Study of Rare Earth Metals Substituted YFeO3 Ceramics

Abstract

This research work presents the effect of rare earth substitution (Dy, Pr, Nd, and Nd-Cr co substituted) on structural, morphological, ferroelectric and dielectric properties of YFeO3. Sol gel method has been used to prepare the four series Y1-xDyxFeO3 (0 ≤ x ≤ 0.16), Y1-xPrxFeO3 (0 ≤ x ≤ 0.16), Y1-xNdxFeO3 (0 ≤ x ≤ 0.16), and Y1-xNdxCr0.4Fe0.6O3 (0 ≤ x ≤ 0.16). X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) were employed for structural and morphology analysis. The substitution of praseodymium (Pr) modified the orthorhombic structure into a hexagonal structure. However, small traces of Fe2O3 and Y2O3 were also appeared. Variations in lattice parameters were observed due to the mismatch of host ions as compared to Y3+ ion in YFeO3. The average crystallite size lies in the range between ~27 nm to ~15 nm. SEM exhibited inhomogeneous shape for pure YFO while the doped samples were in round shape, spherical shape, rod shape and clusters of grains. Line intercept method was used to measure average grain size of four compositions in a wide range between ~62 nm-~149nm. FTIR analysis in the range of 400-800cm-1 showed a presence of two vibrational bands appeared due to the octahedral and tetrahedral stretching vibrations. Force constant and bond length variations are described on basis of oxygen-cation bond distances. Frequency dependent dielectric behavior of four series was investigated at room temperature in a frequency range of 1 MHz~3 GHz. The substitution of rare earth elements shows enhanced dielectric constant and reduces dielectric losses. These reduced losses made this material useful in the fabrication of high-frequency devices and multilayer chip-inductor. The damping effect is significantly observed in all series, is good agreement with Koop's theory and the Maxwell-Wagner model. . For all compositions, AC conductivity is found to be increased in wide frequency range due to the hopping of charge carriers between Fe2+ and Fe3+ and migration of oxygen vacancies. The distinctive behavior of low tangent loss may be suitable for high-frequency applications.