substance:titaniumoxide(TiO2)property:crystalstructure,latticeparametersandrelatedparametersofanatase19crystalstructure:tetragonal,spacegroupD4h–I41/amd,Z=4[70R,72H].ThestructuremaybederivedfromtheB1structureofNaClbyorderingTi4+ionsandTi-vacanciesasshowninFig.1;thebridgingoxygensaredisplacedtowardsoneanothertoproduce-shorterO–Odistances.latticeparametersa3.7845ÅT=28oC70Rc9.5143Åa3.7855ÅT=84oCc9.5185Åa3.7866ÅT=161oCc9.5248Åa3.7875ÅT=210oCc9.5294Åa3.7884ÅT=258oCc9.5342Åa3.7894ÅT=306oCc9.5374Åa3.7907ÅT=354oCc9.5432Åa3.7923ÅT=449oCc9.5548Åa3.7939ÅT=497oCc9.5595Åa3.7948ÅT=534oCc9.5669Åa3.7962ÅT=571oCc9.5754Åa3.7970ÅT=608oCc9.5794Åa3.7989ÅT=645oCc9.5872Åa3.7998ÅT=679oCc9.5933Åa3.8009ÅT=712oCc9.5975Ådensity–3dcalc3.894gcmT=298K70Rinteratomicdistancesandangles(from[72H])(seealsoFig.2)T=25oCT=300oCT=600oCT=900oCd(Ti–O)1.9338(5)Å1.9365(5)Å1.9410(5)Å1.9452(7)Å(s)sharededged(Ti–O||[001])1.9797(23)Å1.9831(22)Å1.9909(23)Å1.9957(31)Åd(O–O)(s)2.4658(29)Å2.4681(29)Å2.4745(30)Å2.4777(39)Åd(O–O)2.7924(13)Å2.7968(13)Å2.8037(14)Å2.8108(18)ÅangleO–Ti–O101.90(7)o101.96(7)o102.01(7)o102.10(9)ocoefficientoflinearthermalexpansionα||7.380·10–6+6.620·10–9(T–273)+1.771·10–11(T–273)2seeFig.370Rα⊥3.533·10–6+5.610·10–9(T–273)+4.315·10–12(T–273)2References:70RRao,K.V.K.,NagenderNaidu,S.V.,Iyengar,L.:J.Am.Ceram.Soc.53(1970)124.72HHorn,M.,Schwertfeger,C.F.,Meagher,E.P.:Z.Kristallogr.136(1972)273.75WWells,A.F.:StructuralInorganicChemistryO.U.P.1975.Fig.1.TiO2,anatase.RelationshipofanatasetoNaCl.MetalionsremovedfromtheNaClstructureareshownasdottedcircles[75W].Fig.2.TiO2,anatase.UpperandlowerboundstothetwonearestTi–Obondlengthsvs.temperature[72H].Fig.3.TiO2,anataseandrutile.Thermalexpansioncoefficientsvs.temperature[70R].