Multiscale characterizations - Expertise

Keywords: spatial and temporal scales (operando); X-rays, neutrons and electron diffraction and scattering; spectroscopies (solid state NMR, NQR, EXAFS, EELS, EDXS), imaging (SEM, TEM, EFTEM, AFM).

The multi-scale characterization of materials covers both spatial and temporal scales. It is primarily concerned with the structures and microstructures of materials on scales ranging from nanometers to micrometers (from the local organization of atoms to medium and long scale arrangements within the shaped/patterned materials) in order to understand and to optimize the targeted properties. Temporal analyses are also essential for understanding the evolution of properties in situ and operando, which often requires a multi-technical approach.

The CSM team has a strong knowledge and know-how in crystal chemistry through the multiscale characterizations of materials. Indeed, the team is developing the characterizations of materials at different spatial scales such as (i) X-ray diffraction (XRD), neutron and electron diffraction; (ii) total X-ray and neutron scattering with pair distribution function analysis (PDF); (iii) solid state NMR spectroscopy including pulsed field gradient (PFG) probe, NQR, EXAFS and EELS; and (iv) scanning electron microscopy (SEM) and transmission electron microscopy (TEM) imaging. These various characterizations are carried out on equipment available in the team, in the platforms of the University of Rennes 1 (UMS ScanMAT) and on large-scale facilities (synchrotron, nuclear reactor, high field NMR infrastructures) with which the team has strong connections.

Powder and single crystal diffractions and diffusion (X-rays, neutrons)
The team has a vast experience in X-ray absorption spectroscopy in particular for data analysis and equipment conception. Such competence allowed to perform in-situ experiment, or develop strongly coupled long range/short range coupled studies. The competences, that characterize the Rennes site in respect of others synchrotron users and EXAFS spectroscopy, are the use of advanced analysis techniques as ITFA and a strong involvement in data analysis software as PrestoPronto or EstraFitEXA.

J. Phys., 2016, 712, 012012; Int. Tables Cryst., 2020, I

Nanoscale characterization of microdevices created by patterning
In the context of the development of X-ray nanopatterning [Truccato et al., Nano Lett., 2016, 16, 1669] which is an innovative, photoresist-free, direct-writing approach recently used to fabricate proof-of-concept electrical devices in CSM group we have developed competences and software to analyzed high-spatial-resolution diffraction.
High-spatial-resolution diffraction is a synchrotron technique that consist to study a crystalline sample with a nanometric beam (20-100 nm) as a function of the position and orientation of the sample. The technique is very often associated with fluorescence mapping allowing to correlate spatial composition with crystal quality, orientation, and structure.
For instance, during the investigation of X-ray nanopatterning of the high-Tc superconductor Bi₂Sr₂CaCu₂O_8+δ (Bi-2212) we were able to determine a small torsion of the Bi-2212 whisker around the crystallographic a axis or the complex effect of the interaction with X-ray mainly associating the oxygen depletion and increase in crystal mosaicity.

Micrometric Josephson junction Bi-2212 whisker device. In the inset the whisker between the two V contact

Integrated intensity of the (006) reflection as a function of z position (a axis) and the device rotation around z axis. On the right schematic representation of crystalline habit of the Bi-2212 whisker in the device.

Post nanopatterning sample, comparison of peak shape (006) reflection, its localization map and the fluorescence map using the Cu Ka signal

CrystEngComm., 2018, 20, 6667-6676; Sci. Reports., 2017, 7, 9066

Operando investigations
The team has developed technical skills to perform in situ XRD experiments in precisely controlled atmospheres and sample environments. It aims at studying solid-state phase transitions, catalysts, MOFs.

Atmosphere-controlled formation of catalysts, studied by combining in situ XRD, solid-state NMR and IR spectroscopies.

J. Solid State Chem., 2017, 253, 73-77

Thin films X-rays diffraction
The team is experienced in XRD characterisation of polycrystalline, preferentially oriented and epitaxial thin films. This expertise gives access to phase identification in very thin polycrystalline films (grazing incidence diffraction), to out-of-plane and in-plane lattice parameters of oriented films and therefore to strain state of the film, to in-plane orientation (poles figure and phi-scans), to domains identification (reciprocal space maps), to stress measurements and to thickness and density (reflectometry). These experiments are carried out on the OSIRIX facility of the UMS ScanMAT. The characterized materials are mainly epitaxial ferroelectric or layered oxides, and polycrystalline oxides and sulphides.

In-plane XRD diagrams of SrVO₃ films grown at different temperatures. Decrease of the in-plane a lattice parameter with increase of temperature is evidenced

Asymmetric 3-13 reciprocal space map of K_0.6(Ta,Nb)₁₀O₃₀ tetragonal tungsten bronze films grown on SrTiO₃

Phi-scans of K_0.6(Ta,Nb)₁₀O₃₀ tetragonal tungsten bronze films grown on sapphire R

Pole figure of a FeO film on sapphire

ACS Appl. Mater. Interf., 2015, 7, 19906-19913; Adv. Mater. Interf., 2016, 1600274-1600280; RSC Adv., 2017, 7, 15482-15491; J. Mater. Sci., 2017, 52, 11306-11313; Thin Solid Films., 2018, 652, 34-38;  Crystal Growth & Design., 2020, 20, 2356-2366

The team as an experience and projects in several fields of nuclear resonance including :

• Combination of high resolution solid state NMR and DFT calculation of NMR parameters for the characterization of solid state compounds,
• Nuclear Quadrupolar resonance : ANR 13-BS08-0007 PiezoNQR (2013-2017), Thèse S. Manya (PhD, C2RMF, ESPCI, ISCR),
• Combination of Pulsed field gradient NMR and molecular dynamic simulation (Coll. A. Ghoufi, IPR Rennes).

Fig. 1 : 11B MAS NMR spectra of {[Y(cpbOH)(H2O)2](cpb)}∞ recorded at 14 T and (inset) 7 T under proton decoupling  (Inorg. Chem. 2015, 54, 5534−5546)

Fig.2 : 63Cu NQR frequency of Cu2O as a function of pressure (R. Dubourget; PhD, Coll. J.B. d’Espinose de Lacaillerie ESCPI)

Journal of Magnetic Resonance, 2019, 303, 48-56; Solid State Nuclear Magnetic Resonance, 2019, 104 , 101623; Journal of Physical Chemistry Letters, 2019, 10 (8), 1698-1708; Inorganic Chemistry, 2018, 57 (5), 2517-2528; Langmuir, 2017, 33, 7; Physical Chemistry Chemical Physics, 2016, 18,  39, 27133-27142; J. Phys. Chem., 2015, C, 119 (21), 11852-11857; Phys. Chem. Chem. Phys., 2015, 17, 43, 29020-29026

TEM, EDS, EELS, EFTEM
CSM has a strong expertise in transmission electron microscopy and coupled spectroscopies. The experiences are carried out on the THEMIS facility of the UMS ScanMAT. These techniques are used to characterize local order, crystalline defects, new phases, compositions, chemical states, epitaxy relationships, etc. of several materials as oxide powders and oxide thin films, intermetallics, cluster compounds, coordination polymers, nitrides among others.

Identification of Ca₃(VO₄)₂ nanostructures grown into CaVO₃ film : a) Electron energy loss spectra of CaVO₃ film and of Ca₃(VO₄)₂  nanostructure. b) CaVO₃ (V⁴⁺) map. c) Ca₃(VO₄)₂ (V⁵⁺) map. d) Energy Filtered TEM map for V states (green: CaVO₃; red: Ca₃(VO₄)₂)

Elemental EDS map of a heterolanthanide core−shell coordination polymers

a,b,c) Electron diffraction patterns of a CaVO₃ film along the [010] zone axis displaying additional reflections due to elongated Ca₃(VO₄)₂ nanostructures. d,e) High resolution TEM images of two different Ca₃(VO₄)₂ variants. f) Scheme of the electron diffraction pattern displayed in c)
 

Thin Solid Films., 2020, 693, 137682; Thin Solid Films., 2020, 693, 137687; J. Alloys Compds., 2020, 816, 152577; Appl. Surf. Sci., 2020, 510, 145522; J. All. Compds., 827, 154341; Chem. Mater., 2020, 32, 6026-6034; ACS Appl. Nano Mater., 2020, 3, 6684-6692; ACS Appl. Ener. Mater., 2020, 2, 8525-8534; Solid State Sci., 2016, 54, 17-21; Adv. Mater. Interf., 2016, 1600274-1600280; RSC Adv., 2017, 7, 15482-15491; CrystEngComm., 2018, 20, 3396-3408; Inorg. Chem., 2019, 58, 1317-1329; J. Eur. Cer. Soc., 2019, 39, 3094-3102; J. Alloys Compds., 2019, 796, 176-184; J. Nuclear Mater., 2019, 526, 151772-151779; ACS Appl. Mater. Interf., 2019, 11, 37302-37312

AFM

Structure on multiscale local/long range order
The coupling between EXAFS, electron diffraction, and X-ray diffraction allows to study the structure of solids further than the limit of conventional crystallography. In particular in the case of solid-solution the ability of EXAFS to single out the characteristic of each bond type allows to quantitatively investigate local distortion.

EXAFS study on the origin of U(Al_1−xGe_x)₃ deviation from Vegard's law for

Structure of UAl₃, UGe₃ and U(Al_1-xGe_x)₃ crystallizing in the AuCu₃ structure-type (Pm-3m)

EXAFS data for U(Al_1-xGe_x)₃ solid solution at U L₃ (green curves) and Ge K (blue curves) edges. (k)k²

Evolution of the U-Al (◼), U-Ge (◼) and average U-Al/Ge distances (★purple stars) obtained from EXAFS as a function of x in U(Al_1-xGe_x)₃. Distances determined from XRD (★) and the linear relation expected from the Vegard's law (black line).

J. Nuclear Mater., 2019, 526, 151772-151779

Local deformation on herometallic cluster core

Models representation and the comparison of the M–M distances for 22 electron {Re₄Mo₂} metal core obtained by theoretical and experimental techniques

Combined EXAFS analysis (weighted by k3) a) Mo K-edge b) Re L3-edge with corresponding Fourier transform magnitudes

Chem. Eur., 2019, 25, 15040-15045

Defects in materials studied by coupling electron diffraction and TEM microscopy with powder diffraction
The coupling of TEM techniques and powder diffraction has allow to obtain a better insight on intermetallics materials with thermoelectric properties. In the case of Higher magnesium silicide (HMS) we were able to study the relationship between stoichiometry, incommensurability, and aging process. While for β FeSi₂ it was possible to quantitatively estimate the amount of stacking faults detected by TEM microscopy and correlate it with thermal conductivity.

Detection of defects in the aperiodic structure of HMS and its dependency from its composition and annealing on the thermoelectric properties  

J. Alloys Compds., 2019, 796, 176-184; J. Alloys Compds., 2020, 816, 152577; Chem. Mater., 2020, 32, 6026-6034

Above stacking aults in β FeSi₂ detection by TEM technique and relationship between sintering and probability of stacking. Below, modelling of the stacking fault and full profile fitting of powder diffraction by FAULT software

Chem. Mater., 2020, 32, 24, 10601-10609

Methanol diffusion in MOFs: a combined PFG-NMR, X-ray diffraction and Molecular Dynamic simulations approach
The diffusion of guest molecules inside the porous host architecture of Metal-Organic-Frameworks (MOFs), which are widely used for their porosity and their important variety of applications such as molecular storage and separation, purification or catalysis, is mandatory in order to understand the dynamic or selectivity of the storage process. The diffusion of methanol through porous systems has been investigated regarding several parameters such as solid-state flexibility of MOFs and the presence of functionalized linkers as amino groups. The multi-scale approach consists to carry out pulse field gradient NMR experiments (PFG-NMR) to measure methanol self-diffusion coefficient according to the sample temperature and in situ temperature-dependent powder X-Ray diffraction experiments performed with a gas-flow to characterise the structural transitions. Monte Carlo molecular dynamic (MD) simulations allows to better understand the dynamic of confined guest molecules and the impact of MOFs flexibility on the diffusion process. For instance, in the flexible MOF NH₂-MIL-53 (Al) the dynamics of guest molecules is impacted by the reversible structural transition between narrow-pore to large-pore and unprecedented very-large pore forms of the framework. The simulations also shed light on anomalous translational diffusion due to a dynamical heterogeneity caused by localized dynamics at the sub-nanometric scale and translational jumps between nanodomains in a zigzag scheme between the hydroxide group of the NH₂-MIL-53 (Al).

Nanomaterials, 2018, 8, 531, 1-10.; J. Phys. Chem. Lett., 2019, 10, 1698-1

In situ experiences

The team is experienced in the study of phase synthesis, stability and decomposition of copper sulphides using several techniques: DSC/TG analyses and in situ X-rays and neutron powder diffraction. This expertise allows to determine (i) the existence and nature of intermediate reaction phases occurring during synthesis process, (ii) optimized synthesis conditions of the phases, and (iii) the temperature range stability of the compounds and their phase decomposition reactions, both fundamental data for thermoelectric applications of sulphides at high temperature.

J. Alloys Compd., 2015, 634, 253; J. Solid State Chem., 2017, 247, 83; Dalton Trans., 2017, 46, 2174; Chem. Mater., 2020, 32, 830; Chem. Mater., 2020, 32, 8993

High-temperature neutron thermograms recorded during the real-time in situ sealed tube synthesis of germanite Cu22Fe8Ge4S32 at the heating rate of 2 K min^-1.

Differential scanning calorimetry and thermogravimetric data (left) and high-temperature neutron thermograms (right) of colusite Cu₂₆Cr₂Ge₆S₃₂ recorded at the heating rate of 2 K min^-1.