A far-IR reflectance spectrum of a disordered Ba(Zn1/3Ta2/3)O3 dielectric resonator has been studied. The spectrum was analyzed with the Generalized Oscillator model. The real part of the dielectric constant (εr) and loss tangent (tanδ) calculated from the parameters obtained from the fit is comparable to the values measured at microwave frequencies. The possible mode identification and their individual mode contribution to the real and imaginary parts of the complex dielectric constant are also analyzed.

Venkatachalam Subramanian

Department Of Physics

V. R.K. Murthya

Ceramic materials

Dielectric devices

infrared spectroscopy

Lattice vibrations

MICROWAVES

Permittivity

Resonators

Dielectric resonators

BARIUM COMPOUNDS

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IIT Madras

Far-IR reflectance study on B-site disordered Ba (Zn1/3Ta2/3)O3 dielectric resonator

Materials Research Bulletin

La (Mg0.5 Ti (0.5-x) Snx) O3 perovskite ceramics with composition (x=0.0-0.5) are prepared by the solid state reaction method. The ceramics are characterized by x-ray diffraction, far-infrared reflectance, Raman spectroscopy, and microwave dielectric properties. The symmetry of ceramics is monoclinic with P 21 /n space group. Intrinsic dielectric constant and loss are estimated by fitting reflectance to the four-parameter semiquantum model. Transverse optic phonon mode strengths and average phonon damping are calculated. The modes corresponding to B -site ordering are identified in Raman spectra and the A1g mode of La (MgTi) 0.5 O3 is analyzed by assuming two merging modes. The variation of long-range order is correlated with full width half maximum of the A1g mode. Microwave measurements are carried out in the frequency range of 8-10 GHz. The dielectric constant (ε′) is found to gradually decrease from 28.4 to 19.7 with an increase in tin concentration, whereas the temperature coefficient of resonant frequency (τf) decreases from -68 to -84 ppm/°C. The product of the quality factor and resonant frequency (Q×f) obtained for La (MgTi) 0.5 O3 is 55,000 GHz, that decreases to 46,000 for x=0.25 composition and then increases to 63,000 GHz for La (MgSn) 0.5 O3. © 2007 American Institute of Physics.

Fulltext

Journal of Applied Physics

Far-infrared, Raman spectroscopy, and microwave dielectric properties of la (Mg0.5 Ti (0.5-x) Snx) O3 ceramics

Dielectric spectroscopy of Ba(B1/2’B1/2‘)O3complex perovskite ceramics: Correlations between ionic parameters and microwave dielectric properties. I. Infrared reflectivity study (1012–1014Hz)

Electronics Letters

Ba(Zn1/3Ta2/3)O3–Ba(Cd1/3Nb2/3)O3 dielectric ceramics with low microwave loss

Journal of Materials Science Letters

Long-wavelength phonons and effective charges in complex perovskite compounds Ba(Mn1/3Ta2/3)O3 and Ba(Ni1/3Ta2/3)O3

Journal of the American Ceramic Society

Two-Mode Behavior in Complex Perovskite Materials

Lattice vibration modes of some complex perovskites

Journal	Data powered by TypesetMaterials Research Bulletin
Publisher	Data powered by TypesetElsevier Science Ltd, Exeter
ISSN	00255408
Open Access	No