Surendran,K P; Bijumon, P V; Mohanan, P; Sebastian,M T(Department of Electronics, April 14, 2005)
[+]
[-]
Abstract:
The MgAl2O4 ceramics were prepared by the conventional
solid-state ceramic route and the dielectric properties
studied in the microwave frequency region (3–13 GHz).
The phase purity and crystal structure were identified using
the X-ray diffraction technique. The MgAl2O4 spinel ceramics
show interesting microwave dielectric properties (εr = 8.75,
Qux f = 68 900 GHz (loss tangent = 0.00017 at 12.3 GHz),
τf =−75 ppm/◦C). The MgAl2O4 has high negative τf, which
precludes its immediate use in practical applications. Hence
the microwave dielectric properties of MgAl2O4 spinels were
tailored by adding different mole fractions of TiO2. The
εr and Q factor of the mixed phases were increased with
the molar addition of TiO2 into the spinel to form mixtures
based on (1−x)MgAl2O4-xTiO2 (x = 0.0−1.0). For x = 0.25 in (1−x)MgAl2O4-xTiO2, the microwave quality factor
reaches a maximum value of Qux f = 105 400 GHz (loss tangent
= 0.00007 at 7.5 GHz) where εr and τf are 11.035 and
−12 ppm/◦C, respectively. The microwave dielectric properties
of the newly developed 0.75MgAl2O4-0.25TiO2 dielectric is
superior to several commercially available low loss dielectric
substrates.
microwave dielectric properties of ceramics based on Ba(Mgv3Ta(2-2x)t3W,t3Tixt3)O3 is investigated as a function of x. The
15 densification as well as dielectric properties deteriorate with increase in the substitution levels of (Ti 1,3W113)333 + at (Ta213)3.33+ site
16 in Ba(Mg113Ta213)03. The rt is approaching zero between x = 0.1 and 0.15 in Ba(Mg it3Ta(2-2,,.)t3W,it3Ti,Tt3)O3 where quality factor is
17 reasonably good (Qu x f = 80,000-90,000 GHz). The Ba(Mg1,3Ta(2_,013W,13Ti,,13)03 with x = 1.0 has e, = 15.4, rf= -25.1 ppm/
18 "C, Q„ x f = 35,400 GHz
Sudha Kartha, C; Vijayakumar, K P; Anita, Warrier R; Sajeesh, T H(Elsevier, February 2, 2010)
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Abstract:
SnS thin films were prepared using automated chemical spray pyrolysis (CSP) technique. Single-phase, p-type,
stoichiometric, SnS films with direct band gap of 1.33 eV and having very high absorption coefficient (N105/cm)
were deposited at substrate temperature of 375 °C. The role of substrate temperature in determining the
optoelectronic and structural properties of SnS films was established and concentration ratios of anionic and
cationic precursor solutions were optimized. n-type SnS samples were also prepared using CSP technique at the
same substrate temperature of 375 °C, which facilitates sequential deposition of SnS homojunction. A
comprehensive analysis of both types of films was done using x-ray diffraction, energy dispersive x-ray analysis,
scanning electron microscopy, atomic force microscopy, optical absorption and electrical measurements.
Deposition temperatures required for growth of other binary sulfide phases of tin such as SnS2, Sn2S3 were also
determined
Girish Kumar,K; Karthikeyan, G; Mohanraj, K; Elango, K P(Pleiades, 2006)
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Abstract:
A series of nonelectrolytic lanthanide(III) complexes,
[
ML
2
Cl
3
]
·
2
H
2
O, where M is lanthanum(III),
praseodymium(III), neodymium(III), samarium(III), gadolinium(III), terbium(III), dysprosium(III), and
yttrium(III), containing sulfamethoxazole ligand (L) are prepared. The structure and bonding of the ligand are
studied by elemental analysis, magnetic susceptibility measurements, IR,
1
H NMR,
TG
/
DTA
, X-ray diffraction
studies, and electronic spectra of the complexes. The stereochemistry around the metal ions is a monocapped
trigonal prism in which four of the coordination sites are occupied by two each from two chelating ligands, sulfonyl
oxygen, and nitrogen of the amide group and the remaining three positions are occupied by three chlorines.
The ligand and the new complexes were tested in
vitro to evaluate their activity against the bacteria
Escherichia
coli
and
Staphylococcus
aureus.