Gel Synthesis of Hexaferrites Pb(1−x)La(x)Fe(12−x)Zn(x)O(19) and Properties of Multiferroic Composite Ceramics PZT–Pb(1−x)La(x)Fe(12−x)Zn(x)O(19)

We investigated the opportunities for obtaining hexaferrites Pb(1−x)La(x)Fe(12−x)Zn(x)O(19) (x = 0–1) from citrate–glycerin gel and showed that synthesis occurs via the formation of the Fe(3)O(4) phase; products with a small amount of hematite impurity Fe(2)O(3) can be obtained after firing at 800 to 900 °C with 0 ≤ x ≤ 0.5. If x > 0.5, perovskite-like LaFeO(3) is formed in samples, so that if x = 0.9–1, the synthesis products virtually do not contain phases with hexaferrite structures and represent a mixture of LaFeO(3), Fe(2)O(3), and Fe(3)O(4). Within the range of 0 ≤ x ≤ 0.5, the electrical and magnetic characteristics of hexaferrites Pb(1−x)La(x)Fe(12−x)Zn(x)O(19) are slightly dependent on x and have the following average values: A relative permittivity ε/ε(0) ~ 45, a dielectric loss tangent tan δ ~ 0.6, an electrical resistivity R ~ 10(9) Ohm cm, coercivity H(c) ~ 3 kOe, saturation magnetization M(s) ~ 50 emu/g, and remanent magnetization M(r) ~ 25 emu/g. The magnetoelectric (ME) ceramics 50 wt.% PZTNB-1 + 50 wt.% Pb(1−x)La(x)Fe(12−x)Zn(x)O(19) (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(33) = 10–60 and −d(31) = 2–30 pC/N, piezoelectric voltage coefficients g(33) = 2–13 and −g(31) = 1–5 mV m/N, an electromechanical coupling coefficient K(p) = 0.03–0.13, magnetic parameters H(c) = 3–1 kOe, M(s) = 50–30, and M(r) = 25–12 emu/g. The maximum ME coupling coefficient ΔE/ΔH ~ 1.75 mV/(cm Oe) was achieved with x = 0.5.