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 ] 11 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