Ca–Al double-substituted strontium hexaferrites exhibit record-high coercivities up to 21.3 kOe.

The review is devoted to compounds and materials demonstrating extremely high magnetic hardness. The recent advances in the synthesis of modern materials for permanent magnets are considered, and a range of exotic compounds interesting for fundamental research is described. The key details of chemical composition, crystal structure and magnetic microstructure responsible for the appearance of high magnetic anisotropy and giant coercivity are analyzed. The challenges of developing the title materials are noted and strategies for their solution are discussed.The bibliography includes 389 references.

A fast method for the synthesis of ε-Fe₂O₃, yielding 100% pure material with a variable FMR frequency, is proposed.

We demonstrate that the ionic conductivity of Li_1+xAl_xGe_2−x(PO₄)₃ glass-ceramic electrolytes can be tailored by adding Y₂O₃ to Li₂O–Al₂O₃–GeO₂–P₂O₅ melts. We found that the addition of 5 vol% Y₂O₃ causes noticeable changes in further glass crystallization process as the key parameters (glass crystallization temperature, viscosity and others) are affected. Small-angle neutron scattering data suggest that Y-containing glasses are suddenly crystallized upon heat treatment producing uniform Li_1+xAl_xGe_2−x(PO₄)₃ ceramics. Due to the lower resistance of intergrain interfaces, such samples demonstrate a specific ionic conductivity of 0.5 mS cm⁻¹, which is nearly 5 times higher in comparison to Y-free ceramics, prepared under similar conditions. We speculate that such an effect is caused primarily by better intergrain contact in Y-containing ceramics, along with better ionic transport in the grain bulk as evidenced by ⁷Li NMR.