Two-Phase η′ + η Region in Cu6Sn5 Intermetallic: Insight into the Order–Disorder Transition from Diffusion Couples

Wieser, Christian; Hügel, W.; Walnsch, Alexander; Leineweber, Andreas

doi:10.1007/s11664-019-07643-3

Cited by 13 publications

(20 citation statements)

References 37 publications

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“…Upon starting to do full-pattern based refinements on the basis of the PXRD data, it first succeeded to get convincing fits to the fundamental reflections using the average structure. Thereby, it turned out that, against original expectation from the evaluation of PXRD patterns of the η′ phase [16,17], visible reflection splitting occurred for some of the fundamental reflections (see Figure 4c). In terms of the monoclinic lattice parameters of the average structure, it turned out that the lattice angle β av deviated 1 In Ref.…”

Section: Rietveld Refinementmentioning

confidence: 74%

“…In recent experimental works involving the present authors [16][17][18], some new insight has been obtained on differently ordered Cu 1+δ Sn phases making up of Cu 6 Sn 5 IMC:…”

Section: Introductionmentioning

confidence: 85%

“…Limiting the homogeneity range to δ ≤ 0.25 allows avoiding likely unfavorable higher connectivities between Cu(2)Sn 5 trigonal bipyramids as, e.g., expected for the hypothetical η x -Cu 1.33 Sn superstructure (see Figure 3). Note, however, that disordered η phase with δ < 0.2 appears to exist at relatively low temperatures implying existence of Sn having no direct Cu(2) neighbors atoms at some low temperatures [17].…”

Section: Properties Of the Ideal Superstructuresmentioning

confidence: 97%

“…The grey lines depict the phase boundaries according to an older work [2]. The black lines are due to assuming a stoichiometric η′ line compound coexisting at a certain temperature range with η high-temperature phase [17] and due to assessing the homogeneity ranges of η at higher temperatures from the lattice parameters [18]. The red lines delimit the approximate ranges of an extended (to higher Cu contents/higher δ) η′ and of the ηʺ region resulting from partitionless ordering of quenched η phase [18].…”

Section: Development Of the Modulated Structure Modelmentioning

confidence: 99%

“…Composition dependences of the unit cell volumes for ordered and disordered Cu 6 Sn 5 IMC [17,18] were derived, allowing determination of compositions/δ values on the basis of sufficiently accurate lattice parameter data. This allowed identification of the extent of a two-phase region η′ + η in a narrow temperature range [17] but also the shape of homogeneity range of the η high-temperature phase [18]. The correspondingly obtained Cu-Sn phase diagram is contained in Figure 2 as black boundaries.…”

Section: Introductionmentioning

confidence: 99%

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Crystal structure of incommensurate ηʺ-Cu_1.235Sn intermetallic

Leineweber

Wieser

Hügel

2020

Zeitschrift Für Kristallographie - Crystalline Materials

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The crystallographic parameters of the incommensurately ordered phase ηʺ of the composition Cu1.235Sn are reported. This phase belongs to the group of ordered Ni2In/NiAs-type phases, with a NiAs-type arrangement Cu(1)Sn and additional Cu(2) atoms partially occupying trigonal-bipyramidal interstices in an ordered fashion, leading to the formula Cu(1)Cu(2)0.235Sn = Cu1.235Sn. The structure model, afterward refined on the basis of powder X-ray diffraction data, has been derived on the basis of the slightly Cu-poorer commensurately ordered η′-Cu6Sn5 (=Cu1.2Sn) phase but also on previously reported commensurate structure models η8-Cu1.25Sn and η4+1-Cu1.243Sn derived from selected area electron diffraction data. In line with a recent work (Leineweber, Wieser & Hügel, Scr. Mater. 2020, 183, 66–70), the incommensurate ηʺ phase is regarded as a metastable phase formed upon partitionless ordering of the η high-temperature phase with absent long-range ordering of the Cu(2) atoms. The previously described η8 and η4+1 superstructure are actually of the same phase, and the corresponding superstructure models can be regarded as approximant structures of the ηʺ phase.The refined structure model is described in 3+1 dimensional superspace group symmetry C2/c(q10-q3)00 with a unit cell of the average structure with lattice parameters of aav = 4.21866(3) Å, bav = 7.31425(5) Å, cav = 5.11137(3) Å and bav = 90.2205(5)° and a unit cell volume V = 157.717(2) Å3. The modulation vector is with q1 = 0.76390(4), q3 = 1.51135(5), and governs the spatial modulation of the occupancy of the Cu(2) atoms described by a Crenel function. The occupational ordering is accompanied by displacive modulations of the atoms constituting the crystal structure, ensuring reasonable interatomic distances on a local level. In particular, the spatial requirements of pairs of edge-sharing Cu(2)Sn5 trigonal bipyramids (Cu(2)2Sn8) lead to a measurable splitting of some fundamental reflections in the powder diffraction data. This splitting is considerable smaller in η′-Cu1.20Sn, which lacks such pairs due to the lower Cu content.

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Section: Rietveld Refinementmentioning

confidence: 74%

“…In recent experimental works involving the present authors [16][17][18], some new insight has been obtained on differently ordered Cu 1+δ Sn phases making up of Cu 6 Sn 5 IMC:…”

Section: Introductionmentioning

confidence: 85%

Section: Properties Of the Ideal Superstructuresmentioning

confidence: 97%

Section: Development Of the Modulated Structure Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Crystal structure of incommensurate ηʺ-Cu_1.235Sn intermetallic

Leineweber

Wieser

Hügel

2020

Zeitschrift Für Kristallographie - Crystalline Materials

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Variable Temperature Crystal Structure of Cu₄TiTe₄

2023

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A variable temperature single crystal X‐ray diffraction study of the ternary compound, Cu4TiTe4 is reported between 200–400 K. The temperature dependent study indicates the compound undergoes an order‐disorder phase transition at ∼320 K. Below the transition temperature, the phase that crystallizes in the primitive cubic space group P 3 m with lattice parameter of a≈5.9 Å, transforms into the two‐fold superstructure. It is modeled as a fourfold twinned rhombohedral structure. The transition is reversible. To relate the phases, a group‐subgroup symmetry relations are established. Upon decreasing temperature, the atomic ordering is noticed in the occupationally disordered Cu‐sites of Cu4TiTe4. This characteristic structural rearrangement may have a significant impact on the electronic structure of Cu4TiTe4. Hence, the detailed structural characterization is supposed to be useful for further understanding of thermoelectric transport properties in the Cu4TiTe4.

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Stabilization of the ζ-Cu10Sn3 Phase by Ni at Soldering-Relevant Temperatures

Wieser

Hügel

Martin

et al. 2020

Journal of Elec Materi

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A current issue in electrical engineering is the enhancement of the quality of solder joints. This is mainly associated with the ongoing electrification of transportation as well as the miniaturization of (power) electronics. For the reliability of solder joints, intermetallic phases in the microstructure of the solder are of great importance. The formation of the intermetallic phases in the Cu-Sn solder system was investigated for different annealing temperatures between 472 K and 623 K using pure Cu as well as Cu-1at.%Ni and Cu-3at.%Ni substrate materials. These are relevant for lead frame materials in electronic components. The Cu and Cu-Ni alloys were in contact to galvanic plated Sn. This work is focused on the unexpected formation of the hexagonal ζ-(Cu,Ni)10Sn3 phase at annealing temperatures of 523–623 K, which is far below the eutectoid decomposition temperature of binary ζ-Cu10Sn3 of about 855 K. By using scanning electron microscopy, energy dispersive X-ray spectroscopy, electron backscatter diffraction and X-ray diffraction the presence of the ζ phase was confirmed and its structural properties were analyzed.

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Two-Phase η′ + η Region in Cu6Sn5 Intermetallic: Insight into the Order–Disorder Transition from Diffusion Couples

Cited by 13 publications

References 37 publications

Crystal structure of incommensurate ηʺ-Cu_1.235Sn intermetallic

Crystal structure of incommensurate ηʺ-Cu_1.235Sn intermetallic

Variable Temperature Crystal Structure of Cu₄TiTe₄

Stabilization of the ζ-Cu10Sn3 Phase by Ni at Soldering-Relevant Temperatures

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Two-Phase η′ + η Region in Cu6Sn5 Intermetallic: Insight into the Order–Disorder Transition from Diffusion Couples

Cited by 13 publications

References 37 publications

Crystal structure of incommensurate ηʺ-Cu1.235Sn intermetallic

Crystal structure of incommensurate ηʺ-Cu1.235Sn intermetallic

Variable Temperature Crystal Structure of Cu4TiTe4

Stabilization of the ζ-Cu10Sn3 Phase by Ni at Soldering-Relevant Temperatures

Contact Info

Product

Resources

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Crystal structure of incommensurate ηʺ-Cu_1.235Sn intermetallic

Crystal structure of incommensurate ηʺ-Cu_1.235Sn intermetallic

Variable Temperature Crystal Structure of Cu₄TiTe₄