Similarly, it is usually much easier to dissolve a perfect crystal in a solvent than to grow again a good crystal from the resulting solution.
32.
Even this simple model of the force required to move a dislocation shows that plasticity is possible at much lower stresses than in a perfect crystal.
33.
I've repeatedly read that Galileo used his telescope to prove that the Moon was not a uniform, unblemished body, shattering the Aristotelian view of perfect crystal spheres.
34.
The next great achievement of Broude was developing a technique for getting the information on energy spectra of excitons in perfect crystals from optical spectra of isotopic solutions.
35.
To obtain the absolute value of the entropy, we need the third law of thermodynamics, which states that " S " = 0 at absolute zero for perfect crystals.
36.
When the smaller idiomorphic crystals of the first-formed are scattered irregularly through the larger and less perfect crystals of later origin, the structure is said to be "'poikilitic " '.
37.
However, this presupposes that the material forms a'perfect crystal'without any frozen in entropy ( defects, dislocations ), which is never completely true because crystals always grow at a finite temperature.
38.
In crystallography, the phrase'perfect crystal'can be used to mean no line or planar defects , as it is difficult to measure small quantities of point defects in an otherwise defect-free crystal.
39.
*Once single perfect crystals have been obtained, it is recommended that the crystals are kept in a sealed vessel with some of the liquid of crystallisation to prevent the crystal from'drying out '.
40.
A perfect crystal is one in which the internal lattice structure is the same at all times; in other words, it is fixed and non-moving, and does not have rotational or vibrational energy.
