Lecture 14: NMR Spectroscopy of Glass Practice and ...inimif/teched/GlassCSC/Lecture_14_Martin.… · SWMartin ISU Lecture 14: NMR Spectroscopy of Glass: Quadrupole Nuclei in Glass

Lecture 14: NMR Spectroscopy of Glass – Practice and

Application : Quadrupolar Nuclei

Examine alkali borate glasses and the formation of tetrahedral borons

Examine alkali thioborate glasses and the formation of tetrahedral borons

Examine temperature dependence of spin lattice relaxation rate to probe ion dynamics in glass

SWMartin ISU Lecture 14: NMR Spectroscopy of Glass: Quadrupole Nuclei in Glass 2

I = 3/2 11B, 27Al….

Bray JNCS 73(1985)19-45


Powder pattern, amorphous, lineshape for I = 3/2

Bray JNCS 73(1985)19-45


11B NMR lineshapes for v=B2O3

Bray JNCS 73(1985)19-45


Theoretical line shapes for I = 3/2 spin

Bray JNCS 73(1985)19-45


NMR “wide line” CW spectra of v-B2O3

Bray JNCS 73(1985)19-45


Computer simulation of 11B NMR CW static spectra

Bray JNCS 73(1985)19-45


Comparison of derivative and integrated spectra

Bray JNCS 73(1985)19-45


Fraction of tetrahedral borons in alkali borate glasses

Bray JNCS 73(1985)19-45


Structural groups in alkali borate glasses

Feller, Dell, and Bray JNCS 51(1982)21-30


B2O3 glass

B2O3 glass exhibits high level

of IRO

Triangles form 6 membered

“boroxyl” rings

25% of borons are not in rings

BO3/2 “loose” triangles

75% of borons are in rings

B3(O)3(O3/2)

Equal numbers of boroxyl rings

and loose triangles


Tetrahedral boron formation in alkali borate glasses

M+BO4/2-1 units form with the

addition of M2O to BO3/2

Two tetrahedral units form, for every M2O added

xM2O + (1-x)B2O3 >>

f (BO4/2) N4 = [BO4]/Total B

= 2x/2(1-x)

= x/(1-x)

B fills it’s shell with octet of electrons

Alkali ion acts as a “spectator”ion not actively involved in bonding


Alkali modified borate glasses

M2O + B2O3 glasses

BO3/2 has 6 valence electrons

Three B-O single bonds

B can lower it’s energy by forming four B-O single bonds to over to 8 (full “octet”) valence electrons

It can do so by using M2O (M22+O=)

an electron donor

xM2O + (1-x)B2O3 >>


= 2x/2(1-x)

= x/(1-x)


Tetrahedral boron formation in alkali borate glasses

Two tetrahedral borons form for every M+ added

Alkali ions are “spectator” ions in the reaction

All of the alkali ions, Li, Na, K, Cs, and Rb act in the same manner

Affect is for M2O to cross-link borate glass structure

xM2O + (1-x)B2O3 >>


= 2x/2(1-x)

= x/(1-x)


Structure and NMR characteristics of various borate groups



Composition dependence of structural groups in Li2O + B2O3 glasses



B MASS NMR of alkali borate glasses

Prabakar, Rao, and Rao, Proc. R. Soc. Lond. A 429(1990)1-15


High field high spin rate B MASS NMR


Fraction of B4 in alkali borate glasses


B4 in alkali borosilicate glasses

Bray JNCS 73(1985)19-45


B3 in alkali borate glasses

Bray JNCS 73(1985)19-45


2D MASS NMR of 11B in B2O3

Zwanziger, Youngman JNCS 168(1994)293-297


2D 11B MASS NMR



2D 11B MASS NMR



Boroxyl ring fraction ~ 75%



11B in alkali thioborate glasses

Sills and Martin, JNCS, 168(1994)86-96


v-B2O3 compared to v-B2S3



Na2S + B2S3 glasses



B4 in alkali thioborate glasses



N4 in alkali thiobrate glasses



C-Na2B4S7


N4 = 1, no quadrupole

broadened line


xCs2S + (1-x)B2S311B NMR

Cho, Meyer, Martin JNCS 270(2000)205-214


N4 in x(Rb, Cs)2S + (1-x)B2S3 Glasses


Rb2S + B2S3Cs2S + B2S3


N4 in xM2S + (1-x)B2S3 Glasses



N4 in alkali thioborate glasses



Dithioborate group: Cs2B4S7



Formation of “normal” B4 in Cs2S + B2S3 glasses



Dithioborate structure with N4 = 1



Na6B10S18 Crystal structure with N4 = 1

Royle, Cho, Martin JNCS 279(2001)97-109


Spin-Lattice relaxation time measurements

When the spins are flipped, it takes time for the spins to relax

to the lower (ground) energy state

This time is characterized by the spin-lattice relaxation time,

T1

T1 is typically very long for solids

Few mechanisms to enable the spin to release its spin

energy

T1 is typically very short for liquids

Rapid atomic, ionic, and/or molecular motion helps release

spin energy through diffusion


Spin-Lattice relaxation time measurements

Spin lattice relaxation T1 can be used therefore to examine

diffusion processes

Temperature dependence of T1 can be used as a measure

of molecular or atomic diffusion

Temperature dependence of T1 can also be used as a

measure of ionic diffusion

Temperature dependence of T1 is a measure of atomic level

displacements, diffusion

T1 can be compared to ionic conduction processes in glasses

Nuclear Spin Lattice Relaxation Time, T1

Nuclear Spin Lattice Relaxation Time, 1/T1 R1


Determination of the DAEs in Glass

Direct measurement through NMR

NSLR data

Conduction process is by the

percolation through low barrier

sites

Conductivity will only measure the

low energy barriers

NSLR measures all cations, both

contribute to NSLR T1 Glassy FIC

Crystalline FIC

Stevels & Taylor DAEs model,


NSLR to DAE to Conductivity

1 2 3 4 5 610

-1

100

101

102

103

104

z = 0.0; x = 0.55

Rela

xation R

ate

(s

-1)

1000 K/T

T1

4 MHz

8 MHz

0 20 40 60 80 100

Pro

ba

bil

ity

Activation Energy (kJ/mol)

x=0.35

x=0.45

x=0.55

1 2 3 4 5 6 710

-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

100

D.C

. C

on

du

ctivity (

Oh

m c

m)-1

1000 / Temp (K-1)

z=0.0;x=0.45

z=0.0;x=0.55

z=0.1;x=0.55

z=0.2;x=0.55

z=0.3;x=0.55

NSLR DAE Conductivity


NMR Relaxation of Spin Energy

H0

H1

z

xy

= H0

Rf pulse


Fluctuations from Ionic Motion

Distance

d/)m2/E(r5.0

act0

)Tk/Eexp(rTrBact0

Thermally activated cation

Not thermally activated


Bloombergen-Purcell-Pound (BPP) Theory

2

c

2

L

c

2

c

2

L

c

1

1

1

T41

T4

T1

TC

TT

1TR

Single relaxation time

theory

R1 = relaxation rate

T1 = relaxation time

L = Larmor frequency

C1 = coupling constant

c = correlation time

Tr

1T

c

Rela

xation R

ate

(s-1

)

1/T (K-1)

1TcL

NSLR Curve


Low Temperature Asymmetry

K. H. Kim, Solid State Ionics 91 (1996).


Distribution of Activation Energies

2

b

2

am

2

b

aNMR

E2

)EE(exp

E2

1)E(Z

J. Zarzycki, Glasses and the Vitreous State (1991).

0 20 40 60 80 100

Pro

babili

ty

Activation Energy, Ea (kJ/Mol)

Em

Em = average

Eb=standard deviation


NMR NSLR Data

Determination of the DAEs from NSLR T1 measurements

NMRNMR

aL

a

aL

a

LLdEZCTRTT

22

0

2211

414

1),(),(/1

22

1

1

2

2

2)(

1

2exp

2

1)1()(

amb

am

b

aNMR

EEE

Ey

E

EE

E

yEZ

Gaussian DAEs with Lorentzian “tail”, y ~ 0.2, to account for

low temperature, high frequency “extra” relaxation


DAEs from FIC Li2S + GeS2 Glasses


DAEs from FIC Li2S + GeS2 Glasses

Average of distribution shifts to

smaller activation energies

with increasing Li2S

Distribution does not change

shape significantly, all have ~

same FWHM

0.55 Glass is slightly

narrower


Multiple FIC Dynamics in Glass

“Multiple Channel” ion relaxation in

FIC glasses

R1 data show evidence of multiple

relaxation processes

Fast process at low T, slower

process at higher T

Alkali thioborate glasses are

speciated into tetrahedral borons

and trigonal borons with NBS

Are “slow” Li+ ions associated with

NBS?

Are “faster” Li+ ions associate with

BS4/2- groups?


Multiple FIC Dynamics in Glass

Relaxation spectra of both mobile

Li+ ions and immobile frame work

B ions were measured

Multiple-channel relaxation was

observed for Li+ ions

BS3 and BS4 units have different

relaxation rates and hence

difference DAEs to characterize

their dynamics

N4 of 0.7Li2S is 0.05

Most Li+ ions are associated with

BS33- groups, as evidenced in the

DAEs


DAE Fittings Two Distributions

0 20 40 60 80

ZN

MR (

Ea)

Activation Barrier Height, Ea (kJ/mol)

Ge sites

B sites

Total Distribution

1 2 3 4 5 60.1

1

10

100

1000

10000

z = 0.0; x = 0.55

Rela

xation R

ate

(s-1

)

1/T (K-1)

T1

70 kHz

4 MHz

8 MHz

xLi2S + (1-x)[0.5B2S3 + 0.5GeS4]


Effects of Li2S Addition

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.01

10

100

1000

Frequency = 8 MHz

xLi2S + (1-x)(0.5 B

2S

3 + 0.5 GeS

2)

Rela

xati

on

Rate

(s

-1)

1000/T (K-1)

x=0.35

x=0.45

x=0.55


Average Activation Energy

0.3 0.4 0.5 0.6 0.725

30

35

40

45

50

55

60

Ave

rag

e A

ctiva

tio

n E

ne

rgy,

Em (

kJ/m

ol)

mole fraction of Li2S

Boron site in xLi2S + (1-x)B

2S

3

Germanium site in xLi2S + (1-x)GeS

2

Germanium site in Ternary system

Boron site in Ternary system


LiI doped – Activation Energy

0.00 0.05 0.10 0.15 0.20 0.25 0.3020

25

30

35

40

45

50

55

60

Avera

ge A

ctivation E

nerg

y,

Em (

K)

mole fraction of LiI

Germanium site

Boron Site


1 2 3 4 5 60.1

1

10

100

1000

10000

z = 0.3 ; x = 0.55

Re

laxa

tio

n R

ate

(s-1

)

1/T (K-1)

4 MHz

8 MHz

1 2 3 4 5 60.1

1

10

100

1000

10000

z = 0.2 ; x = 0.55

Re

laxa

tio

n R

ate

(s-1

)

1/T (K-1)

T1

4 MHz

8 MHz

1 2 3 4 5 60.1

1

10

100

1000

10000

z = 0.1 ; x = 0.55

Re

laxa

tio

n R

ate

(s-1

)

1/T (K-1)

4 MHz

8 MHz

1 2 3 4 5 60.1

1

10

100

1000

10000

z = 0.0 ; x = 0.55

R

ela

xa

tio

n R

ate

(s

-1)

1/T (K-1)

T1

70 kHz

4 MHz

8 MHz

LiI Addition


Distribution of Activation Energies

xLi2S + (1-x)(0.5 B2S3 + 0.5 GeS2)

0 20 40 60 80 100

ZN

MR(

Ea)

Activation Energy (kJ/mol)

x=0.35

x=0.45

x=0.55


Distribution of Lithium atoms

Using coupling constants within 10% of

binary values yielded approximate Lithium

sharing fractions of:

Sample Germanium sites Boron sites

x=0.35 0.70 0.30

x=0.45 0.75 0.25

x=0.55 0.80 0.20


DAEs Treatment

Using a DAEs to treat ion conduction in glass is not new

Von Schweidler used a DRTs as early as 1907

Ann. Physik. 24(1907)711.

Cole and Cole, Cole and Davidson reported log Guassian DAEs

J. Chem. Phys. 9(1941) 341

H. E. Taylor used a DAEs to describe the dielectric relaxation

Modeling ’ and ” in soda-lime-silicate glass in 1955

Trans. Fara. Soc. 51(1955)873.

C. T. Moynihan used a log Guassian treatment

Modeling conductivity relaxation in CKN melts and glasses in 1972

Phys. Chem. Glasses 13(1972)171

Lecture 14: NMR Spectroscopy of Glass Practice and ...inimif/teched/GlassCSC/Lecture_14_Martin.… · SWMartin ISU Lecture 14: NMR Spectroscopy of Glass: Quadrupole Nuclei in Glass

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