Recent content by wangasu

does anybody know the upper limit of the bcc and fcc metals like Fe, Cu, Ag? According to the fact that the planes with high (hkl) indices have small interplanar spacing d_hkl, the smallest spacing would be present. what is that? atomic diameter of a specifc metal?

Does that mean that any crystal has zero entropy at 0K, independent of simple or complex crystals? In case residual entropy is not zero, can we call it configurational entropy different from vibrational one?

How could the interplanar (van der waals) and intraplanar (covalent) bonds be equivalent?

4.56 J/mol-K?

The temperature-dependent entropy will go to zero for both of them. But if one is defined as 'perfect' , others will have the configurational entropy at 0K, which will not be zero, so the total entropy will not be zero any more. Does this make sense?

Hi, all. Does anybody know the 0K entropy of diamond and graphite? According to the third law of thermodynamics, the entropy of one of carbon polymorphs which should be called perfect crystal goes to 0. How about diamond and graphite? Thanks.

Right..an electron diffraction image of TEM is the projection of the crossection between the reciprocal lattice points and Ewald's sphere. it seems that the origin of the electron diffraction image definitely explains both transmission AND diffraction, NOT just transmission..does it make sense?

Thanks Ox..It sounds that it is true that the origin of reciprocal space comes from diffraction, and the diffraction holds the same direction as the incident light with diffraction vector being zero. So, the origin can be easily located as the head of an incident wave vector in Ewald’s sphere...

Hi, all I got a question about the origin of reciprocal space..what is the physical nature of the special point? Does that originate from diffraction? or Is that a diffraction points? We know that a 'normal' reciprocal point designates a group of parallel plane. How about the origin of...

it goes relative to the initial value you put in. the absolute number does not mean much.

Does anybody know about the entropy-driven processes? Are they referred to the systems without enthapy change? so, all the isolated systems like the universe belong to the category. but, I also noticed that the term, entropy-driven, was used in some biological or mesoscopic systems. What is it...

this maximum phenomena are often observed in binary solutions when making a plot of log_viscosity vs. mole fraction. the scale of deviation from the linear correlation, which connects the two liquids (x=0, and 1), might reflect the degree of interaction of liquid molecules. stronger interaction...

For crystals, the dielectric constant does generally not change too much with measurement frequency (if temperatrue is not high), and thus the equation still gets along with the low frequency values of permittivity. But for liquids, molecular movements (or dipole reorientation) have a dominant...

You might be wrong.. Generally, there are two main manifestations about entropy, one being a measure of the disorder of a system, and the other a measure of the amount of energy which is unavailable to do work. sometimes, entropy is also said to be a measure of the multiplicity of a system. If...

Textbook says that entropy is a measure of energy unavailable to do work. For a crystal, entropy will increase with temperature, which, according to the definition, seems to mean that the useless energy increases. but, on the other hand, the quantity of heat energy available to do work depends...