Synthesis of new brownmillerite-type systems A₂(M,M')₂O₅ (A = Ba, Sr; M = Zn; M'= Zr, Ce, Ti, Hf, Sn)

Abstract

Oxide ion conductor has been desired for application to solid oxide fule cells (SOFCs), which can be operated at temperatures below 873K. In order to obtain a new oxide-ion conductor, di-(M) and tetra-(M') valent cations were co-doped to the In-site of Ba 2 In 2 O 5 which is known to be high oxide-ion conductor at high temperature above 1203K. The A 2 (M,M') 2 O 5 systems (A＝Ba, Sr; M=Zn, ; M'=Zr, Ce, Ti. Hf, Sn) having a brownmillerite-type compositions were prepared by solid state reaction. X-ray diffraction analyses confirmed that only the combinations of (Ba-Zn-Zr), (Ba-Zr-Ce), (Ba-Zn-Hf), (Sr-Zn-Zr), (Sr-Zn-Ti) and (Sr-Zn-Hf) for the A-M-M' in the present systems showed single phases of cubic or orthorhombic perovskite-type structures at room temperature. It was found that the electrical comductivities of the new phases increased with increasing the unit cell free volume.

High electrical conductivity in Ba2In2O5brownmillerite based materials induced by design of a Frenkel defect structure

“…Lattice volumes estimated by Rietveld analysis data. Cite this: RSC Adv., 2017, 7, 4688 and T t was examined using Ba 2 (In,M) 2 O 5 (M ¼ Ga, [13][14][15][16] Al, 14,17 Sc, 18,19 Y, 18,19 Yb, 18 Dy, 18 Sm 18 ) system, Ba 2 (In,(Sc,Lu)) 2 O 5 system, 20 Ba 2 (In,M) 2 O 5+d (M ¼ Zr, 21,22 Ce, 23,24 Ti, 25 Sn, 26 Si, 27 V, 28 Mo, 28 W, 29 34 (La, Ce), 35 (La, Zr), 35 (La, Mg) 35 ] system and uorine doped Ba 2 In 2 O 5+x system. 36 The representative examples of aforementioned temperature dependence of conducting properties were summarized in Fig.…”