Mechanism of Flux Action in the Thermal Recrystallization of Zinc Sulfide

Brown, Roy C.

doi:10.1149/1.2408228

Cited by 5 publications

(6 citation statements)

References 14 publications

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“…Details of the precipitation of zinc sulfide (8) and the preparation and measurement of phosphors (7) have been given previously. A brief account will suffice here.…”

Section: Experimental and Resultsmentioning

confidence: 99%

“…Indeed, the data of Gashurov and Levine (4) show that at 880~ ZnS has a very limited solubility of 0.0152 mole/1000g solvent in the common fluxing agent NaC1. More recent work (5)(6)(7) has emphasized the importance of diffusion phenomena in thermal recrystallization and sintering experiments on zinc sulfide powders.…”

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confidence: 99%

“…Studies on the kinetics of hexagonal-cubic phase transformation in ZnS at 800~176 in zinc vapor (6) suggested a diffusion-controlled transition having an activation energy of 67 kcal. Brown (7) investigated the mechanism of flux action in ZnS:Ag phosphors containing either 2 or 10% NaC1. In these systems, and also for zinc sulfide without additives, the rate of increase in particle diameter, D, at a firing time, t, followed the expression D ~ = kt, where k is a constant.…”

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confidence: 99%

“…The objective of the present work was to extend the particle growth experiments reported previously (7) to include other fluxes, with the aim of obtaining a better understanding and control of the particle size characteristics of zinc sulfide phosphors. With this object in mind, measurements were carried out on the rate of increase in particle diameters, as a function of duration and temperature of heating, for the following systems: ZnS:0.015% Ag with either 2% ZnC12, 2% Ntt4C1, or 2% CaC12.…”

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Particle Growth in Zinc Sulfide Phosphor Containing Halide Fluxes

Brown

1976

J. Electrochem. Soc.

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The mechanisms by which zinc sulfide powders grow under the action of heat and in the presence of a fluxing agent have been the subject of considerable discussion and speculation (1). Common fluxes employed in ZnS type phosphors include the halogen salts of ammonium and the alkali or alkaline earth metals, although compounds such as barium thiozincate (2) have been recommended also. According to the classical concept of flux action (3), the function of the additive is to provide a liquid phase in which the zinc sulfide is soluble, so that transport of material can occur readily. Apparently, no experimental evidence has been offered in support of this hypothesis. Indeed, the data of Gashurov and Levine (4) show that at 880~ ZnS has a very limited solubility of 0.0152 mole/1000g solvent in the common fluxing agent NaC1. More recent work (5-7) has emphasized the importance of diffusion phenomena in thermal recrystallization and sintering experiments on zinc sulfide powders.Thus, McQueen and Kuczynski (5) carried out work on the sintering of polycrystalline ZnS as a function of temperature and atmosphere of firing, and interpreted the results obtained in terms of material transport by diffusion mechanisms. Studies on the kinetics of hexagonal-cubic phase transformation in ZnS at 800~176 in zinc vapor (6) suggested a diffusion-controlled transition having an activation energy of 67 kcal. Brown (7) investigated the mechanism of flux action in ZnS:Ag phosphors containing either 2 or 10% NaC1. In these systems, and also for zinc sulfide without additives, the rate of increase in particle diameter, D, at a firing time, t, followed the expression D ~ = kt, where k is a constant. Two distinct regions of growth were noted. Below about 1000~ an activation energy of 29 kcal was obtained, corresponding to movement of zinc through interstitial channels. At higher temperatures the measured activation energy was 59 kcal, suggesting bulk diffusion of zinc. This change in mechanism corresponded to the onset of the cubic-hexagonal phase transformation.The objective of the present work was to extend the particle growth experiments reported previously (7) to include other fluxes, with the aim of obtaining a better understanding and control of the particle size characteristics of zinc sulfide phosphors. With this object in mind, measurements were carried out on the rate of increase in particle diameters, as a function of duration and temperature of heating, for the following systems: ZnS:0.015% Ag with either 2% ZnC12, 2% Ntt4C1, or 2% CaC12. Note that these values correspond to weight per cent (w/o) compositions. Particle dimensions were obtained by Coulter Counter techniques; the numbers quoted represent median point by weight of particles. Experimental and ResultsDetails of the precipitation of zinc sulfide (8) and the preparation and measurement of phosphors (7) have been given previously. A brief account will suffice here.Batches of about 200g of zinc sulfide were obtained from 2 liters of 1M zinc sulfate solution at 25~ using a h...

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“…Details of the precipitation of zinc sulfide (8) and the preparation and measurement of phosphors (7) have been given previously. A brief account will suffice here.…”

Section: Experimental and Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Particle Growth in Zinc Sulfide Phosphor Containing Halide Fluxes

Brown

1976

J. Electrochem. Soc.

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“…A study on the preparation and fundamental properties of zinc sulfide is of considerable importance in the technology of the manufacture of luminescent materials. Although there are numerous reports in the literature (1)(2)(3)(4)(5) concerning the influence of firing conditions and composition on the properties of zinc sulfide phosphors, there appears to be comparatively little published work on the precipitation of this compound, especially from the viewpoint of the effect of precipitating conditions on the characteristics of the resultant phosphors.…”

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Influence of Precipitating Conditions on the Cathodoluminescence of Zinc Sulfide:Silver Phosphors

Brown

Hinnenkamp

1976

J. Electrochem. Soc.

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A study has been carried out on the properties of zinc sulfide obtained by precipitation from aqueous zinc sulfate solution with gaseous hydrogen sulfide. The influence of three factors, namely H2S flow, tempera~ture, and initial concentration of the zinc solution, on (i) the rate of precipitation of zinc sulfide, and (ii) the cathodoluminescent efficiencies of the resultant ZnS:O.015% Ag phosphors has been investigated. Experimental results were interpreted by an empirical method, using a correlation and regression analysis performed by computer procedures. This approach has established quanti~tative relationships on the behavior of both the rate of formation of ZnS and the phosphor eff• as changes occur in the three variables which influence the conditions of precipitation.A study on the preparation and fundamental properties of zinc sulfide is of considerable importance in the technology of the manufacture of luminescent materials. Although there are numerous reports in the literature (1-5) concerning the influence of firing conditions and composition on the properties of zinc sulfide phosphors, there appears to be comparatively little published work on the precipitation of this compound, especially from the viewpoint of the effect of precipitating conditions on the characteristics of the resultant phosphors.For many years the precipitation of zinc sulfide from acidic, or slightly acidic, solutions of a soluble zinc salt has been used extensively for the analytical separation and determination of zinc (6-8). Hydrogen sulfide (9, 10) appears to be the usual precipitant, although more recently analysis from homogeneous solution by the acid hydrolysis of thioacetamide (11, 12) has been reported. Ortmann and Piwonka (13, 14), Lendvay and coauthors (15), and Brown (16) appear to be among the few investigators to have studied the preparatory conditions of ZnS with the object of obtaining luminescent materials.Ortmann and Piwonka (13, 14) demonstrated that a slow reaction with rapid stirring at an H2S pressure of 1.5 atm yielded crystallites up to 30 ~m in size. In addition, precipitation at reduced hydrogen sulfide pressures was studied, and produced good phosphors. These investigations (13,14) showed that the luminescent properties of the materials were dependent largely on the precipitation in the initial stages of the reaction. In all cases, ZnS prepared in strongly acid solution separated in the sphalerite form, the particles being well defined and sufficiently crystalline to give an x-radiogram identical with that obtained from zinc sulfide luminophors recrystallized at 900~ Lendvay et al. (15) prepared ZnS crystals 100-200 ~m in size by slowly interacting hydrogen sulfide with an acidic solution of a zinc salt. What was more interesting, perhaps, was that phosphors could be obtained directly from solution under ambient conditions without subsequent activation and firing at elevated temperatures. Studies on the particle size and morphology of zinc sulfide precipitates have been reported by Brown (16). This work...

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Improved brightness, efficiency, and stability of sputter deposited alternating current thin film electroluminescent ZnS:Mn by codoping with potassium chloride

Waldrip

Lewis

Zhai

et al. 2000

Applied Physics Letters

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In-situ stress monitoring has been employed during metalorganic chemical vapor deposition of AIGaN/GaN distributed Bragg reflectors (DBRs). It was found that the insertion of multiple AIN interlayers is effective in converting the tensile growth stress typically observed in this system into compression, thus alleviating the problem of crack generation. Crack-free growth of a 60-pair Alo.z5G~.75N/GaN quarter-wavelength DBR was obtained over the entire two-inch wafer; an accompanying reflectivity of at least 9970 was observed near the peak wavelength around 380 nm.-Email address: jhml@sandia.gov I

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Mechanism of Flux Action in the Thermal Recrystallization of Zinc Sulfide

Cited by 5 publications

References 14 publications

Particle Growth in Zinc Sulfide Phosphor Containing Halide Fluxes

Particle Growth in Zinc Sulfide Phosphor Containing Halide Fluxes

Influence of Precipitating Conditions on the Cathodoluminescence of Zinc Sulfide:Silver Phosphors

Improved brightness, efficiency, and stability of sputter deposited alternating current thin film electroluminescent ZnS:Mn by codoping with potassium chloride

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