Crafting Spin-State Switchable Strain Profiles within Rb_xCo[Fe(CN)₆]_y@K_jNi[Cr(CN)₆]_k Heterostructures

Abstract

Spin-transition heterostructures have shown promise for inducing large switchable stresses at the nanoscale with a volumetric work density similar to piezoelectrics, but before practical applications are feasible, how heterostructure interfaces and geometry influence the transmission of stress and, in return, how they affect the spin-transition actuator itself, must be better understood. Here, four series of cubic spin-transition Prussian blue analogue (PBA) core–shell heterostructures were developed in order to probe the scaling behavior of the strain induced in the shell by the spin transition of the core. Cubic Rb x Co­[Fe­(CN)6] y·nH2O (RbCoFe-PBA) particles ranging 100–600 nm were used to prepare separate series of Rb x Co­[Fe­(CN)6] y ·nH2O@KjNi­[Cr­(CN)6] k ·mH2O (RbCoFe@KNiCr-PBA) core–shell particles with magnetic KNiCr-PBA shells ranging from 15 to 130 nm. A model fit to the strain-modified magnetization extracts the “strained volume” of the shell, and the results are compared with structural changes observed with powder X-ray diffraction. A linear relationship is found between the strained volume of the shell and the volume of the core for thicker shells, where the magnetic KNiCr-PBA shell is influenced to depths greater than 100 nm in response to the spin transition of the RbCoFe-PBA core. For thin shells, the relationship is more complicated, as the volume change in the actuating core and the strain it induces in the shell become interdependent and a function of shell thickness.

Pressure effect on long-term heat storage ceramics based on Mg-substituted λ-Ti3O5

“…13 An example is lambda-trititanium-pentoxide (λ-Ti 3 O 5 ), which shows a reversible phase transition to beta-trititanium-pentoxide (β-Ti 3 O 5 ) by external stimuli such as light, heat, and pressure. 13–19 Moreover, solid–solid phase transition materials such as charge transfer phase transition materials, 20–26 spin crossover transition materials, 27–40 and metal insulator phase transition materials, 14,41,42 may also be good candidates for long-term heat storage materials. In this study, we synthesize a long-term heat-storage material based on magnesium-substituted lambda-trititanium-pentoxide, λ-Mg x Ti 3− x O 5 .…”

Out-of-equilibrium dynamics driven by photoinduced charge transfer in CsCoFe Prussian blue analogue nanocrystals

“…One of the most fascinating properties of cyanide-bridged bimetallic coordination networks (M–N–C–M′) is their ability to exhibit photoinduced charge transfer (CT) between the constitutive transition metal ions M′ and M. 1–14 This process is responsible for the emergence of various exotic functionalities such as magnetic order at low temperature. In the case of Co–Fe systems forming 3D cubic structures (Fig.…”

Long‐Term Heat‐Storage Ceramics based on Zr‐Substituted λ‐Ti3O5

“…Since λ-Ti 3 O 5 shows responsivity to various external stimuli, the present material also has potential to expand its unique properties using light or electric current. For the future development of long-term heat-storage materials that could contribute to green transformation (GX), investigating other substituting metals, as well as exploring various firstorder solid-solid phase transition materials, such as metalinsulator phase transition materials, [37][38][39] charge-transfer phase transition materials, [40][41][42][43][44][45] spin transition materials [46][47][48][49][50][51][52][53][54][55][56][57][58][59][60] and pressure-responsive phase transition materials, [61][62][63][64][65] should be an effective strategy.…”