Effects of size and shape on the specific heat, melting entropy and enthalpy of nanomaterials

A simple theoretical model is developed to study the size and shape dependence of vibrational and thermodynamic properties of nanomaterials. To show the real connection with the nanomaterials we have studied Debye temperature, Debye frequency, melting entropy, and enthalpy in different shapes, namely, spherical, nanowire, and nanofilm of -Fe, Sn, Ag, and In. The results obtained are compared with the experimental data. A good agreement between the model predictions and the experimental data supports the theory developed in the present paper.

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Specific heat and thermal conductivity of nanomaterials

Modern Physics Letters B ◽

10.1142/s0217984917500117 ◽

2017 ◽

Vol 31 (02) ◽

pp. 1750011 ◽

Cited By ~ 6

Author(s):

Sandhya Bhatt ◽

Raghuvesh Kumar ◽

Munish Kumar

Keyword(s):

Thermal Conductivity ◽

Particle Size ◽

Specific Heat ◽

Au Nanoparticles ◽

Shape Effect ◽

Critical Test ◽

Size And Shape ◽

Model Predictions ◽

Shape Effects ◽

Simulation Results

A model is proposed to study the size and shape effects on specific heat and thermal conductivity of nanomaterials. The formulation developed for specific heat is based on the basic concept of cohesive energy and melting temperature. The specific heat of Ag and Au nanoparticles is reported and the effect of size and shape has been studied. We observed that specific heat increases with the reduction of particle size having maximum shape effect for spherical nanoparticle. To provide a more critical test, we extended our model to study the thermal conductivity and used it for the study of Si, diamond, Cu, Ni, Ar, ZrO2, BaTiO3 and SrTiO3 nanomaterials. A significant reduction is found in the thermal conductivity for nanomaterials by decreasing the size. The model predictions are consistent with the available experimental and simulation results. This demonstrates the suitability of the model proposed in this paper.

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Modeling for the study of thermophysical properties of metallic nanoparticles

SN Applied Sciences ◽

10.1007/s42452-021-04478-8 ◽

2021 ◽

Vol 3 (4) ◽

Author(s):

Ratan Lal Jaiswal ◽

Brijesh Kumar Pandey

Keyword(s):

Thermodynamic Properties ◽

Specific Heat ◽

Thermophysical Properties ◽

Cohesive Energy ◽

Metallic Nanoparticles ◽

Shape Effect ◽

Great Effort ◽

Dangling Bond ◽

Experimental Findings ◽

Melting Entropy

AbstractSuccessful description and explanation of thermophysical properties at the nano level is a task of great challenge even yet today. Although great effort has been made by pioneer workers and scientists in this field but still the exact model for the prediction and explanation of these properties is lagging. In the current work, we have proposed a new model to calculate the thermophysical properties like specific heat, melting enthalpy, and melting entropy of nanomaterials, which are calculated with the help of a cohesive energy model including shape effect in addition to structure of materials at the nano level. The relaxation factor due to the dangling bond at the surface of nanoparticles is taken under consideration. The obtained results using this model is fully consistent with the available experimental findings for the above said thermophysical properties for silver (Ag), copper (Cu), Palladium (Pd), Aluminium (Al), and Indium (In). This encouraging idea has also been used to predict the nature of variation of above mentioned important thermodynamic properties of other materials at their nano level.

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Unbiased estimation of particle number and sizes using the new stereological tools: the disector, the fractionator, the selector, and the nucleator — or just point-sampled intercepts

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104200 ◽

1988 ◽

Vol 46 ◽

pp. 428-429

Author(s):

H.J.G. Gundersen

Keyword(s):

Particle Number ◽

Small Distance ◽

Parallel Plane ◽

Unbiased Estimation ◽

Severe Problem ◽

New Era ◽

Size And Shape ◽

Distinct Property ◽

Sectioned Tissue

Previously, all stereological estimation of particle number and sizes were based on models and notoriously gave biased results, were very inefficient to use and difficult to justify. For all references to old methods and a direct comparison with unbiased methods see recent reviews.The publication in 1984 of the DISECTOR, the first unbiased stereological probe for sampling and counting 3—D objects irrespective of their size and shape, signalled the new era in stereology — and give rise to a number of remarkably simple and efficient techniques based on its distinct property: It is the only known way to obtain an unbiased sample of 3-D objects (cells, organelles, etc). The principle is simple: within a 2-D unbiased frame count or sample only cells which are not hit by a parallel plane at a known, small distance h.The area of the frame and h must be known, which might sometimes in itself be a problem, albeit usually a small one. A more severe problem may arise because these constants are known at the scale of the fixed, embedded and sectioned tissue which is often shrunken considerably.

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The influence of confocal microscope design on imaging performance

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100146564 ◽

1993 ◽

Vol 51 ◽

pp. 144-145

Author(s):

C J R Sheppard

Keyword(s):

Image Quality ◽

Fluorescence Imaging ◽

Confocal Microscope ◽

Industrial Applications ◽

Three Dimensions ◽

Design Parameters ◽

Weak Signals ◽

Size And Shape ◽

Imaging Performance ◽

Fundamental Limitation

The confocal microscope is now widely used in both biomedical and industrial applications for imaging, in three dimensions, objects with appreciable depth. There are now a range of different microscopes on the market, which have adopted a variety of different designs. The aim of this paper is to explore the effects on imaging performance of design parameters including the method of scanning, the type of detector, and the size and shape of the confocal aperture.It is becoming apparent that there is no such thing as an ideal confocal microscope: all systems have limitations and the best compromise depends on what the microscope is used for and how it is used. The most important compromise at present is between image quality and speed of scanning, which is particularly apparent when imaging with very weak signals. If great speed is not of importance, then the fundamental limitation for fluorescence imaging is the detection of sufficient numbers of photons before the fluorochrome bleaches.

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