A perovskite-type cage compound as a temperature-triggered dielectric switchable material

Abstract

The perovskite-type cage compound [C3H6NH2]2[KCoIII(CN)6] shows a temperature-triggered dielectric switch. The switchable properties are derived from an order–disorder phase transition of a system, by changing the motions of the polar azetidine cation guests.

Ferroic multipolar order and disorder in cyanoelpasolite molecular perovskites

“…On further heating of [C 3 N 2 H 5 ] 2 Rb[Co(CN) 6 ], its X-ray diffraction pattern reflected a firstorder phase transition at ∼480 K. The most obvious change in the diffraction pattern was the coalescence of peaks, consistent with an ascent in symmetry. The high temperature phase could be indexed in terms of the cubic spacegroup F m3m, which is consistent with the symmetry observed for other cubic double perovskites [30,37,38] and is related to the R3m ambient-temperature cell as shown in Fig. 2(c).…”

“…On further heating of [C 3 N 2 H 5 ] 2 Rb[Co(CN) 6 ], its X-ray diffraction pattern reflected a firstorder phase transition at approximately 480 K. The most obvious change in the diffraction pattern was the coalescence of peaks, consistent with an ascent in symmetry. The high-temperature phase could be indexed in terms of the cubic space group Fm3m, which is consistent with the symmetry observed for other cubic double perovskites [35,44,45] and is related to the R3m ambient-temperature cell as shown in figure 2e. A structural model in which the C 3 N 2 H + 5 ions are split across four sites-corresponding to the alignment of the rotational axis along each of the cubic 111 body diagonals-was used as a starting point for Rietveld refinement.…”

“…Cyanoelpasolites correspond to the specific case for which X = CN − (elpasolites themselves are the corresponding fluorides). In most cases, the A-site is occupied by a monovalent organic cation, such as imidazolium or tetramethylammonium [31,35,44]. The B and B sites are often occupied by group 1 and transitionmetal cations, respectively; in any case, the total charge on these two species sums to four.…”

Ferroic Multipolar Order and Disorder in Cyanoelpasolite Molecular Perovskites

“…On further heating of [C 3 N 2 H 5 ] 2 Rb[Co(CN) 6 ], its X-ray diffraction pattern reflected a firstorder phase transition at ∼480 K. The most obvious change in the diffraction pattern was the coalescence of peaks, consistent with an ascent in symmetry. The high temperature phase could be indexed in terms of the cubic spacegroup F m3m, which is consistent with the symmetry observed for other cubic double perovskites [35,44,45] and is related to the R3m ambient-temperature cell as shown in Fig. 2(c).…”

“…Cyanoelpasolites correspond to the specific case for which X = CN (elpasolites themselves are the corresponding fluorides). In most cases, the A-site is occupied by a monovalent organic cation, such as imidazolium or tetramethylammonium [31,35,44]. The B and B sites are often occupied by group 1 and transition-metal cations, respectively; in any case, the total charge on these two species sums to four.…”