The current work might provide a guidance for the design and synthesis of multifunctional photothermal conversion materials. The results indicate that the octopod-like structures have characteristics of multi-band photothermal conversion. ![]() Enhanced photothermal conversion effect is observed under the illuminations of 635, 808, and 1064 nm lasers. The synthesized structures show a broad band absorption spectrum from 300 to 1100 nm. The thickness of the Ag2S shell gradually increases from the central surface towards the corners of the structure. The resulting structures show an octopod-like mopgorlogy with a Ag2S bulge sitting at each corner of the Ag nanocubes. We synthesized the structures through the sulfidation of Ag nanocubes by taking the advantage of their spatially different reactivity. In the current work, we reported the synthesis and multi-band photothermal conversion of structures with gradually varying shell thickness. The difficulty is that most nanostructures have specific absoprtion band and are not flexible to different demands. However, the multi-functionalization of a single nanostructure to meet the requirements of multiple photothermal applications is still a challenge. If types.Photothermal conversion materials have promising applications in many fields and therefore they have attracted tremendous attention. If types.split( "_") = "shell":Īnd create the other possible magnetization state where the orientation of the spin moments in the shell are ↓ ↑ ↓ ↑ \downarrow \uparrow \downarrow \uparrow ↓ ↑ ↓ ↑ and in the core are ↑ ↑ ↑ ↑ \uparrow \uparrow \uparrow \uparrow ↑ ↑ ↑ ↑: state2 = list() Let’s implement this energy minimization procedure in the current python script.ĭefine a function to calculate the energy of the system in presence of an external magnetic field Hmax: Hmax = 1.0 def energy (state, Hmax):Į_other = 0.0 for i, site in enumerate(sites):Į_exchange -= state * state * jexĮ_other -= (Hmax * state (kan * state)** 2)Ĭreate one of the two possible magnetization states where the orientation of the spin moments in the shell are ↑ ↓ ↑ ↓ \uparrow \downarrow \uparrow \downarrow ↑ ↓ ↑ ↓ and in the core are ↑ ↑ ↑ ↑ \uparrow \uparrow \uparrow \uparrow ↑ ↑ ↑ ↑: state1 = list() This process ensured a left shift of the hysteresis loop for all particles, consistent with the setting of a fully saturated exchange-bias system (see Evans et al.). For each of the polarities the total system energy is calculated, and the polarity with the lowest energy is then selected. The antiferromagnetic shell is then set with one of two polarities, AFM and AFM−, indicating whether alternate atoms in the lattice are up-down-up-down or down-up-down-up. The ferromagnetic core ions are first oriented along the z z z direction, indicating the desired core orientation at positive field saturation. However, this cooling process can be avoided using an energy minimization procedure. ss = sc = 1.0Ĭreate a dictionary to easily retrieve the parameters defined above. jcc = 1.0 is taken as the unit of energy (see Dimitriadis et al.). ![]() ![]() 0, it should be considered in the units of the magnetic field in a simulation. Because the atomic magnetic moment is taken as 1. ![]() Rc = 7.5ĭefine the core ( sc) and shell ( ss) spin values, the core ( kc) and shell ( ks) anisotropy constants, the core-core ( jcc), core-shell ( jint) and shell-shell ( jss) exchange interaction constants, and the spin update policy for the direction of the magnetic moments. defaultdict is a dictionary where each value has a defined type.ĭefine the values of the core ( Rc) and nanoparticle ( R) radius measured in magnetic unit cells (muc).product returns cartesian product of input iterables.numpy handles numeric arrays and mathematical operations.Let’s build a core/shell nanoparticle with a simple cubic structure using a python script.
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