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Questions and Answers
The defects in crystals may be confined to a ______, line, surface and volume.
point
When an atom is missing or an atom is in an irregular place in the lattice structure, the corresponding defects are known as ______ Defects.
Point
Point defects are of four types: 1.______ 2.Interstitial Defects 3.Substitutional Defects 4.Electronic Defects
Vacancies
______ defects are mainly due to the imperfect packing during the formation of crystal or due to thermal vibrations of atoms at high temperature.
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The defects due to the missing atoms at their lattice sites are called ______.
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Atoms at high temperature are frequently and regularly change their positions leaving empty lattice sites behind their positions, forming ______ defects.
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A ______ is a solid where the atoms form a periodic arrangement.
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Any deviation from the periodic arrangement of atoms in a crystal is known as ______ or imperfections in crystals.
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A ______ defect refers to a lattice irregularity having one or more of its dimensions on the order of an atomic diameter.
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The equilibrium number of ______ in a material can be calculated at a specified temperature, given the relevant constants.
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In a ______ solution, one element is dissolved in another to form a homogeneous mixture.
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It is important to have knowledge about the types of ______ that exist and the roles they play in affecting the behavior of materials.
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VACANCY 𝑵𝑽 = 𝑵𝒆𝒙𝒑 𝑸𝒗 − 𝒌𝑻 𝑵𝒗 = is the equilibrium number of ______
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An Interstitial Defect is a type of point crystallographic defect where an atom of the same or of a different type, occupies a normally unoccupied site in the crystal structure. It occurs when an impurity atom tries to settle in the ______ space
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A substitutional impurity atom is an atom of a different type than the bulk atoms. Usually, substitutional atoms are close in size to the bulk atom within approximately ______%
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Errors in charge distribution in solids are called ______
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An interstitial defect is a type of point crystallographic defect where an atom of the same or of a different type, occupies a normally unoccupied site in the ______ structure
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When an impurity atom occupies one of the positions of the parent atoms of the crystal, then such a defect is known as ______ defect
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Study Notes
Imperfections in Solids
- Studying imperfections in solids is essential because they profoundly influence the properties of materials.
- Crystals are solids with a periodic arrangement of atoms, and any deviation from this periodicity is known as defects or imperfections in crystals.
Classification of Crystalline Imperfections
- Crystalline defects can be classified according to their geometry or dimensionality:
- Point defects: confined to a point in the lattice structure
- Line defects
- Surface defects
- Volume defects
Point Defects
- Point defects are irregularities in the lattice structure that produce strain in a small volume of the crystal.
- Four types of point defects:
- Vacancies
- Interstitial defects
- Substitutional defects
- Electronic defects
Vacancies
- Vacancies are the simplest point defects in a crystal, where an atom is missing at its site.
- Vacancies are mainly due to imperfect packing during crystal formation or thermal vibrations of atoms at high temperatures.
- The equilibrium number of vacancies (NV) can be calculated using the formula: NV = N * exp (-Qv / kT)
Interstitial Defects
- Interstitial defects occur when an atom of the same or a different type occupies a normally unoccupied site in the crystal structure.
- Interstitial impurities are usually smaller than the bulk atoms.
Substitutional Defects
- Substitutional defects occur when an impurity atom occupies one of the positions of the parent atoms of the crystal.
- Substitutional impurity atoms are usually close in size (within approximately 15%) to the bulk atoms.
Electronic Defects
- Electronic defects are errors in charge distribution in solids.
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Description
Explore the classification of crystalline imperfections based on the geometry or dimensionality of the defects. Learn how crystal defects impact properties like mechanical strength, ductility, and conductivity. Understand different types of defects including point, line, surface, and volume defects in crystals.
