Profiles

Gunnar

Gunnar Svensson

Head of Department

Visa sidan på svenska
Works at Department of Materials and Environmental Chemistry
Telephone 08-16 45 05
Email gunnar.svensson@mmk.su.se
Visiting address Svante Arrhenius väg 16 C
Room C 414
Postal address Institutionen för material- och miljökemi 106 91 Stockholm

About me

I am since 2010 head of department for the Materials and environmental chemistry. It is a very interesting and inspiring job especially with so many encouraging, ambitious and friendly colleagues.

Research infrastructure.
For a university and a department, it is important to attract highly qualified staff. This is done by offering excellent working environment such as state of the art research from highly skilled colleagues but also an excellent and well organised infrastructure of research instruments. At MMK we have organised our instruments in to centres: EMC - Electron Microscopy Centre and MACAL – Materials Analysis Centre at Arrhenius Laboratory. I am director for the EMC, which provides researchers at Stockholm University with an unique access to both standard and advanced electron microscopy. A receipt of its high quality and how appreciated it is at SU is that the university and the department has decided to invest in a new state of the art transmission electron microscope – TITAN Themis Z with a budget of ~50 Mkr.

CEM4MAT – Centre of Electron Microscopy for Materials Science
In Stockholm-Uppsala region there three large universities and several research institutes with materials related research using TEM. The research at the different sites differs which gives a unique pool of competent staff but also several well equipped EM-labs in the region. To facility exchange of competence and to increase the access to TEM for researchers in the region but also from other universities and companies the EM-facilities at SU, UU, KTH and Swerea KIMAB have created CEM4MAT.

Teaching

The meeting with students is always fascinating and fun but also demanding. During the years, I have lectured in a number of courses ranging from general chemistry, inorganic chemistry, solid state chemistry, coordination chemistry, chemical bonding to water chemistry. One field which, I feel extra for is the environmental aspects of inorganic chemistry and then specially environmental aquatic chemistry. Unfortunately, the latter course is resting since some years, but I really hope that we will be able to take it up again sometime in the future.

Research

My research interest is solid state chemistry such as synthesis of compounds, their structural characterisation and fundamental properties. Very often the compounds are of interest for various energy related applications.

The elaborate structural characterisation techniques include X-ray powder diffraction, neutron powder diffraction and electron diffraction. We have experience in in situ studies e.g. temperature, but also in constructing and using in operando electrochemical cells for neutron diffraction studies.

I have a long experience in using transmission electron microscopy related techniques such as HREM, ED, EDS and EELS in my research. Worth mentioning is our interest in diffuse scattering in electron diffraction data caused by structural disorder. For such studies the software SUePDF (https://osf.io/c2jq8/) for processing electron diffraction date to obtain quantitative structure factors for pdf studies was developed by Drung Trung Tran during his postdoc here. I am also a partner in a project lead by Cheuk-Wai Tai to quantify and use the diffuse scattering in electron diffraction patterns of ferroelectrics with perovskite related structures to determine structure properties relations.

The fundamental properties of our compounds, which we typically measure includes, conductivity, magnetic susceptibility and gas adsorbing/absorbing prosperities. Electrochemical characterisations are typically made in collaboration with other research groups.

Prussian Blue analogues for energy related applications. (Gunnar Svensson, Jekabs Grins, Dickson Ojwang)

Prussian Blue can be seen as the first and smallest MOF:s. It has a very simple open ReO3-related structure with large cavities and often numerous vacancies, see figure 1. The general composition for Prussian Blue and it analogues (PBA) is AxM´[M(CN)6]y·H2O where M´and M are transition metals and Ax large cations e.g. alkaline metals. The presence of transition metals result as always in compounds in a large variety of interesting properties such as e.g. electrochemical, magnetic, adsorbent.

We are interested in Prussian Blue analogues and specially their CO2-adsorbing properties., although we have also made electrochemical in operando studies using X-ray diffraction. AxCu[Fe(CN)6]2/3·H2O is one compound we have studied in detail using a number of techniques; XRD, NPD, Mössbauer, EXAFS, XANES, IR/Raman, SEM-EDS, TGA/DSC, CO2/N2-adsorption, electrochemistry. The compound is a rather good, fast, robust and selective CO2 adsorbent and we have made extensive kinetic studies using TGA. It is our plan to continue the study of CO2 adsorption in various PBA:s including in situ XRD and NPD measurements combined with kinetic studies using TGA.

Selected references:

Structure Characterization and Properties of K-Containing Copper Hexacyanoferrate
Dickson Ojwang, Jekabs Grins, Dariusz Wardecki, Mario Valvo, Viktor Renman, Lennart Häggström, Tore Ericsson, Torbjörn Gustafsson, Abdelfattah Mahmoud, Raphael̈ P. Hermann and Gunnar Svensson, Inorganic chemistry, 55 (2016) 5924-5933.

Neutron Diffraction and EXAFS Studies of K2x/3Cu[Fe(CN)6]2/3·nH2O
Dariusz Wardecki, Dickson O. Ojwang, Jekabs Grins, and Gunnar Svensson
DOI: 10.1021/acs.cgd.6b01684 Cryst. Growth Des. 2017, 17, 1285−1292

Transition metal related oxides with perovskite related structures. (Gunnar Svensson, Jekabs Grins)

In this project, we are synthesising and characterising transition metal oxides specially with perovskite related structures. At the moment perovskite based iron oxides are of certain interest. For the structural characterisation of these a combination of transmission electron microscopy, X-ray powder diffraction and neutron diffraction is used. The magnetic and electronic and ionic transport properties are measured as well. Of course, I am interested in other transition metal oxides as well.

Selected references:

Crystal structure and high-temperature properties of the Ruddlesden-Popper  phases  Sr3-xYx(Fe1.25Ni0.75)O7-d (0 ≤ x ≤ 0.75).
Louise Samain, Philipp Amshoff, Jordi J Biendicho, Frank Tietz, Abdelfattah Mahmoud, Raphaël P Hermann, Sergey Y Istomin, Jekabs Grins, Gunnar Svensson, Journal of Solid State Chemistry (2015) 227, 45-55

Quantitative electron diffraction – diffuse scattering (Gunnar Svensson, Cheuk-Wai Tai, Alexandre Nageu)

In this project, we are interested in diffuse scattering in electron diffraction data caused by structural disorder. For such studies the software SUePDF (https://osf.io/c2jq8/) for processing electron diffraction date to obtain quantitative structure factors for pdf studies was developed by Drung Trung Tran during his postdoc in my group. I am also a partner in a project lead by Cheuk-Wai Tai to quantifie and use the diffuse scattering in electron diffraction patterns of ferroelectrics with perovskite related structures.

Selected references:
Atomic structure and oxygen deficiency of the ultrathin aluminium oxide barrier in Al/AlOx/Al Josephson junctions
Lunjie Zeng, Dung Trung Tran, Cheuk-Wai Tai, Gunnar Svensson and Eva Olsson. Scientific reports 6 (2106) 29679.

Carbon (Gunnar Svensson, Ulrich Häussermann, Istvan Zoltan Jenei)

Carbon is a fascinating element and its various polymorphs (fullerenes and graphene, graphite, diamond, numerous amorphous and mesoporous forms) provide a rich playground for fundamental and applied sciences. In an earlier project I studied nano porous carbons made via thermal chlorination of carbides. The detailed structure and bonding of these was studied using HREM, EELS, Reverse Monte Carlo modeling on neutron diffraction data, Raman spectroscopy, see Figure 2. Characteristic of these carbons are their tunable limited pore size distributions, which make them interesting for use in various applications.

In an on going project we are studying alkaline/alkaline earth carbides their syntheses and structural transitions at elevated temperatures/pressure. Synthetic routes used are such high pressure/high temperature intercalation/reaction of hydrides like LiH in/and graphite. We are also using various low temperature routes as metathesis like 2·Li2C2(s) + CBr4(l) « 4·LiBr(s) + 3·C(s) to produce new form of carbons. My involvement in these projects mainly concerns TEM studies using HREM, ED and EELS. This is far from straightforward as most compounds are very air sensitive making the use of special sample holders for air sensitive samples necessary.

Selected references:

Structural Transformations of Li2C2 at High Pressure.
D. E. Benson, S. Konar, J. Nylen, U. Häussermann, G. Svensson, K. Syassen, U. Ruschewitz, Phys. Rev. B, (2015) B92, 064111-8

 

 

Publications

A selection from Stockholm University publication database
  • 2017. Dariusz Wardecki (et al.). Crystal Growth & Design 17 (3), 1285-1292

    The crystal structure of copper hexacyanoferrate (CuHCF), K2x/3Cu[Fe-(CN)(6)](2/3)center dot nH(2)O, with nominal compositions x = 0.0 and x = 1.0 was studied by neutron powder diffraction (NPD) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The compound crystallizes in space group Fm (3) over barm, with a = 10.1036(11) angstrom and a = 10.0588(5) angstrom for x = 0.0 and x = 1.0, respectively. Difference Fourier maps for x = 0.0 show that the coordinated water molecules are positioned at a site 1921 close to vacant N positions in the -Fe-C-N-Cu- framework, while additional zeolitic water molecules are distributed over three sites (8c, 32f, and 48g) in the -Fe-C-N-Cu- framework cavities. The refined water content for x = 0.0 is 16.8(8) per unit cell, in agreement with the ideal 16 (n = 4). For x = 1.0, the refinement suggests that 2.6 K atoms per unit cell (x = 0.98) are distributed only over the sites 8c and 32f in the cavities, and 13.9(7) water per unit cell are distributed over all the four positions. The EXAFS data for Fe, Cu, and K K-edges are in agreement with the NPD data, supporting a structure model with a linear -Fe-C-N-Cu- framework and K+ ions in the cavities.

  • 2016. Dickson O. Ojwang (et al.). Inorganic Chemistry 55 (12), 5924-5934

    Copper hexacyanoferrate, Cu-II[Fe-III(CN)(6)](2/3)center dot nH(2)O, was synthesized, and varied amounts of IC ions were inserted via reduction by K2S2O3 (aq). Ideally, the reaction can be written as Cu-II[Fe-III(CN)(6)](2/3)-nH(2)O + 2x/3K(+) + 2x/3e(-)K(+) <-> K-2x/3 Cu-II[Fe-x(II).Fe-1-x(II),(CN)(6)](2/3)-nH(2)O. Infrared, Raman, and Mossbauer spectroscopy studies show that Fe-II is continuously reduced to Fell with increasing x, accompanied by a decrease of the a-axis of the cubic Fn (3) over barm unit cell. Elemental analysis of K by inductively coupled plasma shows that the insertion only begins when a significant fraction similar to 10% of the Fe-III, has already been reduced. Thermogravimetric analysis shows a fast exchange of water with ambient atmosphere and a total weight loss of similar to 26 wt % upon heating to 180 degrees C, above which the structure starts to decompose. The crystal structures of Cu-III[Fe-III(CN)(6)](2/3)center dot nH(2)O and K2/3Cu[Fe(CN)(6)](2/3)center dot nH(2)O were refined using synchrotron X-ray powder diffraction data. In both, one-third of the Fe(CN)(6) groups are vacant, and the octahedron around Cull is completed by water molecules. In the two structures, difference Fourier maps reveal three additional zeolitic water sites (8c, 32f, and 48g) in the center of the cavities formed by the-Cu-N-C-Fe- framework. The K-containing compound shows an increased electron density at two of these sites (32f and 48g), indicating them to be the preferred positions for the K+ ions.

  • 2016. Lunjie Zeng (et al.). Scientific Reports 6

    Al/AlOx/Al Josephson junctions are the building blocks of a wide range of superconducting quantum devices that are key elements for quantum computers, extremely sensitive magnetometers and radiation detectors. The properties of the junctions and the superconducting quantum devices are determined by the atomic structure of the tunnel barrier. The nanoscale dimension and disordered nature of the barrier oxide have been challenges for the direct experimental investigation of the atomic structure of the tunnel barrier. Here we show that the miniaturized dimension of the barrier and the interfacial interaction between crystalline Al and amorphous AlOx give rise to oxygen deficiency at the metal/oxide interfaces. In the interior of the barrier, the oxide resembles the atomic structure of bulk aluminium oxide. Atomic defects such as oxygen vacancies at the interfaces can be the origin of the two-level systems and contribute to decoherence and noise in superconducting quantum circuits.

  • 2015. Louise Samain (et al.). Journal of Solid State Chemistry 227, 45-54

    Ruddlesden-Popper n=2 member phases Sr3-xYxFe1.25Ni0.75O7-delta, 0 <= x <= 0.75, have been investigated by X-ray and neutron powder diffraction, thermogravimetry and Mossbauer spectroscopy. Both samples as-prepared at 1300 degrees C under N-2(g) flow and samples subsequently air-annealed at 900 degrees C were studied. The as-prepared x=0.75 phase is highly oxygen deficient with delta=1, the O1 atom site being vacant, and the Fe3+/Ni2+ ions having a square pyramidal coordination. For as-prepared phases with lower x values, the Mossbauer spectral data are in good agreement with the presence of both 5- and 4-coordinated Fe3+ ions, implying in addition a partial occupancy of the O3 atom sites that form the basal plane of the square pyramid. The air-annealed x=0.75 sample has a delta value of 0.61(1) and the structure has Fe/Ni ions in both square pyramids and octahedra. Mossbauer spectroscopy shows the phase to contain only Fe3+, implying that all Ni is present as Ni3+. Air-annealed phases with lower x values are found to contain both Fe3+ and Fe4+. For both the as-prepared and the air-annealed samples, the Y3+ cations are found to be mainly located in the perovskite block. The high-temperature thermal expansion of as-prepared and air-annealed x=0.75 phases were investigated by high-temperature X-ray diffraction and dilatometry and the linear thermal expansion coefficient determined to be 14.4 ppm K-1. Electrical conductivity measurements showed that the air-annealed samples have higher conductivity than the as-prepared ones.

  • 2014. Jordi Jacas Biendicho (et al.). Journal of Power Sources 248, 900-904

    A novel neutron diffraction cell has been constructed to allow in-situ studies of the structural changes in materials of relevance to battery applications during charge/discharge cycling. The new design is based on the coin cell geometry, but has larger dimensions compared to typical commercial batteries in order to maximize the amount of electrode material and thus, collect diffraction data of good statistical quality within the shortest possible time. An important aspect of the design is its modular nature, allowing flexibility in both the materials studied and the battery configuration. This paper reports electrochemical tests using a Nickel-metal-hydride battery (Ni-MH), which show that the cell is able to deliver 90% of its theoretical capacity when using deuterated components. Neutron diffraction studies performed on the Polaris diffractometer using nickel metal and a hydrogen-absorbing alloy (MH) clearly show observable changes in the neutron diffraction patterns as a function of the discharge state. Due to the high quality of the diffraction patterns collected in-situ (i.e. good peak-to-background ratio), phase analysis and peak indexing can be performed successfully using data collected in around 30 min. In addition to this, structural parameters for the beta-phase (charged) MH electrode obtained by Rietveld refinement are presented.

Show all publications by Gunnar Svensson at Stockholm University

Last updated: May 5, 2018

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