@article{weng_dill_martin_whitfield_hoffmann_ye_2020, title={K-space algorithmic reconstruction (KAREN): a robust statistical methodology to separate Bragg and diffuse scattering}, volume={53}, ISSN={1600-5767}, url={http://dx.doi.org/10.1107/S1600576719017060}, DOI={10.1107/S1600576719017060}, abstractNote={Diffuse scattering occurring in the Bragg diffraction pattern of a long-range-ordered structure represents local deviation from the governing regular lattice. However, interpreting the real-space structure from the diffraction pattern presents a significant challenge because of the dramatic difference in intensity between the Bragg and diffuse components of the total scattering function. In contrast to the sharp Bragg diffraction, the diffuse signal has generally been considered to be a weak expansive or continuous background signal. Herein, using 1D and 2D models, it is demonstrated that diffuse scattering in fact consists of a complex array of high-frequency features that must not be averaged into a low-frequency background signal. To evaluate the actual diffuse scattering effectively, an algorithm has been developed that uses robust statistics and traditional signal processing techniques to identify Bragg peaks as signal outliers which can be removed from the overall scattering data and then replaced by statistically valid fill values. This method, described as a `K-space algorithmic reconstruction' (KAREN), can identify Bragg reflections independent of prior knowledge of a system's unit cell. KAREN does not alter any data other than that in the immediate vicinity of the Bragg reflections, and reconstructs the diffuse component surrounding the Bragg peaks without introducing discontinuities which induce Fourier ripples or artifacts from underfilling `punched' voids. The KAREN algorithm for reconstructing diffuse scattering provides demonstrably better resolution than can be obtained from previously described punch-and-fill methods. The superior structural resolution obtained using the KAREN method is demonstrated by evaluating the complex ordered diffuse scattering observed from the neutron diffraction of a single plastic crystal of CBr4 using pair distribution function analysis.}, number={1}, journal={Journal of Applied Crystallography}, publisher={International Union of Crystallography (IUCr)}, author={Weng, James and Dill, Eric D. and Martin, James D. and Whitfield, Ross and Hoffmann, Christina and Ye, Feng}, year={2020}, month={Feb}, pages={159–169} }
 @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_folmer_martin_2013, title={Crystal Growth Simulations To Establish Physically Relevant Kinetic Parameters from the Empirical Kolmogorov–Johnson–Mehl–Avrami Model}, volume={25}, ISSN={0897-4756 1520-5002}, url={http://dx.doi.org/10.1021/cm402751x}, DOI={10.1021/cm402751x}, abstractNote={A series of simulations was performed to enable interpretation of the material and physical significance of the parameters defined in the Kolmogorov, Johnson and Mehl, and Avrami (KJMA) rate expression commonly used to describe phase boundary controlled reactions of condensed matter. The parameters k, n, and t0 are shown to be highly correlated, which if unaccounted for seriously challenge mechanistic interpretation. It is demonstrated that rate measurements exhibit an intrinsic uncertainty without precise knowledge of the location and orientation of nucleation with respect to the free volume into which it grows. More significantly, it is demonstrated that the KJMA rate constant k is highly dependent on sample size. However, under the simulated conditions of slow nucleation relative to crystal growth, sample volume and sample anisotropy correction affords a means to eliminate the experimental condition dependence of the KJMA rate constant, k, producing the material-specific parameter, the velocity of the ...}, number={20}, journal={Chemistry of Materials}, publisher={American Chemical Society (ACS)}, author={Dill, Eric D. and Folmer, Jacob C. W. and Martin, James D.}, year={2013}, month={Oct}, pages={3941–3951} }
 @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...}, 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} }