Magnetoelectric effect in Sm-substituted tungsten bronze structure Ba4(Sm x La1-x )2Fe2Nb8O30 ceramics

Magnetoelectric effect is directly measured in the Ba₄(Sm_xLa_1-x)₂Fe₂Nb₈O₃₀ ceramics, which is rarely reported in tungsten bronze ceramics. Besides, the effects of Sm-substitution on the crystal structure, dielectric, ferroelectric and magnetic properties have been systematically studied. XRD Rietveld refinement confirms all the ceramics to be single phase with space group of P4bm. With the increase of x, Ba₄(Sm_xLa_1-x)₂Fe₂Nb₈O₃₀ ceramics transform from paraelectric to ferroelectric. The compositions of x = 0.9, 0.95 and 1 show first-order ferroelectric phase transitions above room temperature. Compared to composition x = 0, the dielectric constant of other compositions exhibits frequency stability and the dielectric loss decreases apparently at room temperature. The ferroelectricity improves with increasing x, which can be ascribed to the increased A2-A1 ionic radius difference. Meanwhile, the magnetic hysteresis loops are obtained for some compositions. All the results approve Ba₄(Sm_xLa_1-x)₂Fe₂Nb₈O₃₀ (x = 0.9, 0.95, 1) ceramics as room temperature multiferroic materials with intrinsic magnetoelectric effect.