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    A comprehensive investigation of the structural, chemical, and dielectric properties of co-doped YMnO3 multiferroic component
    (Springer Heidelberg, 2024) Polat, O.; Coskun, M.; Yildirim, Y.; Coskun, F. M.; Durmus, Z.; Sen, C.; Caglar, Y.
    The solid-state reaction technique was employed to synthesize compounds of YMnO3 (YMO) and YMn1-xCoxO3 (YMCO) with various Co doping levels (x = 0.01, 0.10, 0.20, and 0.40), where Co atoms partially substituted Mn sites. XRD studies confirmed the presence of two phases, YMO and Y0.98CoO3 (YCO), for doping ratios above x = 0.10. Additionally, an increase in crystalline size was observed with cobalt substitution. Surface characteristics of synthesized pellets were examined using scanning electron microscopy (SEM), revealing a less porous structure with cobalt doping. XPS analysis elucidated valence states, showing the presence of both Mn3+ and Mn4+, as well as Co2+ and Co3+. The x = 0.20 and 0.40 Co-doped samples exhibited lower grain and grain boundary energies compared to other samples, such as a decrease from 0.556 eV (undoped) to 0.195 eV (x = 0.20). Moreover, the dielectric constants of x = 0.20 and 0.40 cobalt-doped samples (around 320) significantly surpassed the undoped sample (around 22) at 10(6) Hz and 100 degrees C. The x = 0.20 cobalt-doped sample demonstrated the highest conductivity at 100 degrees C and 10(6) Hz (31 x 10(-4) S/cm). FT-IR analysis provided insights into vibration and bending modes, and frequency- and temperature-dependent electrical features were investigated. It was observed that a single conduction model is insufficient to fully explain the conduction mechanism in these samples.
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    High resistivity and low dielectric loss of LuFe1-xOsxO3 (x=0.0-0.10) ferrites
    (Springer, 2023) Coskun, M.; Polat, Ozgur; Yildirim, Y.; Durmus, Z.; Sen, C.; Caglar, Y.; Caglar, M.
    LuFe1-xOsxO3 (x = 0, 0.05, and 0.10) compounds were synthesized and their resistivity, real and imaginary portion of the impedance and frequency-dependent loss tangent were examined at varied temperature settings (from - 100 degrees C to 100 degrees C by 20 degrees C step). Impedance and resistivity values increased as a result of the doping procedure, whereas activation and loss tangent values decreased. According to the X-ray photoelectron spectroscopy (XPS) study, Lu possesses a 3 + oxidation state, and the oxygen 1s spectrum displayed peaks for lattice oxygen and oxygen vacancy. Particle agglomeration and void formation were visible in scanning electron microscopy (SEM) pictures. Single and double oxygen vacancies and ion hopping between Fe2+ and Fe3+ ions were responsible for the reported activation energies. The frequency-dependent loss tangent results showed that all compounds have a highly low loss factor even at 100 degrees C.