Phase Transition and Microwave Dielectric Properties of Nd2Ba(Zn1-xCux)O5 (x=0 to 0.55) by Cu Substitution for Zn

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The effects of Cu substitution for Zn in Nd2Ba(Zn1-xCux)O5 solid solutions on the microwave dielectric properties and phase transitions were investigated in this study. The single phase which corresponds to the tetragonal phase with I4/mcm was obtained in the compositions up to x=0.15. At the higher compositions than x=0.15, the orthorhombic phase with Pnma was recognized as a secondary phase; the single phase with Pnma was obtained at x=0.55. The values of dielectric constant (εr) were approximately constant in the compositions ranging from 0 to 0.15 and those values were decreased in the range of 0.15 to 1. The same tendency was observed with the temperature coefficients of resonant frequency (τf) and εr. The quality factors (Q•f) of the ceramics increased from 4915 to 44107 GHz with increasing the compositions up to x=0.55. These results were attributed to the increase in the orthorhombic phase refined by the Rietveld analysis. Moreover, the effects of Y substitutions for Nd in (Nd2-yYy)Ba(Zn0.45Cu0.55)O5 solid solutions on the microwave dielectric property were also investigated and the (Nd2-yYy)Ba(Zn0.45Cu0.55)O5 solid solutions were single phase over the whole composition range. The Q•f values of samples were extremely improved by the Y substitution for Nd and the Q•f value was 100276 GHz at y=1, whereas the εr and τf values were 17.1 and -30 ppm/°C, respectively.
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