The diamond and zincblende structures are relatively open as the coordination number is only 4. ManyIV-IV,III-VandII-VIcompounds can also be crystallised with the wurtzite structure (based on the hexagonal lattice), maintaining tetrahedral bonding. Some examples areSiC,GaN,ZnS,CdS,CdSeandZnO. ...
Figure 3.3 shows the typical crystal structures: the body-centered cubic (bcc) structure, the face-centered cubic (fcc) structure, and the hexagonal close-packed (hcp) structure. The symmetry of the crystal structure is lower for hcp than bcc and fcc, and the packing density of the atoms ...
•Crystalstructures System AxialLengthsandAngles Bravais(Space)Lattices CubicTetragonalOrthorhombic RhombohedralHexagonalMonoclinicTriclinic a=b=c,===90oa=bc,===90oabc,===90oa=b=c,==90o SimplecubicBody-centeredcubicFace-centeredcubic Simp...
directional. This means that each atom tends to surround itself by as many others as possible. This results in a close packing, similar to that of spheres of equal radius, and yields three distinct systems: close-packed (face-centered) cubic, hexagonal close-packed, and body-centered cubic....
3.3UnitCells Itisoftenconvenienttosubdividethestructureintosmallrepeatentitiescalledunitcells.Unitcellsformostcrystalstructuresareparallelepipedsorprismshavingthreesetsofparallelfaces.Theunitcellisthebasicstructuralunitorbuildingblockofthecrystalstructureanddefinesthecrystalstructurebyvirtueofitsgeometryandtheatompositions...
cubic(FCC),thebody-centeredcubic(FCC)andthehexagonalclose-packed(HCP).Othertypesexist,particularlyamongminerals.Thesimplecube(SC)isoftenusedfordidacticalpurpose,nomaterialhasthisstructure.3.4MetallicCrystalStructuresImportantpropertiesoftheunitcellsare ThetypeofatomsandtheirradiiR. celldimensions(sideaincubiccells...
Although most colloidal crystals prepared by self-assembly are entropy favorable face-centered cubic (fcc) and hexagonal close packing (hcp) stacking, it has been shown that many other complex crystal structures could be fabricated by controlled or template-directed self-assembly, which may possess ...
PRIMITIVE AND NON-PRIMITIVE BRAVAIS LATTICESThe conditions on added points in three dimensionsThus there are limits on latticesFinding the Bravais lattices analyticallyDESCRIPTIONS OF THE FOURTEEN LATTICESTriclinic, monoclinic, orthorhombic and tetragonal systemsThe cubic systemThe trigonal and hexagonal systems...
TheStructureofCrystalSolidsChapter33.1IntroductionCRYSTALSTRUCTURES3.2FundamentalConcepts3.3UnitCells3.4MetallicCrystalStructures3.5DensityComputations3.6PolymorphismandAllotropy3.7CrystalSystemsCRYSTALLOGRAPHICPOINTS,DIRECTIONS,ANDPLANES3.8PointCoordinates3.9CrystallographicDirections3.10CrystallographicPlanes3.11LinearandPlanarDensities3.12...
that link the two structures. This process, while computationally challenging, will provide an exhaustive list of deformations connecting the two periodic unit cells. However, as detailed in the next section, the symmetry of the underlying structures can be exploited to greatly simplify this process....