Synthesis and superconducting properties of fluorinated La2CuO4 using NH4F

Adachi, Seiji; Wu, Xinming; Tamura, Toshiyuki; Tatsuki, T.; Tokiwa‐Yamamoto, A.; Tanabe, K.

doi:10.1016/s0921-4534(97)01707-3

Cited by 12 publications

(13 citation statements)

References 38 publications

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“…24 To solve this problem, fluorination by ionic bombardment with a fluoride beam has been developed. 16,25 Another efficient way to overcome this disadvantage was sought in chemical fluorination based on the use of fluorinating reagents such as NH 4 F, 18,[26][27][28] but here the temperature is still higher than 200 °C and generates the release of fluorine by thermal decomposition. In this method, starting materials are simply heated together with the reagent.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Fluorination of La₂CuO₄: A Mild “Chimie Douce” Route to Superconducting Oxyfluoride Materials

et al. 2009

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The fluorination of La(2)CuO(4) was achieved for the first time under normal conditions of pressure and temperature (1 MPa and 298 K) via electrochemical insertion in organic fluorinated electrolytes and led to lanthanum oxyfluorides of general formula La(2)CuO(4)F(x). Analyses showed that, underneath a very thin layer of LaF(3) (a few atomic layers), fluorine is effectively inserted in the material's structure. The fluorination strongly modifies the lanthanum environment, whereas very little modification is observed on copper, suggesting an insertion in the La(2)O(2) blocks of the structure. In all cases, fluorine insertion breaks the translation symmetry and introduces a long-distance disorder, as shown by electron spin resonance. These results highlight the efficiency of electrochemistry as a new "chimie douce" type fluorination technique for solid-state materials. Performed at room temperature, it additionally does not require any specific experimental care. The choice of the electrolytic medium is crucial with regard to the fluorine insertion rate as well as the material deterioration. Successful application of this technique to the well-known La(2)CuO(4) material provides a basis for further syntheses from other oxides.

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Section: Introductionmentioning

confidence: 99%

Electrochemical Fluorination of La₂CuO₄: A Mild “Chimie Douce” Route to Superconducting Oxyfluoride Materials

et al. 2009

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“…Xenon difluoride serves as an oxidising agent, unlike ammonium fluoride, which creates reductive conditions and leads to an increase in the oxidation state of copper only in the reactions performed in the presence oxygen 18,30 or through disproportionation of the reaction products to form oxidised and reduced phases. 20 Many transition-metal fluorides M H F 2 (M H = Hg or Ag), like XeF 2 , are oxidising fluorinating agents.…”

Section: Methods For the Synthesis Of Layered Copper Oxyfluoridesmentioning

confidence: 99%

High-temperature superconductors based on complex layered copper oxyfluorides

Abakumov¹,

Rozova²,

Ардашникова³

et al. 2002

Russ. Chem. Rev.

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“…F doping has also been proved successful in enhancing the electrical properties of tripleconducting materials (H + , O 2− and e − ), such as BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3−δ and Pr 2 NiO 4−δ , improving both the oxygen exchange capability and hydration of the electrodes [36,37]. Some authors have successfully introduced F − and Cl − into the La 2 CuO 4−δ structure, and the resulting materials achieved different superconducting properties [38,39]. For example, Adachi et al investigated superconductivity in La 2 CuO 4−x F x samples, which were synthesized by heating La 2 CuO 4−δ with NH 4 F as a fluorinating reagent at 240 • C under O 2 flow [38].…”

Section: Introductionmentioning

confidence: 99%

“…Some authors have successfully introduced F − and Cl − into the La 2 CuO 4−δ structure, and the resulting materials achieved different superconducting properties [38,39]. For example, Adachi et al investigated superconductivity in La 2 CuO 4−x F x samples, which were synthesized by heating La 2 CuO 4−δ with NH 4 F as a fluorinating reagent at 240 • C under O 2 flow [38].…”

Section: Introductionmentioning

confidence: 99%

Modification of the Microstructure and Transport Properties of La2CuO4−δ Electrodes via Halogenation Routes

et al. 2022

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Ruddlesden–Popper type electrodes with composition La2CuO4−δ are alternative cathode materials for solid oxide fuel cells (SOFCs); however, the undoped compound exhibits low electrical conductivity for potential applications, which is usually increased by alkaline-earth doping. A promising alternative to alkaline-earth doping is the modification of the anionic framework by halogen doping. In this study, La2CuO4−0.5xAx (A = F, Cl, Br; x = 0–0.3) compounds are prepared by a freeze-drying precursor method, using an anion doping strategy. The composition, structure, morphology and electrical properties are studied to evaluate their potential use in solid oxide fuel cells (SOFCs). The halogen-doped materials show higher electrical conductivity and improved electrocatalytic activity for oxygen reduction reactions when compared to the pristine material, with polarization resistance values 2.5 times lower, i.e., 0.20, 0.11 and 0.08 Ω cm2 for undoped, F- and Cl-doped samples, respectively, at 800 °C. Moreover, halogen doping prevents superficial copper segregation in La2CuO4−δ, making it an attractive strategy for the development of highly efficient electrodes for SOFCs.

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Synthesis and superconducting properties of fluorinated La2CuO4 using NH4F

Cited by 12 publications

References 38 publications

Electrochemical Fluorination of La₂CuO₄: A Mild “Chimie Douce” Route to Superconducting Oxyfluoride Materials

Electrochemical Fluorination of La₂CuO₄: A Mild “Chimie Douce” Route to Superconducting Oxyfluoride Materials

High-temperature superconductors based on complex layered copper oxyfluorides

Modification of the Microstructure and Transport Properties of La2CuO4−δ Electrodes via Halogenation Routes

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Synthesis and superconducting properties of fluorinated La2CuO4 using NH4F

Cited by 12 publications

References 38 publications

Electrochemical Fluorination of La2CuO4: A Mild “Chimie Douce” Route to Superconducting Oxyfluoride Materials

Electrochemical Fluorination of La2CuO4: A Mild “Chimie Douce” Route to Superconducting Oxyfluoride Materials

High-temperature superconductors based on complex layered copper oxyfluorides

Modification of the Microstructure and Transport Properties of La2CuO4−δ Electrodes via Halogenation Routes

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Electrochemical Fluorination of La₂CuO₄: A Mild “Chimie Douce” Route to Superconducting Oxyfluoride Materials

Electrochemical Fluorination of La₂CuO₄: A Mild “Chimie Douce” Route to Superconducting Oxyfluoride Materials