Tag: imperfections in solids
Questions Related to imperfections in solids
In a crystal, at $827^{\circ}C$, one out of $10^{10}$ lattice site is found to be vacant, while in the same solid, one out of $2 \times 10^9$ lattice site is found to be vacant at $927^{\circ}C$. What is the enthalpy of vacancy formation in kJ/mol unit?
Calcium crystallizes in a face centred cubic unit cell with a $=0.556$ nm. Calculate the density if it contains:
(ii) $0.1\%$ Schottky defect
Statement 1: KCl is more likely to show schottky defect while Lil is more likely to show Frenkel defect.
Statement 2: Schottky defect is more likely in ionic solids in which cations and anions are of comparable size while Frenkel defect is more likely is which cations and anions have large differences in their ionic sizes.
Statement-I: Solids having more $F-$centres possess intense colours.
Statement-II: Excess of $Na^{+}$ in $NaCl$ solid having F-centres makes it appear to pink.
Which of the following statements are correct?
Which of the following statements is/are correct ?
A strong current of trivalent gaseous boron passed through a germanium crystal decreases the density of the crystal due to part replacement of germanium by boron and due to interstitial vacancies created by missing Ge atoms. In one such experiment, one gram of germanium is taken and the boron atoms are found to be $150$ ppm by weight when the density of the Ge crystal decreases by $4\%$. Calculate the percentage of missing vacancies due to germanium which are filled up by boron atoms. Atomic weight of Ge $= 72.6$ amu and $B = 11$ amu.
Crystals have 'vacant sites' or 'defects' in them. When light strikes a photographic silver bromide paper, silver atoms move in through these defects to:
The pink colour of lithium chloride crystal is due to: