We have investigated the electrocaloric properties of K + and Na + co-substituted Sr 0.6 Ba 0.4 Nb 2 O 6 (SBN) ceramics using the indirect method. Tetragonal tungsten bronze (K 0.5 Na 0.5 ) 2x (Sr 0.6 Ba 0.4 ) 5-x Nb 10 O 30 (KNSBN) with x = 0.24 was synthesized using dual-step sintering. Despite the low amount, K + and Na + co-substitution resulted in normal ferroelectric behaviour, showing no significant shift in the dielectric maximum temperature of 111°C with increasing frequency. Maximum electrocaloric temperature change (ΔT) of 0.3 K was observed at an electric field of 30 kV/cm (ΔE) yielding the largest electrocaloric responsivity (ΔT/ΔE) among SBN based ceramics. This relatively large value is in agreement with the larger pyroelectric coefficient of KNSBN compared to SBN based ceramics.

REPRINTz Materials Science inc. Nanomaterials &Polymers Synthesis of Sr 1 + + 2x La 1-2x Fe 1-x Nb x O 4 (x = 0, 0.1, 0.3, and 0.5) by Sol-gel Method: Structural, Magnetic, and Dielectric PropertiesArif Kurnia, [a] Emriadi, [a] NandangM ufti, [b] and Zulhadjri* [a] One -l ayered Ruddlesden-Popper phase Sr 1 + 2x La 1-2x Fe 1-x Nb x O 4 doped with niobium was synthesized using as ol-gel method for various Nb concentrations (x = 0, 0.1, 0.3, and 0.5). Singlephase samples could be observed with x = 0a nd 0.1, while x = 0.3 and 0.5 contain additional phases.M icrostructurer esults showed that the increase of niobium content corresponded to ad ecrease in the grain size of the samples. The magnetic measurements indicated that antiferromagnetic interactions of doped samples had decreased. The dielectric constant of the samples decreased as x increased due to the increase in conductivity. The origin of conductioni nthe samples might be caused by hopping conduction due to the mixed oxidation states of iron with charge + 3and + 4.