Electric Field Induced Reversible Phase Transition in Li Doped Phosphorene: Shape Memory Effect and Superelasticity

Abstract

Phosphorene, the single-layer form of black phosphorus, as a new member of atomically thin material family, has unique puckered atomistic structure and remarkable physical and chemical properties. In this paper, we report a discovery of an unexpected electromechanical energy conversion phenomenon-shape memory effect-in Li doped phosphorene P4Li2, using ab initio density functional theory simulations. Two stable phases are found for the two-dimensional (2D) P4Li2 crystal. Applying an external electric field can turn on or off the unique adatom switches in P4Li2 crystals, leading to a reversible structural phase transition and thereby the shape memory effect with an tunable strain output as high as 2.06%. Our results demonstrate that multiple temporary shapes are attainable in one piece of P4Li2 material, offering programmability that is particularly useful for device designs. Additionally, the P4Li2 displays superelasticity that can generate a pseudoelastic tensile strain up to 6.2%. The atomic thickness, superior flexibility, excellent electromechanical strain output, the special shape memory phenomenon, and the programmability feature endow P4Li2 with great application potential in high-efficient energy conversion at nanoscale and flexible nanoelectromechanical systems.

Quasi‐Monolayer Black Phosphorus with High Mobility and Air Stability

“…Black phosphorus (BP) is the most stable allotrope of elemental phosphorus consisting of puckered P atom layers possessing highly anisotropic properties . Alkali metal intercalated BP has recently received considerable attention due to the ability to tune intrinsic p‐doped BP to the n‐doping regime as well as to convert BP into a Dirac semimetal .…”

The Effects of Heteroatom Adsorption on the Electronic Properties of Phosphorene

“…It is interesting to notice that the upper phosphorene layer in phase Ι maintains being flat, which in phase ΙΙ tilts clearly, which can be proved by a longer bond length between Li and P atoms in phaseΙ than that in phase ΙΙ. The difference found is that phase II has a larger band gap (0.4 eV) and sharp band edges around −1.5 eV below the Fermi levels, whereas phase I has a smaller band gap (0.1 eV) and band tail states [18]. From the researches above, we can realize that phase II has a longer lattice constant so that Li1 can have more space to get closer to P atoms and form more stronger bonding.…”

“…(a) Charge densities of Li adatoms on phosphorene[17]. (b) Phase I[18] and (c) phase II of Li doped phosphorene, the difference at −1.5 eV below the Fermi level: phase I possesses a smaller gap (SG) whereas phase II has a larger gap (LG)[18]. (d) DOSs of phosphorene adsorbed with Li-Mg adatoms[17].…”

Structural design of polyurethane/poly(butylene succinate)/polycaprolactone compounds via a multilayer-assembled strategy: achieving tunable triple-shape memory performances

“…Shape memory polymers (SMPs), as a kind of smart materials, can provide the ability to x a deformed shape and recover to the original shape in response to an external stimulus. [1][2][3][4][5][6] In recent years, the eld of SMPs has witnessed a fast growth because of the intrinsic versatility of SMPs in versatile applications ranging from sensors to aerospace structures and medical devices. [7][8][9][10][11] For further extending the capacity of SMPs, numerous SMPs with novel properties have been developed and the triple-shape memory polymer (TSMP) is the typical one.…”