Measurement Techniques
Two techniques allow measurement of the melting point of nanoparticle. As described above, the electron beam of the transmission electron microscope (TEM) can be used to melt nanoparticles. The melting temperature is estimated from the beam intensity, while changes in the diffraction conditions to indicate phase transition from solid to liquid. This method allows direct viewing of nanoparticles as they melt, making it possible to test and characterize samples with a wider distribution of particle sizes. The TEM limits the pressure range at which melting point depression can be tested.
More recently, researchers developed nanocalorimeters that directly measure the enthalpy and melting temperature of nanoparticles. Nanocalorimeters provide the same data as bulk calorimeters, however additional calculations must account for the presence of the substrate supporting the particles. A narrow size distribution of nanoparticles is required since the procedure does not allow users to view the sample during the melting process. There is no way to characterize the exact size of melted particles during experiment.
Read more about this topic: Melting-point Depression
Famous quotes containing the words measurement and/or techniques:
“That’s the great danger of sectarian opinions, they always accept the formulas of past events as useful for the measurement of future events and they never are, if you have high standards of accuracy.”
—John Dos Passos (1896–1970)
“The techniques of opening conversation are universal. I knew long ago and rediscovered that the best way to attract attention, help, and conversation is to be lost. A man who seeing his mother starving to death on a path kicks her in the stomach to clear the way, will cheerfully devote several hours of his time giving wrong directions to a total stranger who claims to be lost.”
—John Steinbeck (1902–1968)