The Electrical Conductivity and the Crystal Structure of Silver Iodide

Takahashi, Takehiko; Kuwabara, Katsumi; Yamamoto, Osamu

doi:10.1149/1.2411846

Cited by 68 publications

(21 citation statements)

References 17 publications

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“…It is then unfavourable to determine the crystalline phases in (AgI) 0.7 -(NaPO 3 ) 0.3 at room temperature using X-ray diffraction without any heat treatment. In addition, hAgI might transform to gAgI under pulverization and transforms back to hAgI in time [18]. However, our Xray diffraction measurements indicate that the phases in the samples do not change in time.…”

Section: Resultsmentioning

confidence: 71%

Disappearance of βAgI in (AgI)0.7–(NaPO3)0.3 composite at room temperature

et al. 2004

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Section: Resultsmentioning

confidence: 71%

Disappearance of βAgI in (AgI)0.7–(NaPO3)0.3 composite at room temperature

et al. 2004

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“…It should be noted here that the silver iodide used in the galvanic cells was in the metastable y-form which is formed by rapid cooling of the melt and shows pure ionic conductivity [18,19]. As could be shown by x-ray diffraction after the e.m.f.…”

Section: Methodsmentioning

confidence: 61%

Electrochemical and Specific Heat Measurements on Tellurium-Halogen Systems

Haag

Alpen

Gmelin

et al. 1979

Zeitschrift Für Naturforschung A

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Gibbs free energies of reaction in the systems Te-TeX4 (X = Cl, Br, I) were determined from e.m.f. measurements of solid state galvanic cells using silver halides as auxiliary electrolytes. From the temperature dependence of the e.m.f. the standard entropies and enthalpies of formation SO (298.15 K) and AHi° (298.15 K) have been calculated for oc-Tel, Tel 4 , Te 2 Br, TeBr 4 , Te 3 Cl 2 and TeCl 4 . The specific heats of oc-Tel and Te2Br were determined from 1.5 K to 300 K by adiabatic and differential scanning calorimetry.

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“…AgI is asemiconductor with low electrical resistance (ca. 500 kW cm at 25 8 8C, Figure 3b)a nd poor thermal conductivity [11] (0.004 Wcm À1 K À1 ). Consequently,a ny temperature gradient across the sample produces athermoelectric voltage and current [12] (Seebeck effect), which mask the pyroelectric effect (Supporting Information, Figure S1).…”

Section: Angewandte Chemiementioning

confidence: 98%

“…500 kW cm at 25 8 8C, Figure 3b)a nd poor thermal conductivity [11] (0.004 Wcm À1 K À1 ). 500 kW cm at 25 8 8C, Figure 3b)a nd poor thermal conductivity [11] (0.004 Wcm À1 K À1 ).…”

mentioning

confidence: 98%

The Contribution of Pyroelectricity of AgI Crystals to Ice Nucleation

et al. 2018

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The pyroelectricity of AgI crystals strongly affects the icing temperature of super-cooled water,a sd isentangled from that of epitaxy.This deduction was achieved by the design of polar crystalline ceramic pellets of AgI, with experimentally determined sense of polarity.T hese pellets are suitable for measuring both their pyroelectric properties as well as the icing temperature of super-cooled water,s eparately on each of the expressed Ag + and I À hemihedral surfaces.T he positive pyroelectric charge at the silver-enriched side elevates the icing temperature,w hereas the negative charge at the iodide side decreases that temperature.M oreover,t he effect of pyroelectric charge remains dominant despite the presence of contaminants on both the silver and the iodide-enriched surfaces.C onsequently an electrochemical process for ice nucleation is suggested, which might be of relevance for understanding the role played by electric charges in heterogeneous icing processes in general.Ice melts at 0 8 8C; however,w ater can be super-cooled homogeneously down to À40 8 8C, despite al arge driving force for the water-ice phase transition (22 JK À1 mol À1 ). Yet the icing temperature can be controlled heterogeneously by using auxiliary additives. [1] Silver iodide (AgI) is one of the most explored compounds for glaciogenic cloud seeding. [1a, 2] Despite the numerous investigations performed ever since its discovery,the mechanism of how AgI promotes ice nucleation is still far from being understood, as emphasized in the recent comprehensive review by Marcolly et al., [2c] stating "Theoretical and experimental studies over the last 60 years provide ac omplex picture of silver iodide as an ice-nucleating agent with conflicting and inconsistent results". Thehexagonal AgI crystals are polar, yet those studies ignored the possible role that might be played by the electric charge created at the two hemihedral faces of apolar crystal upon cooling,known as the pyroelectric effect. [3] It has been reported that surface charge on dielectric materials can affect the icing temperature of super-cooled water (SCW). [4] We have demonstrated, in previous studies,t hat the pyroelectricity of polar amino acids and LiTaO 3 crystals,s trongly affects ice nucleation. [1b,5] As imilar role that might be played by the pyroelectric charge of AgI crystals has not been considered in previous investigations.However,invariance to the above crystals,AgI is as emiconductor [6] and it must be considered that internal currents through the sample may reduce and even eliminate the pyroelectric charge.T hus,i ti sc rucial to determine whether the pyroelectricity of AgI has any effect on the icing temperature.Thep yroelectric properties of AgI have not been measured so far,w hich is presumably due to challenges involved in growing single crystals of the required dimensions for such measurements.T oovercome this hurdle,wedesigned experiments with large poled and non-poled crystalline ceramic pellets of AgI. Herein we demonstrate that the pyroelectricity of ...

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The Electrical Conductivity and the Crystal Structure of Silver Iodide

Cited by 68 publications

References 17 publications

Disappearance of βAgI in (AgI)0.7–(NaPO3)0.3 composite at room temperature

Disappearance of βAgI in (AgI)0.7–(NaPO3)0.3 composite at room temperature

Electrochemical and Specific Heat Measurements on Tellurium-Halogen Systems

The Contribution of Pyroelectricity of AgI Crystals to Ice Nucleation

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