Thermal history of the ferroelastic domain structure of (NH4)2ZNCL4to elucidate the problem of a phase transition

Bruin-Hordijk, G.J. De; Koningsveld, H. van; Laman, C. D.; Tuinstra, F.

doi:10.1080/00150199308008290

Cited by 4 publications

(3 citation statements)

References 10 publications

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“…Nevertheless, in the critical region of the N-/ IC-phase transition symmetry breaking effect in the birefringence behavior of A 2 ZC 4 was not observed by Kim et al [8]. De Bruim-Hordijk et al [9] reported that the phase transition at 319K is due to a change in the ferroelastic domains and it is not a structural phase transition. Study of A 2 ZC 4 by NQR above 266 K revealed an IC-phase [3].…”

Section: Introductionmentioning

confidence: 90%

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Effects induced by chemical non-stoichiometry and γ-irradiation on the habit and unit cell parameters of ammonium tetrachlorozincate

Gaffar¹,

El‐Fadl²,

Anooz³

2006

Cryst. Res. Technol.

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The effect of chemical non-stoichiometry and γ-irradiation on the unit cell parameters of ammonium tetrachlorozincate (NH 4 ) 2 ZnCl 4 (A 2 ZC 4 ) has been studied. The unit cell parameters of crystal grown from solution with NH 4 Cl/ZnCl 2 molar ratio 1:1, apparently non-stoichiometrric, are nearly the same as those given for ammonium tetrachlorozincate in the literature. The 2:1 ratio is actually 'pseudo-stoichiometric' due to the hygroscopic nature of ZnCl 2 . The unit cell parameters of crystal grown from solution with molar ratio 2:1 match those of the structure (NH 4 ) 3 ZnCl 5 (A 3 ZC 5 ). The habit of the crystal grown in the former case, from solution with excess ZnCl 2 , was different from that of the crystal grown in the later case, from solution with excess (NH 4 )Cl. Between these two limits, a set of four samples were prepared from solutions with an excess of ZnCl 2 of 20, 30, 60 and 80 wt % in order to detect exact stoichiometric composition to grow A 2 ZC 4 . Analysis by X-ray diffraction shows that the first two crystals out of this set are mixed from A 2 ZC 4 and A 3 ZC 5 The third and fourth crystals still contain traces of A 3 ZC 5 . Analysis of the X-ray diffraction was then confirmed by DTA study. Irradiating A 2 ZC 4 with γ-dose of 250 kGy slightly increased the unit cell volume due to imperfections created by irradiation. Two computer programs were used to calculate the lattice constants and the results were compared.

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Section: Introductionmentioning

confidence: 90%

“…A difference between the temperature of the phase transition could be observed in the literature. The ferroelectric phase transition was detected at 262 K [11], at 266 K [9], at 270 K [1], and at 268.5 K (weak) and 276 K (strong) [5] using different techniques.…”

Section: Introductionmentioning

confidence: 99%

Effects induced by chemical non-stoichiometry and γ-irradiation on the habit and unit cell parameters of ammonium tetrachlorozincate

Gaffar¹,

El‐Fadl²,

Anooz³

2006

Cryst. Res. Technol.

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“…Differential thermal analysis successfully detected this phase transition at 270 K in addition to the phase transition at 406 K, while it failed to detect the phase transition at 319 K [4]. However, the phase transition at 319 K was assigned as due to change in the ferroelastic domains and it is not a structural phase transition [7]. ____________________ In the literature one can observe discrepancies in reported data about structure and physical properties of AZC.…”

Section: Introductionmentioning

confidence: 90%

Electron irradiation‐induced effects on optical spectra of (NH₄)₂ZnCl₄: x Sr²⁺ single crystals

Gaffar

El‐Fadl

Anooz

2003

Cryst. Res. Technol.

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The effect of electron-beam irradiation with different doses on optical constants of (NH 4 ) 2 ZnCl 4 : x Sr 2+ crystals with x=0.000, 0.020, 0.039, 0.087 or 0.144 wt% has been studied. The optical transmission in the energy range 3.4-6.4 eV was measured hence the absorption coefficient was computed as a frequency function. The absorption coefficient was also calculated as a function of electron-beam dose. Irradiation with e-beam did not affect the allowed indirect type of transition responsible for interband transitions of (NH 4 ) 2 ZnCl 4 : x Sr 2+ crystals. Values of the optical energy gap E g and optical moment E p for electronic interband transition of unexposed and (NH 4 ) 2 ZnCl 4 : x Sr 2+ crystals after e-beam exposure were deduced. The area under the absorption band at 5.30 eV was used to evaluate the effect of e-irradiation on optical parameters of samples with x=0.00, 0.020 or 0.039. A shift in the position and a nonmonotonic change in the intensity of this band with increasing e-beam dose was observed. Changes in the E g value were used to evaluate the effect of e-beam exposure dose on (NH 4 ) 2 ZnCl 4 : x Sr 2+ samples with x=0.087 or 0.144. The obtained results were compared with those obtained for the same crystals after irradiation with different γ-doses.

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Influence of strontium doping on the indirect band gap and optical constants of ammonium zinc chloride crystals

Gaffar

El‐Fadl

Anooz

2003

Physica B: Condensed Matter

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Thermal history of the ferroelastic domain structure of (NH₄)₂ZNCL₄to elucidate the problem of a phase transition

Cited by 4 publications

References 10 publications

Effects induced by chemical non-stoichiometry and γ-irradiation on the habit and unit cell parameters of ammonium tetrachlorozincate

Effects induced by chemical non-stoichiometry and γ-irradiation on the habit and unit cell parameters of ammonium tetrachlorozincate

Electron irradiation‐induced effects on optical spectra of (NH₄)₂ZnCl₄: x Sr²⁺ single crystals

Influence of strontium doping on the indirect band gap and optical constants of ammonium zinc chloride crystals

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Thermal history of the ferroelastic domain structure of (NH4)2ZNCL4to elucidate the problem of a phase transition

Cited by 4 publications

References 10 publications

Effects induced by chemical non-stoichiometry and γ-irradiation on the habit and unit cell parameters of ammonium tetrachlorozincate

Effects induced by chemical non-stoichiometry and γ-irradiation on the habit and unit cell parameters of ammonium tetrachlorozincate

Electron irradiation‐induced effects on optical spectra of (NH4)2ZnCl4: x Sr2+ single crystals

Influence of strontium doping on the indirect band gap and optical constants of ammonium zinc chloride crystals

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Product

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Thermal history of the ferroelastic domain structure of (NH₄)₂ZNCL₄to elucidate the problem of a phase transition

Electron irradiation‐induced effects on optical spectra of (NH₄)₂ZnCl₄: x Sr²⁺ single crystals