 addition on dielectric properties and microstructure of ZnNiO_2: based ceramics

摘要

The present work attempted to investigate the effect of SiO_2 addition on the dielectric properties and microstructure of the ZnNiO_2- ceramics. The content of added SiO_2 is in the range 5–40 wt%, while that of the other additives keeps constant. The given samples were sintered at 1000–1300 ℃ for 120 min, with conventional ceramic processing method. By X-ray diffraction, Zinc silicate, Nickel silicate, Quartz, Nickel Zinc Oxide, Zinc Oxide and Nickel oxide were found in all the samples, and no extra phases were identified in the detection limit. Minimum water absorption was present in specimens fired at 1300 ℃ for 120 min. The DTA pattern shows a clear indication of five maxima happening at the point 104.1 ℃, 112 ℃, 109.5 ℃, 106 ℃, and 117.9 ℃, respectively. SEM studies show that the increase of SiO_2 wt% had significant influence on grain growth and microstructural characteristics of the sintered specimens. There are agglomerated fine particles of NiO, because it has high surface tension. The electrical properties of the samples varied with the increase content of SiO_2. The capacitance (pF) and, dielectric constant (ɛ−), decrease when SiO_2 content increase and with increasing frequency whereas, conductivity increased with increase content of SiO_2.