Download presentation
Published byBarnard Heath Modified over 9 years ago
1
Modern Solid State NMR Techniques for the Study of Glasses
Hellmut Eckert Institut of Physics, Sao Carlos University of Sao Paulo, Brazil
2
Distance distributions in states of matter
3
Ion Conducting Glasses
Network formers: SiO2,B2O3,P2O5,Al2O3 Network modifiers: alkaline, alkaline-earth or silver oxides
4
Short Range Order (0.2-0.3 nm)
network modifier network former B O M directly bonded neighbors Coordination numbers and symmetries Site quantification MAS-NMR
5
Network former-network modifier correlation
Medium-range Order in Glasses B, Si, P O Li-Cs Network former connectivity pm Network former-network modifier correlation Spatial distribution of modifiers
6
Nano- and Microstructure
Chemical Segregation, Phase Separation, Nucleation/growth > 1nm
7
NMR = Nuclear Magnetic Resonance
N: Property of the Atomic Nuclei in Matter M: Magnetic Property, arising from Spin Angular Momentum R: Interaction with electromagnetic waves spectroscopy
8
Solid State NMR applications to inorganic materials
AK H. Eckert Solid State NMR applications to inorganic materials Methods Glass Li Ion battery Hybrid Biomaterials Development Science Components Materials FK-NMR, ESR Preparation electrode s Zeolites Bioceramics Raman, history, Glasses, Inclusion Comp. Implants Sol-Gel polymers Nanocomposites Biopolymers Support Glass/Ceramics Industry: Corning, Schott, Ivoclar, Nippon Glass Fond der Chemischen Industrie State of NRW (Instrumentation und GSC) DFG/ SFB 858 / IRTG Research Networks FAPESP, CNPq – 1A
9
Outline Solid State NMR – General Aspects Anisotropic Interactions:
magnetic shielding dipole-dipole coupling nuclear electric quadrupole coupling Manipulation of Interactions magic angle spinning NMR dipolar spectroscopy –homonuclear dipolar spectroscopy –heteronuclear Some Applications to Glasses
10
Literature Highlight articles
D. Laws, H. M. Bitter, A. Jerschow, Angew. Chem. Int. Ed. 41 (2002), 3096. M. J. Duer, Ann. Rep. NMR Spectrosc. 43 (2000), 1. Fundamental Principles (Theory) A. Abragam, The Principles of Nuclear Magnetism, Clarendon Press Oxford (1961). C. P. Slichter, Principles of Magnetic Resonance, Springer Verlag Heidelberg 1978. B.C. Gerstein, C.R. Dybowski, Transient Techniques in NMR of Solids, Academic Press Inc (1985). M. Mehring, Principles of High Resolution NMR in Solids, Springer Verlag Heidelberg (1983) R.R. Ernst, G. Bodenhausen, A. Wokaun, Principles of Nuclear Magnetic Resonance in One and Two Dimensions, Clarendon Press, Oxford (1987) NMR Applications to Materials Sciences J. Klinowski, Ed. New Techniques in Solid State NMR, Topics in Current Chemistry, 246, Springer-Verlag Heidelberg 2005. K. Schmidt-Rohr, H.W. Spiess, Multidimensional Solid-State NMR and Polymers, Academic Press, London (1996). M. J. Duer, Introduction into Solid State NMR Spectroscopy, Blackwell Publ. 2004
11
Nuclear Magnetism Nuclear magnetic moment:
I, the angular momentum, is subject to quantization laws, concerning both magnitude and orientation I: spin quantum number m: orientational quantum number with m=-I,-I+1,…I-1,I
12
Spin-1/2: two nuclear spin orientations,
Energy splitting in a magnetic field: E(m) = - mghB (Zeeman-energy) (g = gyromagnetic ratio) NMR is element selective
13
Precession B g wp = Precession of spins around external field
similar to gyroscope The precession (Larmor) frequency of the nuclei is given by eff B g wp = where Beff = B0 + Bint Bint contains important structural and chemical information NMR measures the precession (Larmor) frequency
14
How is it done ? By application of a second magnetic field
fluctuating with frequency wo ~ wp B0 E Radio waves hn Resonance absorption occurs if wo ~ wp
15
Macroscopic Sample NMR is quantitative
In a sample spins are distributed among energy levels ( Boltzmann-distribution)l Macroscopic magnetization along B0 No net magnetization in x- or y-direction Curie Law NMR is quantitative
16
The Basic NMR Experiment
90° pulse -> magnetization flip Free Induction Decay Signal- detection (taken from Siemens MR Tutorium) NMR-Spectrum Fourier- Transformation
17
Equipment Magnet Probe Sample in Rotor Console /Computer
18
Magnetic Shielding Resonance frequency (bare nucleus):
Effective magnetic field at nucleus: Resonance frequency (real sample) Chemical shift Effective magnetic field arises from shielding or deshielding of the external magnetic field by electrons Probe for electronic environment ( bonding)
19
Chemical Shielding Anisotropy
Solid state : chemical shielding is anisotropic: tensorial description powdered sample Distribution of orientations cubic Asymmetric Axially symmetric Probe for local symmetry ( bonding geometry)
20
Example : 31P NMR of Phosphates
Asymmetric cubic Axially symmetric
21
Magnetic Dipole-Dipole Interaction
Magnetic moments of nearby spins affect the local magnetic field and thus the resonance frequency. „Through-space“ interaction Probe of internuclear distance Separate parts: homonuclear heteronuclear Anisotropic:
22
Nuclear electric quadrupole interaction
This quadrupole moment interacts with local electric field gradients created by the bonding environment of the nuclei. -> probe of local symmetry
23
Solid State NMR H = HZ + HD + HCS + HQ element-selective
locally selective quantitative experimentally flexible: Selective averaging hn B0 E H = HZ HD HCS + HQ Internucl. distances Coordination numbers and symmetries
24
Magic Angle Spinning H = HZ + HD + HCS + HQ Haniso= A . {3 cos2 q – 1}
B z 54 44 rotation axis q = 54.7° 4 Q 3,4 3 Q 1,2 2 1 H = HZ HD HCS + HQ iso 2nd o.
25
MAS-NMR probe ZrO2 Macor BN Kel-F Vespel
26
The effect of spinning speed
27
31P MAS-NMR of Na-Phosphate Glasses
60 Na2O – 40 P2O5 50 Na2O – 50 P2O5 P(3) 40 Na2O – 60 P2O5
28
Network Transformation In Natrium silicate glasses 29Si MAS-NMR
Maekawa et al. J. Noncryst. Solids 1991, 127, 53
29
27Al Chemical Shifts and Al Coordination Number in Glasses (Na2O)0
27Al Chemical Shifts and Al Coordination Number in Glasses (Na2O)0.33{(Ge2O4)x-(P2O5)1-x}0.67 Al(4)-O-Ge Al(4)-O-P Al(5) Al(6)
30
Short Range Order (0.2-0.3 nm)
network modifier network former B O M directly bonded neighbors Coordination numbers and symmetries Site quantification MAS-NMR
31
Network modifier-network modifier correlations
Spatial cation distribution B,Si,P O Li-Cs can be addressed by selective measurement of magnetic dipole-dipole intractions, D~r-3
32
Spin Echo O B O B B tD dephasing 180y (or x) refocusing Na Na Na z x
33
23Na – Spin Echo Decay H = HZ + HD + HCS + HQ
M2 = (µo/4p)2 g4h2 Srij-6 H = HZ HD HCS + HQ homonuclear Distances
34
Example of Spin Echo Curve
for:
35
23Na Spin Echo Decay: Model Compounds
M2 = (µo/4p)g4h2Srij-6 B.Gee, H.Eckert, SSNMR 5,113 (1995)
36
Spatial sodium distribution in oxide glasses
M2 (23Na -23Na) vs. number density
37
Li Na Electrical conductivity in oxide glasses
(M2O)y(SiO2)1-y and (M2O)y(B2O3)1-y expected: s = z. F . c . u Li Na silicate glasses borate glasses y
38
Comparison between different glass systems
H. Eckert, Z. Phys. Chem. 224, (2010)
39
7Li-{6Li}-SEDOR H = HZ + HD + HCS + HQ 7Li 6Li
Glass contains 95% of Lithium as 6Li, 5% as 7Li 7Li is the observe-nucleus H = HZ HD HCS + HQ heteronuclear Distances
40
7Li-{6Li}-SEDOR in lithium silicate glass
M2(7Li-6Li) (Li2O)0.4(SiO2)0.6
41
M2(7Li-6Li) as a function of cation density
in Oxide Glasses Silicate glasses Borate glasses
42
Medium-range Order in Glasses
Network former connectivity B O can be addressed by measuring magnetic dipole-dipole couplings between constituent network former nuclei
43
11B- MAS –NMR Spectra of Borophosphate Glasses 50% Ag2O. x P2O5
11B- MAS –NMR Spectra of Borophosphate Glasses % Ag2O * x P2O5 * (50%-x) B2O3 BO4 BO3 Connectivity with phosphorus ??
44
Modulation of HD under Sample Rotation
Magic- Angle Spinning (MAS) + - Tr 31P S I Rotational Echo Double Resonance (REDOR) 11B + Tr I-channel p pulse
45
REDOR Pulse Sequence S0 - S S0 DS S0 11B 31P 11B 31P p/2 p = [ Tr ] 1
1 2 3 4 p p/2 S0 11B 31P
46
Site Connectivities in Borophosphate Glasses:
11B {31P}-REDOR on 50% Ag2O - 25% B2O3 - 25% P2O5 difference spin echo with dephasing BO3 BO4 spin echo S. Elbers
47
REDOR Pulse Sequence DS S0 11B 31P 11B depends on:
[ Tr ] 1 2 3 4 p p/2 11B strength of interaction (# neighbors, distance) depends on: 31P dipolar evolution time N . Tr
48
Analysis of REDOR Curves in Glasses
.
49
11B{31P} REDOR of Crystalline BPO4
0.0000 0.0005 0.0010 0.0015 0.0020 0.0 0.2 0.4 0.6 0.8 1.0 M 2 meas = 15.8 0.2 kHz theo = kHz Measurement Simulation (S -S)/S NT r (s) .
50
Site-selective 11B{31P} REDOR
BO4 BO3
51
Mixed network former effect in the
(M2O)0.33[(P2O5)1-x(B2O3)x ]0.67 – System (M = Li, K, Cs): Glass Transition Temperatures
52
Mixed network former effect in the
(M2O)0.33[(P2O5)1-x(B2O3)x ]0.67 – System (M = Li, K, Cs) DC- conductivity (300 K) Activation Energies
53
Structural Issues Regarding the Mixed-Network Former Effect
Network former speciations Coordination polyhedra Types of anionic and neutral species present Connectivity distributions Random Linkages ? Connectivity Preferences ? Clustering/Phase separation ? Competition for the network modifier Proportional sharing vs. preferential attraction Relation to physical properties
54
SOLID STATE NMR CHARACTERIZATION
B(3) B(4) P(1) P(2) P(3) 11B 31P D. Larink, H. Eckert, M. Reichert, S.W. Martin, J. Phys. Chem. C, tbp
55
Structural speciation in the (K2O)0.33[(P2O5)1-x(B2O3)x ]0.67 – system
0 < x < 0.5: P(2) units successively replaced by B(4) units 0.5 < x 1.0: P(3) units successively replaced by B(3) units
56
Tg-value and network connectedness
0 < x < 0.5: P(2) units successively replaced by B(4) units 0.5 < x 1.0: P(3) units successively replaced by B(3) units Glass transition temperature number of bridging oxygen per network former unit
57
Correlation between Tg and [O]
(M2O)0.33[(P2O5)1-x(B2O3)x ]0.67 (M = Li, K, Cs):
58
Structure-property correlations in the
(M2O)0.33[(P2O5)1-x(B2O3)x ]0.67 – system Speciation electrical conductivities Charge delocalization near P31B and B4 0P units creates shallow Coulomb traps, favoring ionic mobility
59
Dynamic characterization by static 7Li NMR
Single Network former Mixed network former M. Storek, R. Böhmer, S. W. Martin, D. Larink, H. Eckert, J. Chem. Phys. 137, (2012)
60
Activation energies for ion dynamics and transport
from sdc from NMR
61
Quantification of network connectivity
Comparison with a statistical scenario Strong preference for heteroatomic linking
62
Quantification of network connectivity: Chemical ordering scenario
maximized B(4)-O-P Connectivity no B(3)-O-P Connectivity no B(4)-O- B(4) Connectivity
63
Solid State NMR Periodic Table
65
Center for Research, Technology and Education in Vitreous Materials
Acknowledgments Center for Research, Technology and Education in Vitreous Materials Andrea de Camargo Edgar Zanotto Claudio Magon Ana Candida Rodrigues José Schneider Pedro Donoso Silvia Santagneli
66
Acknowledgments Dr. J.D. Epping (WWU) Dr. Ulrike Voigt (WWU)
Dr. S. Elbers (WWU) Dr. S. Puls (WWU) Dr. D. Zielniok (WWU) Dr. Dirk Larink (WWU) Frederik Behrends (WWU) Prof. Steve W. Martin (Iowa State) R. Moreira (IFSC) Prof. A.S.S. de Camargo (IFSC) AK Prof. H. Eckert, WWU Münster
Similar presentations
© 2025 SlidePlayer.com Inc.
All rights reserved.