On the phase diagram of the [(CH3)4N]2ZnCl4−xBrx system

Colla, Enrico; Muralt, Paul; Arend, H.; Perret, R.; Godefroy, G.; Dumas, C.

doi:10.1016/0038-1098(84)90504-0

Cited by 31 publications

(6 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This is very likely due to a smearing of the above phase transitions in the x = 0.25 solid solution by defects originating from the structural disorder. The observed phase transition temperatures in the various compounds, gathered in Table 1, show a good agreement with the x-T phase diagram reported by Colla and coworkers [2].…”

Section: Resultssupporting

confidence: 89%

Thermal expansion at the incommensurate phase transition in [N(CH3)4]2ZnCl4-xBrx crystals

Maior

Loosdrecht

Kempen

et al. 1994

Physica B: Condensed Matter

View full text Add to dashboard Cite

The temperature dependence of the thermal expansion in the vicinity of the incommensurate phase transition in [N(CHa)4]2ZnC14-xBrx mixed crystals is found to deviate from that predicted within the Landau theory of phase transitions. It is shown that the dominant contribution to this deviation in the immediate vicinity of T~ is due to the presence of defects. The character of the deviation is found to be in qualitative agreement with the theoretically predicted behaviour in the presence of random field type defects. In some compounds (x = 0, 2.4, 2.9), the temperature dependence of the thermal expansion coefficient at T/> Ti + 3 K can be described by a z'-dependence with ct = 0.5. These values are in reasonable agreement with ~t = 0.5, corresponding to the fluctuation correction to the Landau theory. In solid solutions with a rather smeared paraelectric-incommensurate phase transition (x = 0.25, 0.45), the value of this exponent is found to be between 0.8 and 0.9. This suggests that the contribution to the thermal expansion due to the defects in these crystals is, even quite far from the phase transition, comparable to the contribution due to order parameter fluctuations.

show abstract

Section: Resultssupporting

confidence: 89%

Thermal expansion at the incommensurate phase transition in [N(CH3)4]2ZnCl4-xBrx crystals

Maior

Loosdrecht

Kempen

et al. 1994

Physica B: Condensed Matter

View full text Add to dashboard Cite

show abstract

“…In the low-temperature phase of the pure Br compound the most important rotation is around the c axis (Trou~lan, Lefebvre & Derollez, (5) 1985) and this fact may indicate a trend to decrease the relative rotation around the a axis with increasing Br concentration. All this is reflected in the (x,T) phase diagram of TMA2ZnC14_~.Br x (Colla et al, 1984) which shows for the low-temperature region (~263-173 K) a phase change at x~_ 3 from phases with dominant rotation around the a axis to a dominant rotation around the c axis. For x < 0.5 there is a weaker dependence of the phase diagram on the Br concentration which may be caused by the supposed high Br occupation probability at the motionless top of the tetrahedra.…”

Section: Introductionmentioning

confidence: 98%

“…Recently the (x,T) phase diagram of the solid solution [TMA]2ZnC14_.eBrx was determined by means of DSC and X-ray measurements (Colla, Muralt, Arend, Ehrensperger, Perret, Godefroy & Dumas, 1984). The system shows complete miscibility over the whole concentration range with common high-temperature symmetry Pnma.…”

Section: Introductionmentioning

confidence: 99%

Structure of the solid solution [N(CH3)4]2ZnCl1.8Br2.2 in the high- and in a new low-temperature phase

Colla¹,

Gramlich²,

Petter³

1987

Acta Crystallogr C

Self Cite

View full text Add to dashboard Cite

Domains were encountered in the crystal and a large decrease of the temperature factor was observed. The phases studied are separated by two other phases: an incommensurate one and a monoclinic one with a threefold unit cell (Z = 12). The ZnHal 4 tetrahedra drive the transitions, rotating principally around the a axis (11 °) and shifting their centre along the b axis (0.42/~). Their small distortion is probably due to the crystal field effect (Hal-Zn-Hal angles range from 108.7 to 112.2°). The mean bond length Zn-Hal is 2.352/~ for Pnma and 2.360/~ for P12Jal. Tetrahedra in the same bc plane rotate in the same sense.

show abstract

“…Previous studies of [(CH 3 ) 4 R] 2 MX 4 , where R ¼ N/P, M ¼ Mn 2þ , Co 2þ , Zn 2þ and XeCl/Br showed that the most important effect in the phase transitions is the rotation of the metal tetraheda around an axis passing though the metal ion [30,31]. Also it is to be noted that in these hybrids M-Cl bond distance is shorter than M-Br.…”

Section: Frequency Dependent Dielectric Constantmentioning

confidence: 93%

Characterization, phase change and conductivity crossover of new luminescent ferroelectric Mn (II) organic-inorganic hybrid

Mostafa

Dean

Tammam

2016

Materials Chemistry and Physics

View full text Add to dashboard Cite

On the phase diagram of the [(CH3)4N]2ZnCl4−xBrx system

Cited by 31 publications

References 9 publications

Thermal expansion at the incommensurate phase transition in [N(CH3)4]2ZnCl4-xBrx crystals

Thermal expansion at the incommensurate phase transition in [N(CH3)4]2ZnCl4-xBrx crystals

Structure of the solid solution [N(CH3)4]2ZnCl1.8Br2.2 in the high- and in a new low-temperature phase

Characterization, phase change and conductivity crossover of new luminescent ferroelectric Mn (II) organic-inorganic hybrid

Contact Info

Product

Resources

About