Influence of purity of NdF3 single crystals on their ionic conductivity

Сорокин, Н. И.; Жмурова, З. И.; Кривандина, Е. А.; Соболев, Б. П.

doi:10.1134/s1063774512020228

Cited by 13 publications

(17 citation statements)

References 2 publications

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“…Studies were carried out with single crystals of non stoichiometric praseodymium and neodymium fluo rides grown in the Laboratory of Fluoride Materials of Institute of Crystallography of the Russian Academy of Sciences using the technology suggested in [11,12].…”

Section: Methodsmentioning

confidence: 99%

Voltammetric study of PrF3:Sr2+ and NdF3:Ba2+ solid electrolytes

et al. 2015

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Studies of single crystals of nonstoichiometric fluorides of PrF 3 :Sr 2+ and NdF 3 :Ba 2+ in contact with a Pt electrode were carried out using the method of voltammetry with a linear potential sweep, chrono amperometry, and cyclic voltammetry. The reaction of gaseous oxygen reduction (GOR) at the PrF 3 :Sr 2+ /Pt interface was accompanied by appearance of mobile oxygen forms. The catalytic activity of PrF 3 :Sr 2+ with respect to gaseous oxygen, same as CeF 3 :Sr 2+ , can be explained by variable valency of praseodymium and cerium fluoride, which creates opportunities for using them in oxygen and oxygen-containing gas sensors. The GOR reaction at the NdF 3 :Ba 2+ /Pt interface appeared as a result of anodic polarization. After charging at E = 3.2 V, the NdF 3 :Ba 2+ single crystal was successfully used for fluorination of Sb and Ag. NdF 3 :Ba 2+ is most promising in devices based on reactions with participation of mobile fluoride ion in solid electrolytes, particularly, for generation of gaseous fluorine.

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Section: Methodsmentioning

confidence: 99%

Voltammetric study of PrF3:Sr2+ and NdF3:Ba2+ solid electrolytes

et al. 2015

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“…If the impurity composition of RF 3 agents is not controlled, the σ value may change in a wide range (in comparison with the intrinsic conduc tivity of the crystalline matrix). The question about the influence of impurities on σ of some REE fluorides was investigated in [81].…”

Section: Optimization Of the Compositions Of Single Crystal Solid Elementioning

confidence: 99%

293-K conductivity optimization for single crystals of solid electrolytes with tysonite structure (LaF3): I. Nonstoichiometric phases R 1−yCayF3−y (R = La-Lu, Y)

et al. 2014

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The systematic optimization of single crystal fluoride conducting solid electrolytes R 1 -y Ca y F 3 -y with a tysonite type structure (LaF 3 ) with respect to the conductivity at room temperature, σ(293 K), is based on high temperature measurements of σ(T) of stoichiometric fluorides of rare earth elements, RF 3 (R = La-Nd), in dependence of the radius R 3+ ( ); two component stoichiometric La 1 -y R y F 3 phases (R = Pr, Nd) in dependence on the average cation radius (r cat ); and two component nonstoichiometric phases R 1 -y Ca y F 3 -y (R = La-Lu, Y) in dependence of the CaF 2 content. The optimization of the compo sition with respect to thermal stability is based on studying the phase diagrams of CaF 2 -RF 3 systems and the behavior of R 1 -y Ca y F 3 -y crystals upon heating when measuring temperature dependences σ(T). Single crystal samples of a number of investigated R 1 -y Ca y F 3 -y compounds has σ(293 K) values high enough to be applied in solid state electrochemical devices operating at room temperature (chemical sensors, fluorine ion batteries, and accumulators) and in devices subjected to thermal cycling.

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“…Hence, critical comparisons of the properties of tysonite phases based on the data in the literature are inefficient, because the impurity composition of the agents used and crystals grown has been reported in only few cases. The dependence of the fluorine-ion conductivity σ of tysonite NdF 3 crystals on the impurity composition of the used commercial agents was studied in [12]. The σ value of crystals was found to depend strongly on the purity of initial materials and vary in the range of 10 -4 -10 -3 S/cm at a temperature of 473 K.…”

Section: Structure Of Inorganic Compoundsmentioning

confidence: 99%

“…The structural factors responsible for such a strong dependence of σ on the tysonite phase composition remain unknown. In R 1 -y M y F 3 -y phases with specified R and M, the conductivity depends nonlineraly on y, reaching a maximum at y = 0.04-0.07 [18][19][20][21][22]. The structural prerequisites for this effect have not been studied either.…”

Section: Structure Of Inorganic Compoundsmentioning

confidence: 99%

Relationship between the defect structure and fluorine-ion conductivity of La1 − y Sr y F3 − y (0 ⩽ y ⩽ 0.15) crystals according to X-ray and neutron diffraction data

et al. 2015

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The defect structure of crystals of as-grown nonstoichiometric tysonite (LaF 3 type) La 1 -y Sr y F 3 -y phase (y = 0, 0.05, 0.07, and 0.15) has been investigated by X-ray diffraction and neutron diffraction. A concentration-driven structural transition from the β-La 1 -y Sr y F 3 -y modification to the α-La 1 -y Sr y F 3 -y modification in the range y = 0.05-0.10 has been observed for the first time. This transition correlates with the maximum of fluorine-ion conductivity (y = 0.05 ± 0.02) and the maximum in the melting curve (y = 0.07 ± 0.03). β-LaF 3 and β-La 0.95 Sr 0.05 F 2.95 crystals belong to the trigonal system (sp. gr. P c1, Z = 6) and are twinned according to the merohedral twin law. Fine changes in the fluorine sublattice of β-La 0.95 Sr 0.05 F 2.95 increase conductivity σ 293К to 3 × 10 -4 S/cm; hence, these crystals can be used as fluorine-conducting solid electrolytes (FCSEs) in solid-state ionics devices. Additional possibilities of ion transport over twin joints are discussed. In α-La 0.85 Sr 0.15 F 2.85 crystal the symmetry group changes to P6 3 /mmc, Z = 2; it is not twinned and its fluorine-ion conductivity is reduced.

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Influence of purity of NdF3 single crystals on their ionic conductivity

Cited by 13 publications

References 2 publications

Voltammetric study of PrF3:Sr2+ and NdF3:Ba2+ solid electrolytes

Voltammetric study of PrF3:Sr2+ and NdF3:Ba2+ solid electrolytes

293-K conductivity optimization for single crystals of solid electrolytes with tysonite structure (LaF3): I. Nonstoichiometric phases R 1−yCayF3−y (R = La-Lu, Y)

Relationship between the defect structure and fluorine-ion conductivity of La1 − y Sr y F3 − y (0 ⩽ y ⩽ 0.15) crystals according to X-ray and neutron diffraction data

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