Thermal Stability of Nanocrystals Confined in Nanoporous Media

Abstract

Thermal stability of nanocrystals confined in nanopores is dramatically different from their bulk counterparts. To understand the underlying mechanism and factors that dominate the general trend of tunability, we have established a simple and unified model for size and interface effects on the thermal stability of nanocrystals based on the perspective of Lindemann’s criterion for melting. According to this model, the depression or enhancement of thermal stability of nanoconfined crystals has been illustrated to depend on the confluence effect of size and interfacial conditions. Model predictions are consistent with available experimental results for molecular gases (oxygen, neon, argon, and krypton), organic molecules (benzene, nitrobenzene, carbon tetrachloride, and cyclohexane), water, and metallic (gallium, indium, and mercury) nanocrystals confined in nanoporous media.

Melting of Cu Nanowires: A Study Using Molecular Dynamics Simulation

“…The size-dependent melting temperature of metallic nanowires T m ( D ) can be described by Jiang’s model − T m false( D false) / T m false( normal∞ false) = exp false[ 2 Δ S vib false( normal∞ false) / false( 3 R false) / false( 1 − D / 4 h false) false] where T m (∞) is the melting temperature for the corresponding bulk crystal, D denotes the corresponding diameter, R is the ideal gas constant, and h is the atomic diameter. Δ S vib shows the vibrational part of the overall melting entropy Δ S m . − For metallic crystals, Δ S vib (∞) = Δ S m (∞) + R ( x A ln x A + x B ln x B ).…”

“…The size-dependent melting temperature of metallic nanowires T m (D) can be described by Jiang's model [30][31][32][33][34] where T m (∞) is the melting temperature for the corresponding bulk crystal, D denotes the corresponding diameter, R is the ideal gas constant, and h is the atomic diameter. ∆S vib shows the vibrational part of the overall melting entropy ∆S m .…”

Size Consideration on Shape Factor and Its Determination Role on theThermodynamic Stability of Quantum Dots

“…12 To obtain their sizeand shape-tunable characteristics, the thermodynamic properties of quantum dots should be understood and predicted for practical applications. 13 As is known, the melting temperature T m decreases with increasing surface-to-volume ratio δ, even the surface shape can substantially affects δ values of materials. Up to now, there are numerous models have been developed to describe the sizedependent melting temperature of nanoparticles.…”

“…This will result in high energy, numerous defect sites, distinctive electronic state, altered surface crystal structure, and strong absorption at a specific wavelength, etc . To obtain their size- and shape-tunable characteristics, the thermodynamic properties of quantum dots should be understood and predicted for practical applications …”