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FeSn2 is Khatyrkite structured and crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. Fe is bonded in a 10-coordinate geometry to two equivalent Fe and eight equivalent Sn atoms. Both Fe–Fe bond lengths are 2.67 Å. All Fe–Sn bond lengths are 2.81 Å. Sn is bonded in a 4-coordinate geometry to four equivalent Fe atoms.
ErMn3(FeSn2)3 crystallizes in the hexagonal P6mm space group. The structure is three-dimensional. Er is bonded to six equivalent Fe and eight Sn atoms to form distorted ErFe6Sn8 hexagonal bipyramids that share faces with twelve equivalent FeEr2Fe4Sn6 cuboctahedra and faces with six equivalent ErFe6Sn8 hexagonal bipyramids. All Er–Fe bond lengths are 3.53 Å. There are a spread of Er–Sn bond distances ranging from 3.02–3.15 Å. Mn is bonded in a 12-coordinate geometry to six Sn atoms. There are a spread of Mn–Sn bond distances ranging from 2.73–2.84 Å. Fe is bonded to two equivalent Er, four equivalent Fe, and six Sn atoms to form distorted FeEr2Fe4Sn6 cuboctahedra that share corners with four equivalent FeEr2Fe4Sn6 cuboctahedra, edges with two equivalent FeEr2Fe4Sn6 cuboctahedra, faces with eight equivalent FeEr2Fe4Sn6 cuboctahedra, and faces with four equivalent ErFe6Sn8 hexagonal bipyramids. All Fe–Fe bond lengths are 2.73 Å. There are a spread of Fe–Sn bond distances ranging from 2.73–2.84 Å. There are four inequivalent Sn sites. In the first Sn site, Sn is bonded in a 8-coordinate geometry to one Er, six equivalent Mn, and one Sn atom. The Sn–Sn bond length is 2.97 Å. In the second Sn site, Sn is bonded in a 8-coordinate geometry to one Er, six equivalent Fe, and one Sn atom. In the third Sn site, Sn is bonded in a 12-coordinate geometry to three equivalent Er, three equivalent Mn, and three equivalent Fe atoms. In the fourth Sn site, Sn is bonded in a 6-coordinate geometry to three equivalent Mn and three equivalent Fe atoms.
Sn2Fe(CN)6 crystallizes in the trigonal P-3 space group. The structure is two-dimensional and consists of one Sn2Fe(CN)6 sheet oriented in the (0, 0, 1) direction. Fe2+ is bonded in an octahedral geometry to six equivalent C+1.33+ atoms. All Fe–C bond lengths are 1.88 Å. Sn4+ is bonded in a distorted T-shaped geometry to three equivalent N3- atoms. All Sn–N bond lengths are 2.26 Å. C+1.33+ is bonded in a linear geometry to one Fe2+ and one N3- atom. The C–N bond length is 1.18 Å. N3- is bonded in a bent 150 degrees geometry to one Sn4+ and one C+1.33+ atom.
This study investigates the causes of degradation in organ pipes with low lead content. Using light This study investigates the causes of degradation in organ pipes with low lead content. Using light optical microscopy, SEM/EDS, and TEM/EDS, intermetallic Cu6Sn5, FeSn2, Sn4As3, and Pb particles were observed in the structure of SnPb alloys. Degradation of the low-Pb organ metal, which is primarily caused by the selective corrosion of lead occurring due to the effect of volatile organic compounds (VOCs). Another factor leading to degradation is the structural transformation of tin occurring at low temperatures (tin pest). TEM/EDS allowed the unique observation of α-tin particles found in a β-tin matrix at room temperature. The presence of particles of α‑tin in historical organ pipes has not previously been reported, and it is the first presented observation of all.