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Microstructural and dielectrical characterization of Ho doped BaTiO3 ceramics

Marjanović Miloš (Faculty of Electronic Engineering, Niš)
Dimitrijević Dragana (Faculty of Electronic Engineering, Niš)
Paunović Vesna (Faculty of Electronic Engineering, Niš)
Prijić Zoran (Faculty of Electronic Engineering, Niš)

The Ho doped BaTiO3 ceramics, with different Ho2O3 content, ranging from 0.01 to 1.0 wt % Ho, were investigated regarding their microstructural and dielectric characteristics. Doped BaTiO3 were prepared using conventional solid state reaction and sintered at 1380°C for four hours. SEM analysis of Ho/BaTiO3 doped ceramics showed that the low doped samples exhibit mainly fairly uniform and homogeneous microstructure with the grain size ranged from 20-40 μm. In the samples with the higher dopant concentration the abnormal grain growth is inhibited and the grain size ranged between 2-10 μm. Measurements of dielectric properties were carried out as a function of temperature up to 180 °C at different frequencies. The samples doped with 0.01wt % of Ho, exhibit the high value of dielectric permittivity (εr = 2160) at room temperature. A nearly flat permittivity-response was obtained in specimens with higher additive content. Using a Curie-Weiss law and modified Curie-Weiss law the Curie constant (C), Curie temperature (Tc) and a critical exponent of nonlinearity (g) were calculated. The Curie temperature of doped samples were ranged from 128 to 130°C. The Curie constant for all series of samples decrease with increase of dopant concentration and the lowest values were observed on samples doped with 0.01 wt % of holmium.

Keywords: BaTiO3, microstructures, sintering, additive, dielectric properties

Projekat Ministarstva nauke Republike Srbije, br. OI 172057: Directed synthesis, structure and properties of multifunctional materials i br. TR 32026