Synthesis and stability of Sn(II)-containing perovskites: (Ba,SnII)HfIVO3 versus (Ba,SnII)SnIVO3

Gabilondo, Eric; O’Donnell, Shaun; Broughton, Rachel; Jones, Jacob L.; Maggard, Paul A.

doi:10.1016/j.jssc.2021.122419

Cited by 15 publications

(43 citation statements)

References 34 publications

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“…Micron-scale BaHfO3 particles were synthesized by the ceramic method as described in previous work. 9 BaHfO3 hollow nanoparticles were synthesized via hydrothermal route modified from prior reports. 24 Ba(NO3)2 (Baker, 99.9%) and HfCl4 (Acros Organics, 99%) in a 1.1:1 ratio were suspended in ~5 mL of ethanol.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…Previous work from our research group has challenged the above assumptions by demonstrating that Sn(II)-rich cubic perovskites could be synthesized with low-temperature ion-exchange techniques. 6,9 The limiting Sn(II)-enriched perovskites were determined to be at least 250-450 meV/atom above the convex hull. In the BaMO3 systems (M = Ti(IV), Zr(IV), Hf(IV), Sn(IV)), for example, it was found that the synthesizability could be significantly increased by (a) maximizing the lattice cohesive energy of the underlying MO6 sublattice and (b) targeting composition spaces with few competing lower-energy polymorphs.…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, these works highlighted the critical role of temperature in both the formation and decomposition of the metastable phase via ion-diffusion mechanisms. 9,41 Thus, in an effort to further drive the limits of metastability in Sn(II)-containing perovskites, we herein have employed a multi-pronged 'Chimie Douce' technique specifically in the barium hafnate perovskite system. BaHfO3 was chosen as a precursor for the synthesis of a model SnHfO3 perovskite owing to its high lattice cohesive energy (as exemplified by the high melting point for BaHfO3 of ~2620 ºC).…”

Section: Introductionmentioning

confidence: 99%

“…SnClF. 6,9 The reaction was driven by the large heat of formation of the high-melting BaClF salt vs. SnClF (ΔHf ≈ -456 kJ/mol).…”

Section: Introductionmentioning

confidence: 99%

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Circumventing Thermodynamics to Synthesize Highly Metastable Tin(II) Perovskites: Nano Eggshells of SnHfO3

Gabilondo

Newell

Chestnut

et al. 2022

Preprint

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Sn(II)-based perovskite oxides, being the subject of longstanding theoretical interest for the past two decades, have been synthesized for the first time with a nanoshell approach. All past reported synthetic attempts had been rendered impotent by the extremely high metastabilities, i.e., thermodynamic instability. Herein, a soft topotactic exchange of Sn(II) cations into Ba-containing perovskites is demonstrated to successfully yield ~20 nm thick shells of Sn(II) perovskites, i.e. SnHfO3. Additionally, highly pure SnHfO3 was obtained for the first time as nano-eggshell morphologies that circumvent the intrinsic ion-diffusion limits occurring at a low reaction temperature of 200 oC. In summary, the high metastability of the Sn(II) perovskites is shown to be overcome by leveraging the high cohesive energies of the reactants, the exothermic formation of a stable salt side product, and a shortened diffusion pathway for the Sn(II) cations. The new approach finally provides an effective solution to surmounting highly intractable synthetic barriers, and which can be the key to unlocking the door to many other new metastable oxides.

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Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…SnClF. 6,9 The reaction was driven by the large heat of formation of the high-melting BaClF salt vs. SnClF (ΔHf ≈ -456 kJ/mol).…”

Section: Introductionmentioning

confidence: 99%

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Circumventing Thermodynamics to Synthesize Highly Metastable Tin(II) Perovskites: Nano Eggshells of SnHfO3

Gabilondo

Newell

Chestnut

et al. 2022

Preprint

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“…A common motivation is to prepare visible‐light, semiconducting photocatalysts with a higher energy valence band formed by the Sn(II) cation. These have involved metal oxides in the pyrochlore [28–30] and other structure types [31–34] . The Maggard and Jones groups have pioneered recent studies of Sn(II) exchange into the perovskite structure type, BaMO 3 (M=Ti, Zr, or Hf) with close‐packed ‘BaO 3 ’ layers, as illustrated in Figure 3 and in the reactions below:

true BaHfO_{3} + x SnClF \to (Ba_{1 - x} Sn_{x}) HfO_{3} + x BaClF

true BaZr_{1 / 2} Ti_{1 / 2} normalO_{3} + x SnClF \to (Ba_{1 - x} Sn_{x}) Zr_{1 / 2} Ti_{1 / 2} normalO_{3} + x BaClF

…”

Section: Cation Exchange In the Preparation Of Functional Multinary O...mentioning

confidence: 99%

Renaissance of Topotactic Ion‐Exchange for Functional Solids with Close Packed Structures

Gabilondo

O’Donnell

Newell

et al. 2022

Chemistry A European J

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Recently, many new, complex, functional oxides have been discovered with the surprising use of topotactic ion‐exchange reactions on close‐packed structures, such as found for wurtzite, rutile, perovskite, and other structure types. Despite a lack of apparent cation‐diffusion pathways in these structure types, synthetic low‐temperature transformations are possible with the interdiffusion and exchange of functional cations possessing ns2 stereoactive lone pairs (e. g., Sn(II)) or unpaired ndx electrons (e. g., Co(II)), targeting new and favorable modulations of their electronic, magnetic, or catalytic properties. This enables a synergistic blending of new functionality to an underlying three‐dimensional connectivity, i. e., [‐M−O‐M‐O‐]n, that is maintained during the transformation. In many cases, this tactic represents the only known pathway to prepare thermodynamically unstable solids that otherwise would commonly decompose by phase segregation, such as that recently applied to the discovery of many new small bandgap semiconductors.

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Switching Lead for Tin in PbHfO₃: Noncubic Structure of SnHfO₃**

Gabilondo,

Newell,

Broughton

et al. 2023

Angewandte Chemie

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The removal of lead from commercialized perovskite‐oxide‐based piezoceramics has been a recent major topic in materials research owing to legislation in many countries. In this regard, Sn(II)‐perovskite oxides have garnered keen interest due to their predicted large spontaneous electric polarizations and isoelectronic nature for substitution of Pb(II) cations. However, they have not been considered synthesizable owing to their high metastability. Herein, the perovskite lead hafnate, i.e., PbHfO3 in space group Pbam, is shown to react with SnClF at a low temperature of 300 °C, and resulting in the first complete Sn(II)‐for‐Pb(II) substitution, i.e. SnHfO3. During this topotactic transformation, a high purity and crystallinity is conserved with Pbam symmetry, as confirmed by X‐ray and electron diffraction, elemental analysis, and 119Sn Mössbauer spectroscopy. In situ diffraction shows SnHfO3 also possesses reversible phase transformations and is potentially polar between ≈130–200 °C. This so‐called ‘de‐leadification’ is thus shown to represent a highly useful strategy to fully remove lead from perovskite‐oxide‐based piezoceramics and opening the door to new explorations of polar and antipolar Sn(II)‐oxide materials.

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Synthesis and stability of Sn(II)-containing perovskites: (Ba,SnII)HfIVO3 versus (Ba,SnII)SnIVO3

Cited by 15 publications

References 34 publications

Circumventing Thermodynamics to Synthesize Highly Metastable Tin(II) Perovskites: Nano Eggshells of SnHfO3

Circumventing Thermodynamics to Synthesize Highly Metastable Tin(II) Perovskites: Nano Eggshells of SnHfO3

Renaissance of Topotactic Ion‐Exchange for Functional Solids with Close Packed Structures

Switching Lead for Tin in PbHfO₃: Noncubic Structure of SnHfO₃**

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Synthesis and stability of Sn(II)-containing perovskites: (Ba,SnII)HfIVO3 versus (Ba,SnII)SnIVO3

Cited by 15 publications

References 34 publications

Circumventing Thermodynamics to Synthesize Highly Metastable Tin(II) Perovskites: Nano Eggshells of SnHfO3

Circumventing Thermodynamics to Synthesize Highly Metastable Tin(II) Perovskites: Nano Eggshells of SnHfO3

Renaissance of Topotactic Ion‐Exchange for Functional Solids with Close Packed Structures

Switching Lead for Tin in PbHfO3: Noncubic Structure of SnHfO3**

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Switching Lead for Tin in PbHfO₃: Noncubic Structure of SnHfO₃**