Experimental and theoretical investigation of the structural, chemical, electronic, and high frequency dielectric properties of barium cadmium tantalate-based ceramics

Journal Article · Sat Jan 01 00:00:00 EST 2005 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.1823575· OSTI ID:20664969

Shaojun, Liu; Taylor, Richard; Petrovic, Novak S; Budd, Louisa; Van Schilfgaarde, Mark; Newman, N ^[1]

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1. Chemical and Materials Engineering Department, Arizona State University, Tempe, Arizona 85287-6006 (United States)

Single-phase Ba(Cd{sub 1/3}Ta{sub 2/3})O{sub 3} powder was produced using conventional solid state reaction methods. Ba(Cd{sub 1/3}Ta{sub 2/3})O{sub 3} ceramics with 2 wt % ZnO as sintering additive sintered at 1550 deg. C exhibited a dielectric constant of {approx}32 and loss tangent of 5x10{sup -5} at 2 GHz. X-ray diffraction and thermogravimetric measurements were used to characterize the structural and thermodynamic properties of the material. Ab initio electronic structure calculations were used to give insight into the unusual properties of Ba(Cd{sub 1/3}Ta{sub 2/3})O{sub 3}, as well as a similar and more widely used material Ba(Zn{sub 1/3}Ta{sub 2/3})O{sub 3}. While both compounds have a hexagonal Bravais lattice, the P321 space group of Ba(Cd{sub 1/3}Ta{sub 2/3})O{sub 3} is reduced from P3 lowbar m1 of Ba(Zn{sub 1/3}Ta{sub 2/3})O{sub 3} as a result of a distortion of oxygen away from the symmetric position between the Ta and Cd ions. Both of the compounds have a conduction band minimum and valence band maximum composed of mostly weakly itinerant Ta 5d and Zn 3d/Cd 4d levels, respectively. The covalent nature of the directional d-electron bonding in these high-Z oxides plays an important role in producing a more rigid lattice with higher melting points and enhanced phonon energies, and is suggested to play an important role in producing materials with a high dielectric constant and low microwave loss.

• OSTI ID: 20664969
• Journal Information: Journal of Applied Physics, Vol. 97, Issue 1; Other Information: DOI: 10.1063/1.1823575; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM COMPOUNDS
CADMIUM COMPOUNDS
CADMIUM IONS
CERAMICS
DENSITY FUNCTIONAL METHOD
ELECTRONIC STRUCTURE
GHZ RANGE 01-100
LATTICE PARAMETERS
MELTING POINTS
MICROSTRUCTURE
MUFFIN-TIN POTENTIAL
OXYGEN
PERMITTIVITY
SINTERING
SPACE GROUPS
TANTALATES
THERMAL GRAVIMETRIC ANALYSIS
TRIGONAL LATTICES
X-RAY DIFFRACTION
ZINC OXIDES