@article{martin_hillis_hou_2020, title={Transition Zone Theory Compared to Standard Models: Reexamining the Theory of Crystal Growth from Melts}, volume={124}, ISSN={1932-7447 1932-7455}, url={http://dx.doi.org/10.1021/acs.jpcc.0c03003}, DOI={10.1021/acs.jpcc.0c03003}, abstractNote={Ideas proposed at the beginning of the 20th century to describe the temperature dependence of crystal growth rates have become accepted as the “standard model.” Specifically, it was proposed that rates are controlled by a thermodynamic driving force, liquid/solid interfacial surface energy requires crystal growth to occur at step or kink sites, and particle diffusion/viscous relaxation also controls the rate of growth. However, as described in this article, these underlying assumptions are inconsistent with the fact that crystal growth from supercooled melts is microscopically irreversible, and the well-known fact that short- and intermediate-range order in melts and crystals is essentially equivalent, precluding the existence of sharp interfaces and the need for material diffusion. By contrast, we recently introduced the Transition Zone Theory of crystallization, TZTc, a condensed matter analogue of Eyring’s transition state theory that uses Kauzmann’s conception of configurational entropy and Adam and Gibbs’ ideas of cooperativity to describe the ensemble characteristics governing crystal growth rates. Here, the TZTc model is applied to the same sets of inorganic oxides and organic molecules that were used to evaluate the apparent decoupling of viscosity from the standard model, as well as to several other materials. Without exception, the TZTc model provides a superior fit to temperature-dependent crystal growth-rate data. With a single model accurately describing diverse crystallizing systems, the three parameters extracted from TZTc, for the first time, provide a platform with which to compare and contrast chemical/physical factors that influence crystallization reactions.}, number={34}, journal={The Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Martin, James D. and Hillis, Berkley G. and Hou, Feier}, year={2020}, month={Jun}, pages={18724–18740} }
 @article{hou_martin_2019, title={Isotope Effects Reveal the Template Influence on the Crystal Growth of a Metal–Halide Network}, volume={123}, ISSN={1932-7447 1932-7455}, url={http://dx.doi.org/10.1021/acs.jpcc.9b01334}, DOI={10.1021/acs.jpcc.9b01334}, abstractNote={Crystallization requires the organization of matter into structures with long-range translational order. However, because crystal growth exhibits non-Arrhenius kinetics, it is not possible to apply classical transition state theory to decipher mechanistic details of the crystallization process. With our recently discovered transition zone theory of crystallization, for the first time, it is possible to extract enthalpic and entropic activation parameters for crystal growth from which chemically/physically meaningful mechanistic information is obtained. Here, we measured the respective temperature-dependent crystal growth rates for d0, d1, d9, and d10 isotopomers of the halozeotype CZX-1 to explore how the templating cation impacts the rate of crystal growth. The isotopic dependence of the Kauzmann temperature, TK, and the enthalpic and entropic activation parameters reveal that the mechanism of crystal growth is controlled by both inertial (mass) effects of the template and hydrogen bonding between the template and the metal–halide network. In addition to revealing the role of template–framework interactions for crystal growth of the specific CZX-1 material, this detailed isotope effect study provides an experimental and theoretical framework with which to evaluate details of other condensed-matter reactions.}, number={12}, journal={The Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Hou, Feier and Martin, James D.}, year={2019}, month={Feb}, pages={7475–7485} }
 @article{zoellner_hou_carbone_kiether_markham_cuomo_maggard_2018, title={Activating the Growth of High Surface Area Alumina Using a Liquid Galinstan Alloy}, volume={3}, ISSN={["2470-1343"]}, DOI={10.1021/acsomega.8b02442}, abstractNote={The growth of high surface area alumina has been investigated with the use of a liquid Galinstan alloy [66.5% (wt %) Ga, 20.5% In and 13.0% Sn] as an activator for aluminum. In this process, the aluminum is slowly dissolved into the gallium–indium–tin alloy, which is then selectively oxidized at ambient temperature and pressure under a humid stream of flowing CO2 or N2 to yield amorphous alumina. This preparative route represents a simple and low toxicity approach to obtain amorphous high surface area alumina with very low water content. The as-synthesized high surface area alumina aerogel was a blue-colored solid owing to the Rayleigh scattering by its dendritic fibrous nanostructure consisting of mainly alumina with small amounts of water. Upon annealing at 850 °C, the amorphous product transformed into γ-Al2O3, as well as θ-Al2O3 upon annealing at 1050 °C. Elemental analysis by energy-dispersive spectroscopy provides further evidence that the high surface area alumina is composed of only aluminum and oxygen. The surface area of the amorphous alumina varied from ∼79 to ∼140 m2/g, depending on the initial weight percentage of aluminum used in the alloy. A correlation between the initial concentration of aluminum in the alloy and the surface area of the alumina product was found to peak at ∼30% Al. These results suggest a novel route to the formation of amorphous alumina aerogel-type materials.}, number={12}, journal={ACS OMEGA}, author={Zoellner, Brandon and Hou, Feier and Carbone, Abigail and Kiether, William and Markham, Keith and Cuomo, Jerome and Maggard, Paul A.}, year={2018}, month={Dec}, pages={16409–16415} }
 @article{hou_powel_dougherty_sommer_maggard_2018, title={Tunable Optical and Photocatalytic Properties of Low-Dimensional Copper(I)-Iodide Hybrids Using Coordinating Organic Ligands}, volume={18}, ISSN={["1528-7505"]}, DOI={10.1021/acs.cgd.8b00788}, abstractNote={A family of copper(I)-iodide/organic hybrid compounds was investigated for the impact of coordinating organic ligands on their structures, as well as on their optical and photocatalytic properties. This included the synthesis of two new crystalline compounds, [(CuI)2(bpmd)] and [(CuI)2(bpp)] (bpmd = 2,2′-bipyrimidine, bpp = 2,3-bis(2-pyridyl)pyrazine), both of which consist of chain structures formed by (CuI)2 rhombus-shaped dimers that are further coordinated to the N-groups of the bridging organic ligands. To more broadly investigate structure–property relationships within this system, nine related copper(I)-iodide/organic hybrid compounds, that is, [(CuI)2Ln] (n = 1 or 2; L = 1,2-bis(4-pyridyl) ethylene (bpe); 2,2′-bipyrimidine (bpmd); 2,3-bis(2-pyridyl) pyrazine (bpp); 4,4′-bipyridine (44bpy); pyridazine (pdz); pyrimidine (pmd); pyrazine (pz); pyrazinamide (pza); quinoxaline (quin)) were also prepared in high purity containing extended (CuI)∞ chains or sheets coordinated to bridging or terminating organic ligands. The optical absorption edges of all hybrid compounds were measured using UV–vis diffuse reflectance spectroscopy. Incorporation of the organic ligand functions to significantly decrease the bandgap size with respect to the parent γ-CuI (Eg = 3.1 eV = optical band gap) into the visible-light wavelengths spanning from ∼1.7 to ∼2.6 eV for the [(CuI)2Ln] family. Their optical bandgap sizes were found to be controlled specifically by the framework density, the number of N atoms bonded to each Cu atom, and the number of N atoms in each heterocyclic ring within the ligands. Their photocatalytic properties were investigated and found to show high activity for the light-driven degradation of methylene blue, for example, degrading as fast as within ∼20 min for [(CuI)(pza)]. These photocatalytic activities were found to be related to the orbital energies of the Cu 3d10 and I 5p6 relative to that of the organic ligands, as well as to the local and extended connectivity of their crystalline structures. In contrast to the instability of other metal halide compounds, for example, lead-based halide perovskites, all copper(I)-iodide hybrids were found to be stable within aqueous solutions while under irradiation by ultraviolet and visible light. These results demonstrate the stability and photocatalytic activity copper(I)-iodide/organic hybrids in light-driven redox reactions.}, number={9}, journal={CRYSTAL GROWTH & DESIGN}, author={Hou, Feier and Powel, Matthew and Dougherty, Daniel B. and Sommer, Roger D. and Maggard, Paul A.}, year={2018}, month={Sep}, pages={5406–5416} }
 @article{hillis_losey_weng_ghaleb_hou_martin_2017, title={From rate measurements to mechanistic data for condensed matter reactions: a case study using the crystallization of [Zn(OH2)(6)][ZnCl4]}, volume={7}, ISSN={2073-4352}, url={http://dx.doi.org/10.3390/cryst7010011}, DOI={10.3390/cryst7010011}, abstractNote={The kinetics of crystallization of the R = 3 hydrate of zinc chloride, [Zn(OH2)6][ZnCl4], is measured by time-resolved synchrotron x-ray diffraction, time-resolved neutron diffraction, and by differential scanning calorimetry. It is shown that analysis of the rate data using the classic Kolmogorov, Johnson, Mehl, Avrami (KJMA) kinetic model affords radically different rate constants for equivalent reaction conditions. Reintroducing the amount of sample measured by each method into the kinetic model, using our recently developed modified-KJMA model (M-KJMA), it is shown that each of these diverse rate measurement techniques can give the intrinsic, material specific rate constant, the velocity of the phase boundary, vpb. These data are then compared to the velocity of the crystallization front directly measured optically. The time-resolved diffraction methods uniquely monitor the loss of the liquid reactant and formation of the crystalline product demonstrating that the crystallization of this hydrate phase proceeds through no intermediate phases. The temperature dependent vpb data are then well fit to transition zone theory to extract activation parameters. These demonstrate that the rate-limiting component to this crystallization reaction is the ordering of the waters (or protons) of hydration into restricted positions of the crystalline lattice resulting in large negative entropy of activation.}, number={1}, journal={Crystals}, publisher={MDPI AG}, author={Hillis, B. G. and Losey, B. P. and Weng, J. and Ghaleb, N. and Hou, F. and Martin, J. D.}, year={2017}, pages={11} }
 @article{hou_martin_dill_folmer_josey_2015, title={Transition Zone Theory of Crystal Growth and Viscosity}, volume={27}, ISSN={0897-4756 1520-5002}, url={http://dx.doi.org/10.1021/acs.chemmater.5b00956}, DOI={10.1021/acs.chemmater.5b00956}, abstractNote={Crystal growth and viscous relaxation are known to be activated processes, albeit inadequately described by transition state theories. By considering a transition zone and accounting for the Kauzmann-type temperature dependence of configurational entropy we here develop transition zone theory (TZT). Entropic and enthalpic activation probabilities scale with the cooperativity of the reactant, and the attempt frequency prefactor (kBT/h) is scaled by a characteristic phonon wavelength equal to twice the lattice constant for crystal growth, and the speed of sound squared for viscous relaxation. TZT accurately describes the temperature-dependent crystal growth rates and viscosity of diverse materials over the entire temperature ranges Tg to Tm and Tg to Tc, respectively, and affords a detailed mechanistic understanding of condensed matter reactions similar to that afforded to molecular chemistry by the Eyring equation.}, number={9}, journal={Chemistry of Materials}, publisher={American Chemical Society (ACS)}, author={Hou, Feier and Martin, James D. and Dill, Eric D. and Folmer, Jacob C. W. and Josey, Amanda A.}, year={2015}, month={Apr}, pages={3526–3532} }
 @article{dill_josey_folmer_hou_martin_2013, title={Experimental Determination of the Crystallization Phase-Boundary Velocity in the Halozeotype CZX-1}, volume={25}, ISSN={0897-4756 1520-5002}, url={http://dx.doi.org/10.1021/cm402745e}, DOI={10.1021/cm402745e}, abstractNote={Isothermal crystallization experiments were performed on the halozeotype CZX-1 with 2D temperature- and time-resolved synchrotron X-ray diffraction (TtXRD) and differential scanning calorimetry (DSC). These crystallization experiments demonstrate that the fundamental materials property, the velocity of the phase boundary of the crystallization front, vpb, can be recovered from the Kolmogorov Johnson and Mehl and Avrami (KJMA) model of phase-boundary controlled reactions by introducing the sample volume into the KJMA rate expression. An additional corrective term is required if the sample volume of the crystallization measurement is anisotropic. The concurrent disappearance of the melt and appearance of the crystalline phase demonstrate that no intermediates exist in the crystallization pathway. The velocity of the phase boundary approaches 0 as the glass transition (Tg ≈ 30 °C) is approached and at about 10° below melting point (Tm = 173 °C). The velocity of the phase boundary reaches a maximum of 30 μm s–1 at 135 °C. Single or near-single crystals are grown under conditions where the vpb is much greater than the rate of nucleation.}, number={20}, journal={Chemistry of Materials}, publisher={American Chemical Society (ACS)}, author={Dill, Eric D. and Josey, Amanda A. and Folmer, Jacob C.W. and Hou, Feier and Martin, James D.}, year={2013}, month={Oct}, pages={3932–3940} }