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|Type:||Artigo de periódico|
|Title:||Effect Of Pressure On The Zone-center Phonons Of Pbtio3 And On The Ferroelectric-paraelectric Phase Transition|
|Abstract:||The first-order Raman spectrum of single-crystalline PhTiO3 in the teatragonal ferroelectric phase was studied at room temperature as a function of hydrostatic pressure up to 80 kbar. Mode Grüneisen parameters, as well as higher-order coefficients in the expansion of phonon frequency vs pressure are reported for all zone-center TO phonons. The pressure P1 at which the ferroelectric-paraelectric (FE → PE) phase transition would occur continously can be obtained by fitting the pressure dependence of the lowest E(TO) "soft" mode frequency with a Curie-Weiss-type law. This criterion yields P1=90±4 kbar. Limits for the first derivative of the transition temperature with pressure are similarly obtained and yield 5.2<-dTCdP<5.9 K/kbar. The information on the FE → PE phase transition obtained here is in good agreement with previously reported data obtained by measuring the pressure dependence of the dielectric constant in the PE phase. © 1975 The American Physical Society.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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