Characterization of the Order−Disorder Dielectric Transition in the Hybrid Organic−Inorganic Perovskite-Like Formate Mn(HCOO)₃[(CH₃)₂NH₂]

Abstract

We have found that the hybrid organic-inorganic perovskite-like formate Mn(HCOO)(3)[(CH(3))(2)NH(2)] shows a dielectric transition around 190 K. According to single crystal X-ray diffraction, the compound shows rhombohedral symmetry at room temperature and monoclinic symmetry at low temperature (100 K), and the main difference between both structures is that the (CH(3))(2)NH(2)(+) (DMA) cations are disordered in the high temperature phase but cooperatively ordered in the low temperature one. The vibrational spectra of this compound reveal that significant changes take place in the vibrations ascribed to the DMA cation (changes in the frequency of certain vibrations, splitting of particular vibrations, and changes in the intensities), while no significant changes have been observed in those attributed to the formate anion. On the basis of all this information, we attribute the origin of the dielectric transition to the dynamics of the DMA cations: above 190 K these cations can rotate inside the cubooctahedral cavity created by the [Mn(HCOO)(3)](-) framework, while for lower temperatures such rotation gets frozen, and their cooperative arrangement inside the cavities give rise to the observed dielectric transition.

Muon spin relaxation investigation of magnetic ordering in the hybrid organic-inorganic perovskites[(CH3)2NH2Baker1, Lancaster2, Franke3 et al. 2010Phys. Rev. B512300View full textAdd to dashboardCite

“…6 Work has also led to noncentrosymmetric structures for both optical 7,8 and ferroelectric 9 applications. Combining these magnetic and structural properties can lead to multiferroicity, as has recently been demonstrated in ͓͑CH 3 ͒ 2 NH 2 ͔M͑HCOO͒ 3 with M = Ni, Mn, Co, and Fe, where the antiferroelectric ordering occurs in the range 160-185 K and the magnetic ordering in the range 8-36 K. [10][11][12][13] These dimethylammonium metal formates adopt the ABX 3 perovskite structure with M 2+ ions ͑B͒ bridged by ͑HCOO͒ − ions ͑X͒, and ͓͑CH 3 ͒ 2 NH 2 ͔ − ions ͑A͒ at the center of a ReO 3 -type cavity. 10 The antiferroelectric phase transition appears to be driven by the ordering of hydrogen bonds linking the dimethylammonium cations.…”

Elastic relaxation behavior, magnetoelastic coupling, and order-disorder processes in multiferroic metal-organic frameworks

“…37 Therefore the transition metal analogs can be considered multiferroic. Above the ferroelectric transition the DMA cations can rotate within the framework, while at lower temperatures, such rotation is frozen, leading to the observed dielectric transition.…”

Giant barocaloric effect in the ferroic organic-inorganic hybrid [TPrA][Mn(dca)3] perovskite under easily accessible pressures

“…Remarkable examples are, for instance, (CH 3 NH 3 )PbI 3 and related compounds2526, which exhibit exceptional optoelectronic properties for photovoltaic applications. And also the [AmineH][M(X) 3 ] perovskite families (AmineH=midsized protonated amines, M=divalent transition metal cations, X=bidentate-bridge ligands HCOO − , N 3 − , CN − , and so on) which display outstanding functionalities such as cooperative magnetic, electric and/or elastic order, and magnetically induced multiferroicity; moreover, they can also act as precursors for different nanostructured functional materials272829303132333435363738.…”