Journal ArticleDOI
Confinement effects on freezing and melting
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A review of experimental work on freezing and melting in confinement is presented in this paper, where a range of systems, from metal oxide gels to porous glasses to novel nanoporous materials, are discussed.Abstract:
A review of experimental work on freezing and melting in confinement is presented. A range of systems, from metal oxide gels to porous glasses to novel nanoporous materials, is discussed. Features such as melting-point depression, hysteresis between freezing and melting, modifications to bulk solid structure and solid-solid transitions are reviewed for substances such as helium, organic fluids, water and metals. Recent work with well characterized assemblies of cylindrical pores like MCM-41 and graphitic microfibres with slit pores has suggested that the macroscopic picture of melting and freezing breaks down in pores of molecular dimensions. Applications of the surface force apparatus to the study of freezing and melting phenomena in confinement are discussed in some detail. This instrument is unique in allowing the study of conditions in a single pore, without the complications of pore blockage and connectivity effects. The results have confirmed the classical picture of melting-point depression in larger pores, and allowed the direct observation of capillary condensation of solid from vapour. Other results include the measurement of solvation forces across apparently fluid films below the bulk melting point and a solid-like response to shear of films above the bulk melting point. These somewhat contradictory findings highlight the difficulty of using bulk concepts to define the phase state of a substance confined to nanoscale pores.read more
Citations
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Semiconductor nanowires and nanotubes
TL;DR: In this article, a review highlights the recent advances in the field, using work from this laboratory for illustration, and the understanding of general nanocrystal growth mechanisms serves as the foundation for the rational synthetic control of one-dimensional nanoscale building blocks, novel properties characterization and device fabrication based on nanowire building blocks.
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Effects of confinement on material behaviour at the nanometre size scale
TL;DR: In this article, the effects of size and confinement at the nanometre size scale on both the melting temperature and the glass transition temperature, Tm, are reviewed, and it seems that the existing theories of Tg are unable to explain the range of behaviours seen at the nano-scale.
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Size dependence of nanostructures: Impact of bond order deficiency
Chang Q. Sun,Chang Q. Sun +1 more
TL;DR: The BOLS correlation mechanism has been initiated and intensively verified as discussed by the authors, which has enabled the tunability of a variety of properties of a nanosolid to be universally reconciled to the effect of bond order deficiency of atoms at sites surrounding defects or near the surface edges of the nano-material.
Journal ArticleDOI
Effects of confinement on freezing and melting.
Christiane Alba-Simionesco,Benoit Coasne,Gilberte Dosseh,G. Dudziak,Keith E. Gubbins,Ravi Radhakrishnan,Malgorzata Sliwinska-Bartkowiak +6 more
TL;DR: Both simple and more complex adsorbates that are confined in various environments (slit or cylindrical pores and also disordered porous materials) are considered and how confinement affects the glass transition is addressed.
Journal ArticleDOI
The role of morphology and crystallographic structure of metal oxides in response of conductometric-type gas sensors
TL;DR: In this article, the influence of morphology and crystallographic structure on gas-sensing characteristics of metal oxide conductometric-type sensors have been analyzed, and it was concluded that the structural parameters of metal oxides are important factors for controlling response parameters of resistive type gas sensors.
References
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Journal ArticleDOI
Ordered mesoporous molecular sieves synthesized by a liquid-crystal template mechanism
TL;DR: In this paper, the synthesis of mesoporous inorganic solids from calcination of aluminosilicate gels in the presence of surfactants is described, in which the silicate material forms inorganic walls between ordered surfactant micelles.
Journal ArticleDOI
Triblock copolymer syntheses of mesoporous silica with periodic 50 to 300 angstrom pores
Dongyuan Zhao,Jianglin Feng,Qisheng Huo,Nicholas A. Melosh,Glenn H. Fredrickson,Bradley F. Chmelka,Galen D. Stucky +6 more
TL;DR: Use of amphiphilic triblock copolymers to direct the organization of polymerizing silica species has resulted in the preparation of well-ordered hexagonal mesoporous silica structures (SBA-15) with uniform pore sizes up to approximately 300 angstroms.
Journal ArticleDOI
A new family of mesoporous molecular sieves prepared with liquid crystal templates
Jeffrey S. Beck,James C. Vartuli,Wieslaw J. Roth,M. E. Leonowicz,Charles T. Kresge,Kirk D. Schmitt,Cynthia Ting-Wah Chu,David H. Olson,E. W. Sheppard,S. B. McCullen,J. B. Higgins,J.L. Schlenker +11 more
TL;DR: In this paper, the synthesis, characterization, and proposed mechanism of formation of a new family of silicatelaluminosilicate mesoporous molecular sieves designated as M41S is described.
Journal ArticleDOI
Silicon quantum wire array fabrication by electrochemical and chemical dissolution of wafers
TL;DR: In this paper, free standing Si quantum wires can be fabricated without the use of epitaxial deposition or lithography using electrochemical and chemical dissolution steps to define networks of isolated wires out of bulk wafers.
Journal ArticleDOI
Nonionic Triblock and Star Diblock Copolymer and Oligomeric Surfactant Syntheses of Highly Ordered, Hydrothermally Stable, Mesoporous Silica Structures
TL;DR: In this paper, a family of highly ordered mesoporous (20−300 A) structures have been synthesized by the use of commercially available nonionic alkyl poly(ethylene oxide) (PEO) oligomeric surfactants and poly(alkylene oxide) block copolymers in acid media.