Meta-generalized gradient approximation time-dependent density functional theory study of electron trapping in Hf- and Zr-doped lutetium oxide: influencing the oxygen vacancy
This work analyzes the effects of a nearby Hf or Zr dopant on the electron density trapped at an oxygen vacancy site. The two metals are among the dopants used to achieve thermoluminescence and energy storage in phosphors based on cubic lutetium oxide (c-Lu2O3). The presence of oxygen vacancies is anticipated in those phosphors. If the dopant is located outside the immediate surroundings of the vacancy site, the resulting optical trap depth is similar to that of the isolated oxygen vacancies (1.6 – 1.7 eV versus 1.7 eV). If the dopant is one of the four metal cations surrounding the vacancy site, the correspondin...
Source: Acta Crystallographica Section B - October 6, 2023 Category: Chemistry Authors: Shyichuk, A. Tags: thermoluminescence meta-generalized gradient approximation meta-GGA time-dependent density-functional theory TD-DFT trap depth storage phosphors research papers Source Type: research
In data we trust: X-ray diffraction experiments for charge density investigations
(Source: Acta Crystallographica Section B)
Source: Acta Crystallographica Section B - September 18, 2023 Category: Chemistry Authors: Herbst-Irmer, R. Tags: data quality charge density multipole model topological analysis of the electron density scientific commentaries Source Type: research
The hydrogen-bond network in sodium chloride tridecahydrate: analogy with ice VI
The structure of a recently found hyperhydrated form of sodium chloride (NaCl · 13H2O and NaCl · 13D2O) has been determined by in situ single-crystal neutron diffraction at 1.7 GPa and 298 K. It has large hydrogen-bond networks and some water molecules have distorted bonding features such as bifurcated hydrogen bonds and five-coordinated water molecules. The hydrogen-bond network has similarities to ice VI in terms of network topology and disordered hydrogen bonds. Assuming the equivalence of network components connected by pseudo-symmetries, the overall network structure of this hydrate can be expressed by break...
Source: Acta Crystallographica Section B - September 13, 2023 Category: Chemistry Authors: Yamashita, K. Nakayama, K. Komatsu, K. Ohhara, T. Munakata, K. Hattori, T. Sano-Furukawa, A. Kagi, H. Tags: salt hydrate hydrogen bonds high pressure single-crystal neutron diffraction research papers Source Type: research
Effect of pre-rolling aging treatment on evolutions of the microstructure and the texture of aluminium alloy 7005 subjected to heavy cold rolling
Aluminium alloy 7005 is widely used for structural purposes because of its attractive properties such as good weldability and age-hardening capability. However, since the workability of this alloy falls after a short period of natural aging, the application of cold rolling for the production of strain-hardened sheets of this alloy is a challenge. Two solutions proposed to overcome this challenge are as follows: (a) immediate rolling of the alloy after solution treatment and (b) rolling of the alloy after artificial aging. However, there is no comprehensive study comparing the effect of pre-rolling aging treatments on the e...
Source: Acta Crystallographica Section B - September 13, 2023 Category: Chemistry Authors: Farshidi, M.H. Miyamoto, H. Ito, H. Tags: AA7005 aging treatment cold rolling microstructure texture research papers Source Type: research
Chalcogen Chemistry: Fundamentals and Applications. Edited by Vito Lippolis, Claudio Santi, Eder J. Lenard ã o and Antonio L. Braga. Royal Society of Chemistry, 2023. Hardcover, pp. 728. Price EUR 156.00. ISBN 978-1-83916-422-4
(Source: Acta Crystallographica Section B)
Source: Acta Crystallographica Section B - September 12, 2023 Category: Chemistry Authors: Fourmigu é , M. Tags: book review chalcogens book reviews Source Type: research
An approach to investigate the crystallographic unit cell of human tooth enamel
Human tooth enamel (HTE) is the hardest tissue in the human body and its structural organization shows a hierarchical composite material. At the nanometric level, HTE is composed of approximately 97% hydroxyapatite [HAP, Ca10(PO4)6(OH)2] as inorganic phase, and of 3% as organic phase and water. However, it is still controversial whether the hexagonal HAP phase crystallizes in P63/m or another space group. The observance in HTE of Ca2+, Mg2+ and Na+ ions using X-ray characteristic energy-dispersive spectroscopy in the scanning electron microscope has been explained by substitutions in the HAP unit cell. Thus, Ca2+ can be re...
Source: Acta Crystallographica Section B - September 12, 2023 Category: Chemistry Authors: Reyes-Gasga, J. Tehuacanero-N ú ñ ez, S. S á nchez-Ochoa, F. Tags: human tooth enamel density functional theory lattice-energy minimization electron diffraction. research papers Source Type: research
Bromine versus chlorine substituent in breathing crystals of a copper(I) coordination compound with a triazolamine Schiff base
It is known that N-[4-(chlorobenzylidene)-4H-1,2,4-triazol-4-amine in reaction with copper(I) perchlorate(VII) forms metastable breathing crystals built up of X-shaped binuclear units containing copper(I) ions in a trigonal coordination sphere. Using trifluoromethanesulfonate instead of perchlorate(VII) affects the self-assembly of the X-shaped units and the breathing function of the resulting crystals. The latter are not breathing crystals. Copper(I) trifluoromethanesulfonate with N-[4-(bromobenzylidene)-4H-1,2,4-triazol-4-amine crystallizes in two forms: open (with the presence of 1D channels) and closed (without 1D chan...
Source: Acta Crystallographica Section B - September 8, 2023 Category: Chemistry Authors: Ganczar, E. Bia ł o ń ska, A. Tags: breathing crystals copper(I) coordination compound host – guest chemistry halogen halogen interaction research papers Source Type: research
Comparative study of conventional and synchrotron X-ray electron densities on molecular crystals
Five different electron density datasets obtained from conventional and synchrotron single crystal X-ray diffraction experiments are compared. The general aim of the study is to investigate the quality of data for electron density analysis from current state-of-the-art conventional sources, and to see how the data perform in comparison with high-quality synchrotron data. A molecular crystal of melamine was selected as the test compound due to its ability to form excellent single crystals, the light atom content, and an advantageous suitability factor of 3.6 for electron density modeling. These features make melamine an opt...
Source: Acta Crystallographica Section B - September 4, 2023 Category: Chemistry Authors: Vosegaard, E.S. Ahlburg, J.V. Krause, L. Iversen, B.B. Tags: electron density data quality molecular crystal single crystal X-ray diffraction research papers Source Type: research
Crystal structure refinement, low- and high-temperature X-ray diffraction and M ö ssbauer spectroscopy study of the oxoborate ludwigite from the Iten'yurginskoe deposit
This paper reports an investigation of the chemistry, crystal structure refinement and thermal behavior (80 – 1650 K) of ludwigite from the Iten'yurginskoe deposit (Eastern Chukotka, Russia). Its chemical composition was determined by electron microprobe analysis, giving an empirical formula (Mg1.70Fe2+0.29Mn0.01) Σ 2.00(Fe3+0.90Al0.08Mg0.02) Σ 1.00O2(BO3). A refinement of the crystal structure from single-crystal X-ray diffraction data (SCXRD) was provided for the first time for ludwigite from this deposit (R = 0.047). The structure can be described as a framework composed of [MO6]n − octahedra and isolated [BO3...
Source: Acta Crystallographica Section B - August 17, 2023 Category: Chemistry Authors: Biryukov, Y.P. Zinnatullin, A.L. Levashova, I.O. Shablinskii, A.P. Bubnova, R.S. Vagizov, F.G. Ugolkov, V.L. Filatov, S.K. Pekov, I.V. Tags: oxoborate ludwigite crystal structure M ö ssbauer spectroscopy in situ methods oxidation thermal expansion Iten'yurginskoe deposit research papers Source Type: research
Crystal and magnetic structures of R2Ni2In compounds (R = Tb and Ho)
Crystal and magnetic structures of R2Ni2In (R = Tb and Ho) have been studied using powder neutron diffraction at low temperatures. The compounds crystallize as orthorhombic crystal structures of the Mn2AlB2 type. At low temperatures, the magnetic moments localized solely on the rare earth atoms form antiferromagnetic structures. The Tb magnetic moments, equal to 8.8 (4) μ B and parallel to the c axis, form a collinear magnetic structure described by the propagation vector k = [ ½ , ½ , ½ ]. This magnetic structure is stable up to the N é el temperature TN = 40 K. For Ho2Ni2In a complex, tem...
Source: Acta Crystallographica Section B - August 14, 2023 Category: Chemistry Authors: Baran, S. Deptuch, A. Hoser, A. Penc, B. Przewo ź nik, J. Szytu ł a, A. Tags: magnetic structure antiferromagnetism neutron diffraction symmetry analysis order – order magnetic phase transition research papers Source Type: research
Structural insight into the cooperativity of spin crossover compounds
Spin-crossover (SCO) compounds are promising materials for a wide variety of industrial applications. However, the fundamental understanding of their nature of transition and its effect on the physical properties are still being fervently explored; the microscopic knowledge of their transition is essential for tailoring their properties. Here an attempt is made to correlate the changes in macroscopic physical properties with microscopic structural changes in the orthorhombic and monoclinic polymorphs of the SCO compound Fe(PM-Bia)2(NCS)2 (PM = N-2 ′ -pyridylmethylene and Bia = 4-aminobiphenyl) by employing single-crystal...
Source: Acta Crystallographica Section B - August 11, 2023 Category: Chemistry Authors: Shahed, H. Sharma, N. Angst, M. Voigt, J. Per ß on, J. Prakash, P. T ö rnroos, K.W. Chernyshov, D. Gildenast, H. Ohl, M. Saffarini, G. Grzechnik, A. Friese, K. Tags: spin crossover, radiation damage thermal cyclic entropy intermolecular interactions research papers Source Type: research
Elucidating the nature of chemical bonds in a coordination compound through quantum crystallographic techniques
(Source: Acta Crystallographica Section B)
Source: Acta Crystallographica Section B - July 28, 2023 Category: Chemistry Authors: Genoni, A. Tags: quantum crystallography multipole model Hirshfeld atom refinement topological analysis of the electron density chemical bond scientific commentaries Source Type: research
New Section Editor of Acta Crystallographica, Section B
(Source: Acta Crystallographica Section B)
Source: Acta Crystallographica Section B - July 28, 2023 Category: Chemistry Authors: Blake, A.J. de Boissieu, M. Nangia, A. Tags: new Section Editor editorial Source Type: research
Gladstone – Dale compatibility, electronic polarizability and vibrational spectroscopy of minerals and inorganic compounds with V4+O and V4+O2 vanadyl groups
VO and VO2 vanadyl groups with short (typically 1.57 – 1.68 Å ), essentially covalent, V — O bonds are common for V4+-bearing oxysalts with [5]- and [6]-coordinated vanadium. There is a clear negative correlation between vanadyl bond lengths and wavenumbers of the bands of V — O stretching vibrations in infrared spectra (in the range 1000 – 880 cm − 1). Optical, structural and chemical data for vanadyl minerals are used to calculate Gladstone – Dale compatibility coefficients. Gladstone – Dale compatibility indices of minerals containing vanadyl bonds are compared with total electronic polarizabiliti...
Source: Acta Crystallographica Section B - July 20, 2023 Category: Chemistry Authors: Chukanov, N.V. Fischer, R.X. Kazheva, O.N. Aksenov, S.M. Tags: vanadyl bond Gladstone – Dale compatibility electronic polarizability infrared spectroscopy crystal chemistry research papers Source Type: research
The structure of magnesium stearate trihydrate determined from a micrometre-sized single crystal using a microfocused synchrotron X-ray beam
Crystalline magnesium stearate has been extensively used as an additive in pharmaceutical and other industries for decades. However, the lack of suitably large crystals has hindered the determination of the crystal structure and thereby a more fundamental understanding of the structure – functionality relationship. Presented here is the structure of magnesium stearate trihydrate as determined from X-ray diffraction data of a micrometre-sized single crystal measured at a fourth-generation synchrotron facility. Despite the small size of the single crystals and the weak diffraction, it was possible to determine the position...
Source: Acta Crystallographica Section B - July 8, 2023 Category: Chemistry Authors: Herzberg, M. Rekis, T. St ø ttrup Larsen, A. Gonzalez, A. Rantanen, J. Ø stergaard Madsen, A. Tags: magnesium stearate trihydrate molecular crystals pharmaceutical solids research papers Source Type: research
