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Rapid and robust spatiotemporal dynamics of the first-order phase transition in crystals of the organic-inorganic perovskite (C12H25NH3)2PbI4.

Yangui A, Sy M, Li L, Abid Y, Naumov P, Boukheddaden K - Sci Rep (2015)

Bottom Line: The thermal hysteresis loop is 10 K wide, and the interface velocity is constant at V ≈ 1.6 mm s(-1).The progression of the habit plane is at least 160 times faster than in spin-crossover materials, and opens new prospects for organic-inorganic perovskites as solid switching materials.These hitherto unrecognized properties turn this and possibly similar hybrid perovskites into perspective candidates as active medium for microscopic actuation.

View Article: PubMed Central - PubMed

Affiliation: Groupe d'Etudes de la Matière Condensée, Université de Versailles, CNRS UMR 8635, 45 Avenue des Etats Unis, 78035 Versailles, France.

ABSTRACT
The dynamics of the thermally induced first-order structural phase transition in a high-quality single crystal of the organic-inorganic perovskite (C12H25NH3)2PbI4 was investigated by optical microscopy. The propagation of the straight phase front (habit plane) during the phase transition along the cooling and heating pathways of the thermal hysteresis was observed. The thermochromic character of the transition allowed monitoring of the thermal dependence of average optical density and aided the visualization of the interface propagation. The thermal hysteresis loop is 10 K wide, and the interface velocity is constant at V ≈ 1.6 mm s(-1). The transition is accompanied with sizeable change in crystal size, with elongation of ~6% along the b axis and compression of ~ -2% along the a axis, in excellent agreement with previously reported X-ray diffraction data. The progression of the habit plane is at least 160 times faster than in spin-crossover materials, and opens new prospects for organic-inorganic perovskites as solid switching materials. Moreover, the crystals of (C12H25NH3)2PbI4 are unusually mechanically robust and present excellent resilience to thermal cycling. These hitherto unrecognized properties turn this and possibly similar hybrid perovskites into perspective candidates as active medium for microscopic actuation.

No MeSH data available.


Related in: MedlinePlus

Spatial profile of the habit plane.(a) Profiles of the optical density (OD) recorded along the b axis (the propagation direction) starting from t = 1 s with 0.01 s time-steps between the consecutive curves, showing the uniform character of the front propagation. (b) Average front profile obtained by summing all data in panel a, after translation of the interface center. The red curve is the best fit obtained using equation (1).
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f4: Spatial profile of the habit plane.(a) Profiles of the optical density (OD) recorded along the b axis (the propagation direction) starting from t = 1 s with 0.01 s time-steps between the consecutive curves, showing the uniform character of the front propagation. (b) Average front profile obtained by summing all data in panel a, after translation of the interface center. The red curve is the best fit obtained using equation (1).

Mentions: The spatial profile of the interface could provide additional information on the origin of this fast transition. The profile of the interface was analyzed at different time points by plotting the optical density along a straight line parallel to the b axis (the propagation direction) and across the interface between the two phases. The profiles were sampled at 0.01 s-intervals. The plot of successive profiles in Fig. 4a shows that the shape of the interface is invariant and is ~2 μm wide. An interesting feature are the small variations in optical density of comparable amplitude at either side of the LT/HT interface (Fig. 4a). This effect can be attributed to variation in the refractive index of the crystal in the vicinity of the progressing front and are indicative of mechanical stresses that cause light scattering. Figure 4b shows the average OD profile averaged after all curves were offset to overlap so that their center is fixed at x = 110 μm. This average curve was analyzed using the propagating solutions of the Kolmogorov’s equation27, given as


Rapid and robust spatiotemporal dynamics of the first-order phase transition in crystals of the organic-inorganic perovskite (C12H25NH3)2PbI4.

Yangui A, Sy M, Li L, Abid Y, Naumov P, Boukheddaden K - Sci Rep (2015)

Spatial profile of the habit plane.(a) Profiles of the optical density (OD) recorded along the b axis (the propagation direction) starting from t = 1 s with 0.01 s time-steps between the consecutive curves, showing the uniform character of the front propagation. (b) Average front profile obtained by summing all data in panel a, after translation of the interface center. The red curve is the best fit obtained using equation (1).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4644986&req=5

f4: Spatial profile of the habit plane.(a) Profiles of the optical density (OD) recorded along the b axis (the propagation direction) starting from t = 1 s with 0.01 s time-steps between the consecutive curves, showing the uniform character of the front propagation. (b) Average front profile obtained by summing all data in panel a, after translation of the interface center. The red curve is the best fit obtained using equation (1).
Mentions: The spatial profile of the interface could provide additional information on the origin of this fast transition. The profile of the interface was analyzed at different time points by plotting the optical density along a straight line parallel to the b axis (the propagation direction) and across the interface between the two phases. The profiles were sampled at 0.01 s-intervals. The plot of successive profiles in Fig. 4a shows that the shape of the interface is invariant and is ~2 μm wide. An interesting feature are the small variations in optical density of comparable amplitude at either side of the LT/HT interface (Fig. 4a). This effect can be attributed to variation in the refractive index of the crystal in the vicinity of the progressing front and are indicative of mechanical stresses that cause light scattering. Figure 4b shows the average OD profile averaged after all curves were offset to overlap so that their center is fixed at x = 110 μm. This average curve was analyzed using the propagating solutions of the Kolmogorov’s equation27, given as

Bottom Line: The thermal hysteresis loop is 10 K wide, and the interface velocity is constant at V ≈ 1.6 mm s(-1).The progression of the habit plane is at least 160 times faster than in spin-crossover materials, and opens new prospects for organic-inorganic perovskites as solid switching materials.These hitherto unrecognized properties turn this and possibly similar hybrid perovskites into perspective candidates as active medium for microscopic actuation.

View Article: PubMed Central - PubMed

Affiliation: Groupe d'Etudes de la Matière Condensée, Université de Versailles, CNRS UMR 8635, 45 Avenue des Etats Unis, 78035 Versailles, France.

ABSTRACT
The dynamics of the thermally induced first-order structural phase transition in a high-quality single crystal of the organic-inorganic perovskite (C12H25NH3)2PbI4 was investigated by optical microscopy. The propagation of the straight phase front (habit plane) during the phase transition along the cooling and heating pathways of the thermal hysteresis was observed. The thermochromic character of the transition allowed monitoring of the thermal dependence of average optical density and aided the visualization of the interface propagation. The thermal hysteresis loop is 10 K wide, and the interface velocity is constant at V ≈ 1.6 mm s(-1). The transition is accompanied with sizeable change in crystal size, with elongation of ~6% along the b axis and compression of ~ -2% along the a axis, in excellent agreement with previously reported X-ray diffraction data. The progression of the habit plane is at least 160 times faster than in spin-crossover materials, and opens new prospects for organic-inorganic perovskites as solid switching materials. Moreover, the crystals of (C12H25NH3)2PbI4 are unusually mechanically robust and present excellent resilience to thermal cycling. These hitherto unrecognized properties turn this and possibly similar hybrid perovskites into perspective candidates as active medium for microscopic actuation.

No MeSH data available.


Related in: MedlinePlus