Topochemical Reduction of La₂NiO₃F₂: The First Ni-Based Ruddlesden–Popper n = 1 T′-Type Structure and the Impact of Reduction on Magnetic Ordering

Abstract

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Synthesis of Heavily Hydrated La2NiO4 Through Ion Exchange of Its Fluorinated Derivative: A New Route to the Synthesis of Oxyhydroxide Systems

“…Successful fluorination of La2NiO4 by heating with PVDF was demonstrated by XRD: a large splitting of (020)/(200), (024)/(204), (026)/(206) and (133)/(313) peaks was observed after fluorination, indicating a large increase in the orthorhombic splitting (figure 2). On increasing the fluorination levels to >0.4 moles CH2CF2 per mole of La2NiO4, the sample was no longer a single phase, but rather extra peaks are seen, which are due to the higher fluorinate content phase La2NiO3F2 [25] (Figure 3). CH2CF2)) extra peaks are seen (marked *) which are from a higher F content La2NiO3F2 phase [25].…”

“…On increasing the fluorination levels to >0.4 moles CH2CF2 per mole of La2NiO4, the sample was no longer a single phase, but rather extra peaks are seen, which are due to the higher fluorinate content phase La2NiO3F2 [25] (Figure 3). CH2CF2)) extra peaks are seen (marked *) which are from a higher F content La2NiO3F2 phase [25].…”

“…In this work, we have investigated strategies to increase the water content achievable in La2NiO4 by the use of an indirect route. In this indirect route, we make use of the fact that K2NiF4 type oxides can incorporate F (by 2F − /1O 2− exchange) leading to oxide fluorides, with relatively large anion contents in the interstitial sites [17][18][19][20][21][22][23][24][25], and investigate the potential for subsequent OH − /F − ion exchange.…”

Fluoride ion batteries – past, present, and future

“…So far, the chemical defluorination behavior of n = 1 Sr2TiO3F2, n = 2 Sr3Ti2O5F4 and n = 1 La2NiO3F2 has been investigated. 34,[164][165][166] This defluorination reaction is favoured by the high lattice energy of NaF, which helps to prepare anode materials in the charged state down to a potential of < ~ 1V against Li/LiF. The feasibility of topochemical modifications of these Ruddlesden-Popper-type oxyfluorides, when used as active anode materials, via electrochemical defluorination reactions in FIBs have also been investigated.…”

Synthesis of Heavily Hydrated La2NiO4 Through Ion Exchange of Its Fluorinated Derivative: A New Route to the Synthesis of Oxyhydroxide Systems

“…Successful fluorination of La2NiO4 by heating with PVDF was demonstrated by XRD: a large splitting of (020)/(200), (024)/(204), (026)/(206) and (133)/(313) peaks was observed after fluorination, indicating a large increase in the orthorhombic splitting (figure 2). On increasing the fluorination levels to >0.4 moles CH2CF2 per mole of La2NiO4, the sample was no longer a single phase, but rather extra peaks are seen, which are due to the higher fluorinate content phase La2NiO3F2 [25] (Figure 3). The possibility to ion exchange (OH − for F − ) was then analysed for the La2NiO4 sample fluorinated with 0.25 monomer moles equivalent of PVDF.…”