X-Ray Diffraction Study on a New Incommensurate Phase Transition in Ferroelectric (NH4)2ZnCl4

Sato, Takeru; Osaka, T.; Makita, Yasuharu

doi:10.1143/jpsj.53.1907

Cited by 39 publications

(38 citation statements)

References 7 publications

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“…The temperature 430.2 K refer to the decomposition process proposed to start immediately after the IC-N phase transition. The broad-extending peak representing the first two-phase transitions is a character of A 2 ZC 4 and it was previously reported with dielectric constant measurements [5]. The sequence of phase transitions observed for the case of A 2 ZC 4 is not clear in either of the rest of the DTA scans, fig.…”

Section: Effect Of Chemical Non-stoichiometrysupporting

confidence: 68%

“…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: 99%

“…However, Sato et al [5] subdivided this range into two parts. The first part between 319K and 364K representing a C-phase while the second part extending between 364K and 406K which is covered by an IC-phase characterized by the hkl ±(1/4+δ) satellite reflections where δ≠0.…”

Section: Introductionmentioning

confidence: 99%

“…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%

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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: Effect Of Chemical Non-stoichiometrysupporting

confidence: 68%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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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“…Above 406 K the structure is orthorhombic with space group (Pnam) [1] and a unit cell parameters a o , b o and c o . By cooling, an incommensurate phase has been detected between 406K and 364K [2]. The crystal undergoes another transition at 319K [2,3].…”

Section: Introductionmentioning

confidence: 98%

Growth and characterization of undoped, Sr2+-, and Mn2+-doped ammonium tetrachlorozincate

Gaffar

El‐Fadl

Anooz

2005

Cryst. Res. Technol.

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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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X-Ray Diffraction Study on a New Incommensurate Phase Transition in Ferroelectric (NH₄)₂ZnCl₄

Cited by 39 publications

References 7 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

Growth and characterization of undoped, Sr2+-, and Mn2+-doped ammonium tetrachlorozincate

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

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X-Ray Diffraction Study on a New Incommensurate Phase Transition in Ferroelectric (NH4)2ZnCl4

Cited by 39 publications

References 7 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

Growth and characterization of undoped, Sr2+-, and Mn2+-doped ammonium tetrachlorozincate

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

Contact Info

Product

Resources

About

X-Ray Diffraction Study on a New Incommensurate Phase Transition in Ferroelectric (NH₄)₂ZnCl₄

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