Coexistence of a ferroelectric and a ferroelastic domainstructure: (NH4)2ZNCL4in its phase V

Bruin-Hordijk, G.J. De; Peterse, W. J. A. M.; Laman, C. D.; Berg, A. J. van den; Tuinstra, F.

doi:10.1080/00150199308008297

Cited by 6 publications

(3 citation statements)

References 6 publications

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“…Ferroelectric activity along the b-axis of AZC below 266 K has been reported by Belo-borova et al [4]. Birefringence, X-ray diffraction and X-ray topography indicated that the structure of the ferroelectric phase between 263 and 271 K is triclinic [5].…”

Section: Introductionmentioning

confidence: 89%

Temperature dependence of the indirect band gap and related optical parameters of (NH₄)₂ZnCl₄:xSr²⁺ single crystals

Gaffar

El‐Fadl

Anooz

2003

Physica Status Solidi (b)

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Optical transmittance measurements were carried out near the absorption edge of (NH 4 ) 2 ZnCl 4 : x Sr 2+ single crystals, where x = 0.00, 0.020, 0.039, 0.087 or 0.144 wt%. The dependence of the absorption coefficient (α) on photon energy in the range 3.4 -6.4 eV and on temperature in the range 276 -350 K was examined. With increasing temperature the absorption edge was shifted to the lower energy side; this shift was attributed to the temperature dependence of electron-lattice interactions. Due to the presence of Sr 2+ in (NH 4 ) 2 ZnCl 4 : x Sr 2+ a change in the absorption band centred at 5.30 eV was observed. In the case of higher strontium doping, the optical absorption coefficient showed a 'pre-transition' stage just before the onset of the band-to-band transition. Exponential dependence of α on hν according to the Urbach rule was observed and the Urbach parameters were determined. The steepness parameter was strongly affected by doping; its behaviour at 319 K evidently showed the antiferroelectric to commensurate phase transition. The temperature dependence of E g was also estimated using data for the steepness parameter, and hence E g at different temperatures and Sr 2+ concentrations was evaluated.

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Section: Introductionmentioning

confidence: 89%

Temperature dependence of the indirect band gap and related optical parameters of (NH₄)₂ZnCl₄:xSr²⁺ single crystals

Gaffar

El‐Fadl

Anooz

2003

Physica Status Solidi (b)

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“…Ferroelectric activity along the a-axis of A 2 ZC 4 below 266 K has been reported by Beloborova et al [3]. Birefringence, X-ray diffraction and X-ray topography indicated that the crystal structure of the ferroelectric phase between 263 K and 271 K is triclinic [4]. Sato et al [5] claimed that A 2 ZC 4 in between the weak ferroelectric transition point at 268.5 K and the strong ferroelectric transition point at 276 K is in a commensurate (C) phase.…”

Section: Introductionmentioning

confidence: 89%

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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“…Studies of AZC physical properties using different techniques like high pressure Brillouin scattering and energy dispersive X-ray diffraction [7], ESR spectra [8], birefringence and X-ray topography [9,10], propagation of elastic waves through crystal [11] and growth techniques [12,13] have been reported in literature. Moreover, local phenomena related to structural phase transitions of AZC were investigated using the NMR technique by Michel et al [14].…”

Section: Introductionmentioning

confidence: 99%

The non-isotropic character of electric and dielectric properties of ammonium zinc chloride crystal

Gaffar

El‐Fadl

Anooz

2004

Journal of Physics and Chemistry of Solids

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Coexistence of a ferroelectric and a ferroelastic domainstructure: (NH₄)₂ZNCL₄in its phase V

Cited by 6 publications

References 6 publications

Temperature dependence of the indirect band gap and related optical parameters of (NH₄)₂ZnCl₄:xSr²⁺ single crystals

Temperature dependence of the indirect band gap and related optical parameters of (NH₄)₂ZnCl₄:xSr²⁺ single crystals

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

The non-isotropic character of electric and dielectric properties of ammonium zinc chloride crystal

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Coexistence of a ferroelectric and a ferroelastic domainstructure: (NH4)2ZNCL4in its phase V

Cited by 6 publications

References 6 publications

Temperature dependence of the indirect band gap and related optical parameters of (NH4)2ZnCl4:xSr2+ single crystals

Temperature dependence of the indirect band gap and related optical parameters of (NH4)2ZnCl4:xSr2+ single crystals

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

The non-isotropic character of electric and dielectric properties of ammonium zinc chloride crystal

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Coexistence of a ferroelectric and a ferroelastic domainstructure: (NH₄)₂ZNCL₄in its phase V

Temperature dependence of the indirect band gap and related optical parameters of (NH₄)₂ZnCl₄:xSr²⁺ single crystals

Temperature dependence of the indirect band gap and related optical parameters of (NH₄)₂ZnCl₄:xSr²⁺ single crystals