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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

Thermal variation of the crystal size.Thermal dependence of the relative variation of the length (La) and width (Lb) of the crystal along the crystallographic axes a (a) and b (b), respectively. The crystal size was recorded during heating and cooling at temperature sweep rate 0.2 K min−1.
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f2: Thermal variation of the crystal size.Thermal dependence of the relative variation of the length (La) and width (Lb) of the crystal along the crystallographic axes a (a) and b (b), respectively. The crystal size was recorded during heating and cooling at temperature sweep rate 0.2 K min−1.

Mentions: When subject to heating-cooling cycles, the C12PbI4 microcrystal displays color change from yellow to orange on heating, followed by change from orange to the initial yellow color on cooling (Fig. 1a). Movies S1–S3 in the Supporting Information show this spatiotemporal transformation on two different single crystals. The observed color change is consistent with the first order phase transition reported for C12PbI4919. The interface is almost parallel to the a axis and propagates along the b axis of the unit cell. The snapshots of the crystal at different temperatures in Fig. 1a show that the transformation is accompanied by significant change in crystal size. Upon heating to around 317.5 K, the crystal shows sizable length expansion of ~6% along the b axis, from 186 μm to 197 μm. Concomitantly, the crystal width (along the a axis) contracts by 2%, from 20 μm to 19.6 μm. On cooling, this transformation is reversible and the crystal reverts to its initial size and shape around 307.5 K. We recorded the thermal variation of the length (Lb) and width (La) of the crystal within the thermal hysteresis. The results are summarized in Fig. 2, where the temperature (T) variation of the relative length and width is shown as ∆Lb/Lb = [Lb(T)-Lb(LT)]/Lb(LT) and ∆La/La = [La(T)–La(LT)]/La(LT) (note that, regretably, two-dimensional optical microscopy does not give an access to the change in the thickness (∆Lc/Lc) of the material). A thermal hysteresis loop, centered at T0 = 312.5 K with width ΔT = 10 K was observed in both cases, in line with the first-order character of the transition.


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)

Thermal variation of the crystal size.Thermal dependence of the relative variation of the length (La) and width (Lb) of the crystal along the crystallographic axes a (a) and b (b), respectively. The crystal size was recorded during heating and cooling at temperature sweep rate 0.2 K min−1.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: Thermal variation of the crystal size.Thermal dependence of the relative variation of the length (La) and width (Lb) of the crystal along the crystallographic axes a (a) and b (b), respectively. The crystal size was recorded during heating and cooling at temperature sweep rate 0.2 K min−1.
Mentions: When subject to heating-cooling cycles, the C12PbI4 microcrystal displays color change from yellow to orange on heating, followed by change from orange to the initial yellow color on cooling (Fig. 1a). Movies S1–S3 in the Supporting Information show this spatiotemporal transformation on two different single crystals. The observed color change is consistent with the first order phase transition reported for C12PbI4919. The interface is almost parallel to the a axis and propagates along the b axis of the unit cell. The snapshots of the crystal at different temperatures in Fig. 1a show that the transformation is accompanied by significant change in crystal size. Upon heating to around 317.5 K, the crystal shows sizable length expansion of ~6% along the b axis, from 186 μm to 197 μm. Concomitantly, the crystal width (along the a axis) contracts by 2%, from 20 μm to 19.6 μm. On cooling, this transformation is reversible and the crystal reverts to its initial size and shape around 307.5 K. We recorded the thermal variation of the length (Lb) and width (La) of the crystal within the thermal hysteresis. The results are summarized in Fig. 2, where the temperature (T) variation of the relative length and width is shown as ∆Lb/Lb = [Lb(T)-Lb(LT)]/Lb(LT) and ∆La/La = [La(T)–La(LT)]/La(LT) (note that, regretably, two-dimensional optical microscopy does not give an access to the change in the thickness (∆Lc/Lc) of the material). A thermal hysteresis loop, centered at T0 = 312.5 K with width ΔT = 10 K was observed in both cases, in line with the first-order character of the transition.

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