Miller planes

-
Planes in a crystal are described by notations called Miller indices
 Miller indices of a plane, indicated by h k l, are given by the reciprocal of the intercepts of the plane on the three axes.
 The plane, which intersects X axis at 1 (one lattice parameter) and is parallel to Y and Z axes, has Miller indices h = 1/1 = 1, k = 1/ = 0, l = 1/ = 0. It is written as (hkl) = (100).

 Crystal Planes


To find the Miller Indices of a plane, follow these steps:
 Determine the intercepts of the plane along the crystal axes
 Take the reciprocals
 Clear fractions
 Reduce to lowest terms and enclose in brackets () Ex: Intercepts on a, b, c : ¾, ½, ¼ (h k l) = (4/3, 2, 4) = (2 3 6)

Planes can also have negative intercept e.g. 1, -1/2, 1 h k l = 1 -2 1. This is denoted as ( ) 121

 Family of planes {hkl}
 Planes having similar indices are equivalent, e.g. faces of the cube (100), (010) and (001). This is termed as a family of planes and denoted as {100} which includes all the (100) combinations including negative indices.

Note the shift of origin from blue to red circle for the negative indices


Comments

Post a Comment

Popular posts from this blog

Structures of AX,AX2 and ABX3 type compounds

-
Image
The simple structures come from the arrangement of the anions (though sometimes the cations) in the positions of the spheres in the fcc or hcp lattices, and the cations go into some or all of the octahedral and tetrahedral holes within the lattices. Structures based on face centered cubic lattices The Rock Salt structure This the structure adopted by  Sodium Chloride , NaCl. It is based on the fcc array of the large chloride anions, and the sodium cations occupy all the octahedral holes in the fcc  lattice . However, it could also be seen as an fcc array of sodium ions, with the anions in all the octahedral holes. Each ion is octahedrally coordinated by six counterions, and so this structure has so-called  (6,6)-coordination , where the first number refers to the coordination of the  cation  and the second to the  anion . The structure beyond the first coordination sphere can also be visualized. The Rock Salt, or NaCl, structure The sodium cations (green) occupy the oct
Read more

Oxide-Main group elements

-
Image
Oxides are chemical compounds with one or more oxygen  atoms combined with another element (e.g. Li 2 O). Oxides are binary compounds of oxygen with another element, e.g., CO 2 , SO 2 , CaO, CO, ZnO, BaO 2 , H 2 O, etc. These are termed as oxides because here, oxygen is in combination with only one element. Based on their acid-base characteristics oxides are classified as acidic, basic, amphoteric or neutral: An oxide that combines with water to give an acid is termed as an acidic oxide. The oxide that gives a base in water is known as a basic oxide. An amphoteric solution is a substance that can chemically react as either acid or base. However, it is also possible for an oxide to be neither acidic nor basic, but is a neutral oxide. Defferent type of oxides;- Acidic Oxides Acidic oxides are the oxides of non-metals ( Groups 14-17 ) and these  acid anhydrides form acids with water: Sulfurous Acid SO 2 + H 2 O → H 2 SO 3 (1.1) (1.1) SO 2 + H 2 O → H 2
Read more

Biological electron transport system-Hemeprotein and Nonhemeprotein

-
Image
Heme Protien :- Porphyrin+Iron-----Hemeprotein A  hemeprotein  (or  haemprotein ; also  hemoprotein  or  haemoprotein ), or  heme  protein, is a  protein  that contains a  heme   prosthetic group . They are a large class of  metalloproteins . The heme group confers functionality, which can include oxygen carrying, oxygen reduction, electron transfer, and other processes. Heme is bound to the protein either  covalently  or noncovalently  bound  or both. [1] The heme consists of iron cation bound at the center of the conjugate base of the porphyrin, as well as other ligands attached to the "axial sites" of the iron. The porphyrin ring is a planar dianionic, tetradentate ligand. The iron is typically Fe 2+  or Fe 3+ . One or two ligands are attached at the axial sites. The porphyrin ring has 4 nitrogen atoms that bind to the iron, leaving two other coordination positions of the iron available for bonding to the histidine of the protein and a divalent atom. Roles
Read more