Changing the Usual Interpretation of the Structure and Ground State of Cu<sup>2+</sup>-Layered Perovskites

Aramburu, J. A.; García‐Fernández, Pablo; Mathiesen, Nicolai Rask; Garcı́a-Lastra, J. M.; Moreno, M.

doi:10.1021/acs.jpcc.8b00608

Cited by 58 publications

(164 citation statements)

References 88 publications

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“…18 For transition metal difluorides it was found that the high-pressure phase transition sequence differs considerably between ions of similar size, but with different d electron count, as witnessed by comparing MnF2 (d 5 system) 8,19 and CoF2 (d 7 electron count). 20 Moreover for d 9 cations (Cu 2+ , Ag 2+ ) the high-pressure polymorphism is strongly influenced by structural distortion arising from an uneven occupation of the eg orbitals (often referred to as the Jahn-Teller effect) 28 as well as strong spin-spin magnetic interactions. 24 In this context the phase transitions of zinc difluoride are of interest, as the Zn 2+ cation can be viewed as a non-magnetic (3d 10 electronic configuration) counterpart of Mn 2+ , Co 2+ , and Cu 2+ .…”

Section: Introductionmentioning

confidence: 99%

High-Pressure Phase Transitions of Zinc Difluoride up to 55 GPa

et al. 2020

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Studying the effect of high pressure (exceeding 10 kbar) on the structure of solids allows to gain deeper insight in the mechanism governing crystal structure stability. Here we report a study on the high-pressure behaviour of zinc difluoride (ZnF2) -an archetypical ionic compound which at ambient pressure adopts the rutile (TiO2) structure. Previous investigations, limited to a pressure of 15 GPa, revealed that this compound undergoes two pressure-induced phase transitions: TiO2 → CaCl2 at 4.5 GPa, and CaCl2 → HP-PdF2 at 10 GPa. Within this joint experimental-theoretical study we extend the room-temperature phase diagram of ZnF2 up to 55 GPa. By means of Raman spectroscopy measurements we identify two new phase transitions: HP-PdF2 → HP1-AgF2 at 30 GPa and HP1-AgF2 → PbCl2 at 44 GPa. These results are confirmed by Density Functional Theory calculations which indicate that in the HP1-AgF2 polymorph the coordination sphere of Zn 2+ undergoes drastic changes upon compression. Our results point to important differences in the high-pressure behaviour of ZnF2 and MgF2, despite the fact that both compounds contain cations of similar size. We also argue that the HP1-AgF2 structure, previously observed only for AgF2, might be observed at large compression in other AB2 compounds.

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Section: Introductionmentioning

confidence: 99%

High-Pressure Phase Transitions of Zinc Difluoride up to 55 GPa

et al. 2020

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“…Layered hybrid compounds have drawn great attention as a new generation of high performance materials due to their interesting physical and chemical properties obtained through the combination of organic and inorganic materials at the molecular level [1][2][3]. They consist of a wide range of inorganic anion chains, alternating with a large variety of organic cations as building blocks.…”

Section: Introductionmentioning

confidence: 99%

“…The diversity of such hybrid materials is therefore large, and so offers a wide range of structures, properties, and potential applications [6][7][8][9][10][11]. More specifically, hybrid layered compounds based on the perovskite structure are interesting materials due to their potential application in solar cells [2,3]. However, the toxicity and chemical instability of halide perovskites limit their use.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic, Physical, and Structural Characteristics in Layered Hybrid Type (C2H5NH3)2MCl4 (M = 59Co, 63Cu, 65Zn, and 113Cd) Crystals

Lim

2020

Molecules

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The thermal, physical, and molecular dynamics of layered hybrid type (C 2 H 5 NH 3 ) 2 MCl 4 (M = 59 Co, 63 Cu, 65 Zn, and 113 Cd) crystals were investigated by thermogravimetric analysis (TGA) and magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. The temperatures of the onset of partial thermal decomposition were found to depend on the identity of M. In addition, the Bloembergen-Purcell-Pound curves for the 1 H spin-lattice relaxation time T 1ρ in the rotating frames of CH 3 CH 2 and NH 3 , and for the 13 C T 1ρ of CH 3 and CH 2 were shown to exhibit minima as a function of the inverse temperature. These results confirmed the rotational motion of 1 H and 13 C in the C 2 H 5 NH 3 cation. Finally, the T 1ρ values and activation energies E a obtained from the 1 H measurements for the H-Cl···M (M = Zn and Cd) bond in the absence of paramagnetic ions were larger than those obtained for the H-Cl···M (M = Co and Cu) bond in the presence of paramagnetic ions. Moreover, the E a value for 13 C, which is distant from the M ions, was found to decrease upon increasing the mass of the M ion, unlike in the case of the E a values for 1 H.Molecules 2020, 25, 1812 2 of 12 corner-sharing MCl 6 octahedra, while those of M = Co 2+ and Zn 2+ are simple MCl 4 tetrahedra [13]. In addition, the organic chains are joined by weak hydrogen bonds between the NH 3 groups and the Cl ions. Indeed, the structural geometries and molecular dynamics of the organic molecules within the layered hybrid structures are important for determining the influence of temperature on the structural phase transitions.As an example, (C 2 H 5 NH 3 ) 2 CoCl 4 crystallizes as an orthorhombic structure, which undergoes a reversible phase transition at 235 K [14]. In addition, (C 2 H 5 NH 3 ) 2 CuCl 4 undergoes phase transitions at 236, 330, 357, and 371 K [7,15-19], its crystal structure at room temperature is orthorhombic [20]. In contrast, (C 2 H 5 NH 3 ) 2 ZnCl 4 undergoes five phase transitions at 231, 234, 237, 247, and 312 K [21], crystallizing as an orthorhombic system at room temperature [22]. Finally, (C 2 H 5 NH 3 ) 2 CdCl 4 undergoes structural phase transitions at 114, 216, 358, and 470 K [9,23,24], whereby the room temperature orthorhombic phase has the Abma space group [23]. The structure of the organic component consists of a double layer of alkylammonium ions with the charged nitrogen atoms oriented to the nearest MCl 4 tetrahedra or MCl 6 octahedra. The phase transition temperatures, lattice constants, structures, and space groups for the four crystals are summarized in Table 1.

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“…Hybrid metal-organic compounds based on the perovskite structures are of increasing interest due to their potential use for solar cells. 1,2 However, toxicity and chemical instability issues of halide perovskites still remain as the main drawbacks for use in solar cells. The crystalline structure of compounds of the type (C n H 2n+1 NH 3 ) 2 MCl 4 , where n ¼ 1, 2, 3 .…”

Section: Introductionmentioning

confidence: 99%

Cation dynamics by ¹H and ¹³C MAS NMR in hybrid organic–inorganic (CH₃CH₂NH₃)₂CuCl₄

Lim

Joo

2018

RSC Adv.

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To understand the dynamics of the cation in layered perovskite-type (CH 3 CH 2 NH 3 ) 2 CuCl 4 , the temperature-dependent chemical shifts and spin-lattice relaxation times T 1r in the rotating frame have been measured using 1 H magic angle spinning nuclear magnetic resonance (MAS NMR) and 13 C crosspolarization (CP)/MAS NMR techniques. Each proton and carbon in the (CH 3 CH 2 NH 3 ) + cation is distinguished in MAS NMR spectra. The Bloembergen-Purcell-Pound (BPP) curves for 1 H T 1r in CH 3 CH 2 and NH 3 , and for the 13 C T 1r in CH 3 and CH 2 are revealed to have minima at low temperatures. This implies that the curves represent the CH 3 and NH 3 + rotational motions. The amplitude of the cationic motion is enhanced at the C-end, that is, the N-end of the organic cation is fixed to the inorganic layer through N-H/Cl hydrogen bonds, and T 1r becomes short with larger-amplitude molecular motions.rsc.li/rsc-advances 34110 | RSC Adv., 2018, 8, 34110-34115This journal is

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Changing the Usual Interpretation of the Structure and Ground State of Cu²⁺-Layered Perovskites

Cited by 58 publications

References 88 publications

High-Pressure Phase Transitions of Zinc Difluoride up to 55 GPa

High-Pressure Phase Transitions of Zinc Difluoride up to 55 GPa

Thermodynamic, Physical, and Structural Characteristics in Layered Hybrid Type (C2H5NH3)2MCl4 (M = 59Co, 63Cu, 65Zn, and 113Cd) Crystals

Cation dynamics by ¹H and ¹³C MAS NMR in hybrid organic–inorganic (CH₃CH₂NH₃)₂CuCl₄

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Changing the Usual Interpretation of the Structure and Ground State of Cu2+-Layered Perovskites

Cited by 58 publications

References 88 publications

High-Pressure Phase Transitions of Zinc Difluoride up to 55 GPa

High-Pressure Phase Transitions of Zinc Difluoride up to 55 GPa

Thermodynamic, Physical, and Structural Characteristics in Layered Hybrid Type (C2H5NH3)2MCl4 (M = 59Co, 63Cu, 65Zn, and 113Cd) Crystals

Cation dynamics by 1H and 13C MAS NMR in hybrid organic–inorganic (CH3CH2NH3)2CuCl4

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Changing the Usual Interpretation of the Structure and Ground State of Cu²⁺-Layered Perovskites

Cation dynamics by ¹H and ¹³C MAS NMR in hybrid organic–inorganic (CH₃CH₂NH₃)₂CuCl₄