简介：UltrasonicvelocitieshavebeenmeasuredinsinglephaseBi1.7Pb0.3Sr2CaCu2O8+xandBi1.7Pb0.3Sr2Ca2O10+xpolycrystallinesamples.Anomalouschangesofbothlongitudinalandtransversevelocitieswereobservednear200K,whichindicatesthatsomestructuralphasetransitiomightoccur.Theelasticconstantsofthesesampleshavebeendeterminedfromthemeasuredultrasonicvelocitydata,whicharemuchsmallerthanthoseofYBa2Cu3O7-yandBaTiO3,manifestingthattheinterlayercoup-lingwilldramaticallydecreasewhenthec-axesoftheunitcellsoftheseperovstite-likemultilayerceramicsincrease.ThevaluesofPoissonratio,however,ofthoseceramicsareveryclose,implyingsimilarinteratomicbondingforces.Correctedtovoid-freestate,theDebyetemperatureofthesematerialsisestirnatedas270±20k.ThetemperaturedependenceofDebyetemperaturesforthesematerialsisalsocalculatedbyusingthesamemethodandreportedforthefirsttime.