New tetrahedrally coordinated A2CdBr4 compounds (A = Cs, CH3NH3)

Altermatt, D.; Arend, H.; Niggli, A.; Petter, W.

doi:10.1016/0025-5408(79)90080-1

Cited by 37 publications

(20 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…I n the present work we report on new phase sequences in tetrahedrally coordinated &BX, bromides where no ferroelectric phase occurs. At room temperature, Cs,ZnBr, [el, Cs,CdBr, [7], and Cs,HgBr, [8] have also the space group Pnma with 2 = 4. In Fig.…”

Section: Introductionmentioning

confidence: 99%

New structural phase sequence with incommensurate phases in A2BX4 halides with β-K2SO4 structure

Plesko

Kind

Arend

2006

phys. stat. sol. (a)

Self Cite

View full text Add to dashboard Cite

Cs2ZnBr4, Cs2CdBr4, and Cs2HgBr4 are at room temperature isomorphous with β‐K2SO4 (Pnma, Z = 4). X‐ray diffraction and 81Br NQR measurements show that this structure is stable down to T = 5 K for Cs2ZnBr4. In Cs2CdBr4 and Cs2HgBr4 a new phase sequence is observed: Pnma (Z = 4) ↔ incommensurate phase ↔ P21/n (Z=4) ↔ unknown low temperature phase. The incommensurate phase is modulated in the x‐direction with q = δa*, the lock‐in transition into the P21/n phase occurs at the centre of the Pnma Brillouin zone.

show abstract

Section: Introductionmentioning

confidence: 99%

New structural phase sequence with incommensurate phases in A2BX4 halides with β-K2SO4 structure

Plesko

Kind

Arend

2006

phys. stat. sol. (a)

Self Cite

View full text Add to dashboard Cite

show abstract

“…For other tetrahedral ammonium tetrabromidocadmates, see: Altermatt et al (1979); Battaglia et al (1991); Casals et al (1987); Geselle & Fuess (1994); Ishihara et al (1998); Krishnan et al (1991); Sato et al (1986); Waskowska (1994).…”

Section: Related Literaturementioning

confidence: 99%

Bis[4-(dimethylamino)pyridinium] tetrabromidocadmate(II) monohydrate

2009

Acta Cryst E

View full text Add to dashboard Cite

show abstract

“…MHz at 77 K. We have no information on the crystal structure yet but the intensity ratio vI:vz: v3 = 2: 3 : 1 suggests that in the lattice of phase I1 there are isolated CdBr, tetrahedra and two of the four bromines belong to the same point position, being connected by a symmetry operation. Altermatt et al [12] have determined the crystal structures of (CH3NH3)*CdBr4 and Cs2CdBr4 and observed in the later compound [CdBr,] tetrahedra with such a symmetry that a three line Br NQR spectrum should result. This was shown to be so by Plesko et al [13].…”

Section: Ethylenediammooium Dicadmiumhexabromide Monohydrate (Enhz)(mentioning

confidence: 99%

Solid Phases from the Liquid System H₂N(CH₂)₂NH₂  CdBr₂  HBr  H₂O. An X‐ray and ^79,81Br — NQR Study of (H₃N(CH₂)₂NH₃)CdBr₄, (H₃N(CH₂)₂NH₃) (CdBr₃)₂ · H₂O, and (H₃N(CH₂)₂NH₃)₂CdBr₆

Krishnan

Dou

Paulus

et al. 1991

Ber Bunsenges Phys Chem

View full text Add to dashboard Cite

From the aqueous system ethylenediamine, (en),  CdBr2  HBr  H2O of varying component concentrations, at room temperature the compounds (enH2)CdBr4, (enH2)(CdBr3)2 · H2O, and (enH2)2CdBr6 were crystallized. 79,81Br NQR spectroscopy shows that the three solid phases, crystallized at room temperature, are the stable ones in the temperature range 77 ≤ T/K ≤ 300. (enH2)CdBr4 shows a three line 81Br NQR spectrum, the frequencies lying in the range 53 ≤ v (81Br)/MHz < 68 and having negative temperature coefficients dv/dt over the whole temperature range covered. A phase transition with hysteresis is observed at 340 K. In the high temperature phase I only one 81Br NQR line is observed, with negative temperature coefficient, too. (enH2)(CdBr3)2 · H2O shows also a three line 81Br NQR spectrum, the frequencies lying in the range 38 MHz to 72 MHz at room temperature with positive as well as negative temperature coefficients. (enH2)2CdBr6 reveals a four line 81Br NQR spectrum, three of the lines lying in the range 40 MHz to 70 MHz; the fourth line was observed at frequencies as low as 10 MHz. (enH2)(CdBr3)2 · H2O crystallizes at room temperature monoclinic, space group C2h6‐C2/c with Z = 4 (formula units per unit cell) a = 818 pm, b = 2413 pm, c = 801 pm, β = 107.8°. The structure is characterized by chains of units [Cd4Br12]4. The chains are built up by edge connected octahedra CdBr6 and the corners of two neighbouring octahedra are part of a bridging tetrahedron CdBr4, located alternating cis and trans on the chain. (enH2)2CdBr6 crystallizes also monoclinic, space group C2h2‐P21/m, a = 669 pm, b = 2050 pm, c = 637 pm, β = 93.4°; Z = 4. The structure corresponds to a formulation ((enH2))2(CdBr4)2⊖ · 2Br⊖. In both compounds hydrogen bonding is observed. The NQR results are in full agreement with the crystal structures; structure and bond scheme are discussed.

show abstract

New tetrahedrally coordinated A2CdBr4 compounds (A = Cs, CH3NH3)

Cited by 37 publications

References 6 publications

New structural phase sequence with incommensurate phases in A2BX4 halides with β-K2SO4 structure

New structural phase sequence with incommensurate phases in A2BX4 halides with β-K2SO4 structure

Bis[4-(dimethylamino)pyridinium] tetrabromidocadmate(II) monohydrate

Solid Phases from the Liquid System H₂N(CH₂)₂NH₂  CdBr₂  HBr  H₂O. An X‐ray and ^79,81Br — NQR Study of (H₃N(CH₂)₂NH₃)CdBr₄, (H₃N(CH₂)₂NH₃) (CdBr₃)₂ · H₂O, and (H₃N(CH₂)₂NH₃)₂CdBr₆

Contact Info

Product

Resources

About

New tetrahedrally coordinated A2CdBr4 compounds (A = Cs, CH3NH3)

Cited by 37 publications

References 6 publications

New structural phase sequence with incommensurate phases in A2BX4 halides with β-K2SO4 structure

New structural phase sequence with incommensurate phases in A2BX4 halides with β-K2SO4 structure

Bis[4-(dimethylamino)pyridinium] tetrabromidocadmate(II) monohydrate

Solid Phases from the Liquid System H2N(CH2)2NH2  CdBr2  HBr  H2O. An X‐ray and 79,81Br — NQR Study of (H3N(CH2)2NH3)CdBr4, (H3N(CH2)2NH3) (CdBr3)2 · H2O, and (H3N(CH2)2NH3)2CdBr6

Contact Info

Product

Resources

About

Solid Phases from the Liquid System H₂N(CH₂)₂NH₂  CdBr₂  HBr  H₂O. An X‐ray and ^79,81Br — NQR Study of (H₃N(CH₂)₂NH₃)CdBr₄, (H₃N(CH₂)₂NH₃) (CdBr₃)₂ · H₂O, and (H₃N(CH₂)₂NH₃)₂CdBr₆