Effect of Pr 3+ doping on magnetic and dielectric properties of Ni-Zn ferrites by "one-step synthesis"
Pr 3+-doped Ni-Zn ferrites with a nominal composition of Ni 0.5Zn 0.5Pr xFe 2- xO 4 (where x=0-0.08) were prepared by a one-step synthesis. The magnetic and dielectric properties of the as-prepared Ni-Zn ferrites were investigated. X-ray diffraction data indicated that, after doping, all samples consisted of the main spinel phase in combination of a small amount of a foreign PrFeO 3 phase. The lattice constants of the ferrites initially increased after Pr 3+ doping, but then became smaller with additional Pr 3+ doping. The addition of Pr 3+ resulted in a reduction of grain size and an increase of density and densification of the as-prepared samples. Magnetic measurement revealed that the saturation magnetization of the as-prepared ferrites, Ms, decreased, while the coercivity, Hc, increased with increasing substitution level, x, and the Curie temperature, Tc, kept a rather high value, fluctuating between 308 and 320 °C. Both the real and imaginary parts of permeability of the ferrites decreased slightly after Pr 3+ doping. However, the natural resonance frequency shifted towards higher frequency from 13.07 to 36.17 MHz after the addition of Pr 3+, driving the magnetic permeability to much higher frequency, reaching the highest value (36.17 MHz) when x=0.04. Introduction of Pr 3+ ions into the Ni-Zn ferrite reduced the values of the dielectric loss tangent, especially in the frequency range of 1-400 MHz. However, the magnitude of dielectric loss of the samples doped with different amounts of Pr 3+ raised little.