Proton and oxygen ion conductivity in the pyrochlore/fluorite family of Ln2-xCaxScMO7-δ (Ln = La, Sm, Ho, Yb; M = Nb, Ta; x=0, 0.05, 0.1) niobates and tantalates

被引：27

作者：

Shlyakhtina, A. V. ^{[1
]}

Pigalskiy, K. S. ^{[1
]}

Belov, D. A. ^{[1
,2
]}

Lyskov, N. V. ^{[3
]}

Kharitonova, E. P. ^{[2
]}

Kolbanev, I. V. ^{[1
]}

Borunova, A. B. ^{[1
]}

Karyagina, O. K. ^{[4
]}

Sadovskaya, E. M. ^{[5
,6
]}

Sadykov, V. A. ^{[5
,6
]}

Eremeev, N. F. ^{[5
]}

机构：

[1] Russian Acad Sci, Semenov Inst Chem Phys, Ul Kosygina 4, Moscow 119991, Russia

[2] Moscow MV Lomonosov State Univ, Leninskie Gory 1, Moscow 119991, Russia

[3] Russian Acad Sci, Inst Problems Chem Phys, Academician Semenov Ave 1, Chernogolovka 142432, Moscow Region, Russia

[4] Russian Acad Sci, Emanuel Inst Biochem Phys, Ul Kosygina 4, Moscow 119991, Russia

[5] Russian Acad Sci, Siberian Branch, Boreskov Inst Catalysis, Pr Akad Lavrentieva 5, Novosibirsk 630090, Russia

[6] Novosibirsk State Univ, Pirogova Str 2, Novosibirsk 630090, Russia

来源：

DALTON TRANSACTIONS | 2018年 / 47卷 / 07期

基金：

俄罗斯科学基金会;

关键词：

RARE-EARTH; ELECTRICAL-CONDUCTIVITY; MAGNETIC-PROPERTIES; CRYSTAL-STRUCTURE; PHASE-TRANSITION; LN(3)NBO(7) LN; TEMPERATURE; OXIDES; LU; GD;

D O I：

10.1039/c7dt03912c

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

The tolerance factor is a good criterion to understand the structural transitions in Ln(2-x)Ca(x)ScMO(7-delta) (Ln = La, Sm, Ho, Yb; M = Nb, Ta; x = 0, 0.05, 0.1). Decreasing the Ln ionic radius in Ln(2)ScNb(Ta)O-7 leads to a morphotropic transition from a pyrochlore to a fluorite-like structure. Ca2+-doping leads to a pyrochlore-to-fluorite transition in Ln(2-x)Ca(x)ScMO(7-delta) (Ln = La, Sm) and a fluorite-to-pyrochlore transition in Ho2-xCaxScNbO7-delta. Proton contribution to the total conductivity was observed for Ln(2-x)CaxScNb(Ta)O7-delta (Ln = La, Sm; x = 0, 0.05, 0.1) 3+/5+ pyrochlores and the maximum proton contribution was shown by Sm1.9Ca0.1ScMO6.95 (M = Nb, Ta), which are located at the boundary between pyrochlores and fluorites (comparative study of electrical conduction and oxygen diffusion). Proton conduction of Sm1.9Ca0.1ScNbO6.95 and Sm1.9Ca0.1ScTaO6.95 pyrochlores persists up to 800 and 850 degrees C, respectively. The conductivity of fluorite-like Ho2-xCaxScNbO7-delta (x = 0, 0.05) and Yb2ScNbO7 is dominated by the oxygen ion transport, in accordance with their energy activation values 1.09-1.19 eV. The dielectric permittivity and TG studies were used for the investigation of oxygen vacancy dynamics and water incorporation into the Ln(2-x)Ca(x)ScNb(Ta)O7-delta (Ln = La, Sm, Ho, Yb; x = 0, 0.05, 0.1) lattice. It is shown that oxygen vacancy-related dielectric relaxation in the range of 550-650 degrees C (ambient air), typical of pyrochlores and fluorites with pure oxygen ion conductivity, decreases and disappears for proton-conducting oxides.

引用

页码：2376 / 2392

页数：17

共 4 条

[1] Synthesis, properties and phase transitions of pyrochlore- and fluorite-like Ln2RMO7 (Ln = Sm, Ho; R = Lu, Sc; M = Nb, Ta)
Shlyakhtina, A. V.
Belov, D. A.
Pigalskiy, K. S.
Shchegolikhin, A. N.
Kolbanev, I. V.
Karyagina, O. K.
MATERIALS RESEARCH BULLETIN, 2014, 49 : 625 - 632
[2] Aqueous Synthesis and Structural Comparison of Rare Earth Niobates and Tantalates: (La,K,□)2Nb2O7-x(OH)2 and Ln2Ta2O7(OH)2 (□ = vacancy; Ln = La-Sm)
Nyman, May
Rodriguez, Mark A.
Alam, Todd M.
Anderson, Travis M.
Ambrosini, Andrea
CHEMISTRY OF MATERIALS, 2009, 21 (11) : 2201 - 2208
[3] Evolution of Oxygen-Ion and Proton Conductivity in Ca-Doped Ln2Zr2O7 (Ln = Sm, Gd), Located Near Pyrochlore-Fluorite Phase Boundary
Shlyakhtina, A. V.
Abrantes, J. C. C.
Gomes, E.
Lyskov, N. V.
Konysheva, E. Yu.
Chernyak, S. A.
Kharitonova, E. P.
Karyagina, O. K.
Kolbanev, Lv.
Shcherbakova, L. G.
MATERIALS, 2019, 12 (15)
[4] Tolerance factor as the basic criterion in searching for promising oxygen-ion and proton conductors among Ln2-xDxM2O7-δ (Ln = La-Lu; M = Sn, Ti, Zr, Hf; D = Sr, Ca, Mg; x=0, 0.1) 3+/4+pyrochlores
Shlyakhtina, A., V
Pigalskiy, K. S.
MATERIALS RESEARCH BULLETIN, 2019, 116 : 72 - 78

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