A new ferroelectric compound: Methylammonium trichloromercurate (CH3NH3HgCl3)

Fueß, H.; Körfer, M.; Arend, H.; Kind, R.

doi:10.1016/0038-1098(85)90551-4

Cited by 39 publications

(16 citation statements)

References 5 publications

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“…Weber's original work on Sn appears to have not been actively pursued at first, despite occasional works on HPs employing other metals [123,124] and layered structures, e.g., by Couzi et al [125] (the earliest citation of Weber's Sn work as indexed by Scopus is found in 2004). However, spearheaded by Mitzi, [126] researchers extended Weber's work on Pb compounds in the 1990s.…”

Section: Organic A-site: Hp(a)mentioning

confidence: 99%

Mix and Match: Organic and Inorganic Ions in the Perovskite Lattice

Gebhardt

Rappe

2018

Advanced Materials

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X-site anions are possible, with only two general requirements that must be fulfilled: i) charge neutrality in the ABX 3 unit (typically, X is a divalent or monovalent anion, hence A and B cations with oxidation states between +1 and +5 can be combined) and ii) the ionic radii of the chosen composition must allow the above coordination, or different phases become more stable. Both of these simple design rules have a certain flexibility.The electronic argument i) can be stretched by allowing the combination of multiple ABX 3 units to form an overall charge neutral unit. For example, this is the case when considering A 2 BB′X 6 or AA′B 2 X 6 systems. Such double perovskite systems are known with B and B′ (A and A′) being the same elemental species (disproportion in oxidation state, e.g., Cs 2 Au + Au 3+ I 6 ) [20] or different ones (e.g., SrBaTi 2 O 6 [21] and SrPbTi 2 O 6 [22] for A-site disproportion or K 2 NbTaO 6 [23] and Bi 2 FeCrO 6 [24] for the B-site). Of course, this concept can also be used to combine three ABX 3 units (e.g., (CaTiO 3 ) n (SrTiO 3 ) l (BaTiO 3 ) m [25-27]) and much more complex stoichiometries with mixed ratios (e.g., (Pb 2 InNbO 6 ) 3/4 (Ba 2 InBiO 6 ) 1/4 [28] or [CaMn 3 3+ ][Mn 3 3+ Mn 4+ ] O 12 ] [29] ). Furthermore, although the bonding character in oxide perovskites is often mainly ionic, some compositions have an increased level of covalency (e.g., halides, sulfides, Bi-and Pbbased oxide perovskites). Thus, the electronic shell configuration and other effects like the steric demands of a metal lonepair will influence the structure and stability of ABX 3 perovskite compounds.In addition, the geometric argument ii) allows for some flexibility. For a perfectly cubic perovskite, the (effective) ionic radii r must fulfill the relation of Goldschmidt's tolerance factor 2( ) 1 A X B X t r r r r = + + = . [30,31] However, perovskites can exist also with t being not ideal, usually in a range of about 0.75 < t < 1.05. [8] Whenever t ≠ 1, the crystal distorts from an ideal cubic lattice, usually in form of off-center displacements, octahedral rotations, or a combination of both. The classification of Glazer [32,33] can be used to describe such distortions from a perfectly cubic perovskite. [34] It is further possible that ABX 3 compounds are stable whose t does not fall into the interval that is required for the perovskite crystal structure. In these cases that are no longer stabilized by deformations and tilting, one observes other phases where the connectivity of BX 6Materials science evolves to a state where the composition and structure of a crystal can be controlled almost at will. Given that a composition meets basic requirements of stoichiometry, steric demands, and charge neutrality, researchers are now able to investigate a wide range of compounds theoretically and, under various experimental conditions, select the constituting fragments of a crystal. One intriguing playground for such materials design is the perovskite structure. While a game of mixing and matching ions has been pla...

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Section: Organic A-site: Hp(a)mentioning

confidence: 99%

Mix and Match: Organic and Inorganic Ions in the Perovskite Lattice

Gebhardt

Rappe

2018

Advanced Materials

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“…The mechanism of structural phase transitions in [N(C 2 H 5 ) 4 ] CdCl 3 and other isostructural compounds is supposed to be due to the ordering of the [N(C 2 H 5 ) 4 ] + ions with some small distortion of the inorganic chains [3]. Measurement of dielectric constants for the crystal, CH 3 NH 3 HgCl 3 shows a definite ferroelectric-paraelectric transition at about 60°C [5]. This compound exhibits a first order structural phase transition at 0.6°C and -15.9°C [6].…”

Section: Introductionmentioning

confidence: 97%

Thermal, phase transition and FTIR spectroscopic studies in tetraethylammonium trichlorocadmiate crystals

Amirthaganesan

Kandhaswamy

Srinivasan

2005

Cryst. Res. Technol.

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Single crystals of tetraethylammonium trichlorocadmiate were grown by slow evaporation of aqueous solutions at room temperature. The bright and transparent crystals obtained were characterized through FTIR spectroscopy, thermo gravimetric (TG and DTA) and low temperature DSC analyses. A fitting decomposition pattern for the title compound was formulated based on the TG thermogram which shows a two-stage weight loss between 300°C and 800°C. In this temperature range the DTA curve shows endothermic dips supporting the formulated decomposition pattern. The thermal anomalies observed in the low temperature DSC both during the heating and cooling cycles indicate the occurrence of the first and second order structural phase transitions in the compound. The FTIR and far IR spectra show characteristic vibration frequencies due to [N(C 2 H 5 ) 4 ] + and CdCl 3 -ions. Detailed structural analysis of the compound is under progress.

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“…It is well known that CH 3 NH 3 HgCl 3 undergoes the ferro-to paraelectric phase transition at 335 K [1][2][3]. A 35 Cl NQR study revealed that another transition in the range 108 to 121 K which is closely related to the motion of CH 3 NH + 3 under the influence of the N-H· · · Cl hydrogen bonding [4].…”

Section: Introductionmentioning

confidence: 99%

Br NQR relaxation and successive phase transitions of CH3NH3HgBr3

et al. 2010

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The measurement of 81 Br NQR in CH 3 NH 3 HgBr 3 has been carried out in the temperature range between 80 and 300 K using a pulse NQR method. The temperature dependence of 81 Br NQR frequencies in CH 3 NH 3 HgBr 3 has revealed that it undergoes three characteristic successive phase transitions at T = 123, 184 and 239 K. The phase transition temperature at T = 239 K is the second-order type, whereas those at T = 184 and 123 K are the first-order nature of the phase transitions. Each phase transition seems to be closely related to the motions of methyl ammonium cation as a partial or whole. The enhancement of 1/T 1 at T = 239 K indicates the onset of the molecular motion of the cation as a whole with increasing temperatures.

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A new ferroelectric compound: Methylammonium trichloromercurate (CH3NH3HgCl3)

Cited by 39 publications

References 5 publications

Mix and Match: Organic and Inorganic Ions in the Perovskite Lattice

Mix and Match: Organic and Inorganic Ions in the Perovskite Lattice

Thermal, phase transition and FTIR spectroscopic studies in tetraethylammonium trichlorocadmiate crystals

Br NQR relaxation and successive phase transitions of CH3NH3HgBr3

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