Crystallization of glasses – When to use the Johnson-Mehl-Avrami kinetics?

Svoboda, Roman

doi:10.1016/j.jeurceramsoc.2021.08.026

Cited by 40 publications

(24 citation statements)

References 28 publications

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“…The α max,z values for the present IMC crystallization data are shown in Figure 5 B. The mean α max,z values (averaged over the whole range of q + ) show reasonable correspondence with the 0.632 fingerprint of the JMA model (the 0.999 correlation [ 49 ] with the JMA model is indicated by the dashed lines). This highlights, however, the danger of averaging data exhibiting significant trends.…”

Section: Discussionsupporting

confidence: 53%

Indomethacin: The Interplay between Structural Relaxation, Viscous Flow and Crystal Growth

et al. 2022

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Non-isothermal differential scanning calorimetry (DSC) was used to study the influences of particle size (daver) and heating rate (q+) on the structural relaxation, crystal growth and decomposition kinetics of amorphous indomethacin. The structural relaxation and decomposition processes exhibited daver-independent kinetics, with the q+ dependences based on the apparent activation energies of 342 and 106 kJ·mol−1, respectively. The DSC-measured crystal growth kinetics played a dominant role in the nucleation throughout the total macroscopic amorphous-to-crystalline transformation: the change from the zero-order to the autocatalytic mechanism with increasing q+, the significant alteration of kinetics, with the storage below the glass transition temperature, and the accelerated crystallization due to mechanically induced defects. Whereas slow q+ led to the formation of the thermodynamically stable γ polymorph, fast q+ produced a significant amount of the metastable α polymorph. Mutual correlations between the macroscopic and microscopic crystal growth processes, and between the viscous flow and structural relaxation motions, were discussed based on the values of the corresponding activation energies. Notably, this approach helped us to distinguish between particular crystal growth modes in the case of the powdered indomethacin materials. Ediger’s decoupling parameter was used to quantify the relationship between the viscosity and crystal growth. The link between the cooperativity of structural domains, parameters of the Tool-Narayanaswamy-Moynihan relaxation model and microscopic crystal growth was proposed.

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Section: Discussionsupporting

confidence: 53%

Indomethacin: The Interplay between Structural Relaxation, Viscous Flow and Crystal Growth

et al. 2022

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“…The KJMA model is based on the kinetics of crystallization controlled by the nucleation and growth of crystal domains and is valid for an isotropic crystallization with randomly dispersed nuclei and with growth rate dependent only on temperature, as discussed in refs , , . The time evolution of crystallinity ϕ is described in terms of an apparent crystallinity ϕ 0 of virtually overlapped domains under the concept of an extended volume , where I ( T , t ) denotes a nucleation rate per unit volume, g represents a geometric factor, G ( T ) is the growth rate, and d denotes the dimension of crystal domains.…”

Section: Introductionmentioning

confidence: 99%

Effect of a Nucleating Agent on Polymer Crystallization Analyzed Using the Original Avrami Model

Toda

2022

Macromolecules

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The historically renowned original treatments of Avrami predicted the continuous change in the Avrami index between 3 and 4 with a time-dependent effective nucleation rate I for the nucleation and subsequent linear growth process of spherical domains under isothermal conditions. The nucleation rate I is determined by the number density N 0 of tiny germ-nuclei at t = 0 and the transformation rate r of a germ nucleus to the active nucleus. This model is applied to the crystallization of poly(butylene terephthalate) (PBT), which reveals a continuous change in the Avrami index with temperature when a nucleating agent (NA) talc is added. In particular, for crystallization with NA, N 0 corresponds to the number density of NA particles, and the rate r represents the formation rate of an active nucleus from an NA particle. The product of N 0 and crystal growth rate G, i.e., N 0 1/3 G, and the rate r are independently evaluated from the time-dependent behavior of crystallization with the Avrami index between 3 and 4. The efficiency of NA is evaluated from the rate r and its temperature dependence, which is determined by the thermal activation barrier for the transformation and is characterized by an excess surface free energy Δσ evaluable using the current analysis method. The dispersibility of NA is assessed by the relative increase of N na /N wo in N 0 , with the addition of NAs N na from the number density without agents N wo . The applicability and usability of the analysis method were confirmed for PBT crystallization with talc, using fast-scanning calorimetry. The evaluated rate r exhibited a stronger temperature dependence than the crystal growth rate G, and the relative increase N na /N wo was more than 100 times in the sample with well-dispersed talc.

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“…30,47 The JMA theory can be extended to nonisothermal conditions only in cases where the nucleation centers can be shown to form before or during the initial stages of crystal growth and where the crystal growth rate can be considered Arrhenian in the determined temperature range of crystallization. 30,48,49 The former condition is supported for the SNPB glass through in situ microscopy (described later), whereas Arrhenian growth can be assumed for measurement in the relatively narrow temperature window 49 (i.e., ∼ 373−393 K) over which the activation energy remains nominally constant during the glass-crystal transformation process. 30 Both conditions for use of the nonisothermal approach appear to be satisfied, as shown by the experimental results discussed below.…”

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confidence: 98%

“…However, there are practical limitations in experimentally obtaining a suitable exothermic crystallization curve during an isothermal hold step in a calorimetric experiment (e.g., see Figure S2 in the Supporting Information for the case of data collected for the current SNPB hybrid material), thus suggesting the need for nonisothermal methods. Nonisothermal methods have added advantages, as they are (i) time efficient (no need to equilibrate at each temperature), (ii) not subject to potential temperature over/under-shoot and oscillation during the process of rapid ramp to the isothermal temperature, and, (iii) able to measure phase transformations that occur too rapidly to be measured under isothermal conditions. , The JMA theory can be extended to nonisothermal conditions only in cases where the nucleation centers can be shown to form before or during the initial stages of crystal growth and where the crystal growth rate can be considered Arrhenian in the determined temperature range of crystallization. ,, The former condition is supported for the SNPB glass through in situ microscopy (described later), whereas Arrhenian growth can be assumed for measurement in the relatively narrow temperature window (i.e., ∼ 373–393 K) over which the activation energy remains nominally constant during the glass-crystal transformation process . Both conditions for use of the nonisothermal approach appear to be satisfied, as shown by the experimental results discussed below.…”

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confidence: 99%

Crystallization Kinetics in a Glass-Forming Hybrid Metal Halide Perovskite

Singh

Mitzi

2022

ACS Materials Lett.

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The recent discovery of glass-forming hybrid metal halide perovskite (MHP) semiconductors has opened the opportunity to explore their utility beyond the already celebrated fields of photovoltaics and light emitters, as enabled by their crystalline counterparts. Reversible switching phenomena between glassy and crystalline states further extends the potential application space, prospectively, to memory, computing, photonics, metamaterials, and phase change energy storage. To better identify the characteristic switching properties, the underlying kinetics of glass crystallization is studied for an e x e m p l a r y g l a s s -f o r m i n g ( S ) -( − ) -1 -( 1 -n a p h t h y l )ethylammonium lead bromide (SNPB) perovskite, using a combination of calorimetry, microscopy, and kinetic modeling techniques. The study shows an activation energy of ∼350 kJ/mol for the glass-crystalline transition and an Avrami parameter of n = 2.02 ± 0.11, and points to heterogeneous surface-mediated nucleation of crystallites with two-dimensional laminar growth in space. These results serve as an initial guide toward modeling the glass-crystallization kinetic effects in MHPs and to facilitate assessment of the suitability of the glass-forming MHPs for a broad range of prospective applications.

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Crystallization of glasses – When to use the Johnson-Mehl-Avrami kinetics?

Cited by 40 publications

References 28 publications

Indomethacin: The Interplay between Structural Relaxation, Viscous Flow and Crystal Growth

Indomethacin: The Interplay between Structural Relaxation, Viscous Flow and Crystal Growth

Effect of a Nucleating Agent on Polymer Crystallization Analyzed Using the Original Avrami Model

Crystallization Kinetics in a Glass-Forming Hybrid Metal Halide Perovskite

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