Explain 15 Key Difference between Schottky and Frenkel Defect
When examining the intriguing world of crystal defects, it’s impossible to overlook the distinguished Schottky and Frenkel defects. These imperfections manifest in crystal lattices and possess distinct characteristics, resulting in diverse effects on material properties. Let’s delve into 15 difference between schottky and frenkel defect unravel their unique traits.
15 Difference between Schottky and Frenkel defect
Origin: Frenkel defects involve an ion that has been moved from its normal lattice site to an interstitial position, whereas Schottky defects result from missing ions in both the cation and anion sub-lattices.
Charge: Frenkel defects produce a positively charged cation vacancy and a negatively charged interstitial cation, whereas Schottky defects are electrically neutral because the same number of cations and anions are absent.
Stoichiometry: Schottky flaws preserve the stoichiometry of the crystal, ensuring that an equal number of cations and anions are absent. Due to the displaced cation’s interstitial position, Frenkel defects do not affect stoichiometry.
Schottky defects have a lower defect density because they develop at low temperatures and high coordination numbers. On the other hand, Frenkel defects are more prevalent and have higher defect densities at higher temperatures.
Schottky defects play a role in the conductivity of ions by reducing the number of charge carriers. Due to the existence of mobile ions in interstitial positions, Frenkel defects can enhance ionic conductivity.
Schottky flaws are frequently found in substances with high coordination numbers, such as sodium chloride. Compounds like silver iodide that have low coordination numbers are prone to frenkel defects.
Size Distinction: Schottky defects are more prevalent in crystals with small ion size differences, resulting in a uniform distribution of vacancies. Crystals with large ion size differences develop Frenkel defects, which give rise to interstitial sites.
Schottky defects cause vacancies to form, which reduces the crystal lattice’s density. Since the displaced ion is still inside the crystal’s lattice, Frenkel defects have no effect on the density of the crystal.
Schottky defects can change a crystal’s colour because colour centres form as a result of their optical properties. Frenkel imperfections have a minimal impact on the optical characteristics.
Schottky defects are stable at high temperatures because they are neutral in nature. Frenkel imperfections can be eliminated by annealing at higher temperatures but are stable at low temperatures.
Diffusion Mechanism: Migration of vacancies is a factor in Schottky defects. Ion migration between normal and interstitial lattice sites occurs in frenkel defects.
Schottky defects have a positive impact on melting points because the stronger bonding that results from the absence of ions raises the melting point of a crystal. The melting point is barely impacted by frenkel imperfections.
Schottky defects can cause a crystal’s magnetic properties to change, resulting in paramagnetism or ferromagnetism. The magnetic properties are not significantly impacted by Frenkel defects.
Schottky defects are used in solid-state electronics, such as Schottky diodes. Solid electrolytes and superionic conductors cannot operate without frenkel defects.
Reversibility: Schottky flaws are typically irreversible and need outside forces to be fixed. By cooling the crystal, Frenkel defects can be reversed and restored.
By understanding these 15 key difference, we can appreciate the unique characteristics and diverse impacts of Schottky and Frenkel defects.