Band 235, Heft 11

This article highlights Peter Paufler’s academic genealogy on the occasion of his 80th birthday. We describe the academic background since 1776, which covers 11 generations of scientists: Ritter, Ørsted, Han-steen, Keilhau, Kjerulf, Brøgger, Goldschmidt, Schulze, Paufler, Meyer, and Leisegang. The biographies of these scientists are described in spotlight character and references to scientists such as Dehlinger, Ewald, Glocker, Röntgen, Vegard, Weiss, and Werner are given. A path is drawn that begins in the Romanticism with electrochemistry and the invention of what is probably the first accumulator. It leads through the industrialization and the modern geology, mineralogy, and crystallography to crystal chemistry, metal and crystal physics and eventually returns to electrochemistry and the aluminum-ion accumulator in the era of the energy transition. The academic genealogy exhibits one path of how crystallography develops and specializes over three centuries and how it contributes to the understanding of the genesis of the Earth and the Universe, the exploration of raw materials, and the development of modern materials and products during the industrialization and for the energy transition today. It is particularly characterized by the fields of physics and magnetism, X-ray analysis, and rare-earth compounds and has strong links to the scientific landscape of Germany (Freiberg) and Scandinavia, especially Norway (Oslo), as well as to Russia (Moscow, Samara, St. Petersburg). The article aims at contributing to the history of science, especially to the development of crystallography, which is the essential part of the structural science proposed by Peter Paufler.

The crystal structure of new isostructural compounds MgCo 2 Ga 5 and MgNi 2 Ga 5 has been investigated using single-crystal X-ray diffraction. Both compounds represent a new type of structure: orthorhombic, space group Pnnm , oP 16, with the following lattice parameters: a  = 6.2700(2) Å, b  = 6.6946(2) Å, c  = 6.0789(2) Å (for MgCo 2 Ga 5 ) and a  = 6.2693(3) Å, b  = 6.6968 Å, c  = 6.0794 Å (for MgNi 2 Ga 5 ). The MgCo 2 Ga 5 and MgNi 2 Ga 5 are closely related to the tetragonal structure of CoGa 3 which crystallizes in the ht -IrIn 3 type. The orthorhombic structures of MgCo 2 Ga 5 and MgNi 2 Ga 5 are derived from CoGa 3 via a translationengleiche symmetry reduction of index 2. The symmetry reduction from P 4 2 / mnm to Pnnm causes that the 4 c site splits into two sites 2 c and 2 d . The gallium atoms together with cobalt or nickel form 3D-nets with channels, in which magnesium atoms are inserted. The formation of these polyatomic nets is confirmed by distribution of electron localization function (ELF) and charges of atoms.

In this work, the limit of application of the kinematical theory of X-ray diffraction was calculate integrated intensities was evaluated as a function of perfect crystal thickness, when compared with the Ewald–Laue dynamical theory. The percentual difference between the dynamical and kinematical integrated intensities was calculated as a function of unit cell volume, Bragg angle, wavelength, module, and phase of structure factor and linear absorption coefficient. A critical thickness was defined to be the value for which the intensities differ 5%. We show that this critical thickness is 13.7% of the extinction length, which a specific combination of the parameters mentioned before. Also, we find a general expression, for any percentage of the difference between both theories, to determine the validity of the application of the kinematical theory. Finally, we also showed that the linear absorption decreases this critical thickness.

Single crystals of ABW-type CsAlTiO 4 ( CAT ), CsFeTiO 4 ( CFT ), CsGaTiO 4 ( CGT ), and ANA-type CsTi 1.1 Si 1.9 O 6.5 ( CST ) were grown and characterized by electron microprobe analyses, single-crystal X-ray diffraction, thermal analyses, and spindle-stage optical investigations to determine the electronic polarizability of 4-coordinated Ti 4+ , α ( [4] Ti 4+ ). The crystal structure of CAT was confirmed to crystallize in the highest possible topological symmetry Imma ( a  = 8.9677(2) Å, b  = 5.7322(1) Å, c  = 9.9612(3) Å) with tetrahedrally coordinated Al and Ti equally distributed on Wyckoff position 8i. Twinning by reticular merohedry with a twin index of 2 was observed for most of the crystals resulting in a hexagonal twin lattice ( a  = 11.487(3) Å, c  = 8.968(2) Å) with Laue symmetry 6 / mmm . Refractive indices measured by immersion methods on an untwinned specimen are n x  = 1.716(5), n y  = 1.725(2), and n z  = 1.727(1) with 2 V z  = 127.1(6)°. The diffraction patterns of CFT and CGT clearly showed superstructure reflections causing a symmetry lowering of index 4 with a transformation according to 2 a , b , c from Imma to Pmab w ith a  = 18.3054(7) Å, b  = 5.8083(2) Å, c  = 9.9938(4) Å for CFT , and a  = 18.2921(6) Å, b  = 5.7636(2) Å, c  = 9.9210(3) Å for CGT . Refractive indices for CGT are n x  = 1.750(3), n y  = 1.772(3), and n z  = 1.776(2) with 2 V z  = 132(1)°. The crystal structure of the ANA-type CsTi 1.1 Si 1.9 O 6.5 was confirmed to crystallize in space group Ia 3¯$\overline{3}$ d ( a  = 13.8333(4) Å). The extra 0.5 O atoms are needed for charge compensation and to allow the sum of electronic polarizabilities to give a total electronic polarizability calculated from the refractive index n  = 1.718(4). The electronic polarizability of [4] Ti 4+ was calculated from the difference between the observed total polarizabilities (derived from the mean refractive indices of CAT and CGT ) and the sum of electronic polarizabilities of cations and anions omitting the polarizability of Ti resulting in α ( [4] Ti 4+ ) = 5.15(5) Å 3 .

KCl72H 2 SeO 3 and CsCl7H 2 SeO 3 have been synthesized using solution evaporation methods from aqueous solution. Both compounds are monoclinic ( P 2/ n and P 2 1 / c ) and demonstrate new structure types. One symmetrically unique SeO(OH) 2 molecule is present in each structure. SeO(OH) 2 molecules via strong hydrogen bonds form chains in KCl72H 2 SeO 3 and layers in ?sCl7H 2 SeO 3 . The structures of KCl72H 2 SeO 3 and CsCl7H 2 SeO 3 can be described as consisting of ionic KCl chains and CsCl layers incorporated into the covalent- and hydrogen-bonded H 2 SeO 3 matrix. To the best of our knowledge, the cases when selenious acid acts as a contributor to the molecular building blocks of salt-inclusion structures are not known to date.

Ban Chiang () is an extensively studied archeological site in Northeast Thailand, Udon Thani Province, which became a UNESCO world heritage in 1992. Depending on their production period ceramic artefacts show characteristic patterns at the surface which may be interpreted as iconographic motifs for the site. Two ceramic samples, excavated in 2003, from different periods were re-investigated, previously studied by Tanthanuch W., Pattanasiriwisawa W., Somphon W., Srilomsak S. Synchrotron studies of Ban Chiang ancient pottery. Suranaree J. Sci Technol. 2011, 18, 15–28 who focussed on thermal firing and redox-conditions. Shards selected for this study were sample 5412-S6E15 dated from Bronze Age (ca. 1000–300 BC) with yellow-brown, paint-free surface and a younger sample 8027 from Iron Age (ca. 300 BC–200 AD) with red painted design carrying pictorial patterns typical for the Ban Chiang ceramics. The surface material and colour of both shards was studied in detail using optical reflectance, FTIR spectroscopy and X-ray powder diffraction. Thin sections were used to determine the thickness of the red paint and the elemental composition of the surface using an electron microprobe. Chemical composition of sample 5412-S6E15 consists as oxides of elements mainly of SiO 2 and Al 2 O 3 (representing ca. 59 and 20 wt. %) and that of the red colour of the youngest sample 8027 consists mainly of SiO 2 , Al 2 O 3 and Fe 2 O 3 (representing ca. 52, 13 and 13 wt. %), the average composition adjacent to the red painted area has ca. 72 wt. % SiO 2 , ca. 10 wt. % Al 2 O 3 and only 2 wt. % Fe 2 O 3 . X-ray powder diffraction, FTIR spectroscopy and optical reflectance measurements confirm hematite in the mineralogical composition of the red pigment of shard 8027.

The title compound Ethyl 1-benzyl-2-(thiophen-3-yl)-1H-benzo[d]imidazole-5-carboxylate ( BI ) is prepared and characterized using spectroscopic methods. The theoretical optimization and three dimensional molecular structure are confirmed by X-ray diffraction method (single crystal). The C–H…π intermolecular interactions stabilize the crystal structure. The intermolecular contacts in the crystal structure are quantified using Hirshfeld surfaces and the crystal packing is elucidated using 3D energy frameworks analysis. In the frameworks, the dispersion energy term is dominated over the electrostatic energy term. The structural optimization was carried out with B3LYP/6-311++G (d, p) level of theory. The visual representations of positive and negative potentials (electrostatic potential) are mapped on the electron density isosurface. The band gap energy (HOMO-LUMO) of the molecule is calculated to be 4.36 eV. Structural conformation of BI is compared with similar structures.