INORGANIC CHEMISTRY CHEM 312
Popular in Course
Popular in Chemistry
This 9 page Class Notes was uploaded by Carmela Kilback on Wednesday September 9, 2015. The Class Notes belongs to CHEM 312 at University of Washington taught by Staff in Fall. Since its upload, it has received 88 views. For similar materials see /class/192591/chem-312-university-of-washington in Chemistry at University of Washington.
Reviews for INORGANIC CHEMISTRY
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 09/09/15
Simple Inorganic Solids 199 fj closepacked layer Repetition of the lst and 2nd iayers gives the hexagonal closepacked structure For the hcp structure there are tetrahedral sites at A and B positions and octahedral sites at C positions 3rd closepacked layer in the cubic closestpacked structure or facecentered cubic structure For the up structure there are tetrahedral and octahedral sites at A B and C positions Figure 63 Close39pa c ltlrig layers as A positions and those of the second layer as 8 positions Two arrangements are possible for a third layer in a close packed structure The spheres in the third layer might line up with those in the rst layer to give an ABA arrangement Figure 63 If continued ABABAB this sequence is described as a hexagonal closepacked hcp arrangement The other possibility is 4 2 3 1 C r 39139 A Flour 630 The a hexagonal closepacked b cubic closepacked lacecentered cu bio and c bodycentered cubic structures The nearest neighbors for each structure are shown below the Crystal models 200 VI Inorganic Solids W V a b 1 Figaro 84 Hexagonal a and b cubic closepacked angemem mm st 39 bodydiagonal or a facecentered cubic structure mamas C The cop aquot the 0 g 48 The ptimi ve cubic unit cell and its latticepoint representation h Fig 07 The bodycentere cubic unit cell and its latticepoint tepresentation 112 l VOLUME76NUMBER20 PHYSICAL REVIEW LETTERS 13MAY 1996 Dimensionally Induced Structural transformations in TitaniumAluminum Multilayers Rajarshi Baneijee Rajiv Ahuja2 and Hamish L Fraserl quot 39 quot Department of Materials Science and Engineering The Ohio State University 116 W 19th Avenue Columbus Ohio 43210 2MultiArc Scienti c Coatings 1064 Chicago Road Troy Michigan 48083 Received 23 October 1995 TiAl multilayered thin lms with a range of bilayer thicknesses have been fabricated by dc magnetron sputtering and characterized by transmission electron microscopy and high resolution electron microscopy A series of structural transitions in the form of changes in the stacking sequence of the closed packed atomic planes in the Ti and Al layers have been observed as a function of the bilayer thickness A possible explanation for these transitions based on the model initially proposed by Red eld and Zangwill is presented in this Letter SOO3190079600213X PACS numbers 6860 p 6835Rh 6865g FIG 3 HREM image from the cross section of the multilayer which has a bilayer thickness of 98 nm The fee stacking sequence existing in both the Al layer and the Ti layer is shown in the gure j J 0 vyc aec vanere mama x have been using because the density was given only to three signi cant gures EXERClSE115 Iridium has the cubic close packed structure The edge of the unit cell has a length of 3833 pm The density of iridium is 2261 gemquot Calculate a value for the Avogadro constant 115 Covalent Molecular Crystals The structure of a molecular crystal is determined primarily by the size an Shape of the molecules which determines how they may be most ef ciently packed together Thus methane the molecules of which have a nearly spherical Shape has a cubic closepacked structure The structure of any molecular crystal can be described in terms of the appropriate space lattice and a motif which is usually one molecule X ray crystallography enables the positions of all the atoms in the unit cell to be determined Thus we nd not only the positions of the molecules in the unit cell but also the distances between all the atoms in the molecule and hence the complete structure Of the molecule By operating at a suf ciently low temperature even the structures of substances that are gases 01 liquids at room temperature can be determined by X ray crystallography lgllre 1121 shows the structures of CO2 and of C12 Brz and 12 In these a b FIG U R The Struc of 312 Br 3 The unit centered cu linear and t bond is fou b Clz Brl same structi centered bu bond length Brz 227 pm Alum nu lerpnckcu IK39UAKLI In 1quot II I lhcdul 11 JL 1quot 39Tmmhcd ml h I u L M Fig 4 Tha munitions of m octahaaral holes and CM tewahudral holes raiatwe m Iha Moms in an ft siruclur The holes take names 1mm the dispositinn of atoms around them I Fig 4 5 An mahodml new in the cm bahwean six spheraa bl A tmmhadral hole in ha cleh banJean but when in a clanpacked Janice A 393 Fig1 m The haxagonal hep unit of the ARAB closepackad solid and bl the cubic foul unit of the ABCABC polywpe The tints uf lha sphare s mrrespnnd m lhe layers shown in Fig 43 mm cmmn Comnmuwn Next Pvevmus Nzxt s m met ands ace Grou ofCloserPackedUp Clos Packed Structures Previnlls CloserPacked mm mm Structures Voids in a Close Packing may dJmEnslonal closerpackjngs ofspheres have two kmds ofvoxds arude h wa 7M thV A by0225R d m r wouldjust tmto an octahedral voxdm acloserpackmgxs gvenZvS by 0 414 R A i AIDA V Iquot x vilv i mmmwmmumwkmkummy m md ml he m Vnmnx chewing mm mm saym r u 1 A 1quot ddm u m Thus twomore tetrahedral voxds surround the spheres Thrs resuus m 2 X 3 11 8 tetrahedral voxds and 2 X 3 h r r hm rm A y there are as many octahedral voxds as there are spheres w r requrre that us closerpacked rrerghbours do not touch each other Next Pvevmus Nzxt39 s mmetx ands Structures ace Grou of CloserPacked Up CloserPacked Structures Previnus CloserPacked Cnpyright 1931 1997 Internatinnal Uninn nf Crystallngxzphy IUCI Webmsler mmmmmmrmmmmmmmmmm rum I68 Sphere packings T A B L E 4 6 Closepacked octahedral structures Fraction of octahedral 39 Sequence of cp layers cns of holes V 39 Formula M and X39 occupied AB ABC All NiAs NaCl MX 6 6 aAlzoa szg 6 4 LiSbO3 V b Layer structures Cdlz CdCl MX 6 3 Framework structures CaClz Rutile Atacamite NiWO4 Anatase aPbOz aAIOOH 31 4 Chain structures p Zrl3 I MX3 6 2 Layer structures Bil3 I YCl3 3 39 Framework structures RhF3 I IrF framework 39 2 a w bl chain Nblm layer MX4 6 l 1 Nb2Clm UzClm I 2 5 Ru4F20 molecular M04F20 molecular st 6 I x UFS chain c aWC16 MX5 6 1 For structures intermediate between the NiAs and col C6 structures see sulphides of chromium p 768 and the NiAs structure p 753 For other structures in which onehalf of the octahedral holes are occupied in a cp XY3 assembly see hydroxyhalides M2XOH3 and in particular Table 1015 p 490 c For other structures in which i 39 or of the octahedral holes are occupied in a cp AX3 assembly see Structures built from cp AX3 layers and in particular Table 410 p 185
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'