Many compounds, notably the common mineral fluorite (CaF 2), adopt this structure. Ionic compound of A2B type. Fluorite (CaF2) and Antifluorite (Li2O) Fluorite: CCP of Ca2+with all T+and T-holes filled with F-Antifluorite: CCP of O2-with all T+and T-holes filled with Li+ Coordination= 8, 4 (fluorite) Cation Coord. In Fe3O4, Fe+2 and Fe+3 ions are present in the ratio 2:1. it may be considered as having composition FeO.Fe2O3. Black Friday Sale! Related Structure: Fluorite … Premium Membership is now 50% off! The compound having A2B formula are compounds having anti fluorite structure. FCC packing of anions. Thus the number of CaF2 units per unit cell is 4. (iv) Each Ca+2 ion is surrounded by 8F- ions and each F− ions is surrounded by 4Ca+2 ions. Therefore, Li2O has 4:8 coordination, Examples – Na2O, K2O, K2S, Na2S, Rb2O, Rb2S. … – Na + 4 (tetrahedral) : O 2-8 (cubic). Other examples of structure are SrF2, BaCl2, BaF2, PbF2, CdF2, HgF2, CuF2, SrCl2, etc. →Cubic Anion Coord. Anti fluorite structure is having arrangement of cations and anions opposite to the fluorite structure Li2O has an anti fluorite structure. Cl- ions in ccp Na+ ions occupy all octahedral voids, NH4Cl, NH4Br, NH4I, AgF, AgCl, AgBr, MgO, CaO, TiO, FeO, NiO, S-2 ions in ccp Zn+2 ions occupy alternate tetrahedral voids, S-2 ions in hcp Zn+2 ion occupy alternate tetrahedral voids, Cl- ions in bcc Cs+ ions in the body of cube, Ca+2 ions in ccp, F- ions occupy all tetrahedral voids, CaF2, SrF2, BaF2, BaCl2, SrCl2, CdF2, HgF2, O-2 ions in ccp, Li+ ions occupy all tetrahedral sites, A-1, Acharya Nikatan, Mayur Vihar, Phase-1, Central Market, New Delhi-110091. In Fe3O4 Oxide arranged in ccp. The Coordination number of Ca+2 ion is eight and that of F− ion is four, this is called 8:4 Coordination. Other articles where Antifluorite structure is discussed: sulfide mineral: …eight metal cations—is called the antifluorite structure. Fe+2 ions occupy octahedral voids while Fe+3 ions are equally distributed between octahedral and tetrahedral voids. of Ca+2 ions = 8(at corners)×1/8 + 6 (at face centres)×1/2, No. (v) Each unit cell has 4 calcium ions and 8 fluoride ions as explained below, No. Magnetite has inverse spinet structure. Polyhedra – Edge-sharing , edge-sharing . It is the arrangement of some of the more valuable precious metal tellurides and selenides among which is hessite (Ag2Te), the ore mineral of silver. (ii) The F– ions occupy all the tetrahedral holes. MgFe2O4 also has structure similar to magnetite. Chemical formula: M2X (i) In the crystal structure of Li2O, the O-2 ions constitute a cubic close packed lattice (fcc structure) and the Li+ ions occupy all the tetrahedral voids, (ii) Each oxide ion, O-2 ion is in contact with 8 Li+ ions and each Li+ ions having contact with 4 oxide ion. these ions occupy all the corners and the centres of each face of the cube. It is the arrangement of some of the more valuable precious metal tellurides and selenides among which is hessite (Ag2Te), the ore mineral of silver. (iii) Since there are two tetrahedral holes for each Ca+2 ion and F− ions occupy all the tetrahedral holes, there will be two F− ions for each Ca+2 ions, thus the stoichiometry of the compound is 1:2. Explanation: 1.7.2.1 Antifluorite. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Spinel is a mineral MgAl2O4. Anti fluorite structure is having arrangement of cations and anions opposite to the fluorite structure Li 2 O has an anti fluorite structure. https://www.britannica.com/science/antifluorite-structure. O 2-with Na + in all Td holes. …eight metal cations—is called the antifluorite structure. Anions form the cubic close packing while cations fill all tetrahedral holes. all rights reserved. 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