Towards a Clearer Picture of Complex Borosilicates NMR of Borate Model Glasses Scott Kroeker Department of Chemistry, University of Manitoba Solid-State NMR of Nuclear-Related Materials Cambridge, September 23, 2005

U NIVERSITY OF M ANITOBA Medium-Range Order Cesium Borate Glasses ppm B MAS NMR 11.7 T R = Cs/B = 0.2

U NIVERSITY OF M ANITOBA Quantify contributions to N 4 Smooth variation with R Tetrahedral Boron Fraction Cesium Borate Glasses

U NIVERSITY OF M ANITOBA 11 B MAS NMR 14.1 T R = 0.1 Tetrahedral Boron Alkali Borate Glasses

U NIVERSITY OF M ANITOBA Alkali borate glasses Similar intensity trends for K, Rb, Cs Different relative contributions Potassium Borate Glasses

U NIVERSITY OF M ANITOBA Dispersion in N 4 trends at higher alkali Heavier vs. lighter alkali Light alkalis stabilize tetrahedral boron? Tetrahedral Boron Fraction Alkali Borate Glasses

U NIVERSITY OF M ANITOBA Alkali borate glasses Composition dependence of linewidths Distribution of local boron environments Interaction with borate network

U NIVERSITY OF M ANITOBA Li Na K Rb Cs Steady increase (Li,Na) Complex behaviour (K,Rb,Cs) Discontinuities related to spectroscopic data Feller et al. Phys. Chem. Glasses (2003), 44, Shear Modulus Alkali Borate Glasses

U NIVERSITY OF M ANITOBA Alkali borate glasses Alkali dependence Lighter vs. heavier alkali ions Multiple [4] B peaks N 4 at high alkali content Linewidths Elastic constants Peak assignments?

U NIVERSITY OF M ANITOBA Crystalline alkali borates Cs 2 O-3B 2 O 3 triborate unit

U NIVERSITY OF M ANITOBA Crystalline alkali borates K 2 O-2B 2 O 3 diborate di-triborate

U NIVERSITY OF M ANITOBA Pentaborate (LiB 8 O 18 H 8 ) Diborate (Li 2 B 8 O 17 H 8 ) Di-triborate (Li 2 B 8 O 18 H 10 ) Triborate (LiB 7 O 15 H 10 ) Non-ring [4] B (LiB 5 O 12 H 8 ) B3LYP/cc-pVTZ//HF/6-31G* Theoretical Calculations Chemical Shifts

U NIVERSITY OF M ANITOBA R = 0.5, K = 2 R = Cs/B K = Si/B Borosilicate Glasses Cs 2 O-2B 2 O 3 -4SiO 2

U NIVERSITY OF M ANITOBA Phase Heterogeneity CsB-60

U NIVERSITY OF M ANITOBA Raman spectroscopy Potassium borate glasses Ring breathing modes No diborates or di-triborates at low alkali 808 cm -1 Boroxol ring 765 cm -1 Single [4] B 730 cm -1 Two [4] B

U NIVERSITY OF M ANITOBA Strategy: Measure local Cs dipolar field at [4] B to distinguish between two types of groups REDOR Local charge compensation amongst typical units Network modifier proximity

U NIVERSITY OF M ANITOBA Rotational Echo Double Resonance 11 B (I = 3/2) 133 Cs (I = 7/2) Dipolar interactions depend on distance Multispin interactions Qualitative identification

U NIVERSITY OF M ANITOBA Test experiment and simulations Dipolar field of 120 Hz (3.49 Å ) Actual distances: Å REDOR Crystalline Cesium Triborate

U NIVERSITY OF M ANITOBA REDOR Cesium Borate Glasses

U NIVERSITY OF M ANITOBA 11 B MQMAS CsB-54

U NIVERSITY OF M ANITOBA 5% NBO Chemical shift 17 O MAS NMR CsB-54 (enriched)

U NIVERSITY OF M ANITOBA 11 B{ 133 Cs} REDOR: [4] B peaks Same dephasing behaviour for a given glass R = 0.10

U NIVERSITY OF M ANITOBA Speciation in borate glasses Low-alkali glasses triborate pentaborate High-alkali glasses di-triborate diborate

U NIVERSITY OF M ANITOBA REDOR of Borosilicates Datolite CaBSiO 4 (OH) [4] B surrounded by [4] Si trigonally 11 B{ 1 H} CPMAS 29 Si{ 1 H} CPMAS

U NIVERSITY OF M ANITOBA Conducting Polymers Poly(anilineboronic acid)

U NIVERSITY OF M ANITOBA Paramagnetic Materials Silver Cyanide Compound 15 N MAS Orientational CN disorder

U NIVERSITY OF M ANITOBA Paramagnetic Materials Nickel Cyanide Compound Structure: Draper N., Batchelor R.J., Sih B.C., Ye Z-G., Leznoff D.B., Chem. Mater, 15, 2003, C MAS

U NIVERSITY OF M ANITOBA Paramagnetic Materials Tourmalines < 1% Fe/Mn

U NIVERSITY OF M ANITOBA Sensitivity Enhancement 17 O NMR of B 2 O 3 MultiRAPT pulse sequence (Grandinetti) Signal enhancement Decrease experiment time 16-fold 17 O in under 24 hrs Kwak et al. Solid State NMR (2003), 24, B2O3B2O3 210 mg 22.5 hrs S/N = 40

U NIVERSITY OF M ANITOBA Summary and Conclusions Simple MAS Alkalis behave differently Phase heterogeneity Calculations effective for clusters Double-resonance methods Conducting samples Paramagnetic samples Sensitivity enhancement

U NIVERSITY OF M ANITOBA Acknowledgements

U NIVERSITY OF M ANITOBA

PABA

U NIVERSITY OF M ANITOBA 17 O

U NIVERSITY OF M ANITOBA CsBSi Survey of model nuclear waste glasses B 2 O 3 ( %) SiO 2 ( %) Na 2 O ( %) Planned glasses along K = 2 (K = Si/B) line Varying Cs R = 0.5, K = 2 R = Cs/B K = Si/B

U NIVERSITY OF M ANITOBA Crystalline Inclusions in Glasses 11 B CT and selected ST sidebands neither showing evidence of crystalline components

U NIVERSITY OF M ANITOBA 17 O B 2 O 3 S/N = hrs mg

U NIVERSITY OF M ANITOBA Metal Effects - Ni vs. Cu M = Ni 2+ 6-coordinate S = 1 M = Cu 2+ 6-coordinate S = 1/2 All cyanides directly bonded to paramagnetic center Structure: Draper N., Batchelor R.J., Sih B.C., Ye Z-G., Leznoff D.B., Chem. Mater, 15, 2003, {(tmeda)MHg(CN) 2 }HgBr 4

U NIVERSITY OF M ANITOBA Metal Effects Ni vs. Cu Multiple anisotropic interactions  iso = -205 ppm  > 600 ppm 13 C MAS -205 ppm {(tmeda)NiHg(CN) 2 }HgBr 4 Paramagnetic Materials Silver Cyanide Compound

U NIVERSITY OF M ANITOBA Silver Cyanide Compound Confirms cyanide orientational ordering 15 N MAS 172 ppm (N21) 316 ppm (N11/N20) 288 ppm (N20) 256 ppm (N20/N11) Temperature Sensitivity