Final answer:
Defects in crystalline structures are not always undesirable; they can be introduced intentionally, such as doping in semiconductors, to provide beneficial properties.
Crystal defects occur naturally and their presence can significantly influence material characteristics.
Step-by-step explanation:
The statement that defects in crystalline structure are always undesirable is false. While crystals strive for perfection in their arrangement of atoms, ions, or molecules, crystal defects are unavoidable due to thermodynamic conditions. These defects can, in fact, be beneficial depending on their application.
For example, doping a silicon crystal introduces defects that alter its electrical properties, which is crucial for semiconductor and computer chip manufacturing.
Crystal defects, including vacancies, interstitial atoms, and substitution impurities, contribute to the uniqueness and functionality of various materials.
Defects such as Frenkel defects and Schottky defects occur in ionic crystals and are important for understanding material properties.
At absolute zero, a crystal would be perfect, but since that temperature is unattainable in practice, defects will always exist. Therefore, the imperfections in a crystal's structure can be classified as point, line, or plane defects, each with different implications on the properties of the crystal.