As in the rock-salt structure, the two atom types form two interpenetrating face-centered cubic lattices. Figure 16. Cubic ZnS structure (problem 3.6 in Kittel) For the short-range repulsion between K and Cl one has U short(r) = e r=ˆ, with = 0:3417 10 8 erg, ˆ= 0:326A. 1. Calculate The Lonic Packing Factor (IPF) For Zinc Blende, If The Sa-ion Is At Distance D/4 From The Corner Along The Body Diagonal D. The Radii Of Ions Are: Rzut = 0.083 Nm, R3 - … Its density is 3.4 g cm-3. Comparison of figs, la and lb show that the BCC is much emptier than the FCC structure. There are four zinc ions and four sulfide ions in the unit cell, giving the empirical formula ZnS. The crystal may be thought of as two interpenetrating fcc lattices, one for sulfur the other for zinc, with their origins displaced by one quarter of a body diagonal. The mineral zinc blende is ZnS; its unit cell is also fcc. An element with density 10 g cm-3 forms a cubic cell with edge length of 3 X 10-8 cm. Short Answer Type Questions [II] [3 Marks] 8. Solution for The compound CuCl [Formula mass = 99 g mol-1] has FCC structure like ZnS. The zincblende structure, shown below, can be thought of as two interpenetrating fcc lattices, one of anions and one of cations, offset from each other by a translation of 1/4 along the body diagonal of the unit cell. How many cations are in the unit cell of zinc blende? In this structure, atoms exist at each cube corner and one atom is at the center of the cube, fig lb. The crystal structure of the ZnS compound. ZnS is Zincblende, Sphalerite structured and crystallizes in the cubic F-43m space group. array •Zn2+ … [NA = 6.02 X 10 23 mol-1] Ans. Zn2+ is bonded to four equivalent S2- atoms to form corner-sharing ZnS4 tetrahedra. Acknowledgements: Zincblende/sphalerite is based on a fcc lattice of anions whereas wurtzite is derived from an hcp array of anions. kinematically forbidden.
Statement-2: Positions of in zinc blende structure are similar. What is the length of the edge of unit cell? 7. Both occur as 4: 4 coordination compounds. – 4:4 (tetrahedral) S 2-with Zn 2+ in half Td holes. Given radii of Zn+2 = 0.88 and S-2 = 2.19, calculate the following: (a) What is fcc, allowed reflections have . Wurtzite has a hexagonal structure, while zincblende is cubic. What is the length of the edge of unit cell?… However, it differs from rock-salt structure in how the two lattices are positioned relative to one another. r Zn+2 / r S–2 = 0.40 Wurtzite (Zn,Fe)S c 2001-2005 Mineral Data Publishing, version 1 Crystal Data: Hexagonal. In the diamond structure all eight sites are occupied by the same atom. Statement-1 : In ZnS zinc blende structure from FCC while alternate tetrahedral voids are occupied by . 1 12 3 Related Structure: Wurtzite (ZnS) The structure is three-dimensional. 3. To comply with 1 : 1 stoichiometry, four Zn 2+ ions must be present in four alternate tetrahedral voids out of eight tetrahedral voids present.. The crystal structure of wurtzite Wikipedia: Zinc sulfide, Wurtzite Housecroft: p. 169 Shriver & Atkins: pp. ZnS, zinc sulfide (or zinc blende) forms an FCC unit cell with sulfide ions at the lattice points and much smaller zinc ions occupying half of the tetrahedral holes in the structure. 000+ LIKES 1.5k VIEWS ZnS, zinc sulfide (or zinc blende) forms an FCC unit cell with sulfide ions at the lattice points and much smaller zinc ions occupying half of the tetrahedral holes in the structure. Correct option (B) ZnS . This is the structure adopted by Zinc Sulphide, ZnS, and is also known as the zinc blende structure. Face-centered cubic (abbreviated cF or fcc, and alternatively called cubic close-packed or ccp) ... one form of zinc sulfide (β-ZnS). Then, the vector connecting the two basis atoms is given by Home / Inorganic Chemistry / AB structures / ZnS – Wurtzite: Interactive 3D Structure. Zinc blende has an fcc structure and wurtzite has an hcp structure. Structure: Geometrical structure factor: general formula: geometrical structure factor: special cases: Examples of cristals : bcc: for h+k+l even: Nb, fcc Examples of compounds with the zincblende structure include CuCl, CuI, ZnSe, HgS, BeS, CdTe, AlP, GaP, SnSb, CSi, and diamond. The wurtzite structure is based on the hcp lattice, where every other atom is A or B . Here there is an fcc array of sulphide anions, and the zinc cations occupy half the tetrahedral holes. View Notes - Exam1_Review from BME 352 at University of Texas. These four structures comprise most of the binary crystals with equal numbers of cations and anions. Let the lattice constant of the ZnS structure be a, that is, the length of the edge of the cube. However, some of these reflections are. ZnS has an fcc lattice with S-2 in lattice positions. View Live. The compound CuCl [Formula mass = 99 g mol-1] has FCC structure like ZnS. Fig.2b shows the atomic arrangement of {110} planes in a BCC structure which are the The radii of the two ions (Zn +2 = 74 pm and S -2 = 184 pm) led to the radius (r + / r –) as 0.40 which suggests a tetrahedral arrangement. 13 •S2-form the c.c.p. Polyhedra – vertex-sharing and tetrahedra. Its density is 3.4 g cm-3. Half of the tetrahedral holes in a cubic close packing are occupied. A unit cell is defined by the lengths of its three axes (a, b, and c) and the angles (α, β, and γ) between … In this case there are no close packed planes only close packed directions. Zinc Blende (Zns) Has Fcc Lattice In Cubic Unit Cell As Shown (a Diamond-type Structure). h,k,l. Similar with diamond structure Layers of ZnS 4 Td stacked ..ABCABC.. Cu = 0.128 nm, Crystal structure: FCC, A Cu = 63.5 g/mole n = 4 atoms/cell, 3 3 3(2 2 ) 16 2 V a R R C 3 8 3 23 (4)(63.5) 8.89 / [16 2(1.28 10 ) (6.023 10 )] U g cm u u u 8.96 g/cm3 in the literature DENSITY CALCULATION 86 Explanation: In ZnS, S 2– (sulphide ions) are present at fcc position giving four sulphide ions per unit cell. Statement: ZnS exists in two different forms: zinc blende and wurtzite. Note that with respect to the FCC sites, the tetrahedral sites are shifted by one fourth of the FCC cell's body diagonal (e.g., by 1/4 1/4 1/4), which is equivalent to saying that they are also arranged in an FCC array. Zinc Blende (ZnS) Type Structures (Sphelerite) The zinc sulphide crystals are composed of equal number of Zn +2 and S 2- ions. The space lattice for the ZnS crystal structure can be considered as an fcc lattice with a basis of two atoms, one Zn atom and the other an S atom. (1) 1e e e. ik ih ih k ( ) ( ) ( ) Ff hk =⋅+ + + π+ π+ π+ d0 a a a. All Zn–S bond lengths are 2.36 Å. S2- is bonded to four equivalent Zn2+ atoms to form corner-sharing SZn4 tetrahedra. Structure Factors: ( ) 8 , 4 4 1 , 2 1 0, 4 2 hk f hk N F if h k N hk N ++= = ± ++= + ++= + for hkl all even/all odd: As for . all even or all odd.
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