Now showing items 1-11 of 11
Abstract: | A new microwave dielectric resonator Ba(Tb1/2Nb1/2)03 has been prepared and characterized in the microwave frequency region. 1 wt% CeO2 is used as additive to reduce the sintering temperature. The sintered samples were characterized by XRD, SEM and Raman spectroscopic methods. Microwave DR properties such as er, Q factor and temperature-coefficient of resonant frequency (Ti) have been measured using a HP 8510 B Network Analyzer. Cylindrical DRs of Ba(Tb1/2Nbi/2)03 showed high Er (~ 37), high Q (~3,200) and low Tf (~10 ppm /°C) at 4 GHz and hence are useful for practical applications |
URI: | http://dyuthi.cusat.ac.in/purl/1447 |
Files | Size |
---|---|
Ba(Tb1 2Nb1 2)0 ... e dielectric resonator.PDF | (2.173Mb) |
Abstract: | Ceramic dielectrics with high dielectric constant in the microwave frequency range are used as filters, oscillators [I], etc. in microwave integrated circuits (MICs) particularly in modern communication systems like cellular telephones and satellite communications. Such ceramics, known as 'dielectric resonators (DRs),donot only offer miniaturisation and reduce the weight of the microwave components. but also improve the efficiency of MICs |
URI: | http://dyuthi.cusat.ac.in/purl/1437 |
Files | Size |
---|---|
Dielectric properties of Ba5Nb4O15 ceramic.PDF | (1.376Mb) |
Dielectric properties of Ba5Nb4O15 ceramic.PDF | (1.376Mb) |
Abstract: | A new group of compounds with composition (Ba5-xSrx) Nb4015, having high permittivity and low loss have been prepared and characterized in the microwave frequency region . X-ray diffraction studies showed that monophase compound existed for all values of x from 0 to 5. Microwave dielectric properties such as and c f showed smooth variation with x , while the unloaded quality factor (Qu) showed remarkable improvement with x |
URI: | http://dyuthi.cusat.ac.in/purl/1440 |
Files | Size |
---|---|
Sreemoolanadhan,H & Sebastian,M.T.PDF | (1.655Mb) |
Abstract: | The BaO-2CeO2-nTiO2 ceramics with n = 3, 4 and 5 have been prepared with CeO2 as starting material . The ceramics have been characterized using scanning electron microscopy , X-ray diffraction , Raman and X-ray photoelectron spectroscopy techniques. The microwave dielectric properties have been measured using standard dielectric resonator techniques . BaO-2CeO2-3TiO2 (123), BaO-2CeO2-4TiO2 ( 124) and BaO-2CeO2-5TiO2 ( 125) ceramics showed dielectric constants of 38, 27 and 32, respectively . All the ceramics showed fairly good unloaded Q - factors . 124 and 125 compounds exhibited low tf values, while 123 showed a high rf value |
URI: | http://dyuthi.cusat.ac.in/purl/1493 |
Files | Size |
---|---|
Microwave diele ... -2CeO2-nTiO2 ceramics.PDF | (3.306Mb) |
Abstract: | Dielectric resonator ceramics with composition formula Ba[(D3+0.3 Bi0.2)Nb0.5]O3,where D3+=Y,Pr,Sm,Gd,Dy and Er,were prepared by the conventional ceramic preparation route |
URI: | http://dyuthi.cusat.ac.in/purl/1441 |
Files | Size |
---|---|
Microwave diele ... Y, Pr, Sm, Gd, Dy, Er).PDF | (2.529Mb) |
Abstract: | New dielectric ceramics with formula BaTi3Nb4, O„ and Ba6Til4Nbz039 have been prepared and characterized. BaTi3Nba017 was densified to 92% of TD after firing at 1310 oC for 4 h. However, Ba6Ti 1 4Nb2O39 fired under optimized conditions (1260 ` C for 4 h) showed only 85% TD together with secondary phase. The crystal system of both of the compositions is orthorhombic |
URI: | http://dyuthi.cusat.ac.in/purl/1443 |
Files | Size |
---|---|
New high permit ... TiO2-Nb2O5 composition.PDF | (2.094Mb) |
Abstract: | Ceramics of composition BaO-Ln2O3-STiO2 have been prepared with four elements (Ln=La,Pr,Nd.Sm) by a conventional solid state ceramic preparation route and the dielectric properties measured in the microwave frequency range |
URI: | http://dyuthi.cusat.ac.in/purl/1439 |
Files | Size |
---|---|
Dielectric reso ... (Ln = La, Pr, Nd, Sm).PDF | (3.733Mb) |
Abstract: | The dielectric ceramics BaNd2Ti3Oto, BaNd2Ti4O12 and BaNd2Ti5O14 have been prepared by Conventional solid state ceramic route. The sintered ceramic samples have been characterized by X-ray diffraction and Scanning Electron Microscopy (SEM). The dielectric properties in the microwave frequency range have been measured using conventional microwave dielectric resonator methods. The BaNd2Ti1O10, BaN2Ti4O12 and BaNd2Ti5O14 have dielectric constants (Er) ~ 60, 84 and 77 respectively. They have relatively high quality factors |
URI: | http://dyuthi.cusat.ac.in/purl/1444 |
Files | Size |
---|---|
Preparation,cha ... BaO-Nd2O3-TiO2 system.PDF | (2.220Mb) |
Abstract: | Microwave dielectric resonators (DRs) based on Ba(B1,2Nbi/2)03 [B' = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Yb, and In] complex perovskites have been prepared by conventional solid state ceramic route. The dielectric properties (relative permittivity, Er; quality factor, Q; and resonant frequency, rr) of the ceramics have been measured in the frequency range 4-6 GHz using resonance methods. The resonators have relatively high dielectric constant in the range 36-45, high quality factor and small temperature variation of resonant frequency. The dielectric properties are found to depend on the tolerance factor (t), ionic radius (r), and lattice parameter (ap) |
URI: | http://dyuthi.cusat.ac.in/purl/1494 |
Files | Size |
---|---|
Preparation, ch ... Y, Yb and In] ceramics.PDF | (4.468Mb) |
Abstract: | The (Ba1-x Srx) (Nd1/2, Nb1/2) O3 ceramics have been prepared by the conventional ceramic route for different values of x. Addition of a small amount of CeO2(1 wt%) as a sintering aid increased the density of the samples. The structure and microstructure of the sintered samples are studied by X-ray diffraction and SEM methods. The dielectric properties of the samples are measured in the microwave frequency region as a function of composition. The dielectric constant decreases as x increases. The coefficient of thermal variation of resonant frequency decreases as the Sr content increases and goes to the negative side. The dielectric properties of (Ba1-x Srx) (Nd1/2, Nb1/2) O3 are in the range suitable for application as dielectric resonators in microwave circuits |
URI: | http://dyuthi.cusat.ac.in/purl/1438 |
Files | Size |
---|---|
Sreemoolanadhan H and others.PDF | (2.413Mb) |
Abstract: | 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 |
URI: | http://dyuthi.cusat.ac.in/purl/1445 |
Files | Size |
---|---|
Tailoring the m ... mpositional variations.PDF | (4.793Mb) |
Now showing items 1-11 of 11
Dyuthi Digital Repository Copyright © 2007-2011 Cochin University of Science and Technology. Items in Dyuthi are protected by copyright, with all rights reserved, unless otherwise indicated.