Explain three-dimensional close packing from two-dimensional hexagonal close packing. Explain the formation of face-centered cubic $(FCC)$ unit cell and hexagonal close packing $(HCP)$ in three dimensions.
(N/A) $1$. Three-dimensional close packing from two-dimensional hexagonal layers is achieved by stacking layers one above the other.
$2$. When the second layer $(B)$ is placed over the first layer $(A)$,it covers one set of triangular voids (tetrahedral voids). Placing the third layer over the second layer can lead to two patterns:
- $ABAB...$ pattern: The third layer spheres align with the first layer $(A)$,resulting in hexagonal close packing $(HCP)$.
- $ABCABC...$ pattern: The third layer spheres are placed over the octahedral voids of the second layer,resulting in cubic close packing $(CCP)$ or face-centered cubic $(FCC)$ structure.
$2$. When the second layer $(B)$ is placed over the first layer $(A)$,it covers one set of triangular voids (tetrahedral voids). Placing the third layer over the second layer can lead to two patterns:
- $ABAB...$ pattern: The third layer spheres align with the first layer $(A)$,resulting in hexagonal close packing $(HCP)$.
- $ABCABC...$ pattern: The third layer spheres are placed over the octahedral voids of the second layer,resulting in cubic close packing $(CCP)$ or face-centered cubic $(FCC)$ structure.
Explore More
Similar Questions
$A$ compound is formed by elements $A$ and $B$. Element $B$ forms an $HCP$ lattice,and element $A$ occupies $2/3$ of the tetrahedral voids. What is the formula of the compound formed by $A$ and $B$?
Medium
View Solution$A$ compound made up of elements $A$ and $B$ (with a general formula $A_x B_y$), where $B$ forms an $hcp$ lattice and $A$ occupies $2/3$ of the tetrahedral voids. The formula of the compound is
In a close-packed structure of mixed oxides,the lattice is composed of oxide ions. One-eighth of the tetrahedral voids are occupied by divalent cations $(A^{2+})$,while one-half of the octahedral voids are occupied by trivalent cations $(B^{3+})$. The formula of the mixed oxide is:
Difficult
View SolutionElement '$B$' forms $ccp$ structure and '$A$' occupies half of the octahedral voids,while oxygen atoms occupy all the tetrahedral voids. The structure of bimetallic oxide is
DifficultJEE MAIN 2019
View SolutionIf $z$ represents the number of atoms in a unit cell of a close-packed structure with an $ABCABC$ stacking sequence,then the number of tetrahedral voids in the unit cell is ....
Easy
View SolutionVedclass Products
For Students
Vedclass Test Series
Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.
Start Free TrialFor Teachers
Exam Paper Generator
Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.
Try FreeFor Institutes
Online Exam Module
Live online exams with unlimited students, 360° analytics & white-label branding.
See Demo