Cation-Dependent Magnetic Ordering and Room-Temperature Bistability in Azido-Bridged Perovskite-Type Compounds

Abstract

A series of end-to-end azido-bridged perovskite-type compounds [(CH3)nNH4-n][Mn(N3)3] (n = 1-4) were synthesized and characterized. Structural phase transitions indicating the general lattice flexibility were observed and confirmed by the crystal structures of different phases. These materials show cation-dependent magnetic ordering at up to 92 K and magnetic bistability near room temperature.

An extended Tolerance Factor approach for organic–inorganic perovskites

“…For molecular anion based hybrids, solution chemistry approaches provide a powerful method in many cases. 34,35 …”

“…band-gap engineering due to B or X site substitution in halide based compounds or altering magnetic properties in azido-bridged frameworks. 34,36 Hydrogen bonding interactions between the protonated amine and the cavity have been shown to have a large impact on the materials' properties. 10 For instance, in iodide and formate based frameworks, bonding interactions between amines and the frameworks influence the mechanical properties and are responsible for temperature-driven order–disorder transitions.…”

Switchable Guest Molecular Dynamics in a Perovskite‐Like Coordination Polymer toward Sensitive Thermoresponsive Dielectric Materials

“…Moreover, the dielectrically active molecular dynamics of [(CH 3 3 ], which was recently reported by Wang and co-workers. [19] In contrast to 1 which undergoes a ferroelastic phase transition of P1 $R3 , the Mn II analogue exhibits a non-ferroelastic phase transition of P2 1 $Cmca, and the transition temperature (T c ) is about 115 K higher than that of 1. It is surprising that although the lengths of CdÀN bonds are slightly longer than those of MnÀN bonds, the Cd···Cd distances in the [Cd(N 3 ) 3 ] À cage unit are slightly shorter than the Mn···Mn distances, implying that 1 has a more flexible framework than its Mn II analogue.…”

An Unusual Phase Transition Driven by Vibrational Entropy Changes in a Hybrid Organic–Inorganic Perovskite

“…[2] However,t he thermal vibrations of all atoms in [CH 3 NH 3 ][Mn(N 3 ) 3 ]s how an ormal trend, where the atomic displacement parameters (ADPs) of C, N A ,M n, and N X all decrease upon cooling (Figure 1d), though there is as harp drop in the ADPs of the azide nitrogen atoms.T his unusual phenomenon arises from the competing effects of electrostatic interactions and hydrogen bonding in the perovskite unit across the transition. [24] Thet emperature dependencies of the entropy (S Exp ), shown in the Supporting Information, Figure S4b,d emonstrate that the associated entropy change (DS Exp )i sa bout 4.35 JK À1 mol À1 .T his rather large value is close to that of at wo-fold order-disorder transition (DS = RlnN 2 /N 1 = Rln2 = 5.76 JK À1 mol À1 ,w here N 2 /N 1 represents the ratio of possible configurations after and before PT and R is the gas constant), though our single-crystal X-ray diffraction studies exclude the existence of any obvious structural disorder in the HT phase.S uch an unusually large entropy change suggests that the structure exhibits as ignificant increase in the vibrational degrees of freedom and corresponding active phonon modes on transitioning from the LT to HT structure. [28,29] Differential scanning calorimetry plots show sharp peaks at 277 Konh eating and at 264 Konc ooling which confirms the strong first-order nature of the transition (Supporting Information, Figure S4a).…”