Metastable phases in gallium dispersions

Heyding, R. D.; Keeney, W.; Segel, S. L.

doi:10.1016/0022-3697(73)90068-1

Cited by 26 publications

(18 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[16]) and position [15]. No clear evidence for other previously observed metastable phases [16] is found in the present experiment. The small peaks assigned to g-Ga and d-Ga are quite evident in the process of freezing ( Fig.…”

Section: (Received 25 March 1998)contrasting

confidence: 77%

“…2, lower panel, g-Ga and d-Ga diffraction lines previously observed in Ga dispersions are reported for comparison along with their estimated intensity (see Ref. [16]) and position [15]. No clear evidence for other previously observed metastable phases [16] is found in the present experiment.…”

Section: (Received 25 March 1998)supporting

confidence: 45%

“…2, upper panel). Position [15] and relative estimated intensity [16] of g-Ga and d-Ga Bragg peaks are also reported.…”

Section: (Received 25 March 1998)mentioning

confidence: 99%

See 2 more Smart Citations

Phase Transitions in Confined Gallium Droplets

Cicco

1998

Phys. Rev. Lett.

121

View full text Add to dashboard Cite

Phase transitions in submicrometric Ga droplets confined in epoxy resin are studied by combining energy-dispersive x-ray diffraction (EDXRD), x-ray absorption fine structure, and single-energy x-ray absorption. The restricted fluid is undercooled down to 150 K while the melting point is depressed down to 254 K. Melting and freezing are sharp processes occurring with temperature broadening of 1 and 10 K, respectively. EDXRD patterns are consistent with that of b-Ga, while the stable phase at ambient conditions a-Ga is not found to exist. Appearance of g-Ga and d-Ga solid phases and relevance of present results to recent studies of Ga confined in porous glass are discussed. [S0031-9007(98)07341-4] PACS numbers: 64.70. -p, 61.10.HtThe peculiar properties of matter in confined geometries were investigated by means of experiments and calculations for a long time. In the last two decades, large efforts were devoted to the study of substances confined in various matrices with pore size in the 2-20 nm range (see, for example, [1-3] and references therein). Significant variations of specific physical properties with respect to bulk systems were found to be determined both by the restricted geometry and by the characteristics of the interaction with the porous matrix. In particular, several investigations were concentrated on the influence of restricted geometries on phase transformations in different cryogenic fluids [1-3] and low melting point metals [4,5]. Solidification and melting temperatures were found to be depressed with respect to bulk values.Emulsions of submicrometric gallium droplets buried in solidified epoxy resin, used in recent x-ray absorption fine structure (XAFS) studies [6-8], provide a nice example of a restricted liquid system. Droplets are confined in unconnected regions of approximate spherical shape with sizes in the 100-1000 nm range, and therefore interface interaction and finite-size effects can be neglected due to the relatively large dimensions of the confined particles. The undercooling capabilities of micrometric metal droplets, with typical undercooling temperatures DT 2 in the range 0.13-0.33 times the absolute melting temperature T m , are well known [9]. In particular, large undercooling rates DT 2 ͞T m ϳ 0.325 [10] are easily obtained for Ga droplets and evidence for exceptional undercooling DT 2 ͞T m ϳ 0.5 was also reported [11]. In our previous XAFS experiment we observed extremely large undercooling effects in confined Ga droplets [7], but due to the insufficient energy resolution and to the intrinsic short-range nature of the technique we were not able to detect any phase transition.In this Letter, I report the results of an accurate investigation about phase transitions in confined submicrometric Ga droplets by combining energy-dispersive x-ray diffraction (EDXRD), high resolution XAFS, and single-energy x-ray absorption [12] as a function of temperature. The present study is aimed to shed light on the peculiar freezing and melting properties of gallium under restricted geometry [...

show abstract

Section: (Received 25 March 1998)contrasting

confidence: 77%

Section: (Received 25 March 1998)supporting

confidence: 45%

See 1 more Smart Citation

Phase Transitions in Confined Gallium Droplets

Cicco

1998

Phys. Rev. Lett.

121

View full text Add to dashboard Cite

show abstract

“…[4][5][6] In general, four orthorhombic crystalline structural phases, ␣-, ␤-, ␦-, and ␥-phase with melting points of 29.9°C, −16.2°C , −19.4°C, and −35.6°C, 6 respectively, have been investigated. In these phases, only ␣ is the stable phase, and others are metastable ones.…”

mentioning

confidence: 99%

Relation between size and phase structure of gallium: Differential scanning calorimeter experiments

Fei

Cui

et al. 2005

Phys. Rev. B

View full text Add to dashboard Cite

The relation between sizes and phase structures of gallium has been studied. Gallium droplets with different sizes dispersed in poly͑methyl methacrylate͒ and silicone oil were studied by differential scanning calorimeter and transmission electron microscopy. The results showed that particles with different sizes corresponded to stable or metastable phases of gallium. The stable phase ␣-gallium is dominantly formed when the average size of particles is no less than 0.8 micron, and the metastable phases ␤-, ␥-and ␦-gallium are mainly formed when the average particle size is 0.8-0.6 micron, 0.6-0.3 micron, and below 0.3 micron, respectively. The phase selection in the solidification process under undercooling is used to explain the results.

show abstract

“…This diffractogram is not the one of the more stable gallium phase, i.e. the α phase, but the one corresponding to a mixture of metastables β, γ, δ, η and χ phases [16]. This kind of mixture has already been observed by electron microdiffraction in the case of metallic gallium nanoparticles embedded in an amorphous SiO x matrix [17].…”

Section: Resultsmentioning

confidence: 82%

Structural characterization of original 3D gallium structures grown by LP‐MOCVD

Imhoff

Sacilotti

Courty

et al. 2004

phys. stat. sol. (c)

View full text Add to dashboard Cite

This study is concerned with the growth and characterization of metallic gallium 3D structures, obtained with a single growth step, by the LP-MOCVD technique on various substrates. Commercial organometallic is used as gallium precursor and nitrogen as carrier gas. The growth temperature and the reactor pressure are ranking between 500 and 700 °C, and between 150 and 700 torr, respectively. Depending on the elaboration conditions, different 3D structures are obtained such as droplets, cauliflowers, aggregates or thin stems, with micrometer sizes. The morphology, substrate surface density and thermal stability are studied by optical and scanning electron microscopy. At last, X-ray microanalysis and X-ray diffraction are carried out in order to determine the elemental composition and the crystallographic structure of these 3D objects.

show abstract

Metastable phases in gallium dispersions

Cited by 26 publications

References 9 publications

Phase Transitions in Confined Gallium Droplets

Phase Transitions in Confined Gallium Droplets

Relation between size and phase structure of gallium: Differential scanning calorimeter experiments

Structural characterization of original 3D gallium structures grown by LP‐MOCVD

Contact Info

Product

Resources

About