we know the orthorhombic structure has three axes and hexagonal structure has four axes. therefore, the miller indices for orthorhombic structure and hexagonal structure are (hki) ,(hkil) respectively.
in card we see some planes have four axes although the structure ic orthorhombic why?
As far as I know the Bravais-Miller-Indices (i.e. the four indices (hkil) ) are only used for rhombohedral/trigonal and hexagonal lattices (not orthorhombic, though).
In any case, the fourth index is redundant because i=-(h+k) and is only used to give similar planes in the crystal the same type of indices. You can always use just the (hkl) version without the i-index.
Dear Manar Mustafa,
Do you really see in the attached card (hkil) indices for orthorhombic system??
For example, the index 2 2 18 means that
h = 2 k = 2 l = 18.
Regards
Waldemar
Manar Mustafa: "in card we see some planes have four axes" -- I don't see any at all; please be more specific and name an example. Be aware that the column headings say "2\theta", "Int-f", and "h k l", so everything should be clear (since "Int-f" seems to indicate the intensity). But maybe I missed something...
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science