Brian Phillips

Professor and Chair
Office: ESS 240
Phone: 631-632-6853
E-mail: brian.phillips@stonybrook.edu

B.S., Bowling Green State University, 1984
Ph.D., University of Illinois at Urbana-Champaign, 1990
Postdoctoral Research Associate, Lawrence Livermore
National Laboratory, 1991-1994
Research Associate, University of California, Davis, 1994-2002
Faculty member at Stony Brook since 2002

Thank you for your interest in my research! I have broad interests in areas of geochemistry and mineralogy, with an emphasis on the atomic-level structure of minerals, their surfaces, and defects. Materials of interest to me include poorly crystalline and amorphous materials such those encountered in near-surface soils and contaminated settings. Such materials can take up contaminants and sequester them by a variety of different mechanisms, such as coprecipitation, adsorption onto the surface, or coupled dissolution-precipitation. The mechanism(s) by which contaminants are taken up determines the resiliency and whether they can be remobilized upon change of conditions (change of solution composition, pH, temperature, etc.). I also enjoy investigating the atomic-scale structure of minerals, particularly the details of solid-solutions, mixing, order/disorder phenomena, and modes of trace element incorporation. These properties are responsible for the rich chemical complexity of minerals, determines their stability, and the suitability of trace element systematics to provide information on external conditions at the time of mineral formation.

NMR Spectroscopy

In my research I focus on devising ways to use nuclear magnetic resonance (NMR) spectroscopy to investigate the structure geological materials at the atomic-scale. NMR is element- and isotope-specific and provides information on the local bonding environment of the atoms in terms of how many and what types atoms it’s bonded to (coordination) and the nature of the environment up to about two atoms away. I am particularly interested in applying so-called double-resonance methods that provide information on the relative spatial proximity of distinct types of atoms or environments. Owing to its sensitivity to short-range structure, NMR is particularly useful for systems lacking long-range order and complements other more commonly applied structure-sensitive tools such as X-ray diffraction, vibrational spectroscopy, and X-ray spectroscopy. As a result, much of my work has involved collaboration with other researchers to combine the complementary information from these different tools to better understand earth materials.

Instrumentation:

My research lab includes two NMR spectrometers configured for experiments primarily on solid materials. A 2-channel 400 MHz (9.4 T) Varian Inova instrument provides routine data for a wide range of nuclei of interest to geoscientists (e.g., ³¹P, ²⁷Al, ¹³C, ²⁹Si). It is equipped with probe assemblies configured for 7.5 mm, 4.0 mm, and 3.2 mm rotors (outside diameter). Our 3-channel 500 MHz (11.7 T) Varian Infinity plus spectrometer is used for routine data collection at higher magnetic field, plus double-resonance experiments between many different pairs of nuclei. It is equipped with a broad-band 3-channel probe configured for 4 mm rotors, plus conventional 2-channel probes configured for 3.2, 4.0, and 5.0 mm rotors. A new 1.2 mm probe extends the spinning rates up to 60 kHz.

Examples of recent projects:

Trace element defects in minerals:

During crystallization or precipitation minerals incorporate many elements besides those found in its chemical formula, at minor (1 to 0.1 %) to trace (<0.1 %) concentrations. Many such impurities have been proposed as geochemical “proxies”, meaning that the concentration in the mineral is related to its concentration in the fluid from which it precipitates. Such relationships typically rely on well-behaved partitioning of the element between fluid and mineral. We are using NMR spectroscopy to investigate the forms that trace elements occur in minerals.

As an example we investigated the nature of phosphorus impurities in the calcium carbonate (CaCO₃) minerals calcite and aragonite. Calcite cave deposits (speleothems), contain P concentrations of 10’s up to and over 1000 mg P g⁻¹, as indicated by microanalytical techniques. Our ³¹P NMR analysis indicates that this phosphorus occurs in three distinct forms: 1) phosphate defects in the calcite structure; 2) inclusions of the mineral monetite; and 3) inclusions of an unidentified phosphate-bearing mineral that contains no hydroxyl or water molecules. See:

Mason, H.E., Frisia, S., Tang, Y., Reeder, R.J., and Phillips, B.L. (2007) Phosphorus speciation in calcite speleothems determined from solid-state NMR spectroscopy. Earth and Planetary Science Letters, 254: 313-322.

In aragonite derived from coral skeletal material, we find phosphate defects in the aragonite structure, but also that crystalline apatite inclusions can account for up to 30% of the P in some samples:

Mason, H.E., Montagna, P., Taviani, M., McCulloch, M., Phillips, B. L. (2011) Phosphate defects and apatite inclusions in coral skeletal aragonite revealed by NMR spectroscopy. Geochimica et Cosmochimica Acta, 75:7446-7457. DOI: 10.1016/j.gca.2011.10.002

In both cases, we were able to coprecipitate phosphate with ¹³C-labeled calcite and aragonite, and apply ³¹P/¹³C NMR double resonance methods to identify the phosphate groups in the calcium carbonate mineral, based on their close spatial proximity to carbonate. To test the ability of calcite to host and sequester large defects, we investigated organophosphate molecules coprecipitated with calcite, employing ¹³C/³¹P double resonance to probe spatial proximity of the phosphate group of the organic molecule to calcite carbonate groups. We found that even very large molecules occurred near calcite carbonate groups. These results show that calcite is able to incorporate large molecules as intracrystalline defects during crystal growth:

Phillips, B.L., Zhang, Z., Kubista, L., Frisia, S., Borsato, A. (2016) NMR spectroscopic study of organic phosphate esters coprecipitated with calcite. Geochimica et Cosmochimica Acta 183:46-62. DOI: 10.1016/j.gca.2016.03.022

This work was funded by the National Science Foundation. Similar studies are ongoing.

Solid solution relationships

Minerals are almost never chemically “pure”, often as a result of the ability of one element to substitute for another in the mineral structure if the size is similar and the charge is the same or can be compensated by another, “coupled” substitution. As a result the thermodynamic properties of minerals and therefore the range of conditions over which they are stable varies with composition. To understand this chemical variability, it’s necessary to know the details of how the substitutions are located in the mineral structure. In a recent study, we investigated the nature of F⁻/Cl⁻ solid solution in the apatite group minerals: Ca₅(PO₄)₃(OH,F,Cl), where (OH,F,Cl) denotes potential solid solution among these anions. Understanding the composition of apatite can help constrain the volatile content of the parent magma. In the case of fluor/chlor apatite, Cl⁻ is considerably larger than F⁻ such that the atomic positions in the respective endmember fluorapatite and chlorapatite are distinctively different. There does not appear to be an ordered way to arrange F and Cl along the same unidimensional channel. As a result it was not known how F and Cl are accommodated, for example whether there is a disordered arrangement within the channels or if F and Cl segregate into separate channels or regions. We investigated a series of synthetic F/Cl apatite samples using NMR spectroscopy. Using ¹⁹F/³⁵Cl double resonance methods, we found that F and Cl occur adjacent to each other in the structure. By analyzing the ¹⁹F NMR peak shape, we could determine that the position of the fluoride ion in the channel varies continuously to accommodate the differing sized of Cl and F along these 1-dimensional channels:

Vaughn, J. S., Lindsley, D. H., Nekvasil, H., Hughes, J. M., Phillips, B. L. (2018) Complex F,Cl apatite solid solution investigated using multinuclear solid-state NMR methods. Journal of Physical Chemistry C,122: 530-539. http://dx.doi.org/10.1021/acs.jpcc.7b09912

This work was supported by the National Science Foundation.

Surface adsorption complexes

Mineral surfaces are reactive towards dissolved ions in the surrounding fluid because of charge and incomplete coordination caused by termination of bonding arrangements at the surface. Traditional methods of studying the uptake of dissolved ions by surfaces involve measuring the amount of solute missing from solution after contact with a mineral suspension. By varying the conditions (e.g., pH, solute concentration, presence of other dissolved ions), some inference can be made about the mechanism responsible for removing ions from solution, which is important for understanding conditions that might result in remobilization.

In favorable conditions/systems, NMR spectroscopy can provide more specific information about the nature of the interaction between the mineral surface and the sorbed ions. As an example, we studied the uptake of phosphate ions by the mineral boehmite:

Li, W., Feng, J., Kwon, K. D., Kubicki, J. D., Phillips, B. L. (2010) Surface speciation of phosphate on boehmite (g-AlOOH) determined from NMR spectroscopy. Langmuir, 26:4753-4761. DOI: 10.1021/la903484m

The ³¹P NMR spectra revealed the presence of two distinct phosphate environments, even though the uptake displayed classical Langmuir-like behavior. Detailed ³¹P/²⁷Al double resonance experiments indicate that both environments correspond to phosphate groups bonded to two surface Al atoms. Comparison of ³¹P spectral characteristics with those calculated for model adsorption complexes suggests that the two observed phosphate environments differ in the number of hydrogen atoms bonded to the phosphate oxygens. In contrast, if calcium ions are also present in the solution, then the mineral apatite precipitates at pH 7 and higher, rather than forming phosphate adsorption complexes:

Li, W., Xu, W., Parise, J. B., and Phillips, B. L. (2012) Formation of hydroxylapatite from co-sorption of phosphate and calcium by boehmite. Geochimica et Cosmochimica Acta, 85:289-301. DOI: 10.1016/j.gca.2012.02.021

This work was funded by the National Science Foundation, through the Center for Environmental Molecular Science (CEMS), an Environmental Molecular Science Institute.

Selected publications:

Phillips, B. L., Ohlin, C. A., Vaughn, J. S., Woerner W. R., Smart, S., Subramanyam, R., Pan, L. (2016) Solid-state ²⁷Al NMR spectroscopy of the γ‑Al₁₃ Keggin containing Al coordinated by a terminal hydroxyl ligand. Inorganic Chemistry 55:12270–12280. http://dx.doi.org/10.1021/acs.inorgchem.6b01968

Phillips, B. L., Vaughn, J.S., Smart, S., Pan, L. (2016) Solid-state ²⁷Al NMR spectroscopic characterization of commercial poly-aluminum chlorohydrate. Journal of Colloid and Interface Science476:230-239. DOI: http://dx.doi.org/10.1016/j.jcis.2016.05.019

Vaughn, J.S., Woerner, W.R., Lindsley, D.H., Nekvasil, H., Hughes, J.M. and Phillips, B.L. (2015) Hydrogen environments in low-OH, F,Cl apatites revealed by double resonance solid-state NMR. Journal of Physical Chemistry C,119: 28605-28613. DOI: 10.1021/acs.jpcc.5b10561

Schmidt, M.P., Ilott, A. J.; Phillips, B. L.; Reeder, R. J. (2014) Structural changes upon dehydration of amorphous calcium carbonate. Crystal Growth & Design,14: 938-951. DOI: 10.1021/cg401073n

Li, W.; Feng, X. H.; Yan, Y. P.; Sparks, D. L.; Phillips, B. L. (2013) Solid state NMR spectroscopic study of phosphate sorption mechanisms on aluminum (hydr)oxides. Environmental Science and Technology,47: 8308-8315. DOI: 10.1021/es400874s

Reeder, R. J.; Tang, Y.; Schmidt, M. P.; Kubista, L. M.; Cowan, D. F.; Phillips, B.L. (2013) Characterization of structure in biogenic amorphous calcium carbonate: pair distribution function and nuclear magnetic resonance studies of lobster gastrolith. Crystal Growth and Design, 13: 1905-1914. DOI: 10.1021/cg301653s

Li, W., Pierre-Louis, A. M., P.-L., Kwon, K.D., Kubicki, J.D., Strongin D.R., and Phillips, B. L. (2013) Molecular level investigations of phosphate sorption on corundum (α-Al₂O₃) by ³¹P solid state NMR, ATR-FTIR and quantum chemical calculation. Geochimica et Cosmochimica Acta, 107:252-266. DOI: 10.1016/j.gca.2013.01.007

Mason, H.E., Hirner, J., Xu, W., Parise, J.B., and Phillips, B.L. (2009) Solid-State NMR spectroscopy of Pb-rich apatite. Magnetic Resonance in Chemistry, 47:1062-1070.

Mason, H.E., McCubbin, F.M., Smirnov, A., Phillips, B. L. (2009) Solid-state NMR and IR spectroscopic investigation of the role of structural water and F in carbonate-rich fluorapatite. American Mineralogist, 94:507-516.

Cochiara, S.G. and Phillips, B.L. (2008) NMR spectroscopy of naturally occurring surface-adsorbed fluoride on Georgia kaolinite. Clays and Clay Minerals, 56:90-99.

Phillips, B.L., Mason, H.E., Guggenheim, S. (2007) Hydrogen bonded silanols in the 10 Å phase: evidence from NMR spectroscopy. American Mineralogist, 92:1474-1485.

Mason, H.E., Kozlowski, A., and Phillips, B.L. (2008) Solid-State NMR study of the role of H and Na in AB-type Carbonate Hydroxylapatite. Chemistry of Materials, 20:294-302. DOI: 10.1021/cm0716598

Feng, J., Lee, Y.J., Reeder, R.J., Phillips, B.L. (2006) Observation of bicarbonate in calcite by NMR spectroscopy. American Mineralogist, 91:957-960.

Phillips, B.L., Lee, Y.J., Reeder, R.J. (2005) Organic coprecipitates with calcite: NMR spectroscopic evidence. Environmental Science and Technology, 39:4533-4539.

Swaddle, T.W., Rosenqvist, R., Yu, P., Bylaska, E., Phillips, B.L., Casey, W.H. (2005), Kinetic evidence for five-coordination in AlOH(aq)²⁺ ion. Science, 208:1450-1453. DOI: 10.1126/science.1110231

Furrer, G; Phillips, BL; Ulrich, K-W; Pothig, R; Casey WH (2002) The origin of aluminum flocs in polluted streams. Science 297:2245-2247. DOI:10.1126/science.1076505

Phillips, B.L., Casey, W.H., and Karlsson, M. (2000) Bonding and reactivity at oxide mineral surfaces from model aqueous complexes. Nature 404:379-382. DOI:10.1038/35006036

Phillips, B.L., Kirkpatrick, R.J., and Carpenter, M.A., (1992) Investigation of short-range Al,Si order in synthetic anorthite by ²⁹Si MAS NMR spectroscopy. American Mineralogist, 77:490-500.

Phillips, B.L., Allen, F.M., and Kirkpatrick, R.J. (1987) High-resolution solid-state ²⁷Al NMR spectroscopy of Mg-rich vesuvianite. American Mineralogist, 72:1190-1195.

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