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Define the following terms : (i) Primitive unit cell (ii) Schotty defect (iii) Ferromagnetism |
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Answer» Solution :(i) When a unit cell contains constituent particles only at the corner positions, it is called a primitive unit cell. (ii) If in an ionic solid of the type `A^(+)B^(-)`, equal number of CATIONS and anions are missing from their USUAL positions, it is called Schottky defect. Electrical neutrality is maintained in this type of defect. (iii) The substances which show magnetism EVEN in the absence of magnetic field are called ferromagnetic substances and this property is called ferromagnetism. Fe, Co, `CrO_(2)` are examples of substances showing this property. Ferromagnetism is due to permanent alignment of domains of METAL atoms in the same direction as shown below. `{:(uarr,uarr,uarr,uarr,uarr,uarr):}` |
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