Gel Synthesis of Hexaferrites PbLaFeZnO and Properties of Multiferroic Composite Ceramics PZT-PbLaFeZnO.

We investigated the opportunities for obtaining hexaferrites PbLaFeZnO ( = 0-1) from citrate-glycerin gel and showed that synthesis occurs via the formation of the FeO phase; products with a small amount of hematite impurity FeO can be obtained after firing at 800 to 900 °C with 0 ≤ ≤ 0.5. If > 0.5, perovskite-like LaFeO is formed in samples, so that if = 0.9-1, the synthesis products virtually do not contain phases with hexaferrite structures and represent a mixture of LaFeO, FeO, and FeO. Within the range of 0 ≤ ≤ 0.5, the electrical and magnetic characteristics of hexaferrites PbLaFeZnO are slightly dependent on and have the following average values: A relative permittivity ε/ε ~ 45, a dielectric loss tangent tan δ ~ 0.6, an electrical resistivity R ~ 10 Ohm cm, coercivity H ~ 3 kOe, saturation magnetization M ~ 50 emu/g, and remanent magnetization M ~ 25 emu/g. The magnetoelectric (ME) ceramics 50 wt.% PZTNB-1 + 50 wt.% PbLaFeZnO (PZTNB-1 is an industrial piezoelectric material based on lead titanate zirconate (PZT) do not contain impurity phases and have the following characteristics: Piezoelectric coefficients d = 10-60 and -d = 2-30 pC/N, piezoelectric voltage coefficients g = 2-13 and -g = 1-5 mV m/N, an electromechanical coupling coefficient K = 0.03-0.13, magnetic parameters H = 3-1 kOe, M = 50-30, and M = 25-12 emu/g. The maximum ME coupling coefficient ΔE/ΔH ~ 1.75 mV/(cm Oe) was achieved with = 0.5.