Effect of doping on the local structure of new block‐layered proton conductors based on BaLaInO₄

Abstract

In this work, the effect of acceptor of La3+‐sublattice and donor of In3+‐sublattice doping on the local structure of proton conductor BaLaInO4 with block‐layered Ruddlesden–Popper structure was investigated. It was showed that both types of doping led to appearance of new kinds of the defects (oxygen vacancy and oxygen interstitial) and to the decrease in the tilting angles of [InO6] octahedra due to the expansion of unit cell in the ab direction. The formation of a less distorted structure provided facilitated oxygen‐ionic and protonic transport and increased ionic conductivity.

Spectroscopic and transport properties of Ba‐ and Ti‐doped BaLaInO4

“…The mid-wavenumbers (230 to 500 cm −1 ) area is characterized by several modes of tilting/bending and stretching vibrations of In-contained polyhedra. The presence of oxygen defects in the structure can be detected by the presence of the band around 230-280 cm −1, [54][55][56] and we can ascribe the mode ν 6 to the metal−V O…”

“…The mid‐wavenumbers (230 to 500 cm −1 ) area is characterized by several modes of tilting/bending and stretching vibrations of In‐contained polyhedra. The presence of oxygen defects in the structure can be detected by the presence of the band around 230–280 cm −1, [ 54–56 ] and we can ascribe the mode ν 6 to the metal−V O •• and metal− motions. The appearance of mode ν 6 in the spectrum of undoped compositions is obviously due to the presence of local disordering of the crystal lattice.…”

“…[51][52][53] The local distortion of the crystal lattice of BaLaInO 4 leads to the formation of oxygen vacancies in the [InO 6 ] polyhedra, so the polyhedra with lower coordination number [InO x ] (x < 6) and with higher wavenumber of In−O stretching vibration (ν 10 ) appear. [56] The acceptor doping leads to the shift of ν 12 band in the area of low wavenumbers. It is indicates some increase in the In−O2 bond lengths in the [InO x ] polyhedra (Table S1).…”

Simultaneous Hetero- and Isovalent Doping as the Strategy for Improving Transport Properties of Proton Conductors Based on BaLaInO4

“…Over the past forty years, the proton-conducting solid oxides went beyond perovskites family ( Figure 1 ). After variously doped barium cerates and zirconates [ 8 , 9 , 10 ], classes of proton-conducting materials like hexagonal [ 11 , 12 , 13 , 14 , 15 , 16 , 17 ], oxygen-deficient [ 18 , 19 , 20 ], block-layered [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ] perovskites, brownmillerites [ 32 , 33 , 34 ], pyrochlores [ 35 , 36 , 37 , 38 ], apatites [ 39 ], monazites [ 40 , 41 , 42 ], gallium-based oxides [ 43 , 44 , 45 ], materials with fluorite- [ 46 , 47 , 48 ], fergusonite- [ 49 , 50 , 51 ], and weberite-types [ 52 , 53 ] of structures were described.…”

“…From the point of view of protonic conductivity, the layered perovskites based on BaLaInO 4 , SrLaInO 4 , BaNdInO 4, and BaNdScO 4 were investigated [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. The possibility of acceptor (Ca 2+ /Sr 2+ /Ba 2+ → La 3+ /Nd 3+ ) and donor (Zr 4+ /Ti 4+ /Nb 5+ → In 3+ ) doping was proven.…”