Structural Change of Cu(HCOO) 2 ·4H 2 O Associated with the Antiferroelectric Phase Transition

X-ray diffraction and incoherent inelastic neutron scattering studies are performed to clarify the phase transition mechanism of Cu(HCOO) 2 ·4H 2 O. Contrary to the previous electrical study, we find no evidence of the existence of an intermediate ferrielectric phase. We determine the accurate antiferroelectric structure. It turns out that the atomic arrangement of the Cu(HCOO) 2 layers remains unchanged through the phase transition, while the antiferroelectric H 2 O layers take one of two disordered paraelectric arrangements alternately along the c-axis. We discuss that the rotation of the H 2 O molecules induces the structural correlation one-dimensionally along the antiferroelectric b-axis.

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“…[16], the AFE structure can be induced by freezing of the H 2 O molecules. Two possible patterns of H 2 O molecular rotation are depicted in Fig.…”

Section: Dynamics Of the H 2 O Moleculementioning

confidence: 99%

“…On deuteration, T t increases by ≈10 K [14,15]. Recently, we determined the disordered PE structure by means of X-ray crystal structure analysis and discussed the structural change associated with the phase transition [16]. However, we still have the following four unsolved problems.…”

Section: Introductionmentioning

confidence: 98%

X-ray and Neutron Studies of Antiferroelectric Phase Transition in Cu(HCOO) 2 ·4H 2 O

et al. 2003

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“…X-ray powder diffraction was employed to solve the crystal structure ab initio. From the crystal structure, a phase composition of Zn 4 Cu 3 (Zn 1-x Cu x ) 6 -(HCOO) 8 (OH) 18 ·6(H 2 O) could be derived. IR spectroscopy was used to confirm the presence of hydrate water, hydroxide and monodentate coordinating formate ions.…”

Section: Discussionmentioning

confidence: 99%

“…The structural motifs of the corrosion phase Zinc C, Zn 4 Cu 3 -(Zn 1-x Cu x ) 6 (HCOO) 8 (OH) 18 ·6(H 2 O) shall be compared with related zinc and copper phases. There are two known copper(II) formate hydroxides: Cu(HCOO)(OH) [13] and Cu 2 (HCOO)(OH) 3 .…”

Section: Crystal Chemistry Of Related Phasesmentioning

confidence: 99%

“…Hence, there is a great variety of possible corrosion phases of brass. A few have been identified so far, such as Na 4 Cu 4 O(HCOO) 8 (OH) 2 ·4H 2 O, [5] Cu(OH) 3 HCOO [6] or Zn(HCOO) 2 · 2H 2 O [7] but most of them still remain unidentified due to a lack of reliable reference data for phase identification by X-ray powder diffraction (XRPD), IR or Raman spectroscopy. [2] Simple, binary copper(II) and zinc formate hydrates, M(HCOO) 2 ·nH 2 O with M = Cu, Zn, are well known.…”

Section: Introductionmentioning

confidence: 99%

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Brass and Glass: Crystal Structure Solution and Phase Characterisation of the Corrosion Product Zn₄Cu₃(Zn₁_–_xCu_x)₆(HCOO)₈(OH)₁₈·6(H₂O)

Bette

Fischer²,

Stelzner³

et al. 2019

Eur J Inorg Chem

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The title compound, Zn4Cu3(Zn1–xCux)6(HCOO)8(OH)18·6(H2O), also denoted as “Zinc C”, a previously unknown corrosion phase of brass in contact with glass, was found on four different historic objects stored in three different collections. Model experiments demonstrated that formaldehyde emitted e.g. from wooden cabinets undergoes a Cannizarro reaction in the alkaline surface film on the historic glass making formate available for the formation of this corrosion phase. The crystal structure of “Zinc C” was solved ab initio from X‐ray powder diffraction data. From the crystal structure and EDX analyses, a phase composition of Zn4Cu3(Zn1–xCux)6(HCOO)8(OH)18·6(H2O) was derived. Zinc C crystallizes in a trigonal unit cell in space group R3(148) with lattice parameters of a = 10.9185(1) Å, c = 27.5058(4) Å, and V = 2839.74(6) Å3. Layers of edge sharing MO6/3 octahedra with voids capped by Zn(HCOO) forming Zn(HCOO)(OH)3/3 tetrahedra are the main motif in the structure. The zinc/copper ratio of the corrosion phase “Zinc C” can vary between 10:3 and 4:9, due to a partial occupational disorder between copper and zinc in the crystal structure.

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Precise Control of Nanoscale Cu Etching via Gas-Phase Oxidation and Chemical Complexation

et al. 2021

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We present a cyclic process for selective and anisotropic atomic layer etching of copper: an oxygen plasma modulates the depth and directionality of the oxidized layer, while formic acid vapor selectively removes the copper oxide scale from the metallic copper. Via density functional theory, with finite temperature and pressure free energy corrections, we evaluate the feasibility of formation of gas-phase Cu(II) and Cu(I) complexes with formate, water, formic acid, and combinations thereof as ligands. These complexes result from the neutralization reaction between copper oxide (CuO and Cu2O) and formic acid, with and without water. We identified and evaluated the formation free energies of formato, formic acid, aquahydroxo, and aquaformato complexes of Cu(II) and Cu(I). Under relevant experimental pressures, we find the water-free dimeric tetra(μ-formato)dicopper(II) “paddlewheel” complex (Cu2(HCOO)4) to be the most favorable etching product, with its formation reaching equilibrium conditions from CuO. The most likely precursor for the dimer is the diformatodi(formic acid)copper(II) monomer, which favorably dimerizes under the same water-lean condition at which the dimer persists. Stabilization of gas-phase Cu (oxide) derivatives thus can be achieved through complexation, enabling gas-phase etching of Cu. This work provides complementary experimental and theoretical studies that illuminate the nature of highly controlled etching with formic acid of nanoscopic CuO(s) layers covering Cu nanoarchitectures, which is relevant for the fabrication of next-generation integrated circuits.

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Structural Change of Cu(HCOO) 2 ·4H 2 O Associated with the Antiferroelectric Phase Transition

Cited by 6 publications

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X-ray and Neutron Studies of Antiferroelectric Phase Transition in Cu(HCOO) 2 ·4H 2 O

X-ray and Neutron Studies of Antiferroelectric Phase Transition in Cu(HCOO) 2 ·4H 2 O

Brass and Glass: Crystal Structure Solution and Phase Characterisation of the Corrosion Product Zn₄Cu₃(Zn₁_–_xCu_x)₆(HCOO)₈(OH)₁₈·6(H₂O)

Precise Control of Nanoscale Cu Etching via Gas-Phase Oxidation and Chemical Complexation

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Structural Change of Cu(HCOO) 2 ·4H 2 O Associated with the Antiferroelectric Phase Transition

Cited by 6 publications

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X-ray and Neutron Studies of Antiferroelectric Phase Transition in Cu(HCOO) 2 ·4H 2 O

X-ray and Neutron Studies of Antiferroelectric Phase Transition in Cu(HCOO) 2 ·4H 2 O

Brass and Glass: Crystal Structure Solution and Phase Characterisation of the Corrosion Product Zn4Cu3(Zn1–xCux)6(HCOO)8(OH)18·6(H2O)

Precise Control of Nanoscale Cu Etching via Gas-Phase Oxidation and Chemical Complexation

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Brass and Glass: Crystal Structure Solution and Phase Characterisation of the Corrosion Product Zn₄Cu₃(Zn₁_–_xCu_x)₆(HCOO)₈(OH)₁₈·6(H₂O)