Mohanan, T(American Institute of Physics, August 22, 2005)
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Abstract:
The effect of dopants with different valencies and ionic radii on the densification, structural
ordering, and microwave dielectric properties of Ba(Mg1/3Ta2/3)O3 (BMT) is investigated. It is
found that dopants such as Sb2O5, MnO, ZrO2, WO3, and ZnO improve the microwave dielectric
properties of BMT. Addition of trivalent dopants is detrimental to the cation ordering and dielectric
properties of BMT. A correlation between the microwave dielectric properties of BMT and ionic
radii of the dopant has been established. The variation of the dielectric properties of pure and doped
BMT at cryogenic temperatures is also discussed.
Surendran,K P; Sebastian,M T; Mohanan, P; Mohanan,Jacob V(American Institute of Physics, 2005)
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Abstract:
The effect of dopants with different valencies and ionic radii on the densification, structural
ordering, and microwave dielectric properties of Ba(Mg1t3Tazt3)O3 (BMT) is investigated. It is
found that dopants such as Sb,05, MnO, ZrO,, WO1, and ZnO improve the microwave dielectric
properties of BMT. Addition of trivalent dopants is detrimental to the cation ordering and dielectric
properties of BMT. A correlation between the microwave dielectric properties of BMT and ionic
radii of the dopant has been established. The variation of the dielectric properties of pure and doped
BMT at cryogenic temperatures is also discussed
Isuhak, Naseembeevi Jawahar; Narayana Iyer, Santha; Mailadil, Thomas Sebastian(Materials Reserach Society, December , 2002)
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Abstract:
Single-phase polycrystalline ceramics in the MO-La2O3-Ti02 (M = Ca, Sr, Ba)
system, such as cation-deficient hexagonal perovskites CaLa4Ti4O15, SrLa4Ti4O15,
BaLa4Ti4O15, and Ca2La4Ti5O18 and the orthorhombic phases CaLa4Ti5O17 and
CaLa8Ti9O31, were prepared through the solid-state ceramic route. The phases
and structure of the ceramics were analyzed through x-ray diffraction and scanning
electron microscopy. The microwave dielectric properties of the ceramics were studied
using a network analyzer. The investigated ceramics show high Er in the range 42 to
54, high quality factors with Q x f in the range 16,222 to 50,215 GHz, and low Tf in
the range -25 to +6 ppm3/°C. These high dielectric constant materials with high Q x f
up to 50,215 GHz are suitable for applications where narrow bandwidth and extremely
low insertion loss is necessary, especially at frequencies around 1.9 GHz
Ceramic dielectric resonators in the BaO-RE2O3-TiO2 (RE = rare earth) system have been
prepared by the conventional solid state ceramic route. The dielectric properties have been
tailored by substitution of different rare earth oxides and by bismuth oxide addition. The
dielectric constants increased with Bi addition whereas the 0 decreased. The temperature
coefficient of the resonant frequency improved with bismuth addition