The hexagonal structure of alternating layers is shifted so its atoms are aligned to the gaps of the preceding layer. The atoms from one layer nest themselves in the empty space between the atoms of the adjacent layer just like in the fcc structure. However, instead of being a cubic structure, the pattern is hexagonal.
The hcp structure has three layers of atoms. In each the top and bottom layer, there are six atoms that arrange themselves in the shape of a hexagon and a seventh atom that sits in the middle of the hexagon. The middle layer has three atoms nestle in the triangular "grooves" of the top and bottom plane. Note that there are six of these "grooves" surrounding each atom in the hexagonal plane, but only three of them can be filled by atoms.
SAMPLE:
· Nickel Arsenide Structure s based on a distorted hcp array of Arsenide anions. By contrast with the wurtzite structure, however, which is also of formula AB, the cations now occupy all the octahedral sites rather than half the tetrahedral holes. There is one octahedral hole for each hcp lattice site, and so the AB stoichiometry is preserved.· Titanium Oxide, TiO2. he anions occupy the hcp lattice, and the cations occupy half of the octahedral holes.Together the four spheres of the Earth make up the Earth system. These spheres are the geosphere, hydrosphere, biosphere and the atmosphere.
The two spheres that are responsible for erosion are the hydrosphere and the atmosphere. These spheres interact all of the time.
Earth's spheres are defined based on the different physical and chemical properties that characterize distinct regions of our planet. The main spheres are the atmosphere (air), hydrosphere (water), lithosphere (land), and biosphere (living organisms). These spheres interact and influence each other, leading to the Earth system as a whole.
The six spheres of Earth Systems are the atmosphere (air), hydrosphere (water), geosphere (land), biosphere (living organisms), cryosphere (ice), and anthroposphere (human activities). These spheres interact and influence each other to maintain Earth's delicate balance and support life.
The major spheres of the environment are the lithosphere (land), hydrosphere (water), atmosphere (air), and biosphere (living organisms). These spheres interact and influence each other, contributing to the overall health and balance of the environment.
why one of unit cell angles of hexagonal crystal is 120 digree
The Crystal Spheres was created in 1984.
Crystal Cradles (www.crystalcradles.co.uk)
Cubic closest packing (ccp) - has the highest efficiency of space due to spheres being packed closely in all three dimensions. Hexagonal closest packing (hcp) - has slightly lower efficiency compared to ccp due to the alternating layers of spheres. Body-centered cubic (bcc) - has lower efficiency than ccp and hcp due to less efficient packing arrangement. Simple cubic - has the lowest efficiency of space with only spheres at the corners of the cube.
No.
Opal has an amorphous or non-crystalline structure, meaning it lacks a repeating atomic arrangement like that found in crystals. Instead, opal is made up of tiny silica spheres arranged in a disordered pattern, which gives it its beautiful color play known as "play-of-color."
These small crystal-lined spheres are called geodes. They form when minerals crystallize inside a cavity within the limestone rock.
Opal is not classified as a true crystal; instead, it is a mineraloid. Unlike crystals, which have a defined and ordered atomic structure, opal has a more irregular arrangement of silica spheres. This unique structure contributes to its characteristic play-of-color, making opal a popular gemstone despite its non-crystalline nature.
Spheres are cool. Spheres are the beauty of this galaxy.
Coordination number is the number of atoms or ions immediately surrounding a central atom in a complex or crystal structure. It gives information about the geometry and bonding around the central atom.
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Closed packed derections.. are derections of the lines drawn through atoms such that no void space is in bitween.. Refer this, i also got the idea from here http://books.google.lk/books?id=wh4v6UWjYdIC&pg=PA5&dq=close%2Bpacked%2Bdirections&hl=en&ei=vo3WTKLbIYKYvAPp_ZXqCQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCYQ6AEwAA#v=onepage&q=close%2Bpacked%2Bdirections&f=false