Browsing by Author "Krapchanska M."

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    Synthesis of doped bismuth titanate ceramics with Nd2O3 and SiO2 and their electrical properties
    (2013-05-21) Slavov S.; Krapchanska M.; Kashchieva E.; Parvanov S.; Dimitriev Y.
    Bismuth-titanate ceramics containing SiO2 and Nd2O3 as additives are synthesized by melt quenching method in the system Bi2O3-TiO2-Nd2O3-SiO2 at temperature range 1260 - 1500oC. The phase composition of the obtained materials is determined by X-ray diffraction analysis and energy dispersive spectroscopy. Using scanning electron microscopy different microstructures are observed in the samples depending on the composition. The addition of SiO2 and Nd2O3 allows controlling the crystallization, glass formation ability, melting temperature and Curie temperature. Different values of conductivity, dielectric losses and relative permittivity are obtained depending on the composition. Measurements of the electrical conductivity, capacitance and dielectric losses of selected samples are performed by DC resistible bridge and digital capacity meter (with frequency of 1 kHz) using two-terminal method and a suitable sample holder with graphite electrodes. It is established that all investigated samples are dielectric materials with conductivity between 10-9 and 10-13 (O cm)-1 at room temperature, dielectric permittivity from 1000 to 3000 and dielectric losses tgd between 0,0002 and 0,1.