Fluorination of La2−xSrxCuO4 (x=0, 0.15, 0.3) and study on the crystal structures, magnetic properties of their fluorinated products

Chen, Xiuhua; Tang, Kaibin; Zeng, Suyuan; Hao, Qiaoyan; Wang, Dake; Gao, Zhan; Wang, Yan

doi:10.1016/j.jallcom.2014.12.027

Cited by 14 publications

(4 citation statements)

References 39 publications

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“…As a result, the highest fluorinated phases known so far are La 2 CuO 3.6 F 0.8 from the reaction of La 2 CuO 4 with F 2 at 300 °C6 and La 2 CuO 4−d F 0.9 obtained by the reaction with ZnF 2 . 21 In this study, we report on the new oxyfluorides La 2 CuO 3 F 2 and La 2 Cu 0.8 Ni 0.2 O 3 F 2 being the first lanthanum cuprates with more than one fluoride ion per formula unit. The samples were obtained through topochemical low-temperature fluorination of reactive oxide precursors prepared by the citrate route with PVDF as the fluorination agent.…”

Section: ■ Introductionmentioning

confidence: 99%

“…In the case of La 2 CuO 4 , the amount of fluorine per formula unit usually remains low, although different fluorination methods have been applied. ,,,− Efforts toward higher fluorinated materials often lead to (partial) decompositions. As a result, the highest fluorinated phases known so far are La 2 CuO 3.6 F 0.8 from the reaction of La 2 CuO 4 with F 2 at 300 °C and La 2 CuO 4– d F 0.9 obtained by the reaction with ZnF 2 …”

Section: Introductionmentioning

confidence: 99%

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Cuprate Oxyfluorides La₂Cu_0.8Ni_0.2O₃F₂ and La₂CuO₃F₂ with “Channel-like” Anion Ordering

2022

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Highly fluorinated cuprate Ruddlesden–Popper oxyfluorides La2Cu0.8Ni0.2O3F2 and La2CuO3F2 were obtained by topochemical reaction between poly(vinylidene fluoride) (PVDF) and the corresponding oxides La2Cu0.8Ni0.2O4 and La2CuO4 prepared by citrate-based soft chemistry synthesis. The crystal structures of both oxyfluorides were investigated by powder diffraction techniques. The structure of La2Cu0.8Ni0.2O3F2 was solved based on combined neutron and X-ray powder diffraction. It crystallizes in a new monoclinic distorted version [C2/c a = 13.1880(3) Å, b = 5.7244(1) Å, c = 5.6007(1) Å, and β = 90.85(1)°] of the anionic ordered structure lately reported for La2NiO3F2. For La2CuO3F2, an even less symmetrical triclinic structure was derived from X-ray powder diffraction data [P1̅ a = 5.6180(5) Å, b = 5.7316(6) Å, c = 7.1978(9) Å, α = 113.32(1)°, β = 90.89(9)°, and γ = 90.16(11)°]. For both compounds, an additional tilt component of the partially Jahn-Teller elongated (Cu,Ni)O4F2 octahedra was found as the origin for the lowered symmetry. The formation reaction of La2CuO3F2 was studied by in situ XRD measurements. In these investigations, two new reaction intermediates were identified. The magnetic properties of both oxyfluorides La2Cu0.8Ni0.2O3F2 and La2CuO3F2 were characterized by field- and temperature-dependent measurements. An antiferromagnetic ordering with T N = 240 K was found for La2Cu0.8Ni0.2O3F2. In La2CuO3F2, additional weak ferrimagnetism was observed, resulting in a pronounced hysteresis but a weak saturation moment, which was attributed to result from a canted antiferromagnetic spin arrangement.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cuprate Oxyfluorides La₂Cu_0.8Ni_0.2O₃F₂ and La₂CuO₃F₂ with “Channel-like” Anion Ordering

2022

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“…Cationic substitutions have widely been used to tailor the physical properties of RP oxides. An alternative method is the partial anionic substitution of oxygen with N 3– , X – (X = halogen), or H – , resulting in the corresponding oxynitrides, , -halides, − and -hydrides. − The n = 1 RP compounds (A 2 BX 4 ) adopt the K 2 NiF 4 structure, which can be described as perovskite layers (ABX 3 ), with apical (X1) and equatorial (X2) anion sites. These layers are separated by AX1 rock salt layers.…”

Section: Introductionmentioning

confidence: 99%

Structure, Magnetism, and Thermal Stability of La₂NiO_2.5F₃: A Ruddlesden–Popper Oxyfluoride Crystallizing in Space Group P4₂/nnm

et al. 2021

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We report on the new Ruddlesden–Popper (RP) oxyfluoride La2NiO2.5F3 containing an unprecedented high amount of fluorine and Ni2+. This oxyfluoride was prepared by topochemical low-temperature fluorination of La2NiO4, which was obtained by a soft chemistry synthesis, with poly(vinylidene difluoride) (PVDF) as fluorinating agent. La2NiO2.5F3 is the first n = 1 RP compound crystallizing in the tetragonal space group P42/nnm (a = 5.7297(6) Å and c = 13.0106(2) Å). The crystal structure shows a unique tilting scheme of the NiO4F2 octahedra that has so far been only theoretically predicted. Combined neutron and X-ray powder diffraction experiments together with bond-valence-sum and DFT+U calculations reveal an unusual anion ordering with fluoride being located on the apical anion sites of the NiO4F2 octahedra. Excess fluorine ions were found to populate two of the four interstitial anion sites in an ordered fashion. A third interstitial anion position is occupied by oxygen ions while the fourth site remains unoccupied. This hitherto unobserved ordering scenario in RP oxyfluorides promotes a strong layerwise alternating tilting of the NiO4F2 octahedra. Magnetic measurements show strong antiferromagnetic interactions with a high Néel temperature of about 225 K and a pronounced ZFC/FC splitting most likely as the result of a small ferromagnetic moment arising from spin canting. The electronic structure was characterized by DFT and UV–vis spectroscopy, and a strong increase of E g was found compared to La2NiO4 (3.4 eV vs 1.3 eV).

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“…One particular class of materials are the oxyfluorides, of which an increasing number of compounds with different O/F compositions are known to date. These oxyfluorides range from compounds with small fluoride excess like superconducting La 2 CuO 4 F δ (0 < δ < 0.25) − over stoichiometric compounds with O + F = 4 like Sr 2 FeO 3 F to highly fluorinated compounds with O + F > 4 (e.g., LaSrMnO 4 F 1 , La 2 CoO 4 F 1.2 , Ba 2 ZrO 3 F 2 , and Ba 2 SnO 2.5 F 3 ). Different low-temperature fluorination methods like the solvothermal reaction with XeF 2 as well as reactions with the fluorine-containing polymers polyvinylidene fluoride (PVDF) − and polytetrafluoroethylene (PTFE) have emerged in recent years, yielding less oxidative synthesis conditions compared to the reaction with F 2 gas, enabling the synthesis of less redox stable oxyfluorides.…”

Section: Introductionmentioning

confidence: 99%

Ruddlesden–Popper Oxyfluorides La₂Ni_1–xCu_xO₃F₂ (0 ≤ x ≤ 1): Impact of the Ni/Cu Ratio on the Structure

Jacobs,

Wang,

Marques

et al. 2024

Inorg. Chem.

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≤ x ≤ 1) were obtained by topochemical reaction of oxide precursors La 2 Ni 1−x Cu x O 4 , prepared by citrate-based soft chemistry synthesis, with polyvinylidene fluoride (PVDF) as the fluorine source. Systematic changes of the crystal structure in the oxide as well as the oxyfluoride substitution series were investigated. For 0.2 ≤ x ≤ 0.9, the oxyfluorides adopt the monoclinic (C2/c) structural distortion previously solved for the x = 0.8 compound based on neutron powder diffraction data, whereas the sample with a lower Cu content of x = 0.1 crystallizes in the orthorhombic (Cccm) structure variant of La 2 NiO 3 F 2 . The orthorhombic-to-monoclinic structural transition was found to be the result of an additional tilt component of the Jahn−Teller elongated CuO 4 F 2 octahedra. The structural transitions were additionally studied by DFT calculations, confirming the monoclinic space group symmetry. The "channel-like" anionic ordering of the endmembers La 2 NiO 3 F 2 and La 2 CuO 3 F 2 was checked by 19 F MAS NMR experiments and was found to persist throughout the entire substitution series.

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Fluorination of La2−xSrxCuO4 (x=0, 0.15, 0.3) and study on the crystal structures, magnetic properties of their fluorinated products

Cited by 14 publications

References 39 publications

Cuprate Oxyfluorides La₂Cu_0.8Ni_0.2O₃F₂ and La₂CuO₃F₂ with “Channel-like” Anion Ordering

Cuprate Oxyfluorides La₂Cu_0.8Ni_0.2O₃F₂ and La₂CuO₃F₂ with “Channel-like” Anion Ordering

Structure, Magnetism, and Thermal Stability of La₂NiO_2.5F₃: A Ruddlesden–Popper Oxyfluoride Crystallizing in Space Group P4₂/nnm

Ruddlesden–Popper Oxyfluorides La₂Ni_1–xCu_xO₃F₂ (0 ≤ x ≤ 1): Impact of the Ni/Cu Ratio on the Structure

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Fluorination of La2−xSrxCuO4 (x=0, 0.15, 0.3) and study on the crystal structures, magnetic properties of their fluorinated products

Cited by 14 publications

References 39 publications

Cuprate Oxyfluorides La2Cu0.8Ni0.2O3F2 and La2CuO3F2 with “Channel-like” Anion Ordering

Cuprate Oxyfluorides La2Cu0.8Ni0.2O3F2 and La2CuO3F2 with “Channel-like” Anion Ordering

Structure, Magnetism, and Thermal Stability of La2NiO2.5F3: A Ruddlesden–Popper Oxyfluoride Crystallizing in Space Group P42/nnm

Ruddlesden–Popper Oxyfluorides La2Ni1–xCuxO3F2 (0 ≤ x ≤ 1): Impact of the Ni/Cu Ratio on the Structure

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Cuprate Oxyfluorides La₂Cu_0.8Ni_0.2O₃F₂ and La₂CuO₃F₂ with “Channel-like” Anion Ordering

Cuprate Oxyfluorides La₂Cu_0.8Ni_0.2O₃F₂ and La₂CuO₃F₂ with “Channel-like” Anion Ordering

Structure, Magnetism, and Thermal Stability of La₂NiO_2.5F₃: A Ruddlesden–Popper Oxyfluoride Crystallizing in Space Group P4₂/nnm

Ruddlesden–Popper Oxyfluorides La₂Ni_1–xCu_xO₃F₂ (0 ≤ x ≤ 1): Impact of the Ni/Cu Ratio on the Structure