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1、SensorsandActuatorsB114(2006)969977Amicrostructuralmodelofsemiconductinggassensorresponse:Theeffectsofsinteringtemperatureontheresponseofchromiumtitanate(CTO)tocarbonmonoxideS.C.Naisbitt∗,K.F.E.Pratt,D.E.Williams,I.P.ParkinChristopherIngoldLaboratories,DepartmentofChemist
2、ry,UniversityCollegeLondon,20GordonStreet,LondonWC1H0AJ,UKReceived15April2005;receivedinrevisedform25July2005;accepted26July2005Availableonline3October2005AbstractAsimplemodelofthemicrostructureofasensorasanetworkofthreeresistors,representingthesurface,thebulkandthepartic
3、leboundary,iscombinedwithasimplemodelofsensorresponseinordertounderstandtheeffectsofsinteringtemperatureonresponseofaceramicgas-sensitiveresistor.Thisdescriptionaccuratelyfittedtheresponseofchromiumtitaniumoxidetocarbonmonoxideoverarangeoffourordersofmagnitudeingasconcentr
4、ation.Theparametersrepresentingthemicrostructurearefoundtovarywithsinteringtemperatureaccordingtopredictionsmadefrommicroscopyofthestructures.Theparameterrepresentingchemistryalsovariedwithsinteringtemperature:understandablebecausetitaniumsegregation,whichisthemajordeterm
5、inantofthechargecarrierdistribution,varieswithsinteringtemperature.©2005ElsevierB.V.Allrightsreserved.Keywords:CTO;Gassensorresponse;Modelofmicrostructure1.IntroductionThebehaviourofthegassensitiveregionsisdeterminedbytheinteractionsofoxygenandgaswiththesensingmaterial:Ch
6、romiumtitanate(CTO),ofcompositionCr2−xTixOyhasbeenusedcommerciallyforsomeyearsinsemiconductingmetal1k1−+O2O+p(1)oxidegassensors[1,2].Ithasanumberofbenefitsoverthemore2k−1commonlyusedtinoxide(SnO2)intermsofbaselinestability,selectivityandnegligiblehumidityinterference.Ones
7、ignificant+−k2p+O+CO−→CO2(2)differencebetweenthesematerialsisthattinoxideisn-type,i.e.itsresistivitydecreasesinthepresenceofreducinggasessuchwhereO−istheadsorbedoxygenspeciesandp+apositivehole.ascarbonmonoxide,whereasCTOisp-type,i.e.itsresistanceIfthesurfacecoverageofO−isa
8、ssumedtobelowthisgivesincreasesinthepresenceofreducinggases.Avastamountofrisetothefollowingrespo