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Nanocrystalline nickel ferrites with substitution of Fe3+ by rare-earth La3+, according to the formula NiLaxFe2-xO4 (with x=0, 0.05, 0.1 and 0.15), were prepared by polyacrylamide gel method. Influences of the amount of La3+ substitution on the structure and electromagnetic properties of NiLaxFe2-xO4 compounds were systematically investigated by DSC-TG, XRD, TEM and wave-guide method. XRD results indicated that the pure spinel-type crystal structure of the NiLaxFe2-xO4 (x=0 and 0.05) was obtained at 500 ℃. TEM results showed that the average particle sizes of NiFe2O4 and NiLa0.1Fe1.9O4 particles were about 10 and 15 nm, respectively. The complex permittivity and complex permeability was measured in the frequency range of 8.2～12.4 GHz. The results revealed that the nanocrystalline NiLaxFe2-xO4 had both dielectric loss and magnetic loss in the frequency range of 8.2～12.4 GHz. The tgδε and tgδm of NiLaxFe2-xO4 (with x=0 and 0.05) decreased with the increase of La3+ ions content, and some strong resonance peaks of the tgδε and tgδm of NiLaxFe2-xO4 (with x=0.1 and 0.15) appeared because of the secondary phases (LaFeO3) and more lattice defects.
Nanocrystalline nickel ferrites with substitution of Fe3 + by rare-earth La3 +, according to the formula NiLaxFe2-xO4 with x = 0, 0.05, 0.1 and 0.15, were prepared by polyacrylamide gel method. Influences of the amount of La3 + substitution on the structure XRD results indicated that the pure spinel-type crystal structure of the NiLaxFe2-xO4 (x = 0 and 0.05) was obtained at 500 ° C. TEM results showed that the average particle sizes of NiFe2O4 and NiLa0.1Fe1.9O4 particles were about 10 and 15 nm, respectively. The complex permittivity and complex permeability was measured in the frequency range of 8.2 ~ 12.4 GHz. The results revealed that the nanocrystalline NiLaxFe2-xO4 had both dielectric loss and magnetic loss in the frequency range of 8.2-12.4 GHz. The tgδε and tgδm of NiLaxFe2-xO4 (with x = 0 and 0.05) decreased with the increase of La3 + and some strong resonance peaks of the tgδε and tgδm of NiLaxFe2-xO4 (with x = 0.1 and 0.15) because of the secondary phases (LaFeO3) and more lattice defects.