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Danish National Research Foundation Center for Materials Crystallography
Annual report 2015
Summary
2015 was in a sense a new beginning. It followed a very busy 2014, which was the final year of the first period
of the Center for Materials Crystallography (CMC), and which coincided with the strong world‐wide efforts
of United Nations International Year of Crystallography. CMC‐2 and 2015 brought a strengthened CMC team,
where new partners augmented the existing activities and the new grant from the Danish National Research
Foundation had to be implemented. Thus, professor George Koutsantonis and Dr. Davide Ceresoli joined CMC
in Perth and Milano, respectively. CMC has built up very strong momentum with a presence in
crystallographic communities around the globe. In 2015 we published 99 peer reviewed publications, and
once again many papers reached international top journals. 2015 was also the year where the efforts on
building the DanMAX beamline at the MAX4 synchrotron became real, and Dr. Mads Jørgensen, a former
CMC post doc at the partner‐facility SNS in Oak Ridge, was hired to be responsible for the powder diffraction
instrument. Furthermore, due to tremendous efforts by Mogens Christensen the Heimdal beam line at ESS
matured, and AU officially decided to be lead on the construction.
The ‘new beginning’ notwithstanding, scientific activities CMC is not resting or looking back. New fields
develop, new collaborations are constantly emerging, while other activities decrease in importance. Overall,
CMC continues to be a very dynamic entity, where the sum is greater than the combined individual parts,
and where crystallographic methods are developed and applied to tackle important challenges in materials
and chemical science. In Aarhus the original CMC ambition of building up three new independent research
groups has been extremely successful, and both internally and externally the groups of associate professor
Mogens Christensen (magnetic materials), senior scientist Jacob Overgaard (molecular materials) and
assistant professor Martin Bremholm (high pressure science) are now highly visible. The new groups
attracted substantial new funding in 2015 and Jacob Overgaard defended his Doctor of Science thesis.
The present annual report attempts to give an overview of the many CMC activities. The highlights selected
below represent important CMC contributions from 2015, but they cannot do full justice to the diverse efforts
published in 99 papers. As always our first and foremost ambition is to contribute scientific excellence at the
highest international level within the field of materials crystallography.
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Center for Materials Crystallography: Highlights in 2015 CMC published 99 peer review papers in 2015 and as in previous years many studies were reported in international top journals. The long term impact was further strengthened with awarding 1 doctoral degree, 9 PhD degrees and 22 Master degrees. Thus, the cumulative number for 2010‐2015 is 626 publications, 3 doctoral, 52 PhD and 87 MSc degrees.
Selected scientific highlights:
Insights on spin polarization through the spin density source function Understanding transmission of spin information from paramagnetic to non‐magnetic centers is crucial in advanced materials research. A novel tool has been developed to e.g. quantify atom contributions to spin polarization (Gatti et al., Chem. Sci. 2015, 6, 3845‐3852).
In situ X‐ray diffraction environments for high‐pressure reactions New sample environments and techniques customized for in situ powder X‐ray diffraction studies up to 1000 bar gas pressure were developed. The cells can be utilized for multiple purposes in a range of research fields (Hansen et al., J. Appl. Cryst. 2015, 48, 1234–1241).
High Alignment of magnetic SrFe12O19 nanoplatelets by Spark Plasma Sintering Spark plasma sintering has been used to compact SrFe12O19 powders into a quasi‐single crystal with an almost completely aligned c‐axis observed by measurement of magnetic properties and pole figures from XRD (Stingaciu et al., Sci. Rep. 2015, 5, 14112; Saura‐Múzquiz et al., Nanoscale 2016, DOI: 10.1039/C5NR07854G).
Thin film pair distribution function analysis demonstrated for the first time Local atomic structure has for the first time been determined in amorphous and crystalline thin films by PDF analysis. The breakthrough was the use of transmission geometry, which allows analysis of even extremely weak sample signals (Jensen et al., IUCR‐J 2015, 2, 481‐489; Bauers et al., J. Am. Chem. Soc. 2015, 137, 9652–9658).
Chemical Bonding and Electronic Localization in a GaI Amide The electron density in a [GaIN(SiMe3)R] complex has been determined from ab initio calculations and multipole modeling of 90 K XRD data. Electron density analysis suggests a reversal of bonding roles with an electron donating metal (Thomsen et al., Chem. Eur. J. 2015, 21, 14460‐14470).
High‐pressure phase transitions in ordered and disordered Bi2Te2Se High pressure XRD studies of the topological insulator and thermoelectric Bi2Te2Se revealed an electronic transition followed by two structural transitions leading to an unusual disordered alloy (Nielsen et al., Dalton Trans. 2015, 44, 14077‐14084).
Novel method to estimate nuclear densities from X‐ray data ‐ NXMEM A method to derive nuclear weighted MEM electron densities was developed and tested on high performance thermoelectric materials containing subtle disorder. The general method provides a highly significant improvement to normal maximum entropy method analysis (Christensen et al., Acta Crystallogr. Sect. A 2015, 71, 9–19).
Rationalising mechanical behaviour of molecular crystals at a molecular level Combining model interaction energies with a novel graphical representation of their magnitude – energy frameworks – addresses intriguing questions about the mechanical behavior of crystals (Turner et al., Chem. Commun. 2015, 51, 3735).
DOSY‐NMR used to probe organometallic aggregation behaviour Lithium diisopropyl amide is one of the most common non‐nucleophilic Brønsted bases in industry, but its aggregation in donor‐base free solvents has so far been unclear. A new DOSY‐NMR method quantifies the aggregation in solution (Neufeld et al., Angew. Chem. Int. Ed. 2015, 54, 6994‐6998).
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Center for Materialekrystallografi: Højdepunkter i 2015 CMC publicerede 99 artikler med peer‐review i 2015, og ligesom i foregående år blev mange udgivet i internationale toptidsskrifter. CMCs langtidseffekt blev yderligere styrket med tildeling af 1 doktorgrad, 9 PhD grader og 22 kandidatgrader. Det samlede antal for 2010‐2015 er hermed 626 publikationer, 3 doktor, 52 PhD og 87 kandidatgrader.
Udvalgte videnskabelige højdepunkter:
Indsigt I spin‐polarisering via spintætheds‐Sourcefunktionen Indenfor avanceret materialeforskning er det essentielt at forstå overførsel af spin‐information fra paramagnetiske til ikke‐magnetiske centre. Et nyt værktøj er blevet udviklet til f.eks. at kvantificere atomare bidrag til spinpolariseirng (Gatti et al., Chem. Sci. 2015, 6, 3845‐3852).
Instrumentel til in situ røntgendiffraktion på højtryks‐reaktioner Nyt eksperimentelt udstyr designet specielt til in situ pulver‐røntgendiffraktion op til 1.000 bar er blevet udviklet. Reaktorerne kan udnyttes til en lang række formål indenfor adskillige forskningsområder (Hansen et al., J. Appl. Cryst. 2015, 48, 1234).
Stærk ordning af magnetiske SrFe12O19 nanopartikler via Spark Plasma Sintering Spark plasma sintering har været udnyttet til at komprimere SrFe12O19 pulvere til kvasi‐enkrystaller med en næsten perfekt orienteret c‐akse, karakteriseret ved måling af magnetiske egenskaber og pol‐figurer fra røntgendiffraktion (Stingaciu et al., Sci. Rep. 2015, 5, 14112; Saura‐Múzquiz et al., Nanoscale 2016, DOI: 10.1039/C5NR07854G).
Første demonstration af PDF‐analyse på tynd‐film Lokal atomar struktur er for første gang blevet bestemt i amorfe og krystallinske tyndfilm via PDF‐analyse. Gennembrudet skete ved anvendelse af transmissions‐geometri, der tillader analyse af selv meget svage intensiteter (Jensen et al., IUCR‐J 2015, 2, 481‐489; Bauers et al., J. Am. Chem. Soc. 2015, 137, 9652–9658).
Kemisk binding og elektron‐lokalisering i et GaI Amid kompleks Elektrontætheden i et [GaIN(SiMe3)R] kompleks er blevet bestemt via ab initio metoder og multipol‐modellering af diffraktionsdata optaget ved 90 K. Elektrontæthedsanalyse antyder en invers binding med et elektron‐donerende metal (Thomsen et al., Chem. Eur. J. 2015, 21, 14460‐14470).
Højtryks‐faseomlejring I ordnet og uordnet Bi2Te2Se Højtryks‐pulverdiffraktionsstudier af den topologiske isolator og termoelektriske materiale Bi2Te2Se afslørede en elektronisk overgang efterfulgt af to strukturelle omlejringer, førende til en usædvanlig, uordnet legering (Nielsen et al., Dalton Trans. 2015, 44, 14077‐14084).
En ny metode til et estimere kernetætheder fra røntgendata – NXMEM En metode til at udlede kerne‐vægtede MEM elektrontætheder fra røntgendata er blevet udviklet og testet på højeffektive termoelektrika der indeholder subtile grader af uorden. Den generelle metode oer en meget betydelig forbedring af normal MEM‐analyse (Christensen et al., Acta Crystallogr. Sect. A 2015, 71, 9–19).
Rationalisering af den mekaniske opførsel af molekylære krystaller på molekyleniveau Kombination af interaktions‐energier fra modellering med nye grafiske repræsentationer af deres styrke – energy frameworks – adresserer interessante spørgsmål vedrørende den mekaniske opførsel af krystaller (Turner et al., Chem. Commun. 2015, 51, 3735).
DOSY‐NMR anvendt til at undersøge opførslen af organometallisk aggregering Lithium diisopropyl amid er en af de mest almindelige non‐nukleofile Brønsted‐baser i industrien, men stoffets aggregering i donorbase‐frie solventer har været uklar. En ny DOSY‐NMR metode kvantificerer aggregerings‐opførslen i opløsningen (Neufeld et al., Angew. Chem. Int. Ed. 2015, 54, 6994‐6998).
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CMC Science in 2015 So far the CMC scientific efforts have been divided into 12 main research themes. Efforts within some of the
original themes are no longer as strong as in previous years, while new directions have emerged. The new
groups in CMC bring new topics and perspectives with Mogens Christensen on magnetic materials, Jacob
Overgaard on molecular materials, Martin Bremholm/Davide Ceresoli on high pressure materials and George
Koutsantonis on organometallic chemistry. Therefore, we have redefined the topics. Research in all the
original 12 themes is still contained in the themes, but no matter how the research themes are categorized
the level of activity in the themes will vary significantly. The new themes are: T1: Photoactive materials, T2:
Intermolecular interactions, T3: Magnetic materials, T4: Nanoporous materials, T5: Nanoparticles, T6: High
pressure studies, T7: Energy materials, T8: Organometallic chemistry, T9: Electronic materials, T10: New
methods, T11: New equipment
T1: Photoactive materials
In previous years CMC has carried out extensive photo‐crystallographic studies of hetero‐atomic bimetallic
complexes, [Ln(DMF)4(H2O)3(‐CN)M(CN)5]H2O, which exhibit photo‐induced magnetization. It was
discovered that the same complexes undergo pressure induced magnetization, and the structural changes
were probed with high pressure XANES and single crystal X‐ray diffraction (Wu et al., Chem. Commun. 2015,
51, 8868). Ongoing activities on spin cross‐over complexes will be reported next year.
T2: Intermolecular interactions
Quantification of intermolecular interaction energies is a very strong theme in current chemical and materials science, and a major milestone was reached with the launch of a new version of the CrystalExplorer software which e.g. included the concept of energy frameworks (Turner et al., Chem. Commun. 2015, 51, 3735). The new approach allows fast but still accurate calculation of interaction energies between molecules based on four energy terms: Electrostatic energy, dispersion energy, repulsion energy and polarization energy. In the crystal engineering field, many publications in recent years have attempted to estimate intermolecular interaction energies from topological properties of electron densities. This approach was shown to be inaccurate and CMC research strongly urge this field of science to rethink the approach (Spackman, Cryst. Growth. Des. 2015, 15, 5624). In a benchmark combined X‐ray and neutron electron density study the intermolecular interactions in Rubrene were quantified and analysed (Hathwar et al., IUCr‐J 2015, 2, 563). Rubrene is the best performing organic semiconductor and the extraordinary properties originate from favorable intermolecular interactions. Based on comparison of atomic displacement parameters determined separately from X‐ray and neutron diffraction, the study of rubrene is one of the most accurate ever published. Another focused on the electrostatic complementarity in pseudoreceptor modeling based on drug molecule crystal structures (Shi et al., New J. Chem. 2015, 39, 1628). A striking similarity of intermolecular interactions between the specific crystal structure and those observed in a biological environment was established, and the electrostatic potential of a protease inhibitor molecule was successfully used to map the characteristics of a pseudo‐enzyme pocket. Non‐covalent interactions (NCIs) dictate how molecules interact with their surroundings. By using a sample of 30 molecular adducts, spanning dispersive, hydrogen bonds and X‐H∙∙∙π interactions, it was demonstrated that stabilization energies may be inexpensively estimated using the Reduced Density Gradient (RDG) in tandem with energy density descriptors (Saleh et al., Comp. Theo. Chem. 2015, 1053, 53–59). This novel method is powerful and potentially applicable also to crystals and experimentally derived electron densities.
T3: Magnetic materials
CMC activities on magnetic materials are increasing considerable with the maturation of the groups on
inorganic magnets (Mogens Christensen) and molecular magnets (Jacob Overgaard). The evolution of size
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and size distribution of CoFe2O4 nanocrystallites was followed by in situ synchrotron PXRD. Size control, and
thereby magnetic property control, was obtained via precursor concentration upon base addition (Andersen
and Christensen, Nanoscale 2015, 7, 3481). The hard magnetic system SrFe12O19 was studied intensively with
a top‐down ball milling approach to obtain single domain particles (Stingaciu et al., Sci. Rep. 2015, 5, 14112).
The processing had detrimental effects on the magnetism due to amorphization, and another study instead
focused on bottom‐up hydrothermal synthesis (Saura‐Múzquiz et al., Nanoscale 2016, DOI:
10.1039/C5NR07854G). Here excellent alignment of the crystallites was obtained by SPS. Molecular magnets
were in focus with experimental recording of a very large magnetic anisotropy using angular resolved
magnetic susceptibility measurements on a single crystal (Qian et al., Chem Sci. 2015, 6, 4587‐4593).
Theoretical approaches reproduce almost exactly the size and direction of the magnetic easy axis. It has been
questioned whether theoretical calculation of anisotropy is reliable based on molecular structure determined
at liquid‐nitrogen temperatures. The paper proves, by comparing theoretical results based on 15 K and 100
K structural data, that the effect on magnetic anisotropy is negligible.
T4: Nanoporous materials
There are ongoing activities on zeolite catalysts for deNOx processes, but no publications in 2015.
T5: Nanoparticles
The activities on nanoparticles continue to be strong and the unique in situ reactor developed to follow the
nucleation and growth of nanoparticles in solvothermal reactions is world leading. One study concerned Pt
and Pt3Gd nanoparticles, which are suitable for applications in micro fuel cells (Saha et al., J. Phys. Chem. C
2015, 119, 13357). Using X‐ray total scattering and PDF analysis it was shown that the reduction of the
precursor Pt4+ species takes place via an intermediate Pt2+ complex before the nucleation of Pt and P3Gd
nanoparticles. Analysis of in situ PXRD data showed that growth occurs via a combination of aggregation and
ripening. Another study developed a hydrothermal flow synthesis method for Bi substituted CeO2, and
provided a comprehensive comparison with powders synthesized by conventional batch methods (Houlberg
et al., Cryst. Growth Des. 2015, 15, 3628). Interestingly, the in situ PXRD data showed that pristine
nanocrystals are formed already during mixing of the precursor solutions, and this has led to the
development of a new in situ reactor, which is capable of following the reactions already during mixing (first
beam time in June 2016). In situ PDF analysis on solvothermal synthesis of TiO2 provided the first strong
evidence for the importance of amorphous structures in determining the nucleation of a given crystal
polymorph (Mi et al., CrystEngComm 2015, 17, 6868). It was shown that the kinetic product anatase is formed
due to strong structural similarity to cluster existing in the amorphous precursor, and these structures can
also explain the presence of specific defects in the synthesized nanoparticles.
T6: High pressure studies
The activities on flat potential energy surface materials have not been so strong as in previous years, but one
study explored the high pressure behavior of the linear metal chain compound Co3(dpa)4Br2•CH2Cl2 (Madsen
et al., Dalton Trans. 2015, 44, 9038) as a follow up to the earlier studies of Co3(dpa)4Cl2•CH2Cl2 and
Cr3(dpa)4Cl2•CH2Cl2. The study demonstrated a nice technical advance since peak broadening resulting from
non‐hydrostatic conditions in the diamond anvil cell was avoided by annealing the loaded DAC prior to data
collection. This allowed reliable structural models to be refined up to a pressure of 11.8(2) GPa. On increasing
pressure, the disordered CH2Cl2 crystal solvent molecule gradually becomes redistributed from one site to
another. Hirshfeld surface analysis suggests that the redistribution is a result of repulsive H⋯H interactions.
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Pressure also affects the molecular geometry, in particular the Co–Co and Co–Br bond lengths which decrease
by 4% and 12%, respectively, at 11.8(2) GPa. Another study focused on square‐planar d8‐ML4 complexes,
which might display subtle local Lewis acidic sites in the axial direction in the valence shell of the metal atom.
These sites of local charge depletion provide the electronic prerequisites to establish weakly attractive 3c–
2e M∙∙∙H–C agostic interactions. A new characterization method was suggested that probe the response of
these M∙∙∙H–C interactions under pressure by combined high pressure IR and diffraction studies (Scherer et
al., Angew. Chem. Int. Ed. 2015, 54, 2505‐2509). Finally, a meticulous investigation of the high‐pressure
structural behaviour have improved the understanding of the electronic transitions in the topological Kondo
insulator SmB6 by observation of structural anomalies that earlier studies were not able to identify (Parisiades
et al., EPL 2015, 110, 66002).
T7: Energy materials
The work on advanced energy materials continues to be a very strong activity in CMC with more than 20
publications in 2015. Ammine metal borohydrides have attracted attention as hydrogen and/or ammonia
storage materials, and trends in syntheses, structures and properties for new ammine metal borohydrides,
M(BH4)3∙nNH3 were studied extensively (Jepsen et al., Inorg. Chem. 2015, 54, 7402−7414; Jepsen et al.,
ChemSusChem, 2015, 8, 1452 – 1463; Roedern et al., Inorg. Chem. 2015, 54, 10477). Extensive series of
coordination complexes with systematic variation in the number of ligands were explored, synthe‐sized by
combined mechanochemistry, solvent‐based methods, solid‐gas reactions and thermal treatment. New
series of solvent‐ and halide‐free ammine metal borohydrides M(NH3)n(BH4)2 (n = 1 to 7, M = Mg, Ca, Sr, Y,
Mn, La, Ce, Gd and Dy) were prepared as crystalline powders and structurally characterised by PXRD, 11B
NMR and DFT calculations. The detailed effect of nanoconfinement on desorption and cycling properties
were investigated for a series of LiBH4 based materials (Javadian et al., Nanoenergy 2015, 11, 96‐103;
Javadian et al., Int. J. Hydrogen Energy 2015, 40, 14916 ‐14924; Javadian et al., J. Phys. Chem. C 2015, 119,
5819–5826). On the more fundamental side, a very detailed PXRD study led to a complete mapping of the
bonding network in KBH4 (Bindzus et al., Comp. Theo. Chem. 2015, 1053, 245‐253). Development of aqueous
solution synthesis methods of photovoltaic materials is a huge and important challenge for general
application of thin film solar cells. A significant progress was reported with the synthesis of flexible SnS2 thin
films and nanosheets (Nørby et al., PCCP 2015, 17, 9282‐9287); characterization of precursor materials lead
to discovery of new thiostannate(IV) complexes (Nørby et al., CrystEngComm, 2015, 17, 2413‐2420). In
battery research, a comprehensive study was done on the structure and electrochemical properties of the
bronze polymorph of TiO2 (Søndergaard et al., J. Mater. Chem. A, 2015, 3, 18667‐18674). Multiphase TiO2‐
based photocatalysts for environmental remediation were studied with a broad range of characterization
methods (PXRD, EXAFS, EDX, BET, SEM, EPR, DRS) and quantum‐mechanical tools (DFT, DFT+U) to explore
structural, morphological and electronic properties of differently doped materials (Rimoldi et al., J. Phys.
Chem. C 2015, 119, 24104‐24115). In thermoelectric research a seminal paper was published in a continuing
collaboration with the CAS Institute of Physics in Beijing, which pointed out novel ways to enhance the
Seebeck coefficient by charge mobility engineering (Sun et al., Nature Comm. 2015, 6, 7475). Another
important progress was the development of a fast and direct synthesis route to ZnSb, which is the key
material used by the company TEGnology in development of a Danish thermoelectric generator (Blichfeld &
Iversen, J. Mater. Chem. C 2015, 3, 10543‐10553). An already highly cited review paper was published on
thermoelectric measurement (Borup et al., Energy Environ. Sci. 2015, 8, 423‐435). The thermoelastic
properties of bcc‐iron were studied with DFT total energy and lattice dynamics calculations (Dragoni et al.,
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Phys. Rev. B 2015, 91, 104105). By employing the Quasi Harmonic Approximation method the softening of
the elastic constants was predicted. The method can also be applied to calculate ADPs from first principles,
as well as anharmonic properties and thermal conductivity of materials. Finally, a contribution was also made
to the overwhelming topic of CO2 storage with a study of olivine carbonation in supercritical CO2 (Eikeland et
al., ACS Appl. Mater. Inter. 2015, 7, 5258‐5264)
T8: Organometallic chemistry
Although lithium diisopropyl amide (LDA) is one of the most common and widely used non‐nucleophilic
Brønsted bases in industry, its donor‐base free solid‐state crystal structure was only determined in 1991 and
the aggregation of LDA in donor‐base free solvents has been unresolved. Using the DOSY‐NMR method a
reliable and straight‐forward indication of the degree of organometallic aggregation in solution was
established (Neufeld et al., Angew. Chem. Int. Ed. 2015, 54, 6994‐6998). Another study focused on the
enhanced bi‐stability in a ruthenium alkynyl spiropyran complex. The ruthenium alkynyl unit appended to a
spiropyran core prolongs the lifetime of the merocyanine form of the molecule more than twenty‐fold. The
metal enhances the extent of charge delocalization through donation of electron density into the organic
ligand and acts to slow the electrostatically driven ring closing reaction (Walkey, et al., Dalton Trans. 2015,
44, 8812). The Me‐cAAC: stabilized dimer of SiS2 has been isolated in the molecular form in the compound
(Me‐cAAC:)2Si2S4. This is the smallest molecular unit of SiS2 characterized by X‐ray crystallography, electron
ionization mass spectrometry and NMR spectroscopy (Mohapatra et al., Chem. Eur. J. 2015, 21, 12572).
T9: Electronic materials
The very productive collaboration with Prof. Hofmann’s group on structure and properties of topological
insulators was continued with a study of strongly anisotropic spin‐orbit splitting in a two‐dimensional
electron gas (Michiardi et al., Phys. Rev. B 2015, 91, 035445).
T10: New methods
A significant breakthrough was achieved with the introduction of the spin density source function (Gatti et
al., Chem. Sci, 2015, 6, 3845‐3852). The new approach helps to understand how spin information is
transmitted in advanced materials. In the study, the Bader and Gatti source function was firmly extended to
the spin density. Each atomic spin source function contribution may be conveniently decomposed in a
magnetic term and a relaxation term providing a new interpretative tool. A significant new development of
the maximum entropy method was published with the introduction of the nuclear‐weighted X‐ray MEM
(Christensen, Acta Crystallogr. Sect. A 2015, 71, 9‐19). The method allows calculation of pseudo nuclear
densities based on X‐ray data and it was shown to be much stronger than traditional MEM in revealing subtle
disorder features. Further development and application of the vacuum PXRD method for measurement of
extremely accurate structure factors was demonstrated for cubic boron nitride (Wahlberg et al., J. Phys.
Chem. C 2015, 119, 6164‐6173). As mentioned in the highlight section a groundbreaking development was
achieved with the first ever PDF study of thin films (Jensen et al., IUCrJ, 2015, 2, 481‐489). The trick was to
use transmission geometry and apart from publication of the method a detailed study of thermoelectric
FeSb2 and FeSb3 was made (Bauers et al., J. Am. Chem. Soc. 2015, 137, 9652–9658). A paper on absorption
correction improvements is already highly cited (Krause et al., J. Appl. Crystallogr. 2015, 48, 3‐10). In the
study the quality of diffraction data obtained using silver and molybdenum microsources was compared for
six model compounds with a wide range of absorption factors. A numerical absorption correction based on
the positions and indices of the crystal faces was shown to be of limited use for the highly focused micro‐
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source beams, but fortunately the empirical corrections implemented in SADABS also correct rather well for
the variations in the effective irradiated volume of the crystal. A broad CMC team at Gøttingen, Aarhus, APS
and SNS resolved the structure and charge density of [2,2]‐paracyclophane (Wolf et al., Chem. Eur. J. 2015,
21, 4556‐4560; Wolf et al., Acta Crystallogr. Sect. B 2015, 71, 10‐19). The first study provided insight into the
famous phase transitions of [2,2]‐paracyclophane. Based on simultaneous Raman spectroscopy and inelastic
neutron scattering experiments it was shown that a twisting motion of the ethylene bridge perpendicular to
the plane of the aromatic rings drives the phase transition. The second study provided a comparison of in‐
house and synchrotron data and demonstrated the necessity of measuring accurate low order data. The most
neglected systematic error in diffraction data is thermal diffuse scattering. This is because quantitative
correction for TDS is very complicated. A new empirical correction method may alleviate this (Niepötter et
al., J. Appl. Crystallogr. 2015, 48, 1485‐1497). The method was developed based on charge density
investigations of [Mg{(pz*)3C}2] (pz* = 3,5‐dimethylpyrazolyl), where models derived from datasets at
different temperatures differ strongly indicating significant TDS. Refinement of resolution‐dependent scale
factors can be used to detect TDS. Low energy contamination of mirror focused X‐rays is another often
encountered systematic error, and a new correction scheme was implemented in SADABS an SHELXL (Krause
et al., J. Appl. Crystallogr. 2015, 48, 1907‐1913). Contamination mainly affects the 3h3k3l reflections. A
correction factor can be determined from the model but in many cases a default value depending on the
experimental settings is acceptable. Determining aggregation and solvation numbers of organometallic
complexes in solution is an important task to increase insight in nucleation and materials formation.
Diffusion‐ordered NMR spectroscopy (DOSY), which separates NMR signals according to the diffusion
coefficient finds increasing use to identify species in solution. A novel method for molecular weight
determination was developed that allow MW‐predictions with a maximum error smaller than ±9% (Neufeld
et al., Chem. Sci. 2015, 6, 3354‐3364).
T11: New equipment
Core‐shell and hybrid nanoparticles are targeted in numerous applications due to the possibility for
manipulating properties when combining materials with complementary electronic and structural features.
The main difficulty in this field is to develop synthesis reactors that provide enough material (gram to
kilogram scale) to enable process characterization and device fabrication. Large scale synthesis of core‐shell
nanoparticles was achieved in a new dual‐stage supercritical flow‐reactor (Hellstern et al., Ind. Eng. Chem.
Res. 2015, 54, 8500‐8508). It has already been used in a range of nanoparticle studies, which will be reported
next year. In thermoelectric research it is well known that many high performing materials are highly
anisotropic (the best example being Bi2Te3). Since it is time consuming to determine anisotropic properties,
in general very little is known about them. A significant development was reported through generalization of
the van der Pauw method to resistivity measurement, and it provides fast measurement of the in plane
resistivity tensor. The method was implemented on the CMC‐developed high temperature transport
measurement equipment at AU (Borup et al., Phys Rev. B, 2015, 92, 045210).
Organization and facilities The CMC contract includes hiring of two permanent positions at associate professor level. The first was hired
in 2014 (Mogens Christensen), and in the fall of 2015 a second open call was announced. The evaluation is
currently ongoing and hiring is expected in the first part of 2016. This will bring the CMC activities in Aarhus
to consist of five permanent research groups: Prof. Bo Brummerstedt Iversen, assoc. prof. Torben René
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Jensen, senior scientist Jacob Overgaard, assoc. prof. Mogens Christensen and NN. Indeed a quite remarkable
strengthening of the field of materials crystallography in just 6 years. The CMC groups continue to have
common group meetings every second week as well as regular CMC staff meetings. The latter include
technical staff and are important to the daily function of CMC and to the overall planning and coordination.
The daily administration of CMC in Aarhus continues to be in the hands of Jacob Becker (general manager),
Peter Hald (laboratory manager), Bo Richter (research technician), Britta Lundtoft (laboratory technician),
Marianne Sommer (secretary) and Rikke Gjerulff (accounting).
The main CMC meeting was held in June in connection with the annual review, with participation from
Australia, Göttingen, Milano and Aarhus. As usual the meeting provided a wonderful setting for extensive
exchange of ideas. In June Professor Spackman stayed for a month in Aarhus – a stay that directly resulted in
a strong publication on interaction energies (Spackman, Cryst. Growth. Des. 2015, 15, 5624). In June many
CMC members from Milano, Göttingen and Aarhus also gathered in Sardinia at the Sagamore conference on
Charge, Spin and Momentum densities organized by Dr. Carlo Gatti; an outstanding scientific meeting in a
stunning location. The second main CMC meeting was supposed to be held in November, but was eventually
moved to January 2016 in Göttingen with strong attendance from Milano and Aarhus. CMC‐Aarhus alone
participated with 34 people; following an excellent full day scientific meeting, a wonderful excursion and hike
was done in the Harz mountains. Another important event was Jacob Overgaard’s defense of a Doctor of
Science dissertation. This followed the Doctor of Science defense that Torben Jensen did a few years ago. In
2015 the ties between CMC and Japan were significantly strengthened, when Director Masaki Takata became
adjunct professor at Aarhus University. Professor Masaki Takata is currently heading the Japanese efforts to
build a new fourth generation synchrotron in northern Japan near Sendai. Furthermore, Bo Brummerstedt
Iversen became international guest professor at University of Tsukuba with a shared research group with
Professor Eiji Nishibori situated at Tsukuba. The close interaction between research groups is coordinated by
two assistant professors, Hidetaka Kasai (stationed two years in Aarhus), and Venkatesha Hathwar (stationed
in Tsukuba from May 2016).
With respect to funding and new projects, the most important development was the decision of Aarhus
University to officially take lead on building the Heimdal beamline at ESS. The revolutionizing instrument will
be constructed in close collaboration with ESS and groups in Switzerland and Norway. The other CMC led
beamline is the DanMAX at MAX4, which is now well under way with funding assured and lead scientists in
place. In close collaboration with DTU and Copenhagen University, CMC obtained a new grant from the
Innovation Foundation (50 M.kr.) to Link Industry with Neutrons and X‐rays – LINX (to be commenced 2016).
The project has initial participation by 16 industrial companies, and the idea is that university groups will
bridge the use of X‐ray and Neutrons by Danish Industry. This will be important for the ability of Danish
industry to take advantage of the huge investment in MAX4 and ESS. Another strong development was a 6
million kroner grant to Jacob Overgaard and Martin Bremholm from the Villum Foundation to build a new in‐
house ultralow‐temperature single crystal diffractometer with a state of the art pixel detector.
Every professor who has led a research group knows the challenge of maintaining continuity. Students build
up expert knowledge through their studies, but how does one assure that this knowledge is not lost when
they graduate and leave the group? It is all the little details about how to run a certain piece of software or
operate some vital equipment that makes a research group productive. In CMC we decided to try to tackle
this problem by building up a central wiki‐page system that everyone can continuously contribute to. The
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content is very diverse and spans from manuals for equipment, to theoretical derivation of some important
equation or general introduction to a certain field. To initiate the CMC wiki‐pages we went on a 3‐day retreat
in a big summer house at Marslev on the island of Fuhnen, and the wiki content that was produced was
fantastic. It is now used by new students in all kinds of subfields, and it is continuously updated. Retreats are
also great for group dynamic and we certainly plan follow‐up with new wiki‐retreats.
Finally, it is asked that the annual report comments on scientific conduct and gender issues. The approach to
assure good scientific conduct in CMC was previously detailed in a separate document submitted to the
Danish National Research Foundation, and due to space limitations it will not be repeated here. Similarly the
issue of gender balance was discussed in detail at an earlier annual review. CMC continues to strongly oppose
discrimination based on gender, race, nationality, sexual orientation, religion or any other trait which is
irrelevant to scientific research. CMC will continue to strive for equal opportunity for everyone, and to create
an ambience, where scientific excellence is the common measure for everyone.
CMC Annual Review and Workshop, June 3‐4th in Aarhus
Left: Scientific Advisory Committee visit to ESS building site October 2015 – CMC is lead on building the Heimdal beamline. Right: DanMAX
contract agreement reached at Norsminde Kro (MAX4 Director Christoph Quitman and CMC Director Bo Brummerstedt Iversen).
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Members of CMC‐Aarhus and ‐Göttingen at the Sagamore Conference organized by Dr. Carlo Gatti. Right: CMC beamtime‐crew at Spring‐8.
The amazing CMC football team once again won the trophy of the AU iNANO tournament.
Right: CMC poster contributions at the 2015 Danish Crystallography & Danscatt meeting
Jacob Overgaard explains details of charge density studies at his Doctor of Science defence. Right: CMC‐Aarhus hike in the Harz Mountains
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Left: Popular science contribution to Aktuel Naturvidenskab (MAX‐IV/ESS theme). Center/Right: Teaching resources on inorganic materials
chemistry developed for Danish high schools by collaboration between CMC and Dept. of Chemistry, AU.
Outlook
2015 was the first year of CMC‐2. Many PhD students hired in CMC‐1 have now obtained their degrees and
moved on to successful careers in academia, teaching and industry. Importantly, a new generation of
students and post docs has been hired and they will bring CMC to new heights. The challenge for any large
research center is to maintain the spirit of adventure and discovery, which keeps everyone pushing in new
unforeseen directions. In plain words it is a challenge for all mature centers to avoid fatigue and “business as
usual”. The magic of a university is that every year large numbers of new young students begin their academic
life with an incredible energy and a wonderful wish to challenge existing knowledge. CMC is strongly
positioned at the Faculty, and this makes it possible to attract the best local students. In fact in 2015 three
new CMC student were admitted to the prestigious 3+5 Elite PhD program due to their outstanding
qualifications. Since CMC has a strong name in materials crystallography worldwide it is also easy to attract
top students and post docs internationally. CMC is by its very construction highly international, and this
dynamic environment is a key to success. In previous years, the close interaction between CMC groups across
four continents has created novel scientific results, but it is clearly a challenge to keep up this momentum.
Also in 2015 students were exchanged between laboratories, but with the new generation of CMC members
the ties have to be continuously fortified. Lots of new projects have been launched and CMC pushes on.
Signature
Ved underskriften bekræftes det, at beretning og regnskab med tilhørende noter og oversigter indeholder alle
relevante oplysninger, som vedrører årets primære aktiviteter i Danmarks Grundforskningsfonds Center for
Materialekrystallografi.
Bo Brummerstedt Iversen
Aarhus, 31‐03‐2015