Narrow Results

The sintering behavior and dielectric properties of Bi${}^{3+}$-substituted Nd(Zn${}_{0.5}$Ti${}_{0.5})$O₃ (abbreviated as NZT) microwave ceramics (Nd${}_{1-x}$Bi${}_x$)(Zn${}_{0.5}$Ti${}_{0.5}$)O₃$(0\le x\le 0.15)$ (abbreviated as NBZT) are investigated. XRD results reveal the formation of single perovskite solid solutions for $x\le 0.05$ samples. For $x>0.05$ samples, pyrochlore phase begins to segregate from the perovskite phase and its volume fraction increases with $x$. B-site Zn${}^{2+}$/Ti${}^{4+}$ 1:1 long range order (LRO) is detected by Raman Spectroscopy. The degree of LRO varies as a function of sintering conditions and chemical composition. The microwave dielectric properties of the composition are measured. By substituting Bi${}^{3+}$ for Nd${}^{3+}$, the temperature coefficient of resonant frequency $({\tau }_f)$ tunes toward zero, however, the microwave quality factor, $(Qf)$ deteriorates. For $x=0.03$, ${\tau }_f$ reaches a minimum value of $-18.9\mathrm{\text{ppm}}{/}^{\circ }\mathrm{\text{C}}$ with relative permittivity of ${\epsilon }_r=48.2$ and $Qf=1430\mathrm{\text{GHz}}$, respectively. The effect of Bi-doping on the $Qf$ value is discussed.

Bi₂FeCrO₆ thin films were epitaxially grown by pulsed laser deposition on (100)-oriented LaAlO₃, (LaAlO₃)_0.3(Sr₂LaTaO₆)_0.7 and SrTiO₃ single crystalline substrates with and without epitaxial CaRuO₃ buffered layer. The in-plane compressive strain induces monoclinic distortion of the Bi₂FeCrO₆ lattice cell. The strain originates from lattice mismatch between CaRuO₃ and single crystal substrates. The similar crystal structure of the substrate and the layer lead to coherent epitaxial growth of the heterostructures and avoid strain relaxation in particular for BFCO films deposited on LaAlO₃ substrates. The ferroelectric character is demonstrated for all grown BFCO films. The residual in-plane strain weakly affects the effective piezoelectric coefficient of BFCO layers.