Structural and dielectric properties of yttrium substituted nickel ferrites

• Dense NiFe2−xYxO4 ceramics (with 0 ≤ x ≤ 0.3) were prepared.
• Pure spinels were obtained for x ≤ 0.07 while for x ≥ 0.15 samples had secondary phases.
• With addition of yttrium, ac conductivity slightly increased.
• We suggest several effects that can explain the observed changes in ac conduction.
• With addition of yttrium, dielectric constant increased while the tg δ decreased.

The influence of Y3+ ions on structural and dielectric properties of nickel ferrites (NiFe2−xYxO4, where 0 ≤ x ≤ 0.3) has been studied. The as-synthesized samples, prepared by the co-precipitation method, were analyzed by XRD and FTIR which suggested that Y3+ ions were incorporated into the crystal lattice for all the samples. However, the XRD analysis of the sintered samples showed that secondary phases appear in the samples with x > 0.07. The samples have densities greater than 90% TD and the SEM images showed that the grain size decreases with the addition of yttrium. Dielectric properties measured from 150 to 25 °C in the frequency range of 100 Hz–1 MHz showed that the addition of yttrium slightly increases the ac conductivity and decreases the tg δ therefore making the materials better suited for the use in microwave devices.

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