Electrical Conductivity in Lanthanum‐Doped Strontium Titanate

Balachandran, U.; Eror, N. G.

doi:10.1149/1.2124008

Cited by 141 publications

(74 citation statements)

References 6 publications

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“…Thermopower measurements demonstrate that these materials become n-type in air [21]. However, the understanding of defect chemistry is still inconclusive due to uncertainty concerning the incorporation of donor species (as found for Srl.xLaxTiO 3 materials [20]), or unusual changes in conductivity on changing from reducing to oxidizing conditions. Vernicke [15,16] suggested that slow reequilibration of the main charge carrier concentration on the reoxidation might be slow due to its dependence on the diffusion of vacancies.…”

Section: Proposed Defect Chemistry Model Formentioning

confidence: 99%

“…For example, high temperature volatilization losses of SrO may cause A-site deficiency, and this is probably accounted for by the formation of strontium vacancies and oxygen vacancies. An alternative defect chemistry model is also easily derived on assuming the formation of Schottky defects, and a third hypothesis may be based on assuming segregation of SrO in SrO-rich domains as proposed by the Balachandran and Eror [20]. These authors proposed the formation of layered structures (SrO.nSrTiO3) to accommodate the excess of Sr in SrvxLaxTiO3+~.…”

Section: Introductionmentioning

confidence: 99%

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Combined effects of A-site deficiency and dopant content on the transport properties of Nb-doped strontium titanate

Abrantes

Labrincha

Frade

1997

Ionics

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Abstract. Strontium titanate based materials with A-site deficiency and Nb-additions were prepared to study the effects of these changes in composition on the transport properties and sinterability. X-ray diffraction was used for phase identification and to evaluate changes in the lattice parameters with composition. The dependence of the conductivity on the oxygen partial pressure was measured in the range 700-1000 ~ using an electrochemical oxygen pump to adjust the oxygen partial pressure in the furnace. Porous samples were used for this purpose to enhance the rate of exchange between the atmosphere and the samples. Changes in the composition have important effects on the relevant transport properties and also on the materials sinterability; this is especially true for Nb additions, which tend to suppress the p-type contribution under oxidizing conditions.

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Section: Proposed Defect Chemistry Model Formentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Combined effects of A-site deficiency and dopant content on the transport properties of Nb-doped strontium titanate

Abrantes

Labrincha

Frade

1997

Ionics

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“…Overall electroneutrality of the lattice can be achieved by two different mechanisms, namely, electronic compensation and cation-vacancy compensation. [30][31][32] . As a result, the electrical conductivity of the material is again improved.…”

Section: Introductionmentioning

confidence: 99%

Density functional theory study on the electronic structure ofn- andp-type doped SrTiO3at anodic solid oxide fuel cell conditions

et al. 2011

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The electronic conductivity and thermodynamic stability of mixed n-type and ptype doped SrTiO 3 have been investigated at anodic solid oxide fuel cell (SOFC) conditions using density functional theory (DFT) calculations. In particular, constrained ab initio thermodynamic calculations have been performed to evaluate the phase stability and reducibility of various Nb-and Ga-doped SrTiO 3 at synthesized and anodic SOFC conditions. The density of states of these materials was analyzed to study the effects of nand p-doping on the electronic conductivity. In agreement with experimental observations, we find that the transformation from 20% Nb-doped Sr-deficient SrTiO 3 to a non Sr-deficient phase occurs at high temperature and low oxygen partial pressure which leads to a significant improvement in electronic conductivity. A mixed ionic/electronic conductor is obtained when doping 20% Nb-doped SrTiO 3 with small amounts of Ga (10%) in a reducing environment and high temperature. Doping with higher concentrations of Ga, e.g., 20%, diminishes the electronic conductivity of the material. These findings suggest that independent of the specific dopant, mixed ionic/electronic conductivity can be obtained in perovskite oxides under reducing 2 conditions and high temperatures by doping the B-site with small amounts of both n-type and p-type dopants.

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“…(2) . However, there are at least three compensation mechanisms in Ladoped SrTiO 3 , which can also be dependent on the conditions of synthesis, e.g., and temperature [20][21][22] . These are listed as mechanisms (2)- (4) and represent electronic, A-site and B-site vacancies, respectively.…”

Section: Introductionmentioning

confidence: 99%

The Influence of La Doping and Heterogeneity on the Thermoelectric Properties of Sr₃Ti₂O₇ Ceramics

Sinclair

Reaney

2015

J. Am. Ceram. Soc.

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La-doping mechanisms and thermoelectric properties of Sr 3 Ti 2 O 7 Ruddlesden-Popper (RP) ceramics sintered under air and flowing 5% H 2 at 1773 K for 6 hours have been investigated. Changes in lattice parameters and conductivity revealed a limited interstitial anion mechanism (~1 at.%) based on La 3+ + ½O ] are the dominant mechanism(s) in 5% H 2 -sintered ceramics with a solution limit of ~5 at.%. The increased solubility limit is attributed to the formation of Ti 3+ during reduction which compensates for the extra positive charge associated with La on the A-site and also to the occurrence of oxygen loss due to the reducing conditions. For 5% H 2 -sintered samples, an insulating surface layer formed associated with SrO volatilisation and oxygen up-take (during cooling) from the sintering. Unless removed, the insulating layer masked the conductive nature of the ceramics. In the bulk, significantly higher power factors were obtained for ceramics that 2 were phase mixtures containing highly conductive perovskite-based (Sr,La)TiO 3- (ST).This highlights the superior power factor properties of reduced perovskite-type ST phases compared to reduced RP-type Sr 3 Ti 2 O 7 and serves as a precaution for the need to identify low levels of highly conducting perovskite phases when exploring rare-earth doping mechanisms in RP-type phases.

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Electrical Conductivity in Lanthanum‐Doped Strontium Titanate

Cited by 141 publications

References 6 publications

Combined effects of A-site deficiency and dopant content on the transport properties of Nb-doped strontium titanate

Combined effects of A-site deficiency and dopant content on the transport properties of Nb-doped strontium titanate

Density functional theory study on the electronic structure ofn- andp-type doped SrTiO3at anodic solid oxide fuel cell conditions

The Influence of La Doping and Heterogeneity on the Thermoelectric Properties of Sr₃Ti₂O₇ Ceramics

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Electrical Conductivity in Lanthanum‐Doped Strontium Titanate

Cited by 141 publications

References 6 publications

Combined effects of A-site deficiency and dopant content on the transport properties of Nb-doped strontium titanate

Combined effects of A-site deficiency and dopant content on the transport properties of Nb-doped strontium titanate

Density functional theory study on the electronic structure ofn- andp-type doped SrTiO3at anodic solid oxide fuel cell conditions

The Influence of La Doping and Heterogeneity on the Thermoelectric Properties of Sr3Ti2O7 Ceramics

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The Influence of La Doping and Heterogeneity on the Thermoelectric Properties of Sr₃Ti₂O₇ Ceramics