A combined study on structural, magnetic and specific heat on double perovskite iridates Ln<sub>2</sub>CoIrO<sub>6</sub> [Ln = Pr, Nd]

Datta, Raktim; Pradhan, Suman Kalyan; Saha, Rafikul Ali; Kumar, Ravi; Majumdar, Swapan Kumar; De, S. K.

doi:10.1088/1361-648x/acafc8

Cited by 3 publications

(2 citation statements)

References 40 publications

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“…The X-ray diffraction (XRD) pattern and crystal structure for all the compositions are depicted in Figure , and the perovskite phase formation is confirmed through Rietveld analysis. Generally, the XRD peak at 2θ = 20° is associated with the ordering of Co and Fe in the system . However, the intensity of this peak is notably weak and screened by the background level in comparison to the more prominent peak at 2θ = 33°.…”

Section: Resultsmentioning

confidence: 99%

“…Generally, the XRD peak at 2θ = 20°is associated with the ordering of Co and Fe in the system. 38 However, the intensity of this peak is notably weak and screened by the background level in comparison to the more prominent peak at 2θ = 33°. The similar atomic absorption coefficient of the Co (∼3240) and Fe (∼2860) elements for the Cu−K α source leads to this weak nature.…”

Section: ■ Introductionmentioning

confidence: 93%

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Enhancing Trifunctional Electrocatalytic Activities via Lanthanide Modulation in Fe–Co-Based Double Perovskite Oxides

Ganguly,

Datta,

Loha

et al. 2024

Energy Fuels

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In the global development of alternative and sustainable fuels, H 2 has gained prime research interest as combustion of it results in energy with zero carbon footprint. In this context, non-noble metal-based double perovskite oxides with their wide tunable structure gained interest from researchers as an effective electrocatalyst for water oxidation in alkaline medium. However, their low catalytic efficacy and durability limit their application for the industrial scale. Here, we present several Fe−Co-based double perovskite oxides tuning their Asite with lanthanides for overall water splitting and hybrid electrolysis for energysaving H 2 production. The best Fe−Co-based double perovskite oxide, Eu 2 FeCoO 6 , demonstrates very high trifunctional electrocatalytic activity for oxygen evolution reaction (OER) and small alcohol molecule oxidation, along with hydrogen evolution reaction (HER). Overpotentials (η 10 ) of 220 mV for the OER and 238 mV for the HER were attained at 10 mA cm −2 current density in 1 M NaOH (pH = 14). Also, Faradaic yields of 85 and 89% were achieved for ethanol oxidation (EtOR) and benzyl alcohol oxidation (BnOR), respectively, with the best catalyst. Moreover, in a two-electrode electrolyzer with 0.1 M benzyl alcohol (as an electrolyte) and Eu 2 FeCoO 6 as a bifunctional catalyst (both as the cathode and anode, Eu 2 FeCoO 6 (−)∥Eu 2 FeCoO 6 (+)), a cell potential of 1.75 V was enough for oxygenation of benzyl alcohol along with the production of H 2 . A 150 mV advantage in cell potential was gained in BnOR-aided H 2 generation compared with overall water oxidation.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 93%

Enhancing Trifunctional Electrocatalytic Activities via Lanthanide Modulation in Fe–Co-Based Double Perovskite Oxides

Ganguly,

Datta,

Loha

et al. 2024

Energy Fuels

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A complex magnetic study: evidence of spin-glass transition below long-range magnetic ordering and its correlation with renormalization of phonon modes

Mohanty,

Mukherjee

2024

J. Phys.: Condens. Matter

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In this paper, we report a complex magnetic behavior arising due to the interplay of three active magnetic cations (Nd/Sm, Co and Ir), forming 3d-5d-4f magnetic sublattices. The B-site ordered double perovskites Nd2CoIrO6 and Sm2CoIrO6 were successfully prepared by conventional solid-state method. Detailed structural analysis revealed that both samples crystallized in monoclinic structure with P21/n (No.-14) space group. XPS analysis confirms the presence of multiple oxidation states of Ir (i.e., Ir4+ and Ir5+). Both samples show a paramagnetic-ferrimagnetic (TFiM) transition around 100 K, additionally, a low temperature transition is observed at around 10 K in the SCIO sample. This FM-like behaviour of the samples is attributed to the antiparallel alignment of the Co2+ and Ir4+ spins, resulting in FIM ordering. The ac susceptibility analysis confirms a spin glass type transition just below the long-range ordering temperature in NCIO sample, The obtained characteristic flipping time of a single spin from both the law (Power law and Vogel-Fulcher law) and nonzero Vogel-Fulcher temperature (T0≃ 89.1 K) further verified the existence of cluster spin-glass behavior below the ordering temperature. The temperature evolution of phonon modes (up to 4 K) suggests that the phonon mode above the magnetic ordering temperature is mainly governed by the lattice degrees of freedom, notable renormalization of the mode frequency below the ordering temperature is due to the coupling of lattice with the underlying magnetic degrees of freedom.

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Evolution of structural, magnetic and transport properties of 3d-5d based double perovskites Nd_2–xSr_xCoIrO₆

Datta,

Mondal,

Mondal

et al. 2024

J. Phys.: Condens. Matter

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The evolution of the structural, magnetic and transport properties of the intermediate compounds Nd 2 − x Sr x CoIrO6 with x = 0.2, 0.4, 0.6, 1 and 1.5 have been studied to establish important roles of sizes and oxidation states of cations on various phases. The replacement of Nd3+ by Sr2+ primarily influences the oxidation states of Co (Co2+ → Co3+) and Ir (Ir4+ → Ir5+) ions to maintain the charge neutrality in the entire system. The Sr dopants give rise to an increasing Co/Ir antisite disorder (ASD) to accommodate the variation of charge state and ionic radius of Co and Ir. The nature of magnetic interaction induced by Sr changes from being a ferrimagnetic (FIM) to a more dominant antiferromagnetic. The suppression of the second magnetic transition below 30 K in samples for x > 0.2 is entirely due to dilution of the Nd–Nd magnetic interaction. The combined effects of ASD and mixed oxidation state of Co and Ir ions generate various types of magnetic exchange pathways and create competitive magnetic interactions to stabilize a particular magnetic ground state. In the middle compound NdSrCoIrO6, a Griffith like phase in the temperature region 65–150 K and exchange bias field of 658 Oe at 2.3 K under a cooling field of 50 kOe has been observed. The compounds show an insulating kind of behaviour, and with hole doping the value of room temperature resistivity drastically decreases. The nature of conduction is found to follow three dimensional Mott’s variable range hopping process.

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A combined study on structural, magnetic and specific heat on double perovskite iridates Ln₂CoIrO₆ [Ln = Pr, Nd]

Cited by 3 publications

References 40 publications

Enhancing Trifunctional Electrocatalytic Activities via Lanthanide Modulation in Fe–Co-Based Double Perovskite Oxides

Enhancing Trifunctional Electrocatalytic Activities via Lanthanide Modulation in Fe–Co-Based Double Perovskite Oxides

A complex magnetic study: evidence of spin-glass transition below long-range magnetic ordering and its correlation with renormalization of phonon modes

Evolution of structural, magnetic and transport properties of 3d-5d based double perovskites Nd_2–xSr_xCoIrO₆

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A combined study on structural, magnetic and specific heat on double perovskite iridates Ln2CoIrO6 [Ln = Pr, Nd]

Cited by 3 publications

References 40 publications

Enhancing Trifunctional Electrocatalytic Activities via Lanthanide Modulation in Fe–Co-Based Double Perovskite Oxides

Enhancing Trifunctional Electrocatalytic Activities via Lanthanide Modulation in Fe–Co-Based Double Perovskite Oxides

A complex magnetic study: evidence of spin-glass transition below long-range magnetic ordering and its correlation with renormalization of phonon modes

Evolution of structural, magnetic and transport properties of 3d-5d based double perovskites Nd2–xSrxCoIrO6

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A combined study on structural, magnetic and specific heat on double perovskite iridates Ln₂CoIrO₆ [Ln = Pr, Nd]

Evolution of structural, magnetic and transport properties of 3d-5d based double perovskites Nd_2–xSr_xCoIrO₆