Raman Spectroscopy and Microwave Properties of CaTiO3-Based Ceramics

H. Zheng, H. Bagshaw, G. D.C. Csete de Györgyfalva, I. M. Reaney, Rick Ubic, J. Yarwood

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50 Scopus citations

Abstract

x CaTiO 3 –(1– x )Sr(Mg 1/3 Nb 2/3 )O 3 (CTSMN) and y CaTiO 3 –(1– y )NdAlO 3 (CTNA) microwave ceramics have been studied by x-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy. TEM and XRD revealed that all compositions underwent octahedral tilt transitions on cooling, generally resulting in an a a c + tilt system. The exception was the NdAlO 3 end member, which had the R ¯3 c space group, consistent with an a a a tilt configuration. Sr(Mg 1/3 Nb 2/3 )O 3 (SMN), ( x = 0) also exhibited +/–1/3{ hkl } reflections in x-ray and electron diffraction patterns associated with 1:2 long-range ordering of the B-site cations. For x ≥ 0.2, no 1:2 ordered reflections were observed. The long-range B-site ordering in SMN gave rise to sharp Raman bands at 391 and 825 cm –1 . The 391 cm –1 band disappeared for x ≥ 0.2 and the width of the 825 cm –1 band became broader as x increased. It was concluded that for samples with x ≥ 0.2, only short-range ordering remained which decreased in correlation length as x increased. In CTNA solid solutions, a broad Raman band occurred at ~800 cm –1 (absent for y = 0 and 1 and strongest for y = 0.5). The position of this band suggested that its origin was similar in nature to the ~825 cm –1 band observed in CTSMN and therefore related to local short-range cation ordering. A relation between the presence of strong local order and poor Q in zero-temperature coefficient of the resonant frequency CTSMN ( x ≈ 0.2) is postulated.

Original languageAmerican English
Pages (from-to)2948-2956
Number of pages9
JournalJournal of Applied Physics
Volume94
Issue number5
DOIs
StatePublished - 1 Sep 2003

EGS Disciplines

  • Materials Science and Engineering

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