Low loss alumina dielectrics by aqueous tape casting: The
influence of composition on the loss tangent

J 2012

Low loss alumina dielectrics by aqueous tape casting: The influence of composition on the loss tangent

CHOVANEC, Jozef, Dusan GALUSEK, Jozef RÁHEĽ and Pavol ŠAJGALÍK

Basic information

Original name

Low loss alumina dielectrics by aqueous tape casting: The influence of composition on the loss tangent

Name in Czech

Nízkostrátové korundové dielektrikum připravené technikou tape casting: Vliv složení na strátový úhel

Authors

CHOVANEC, Jozef (703 Slovakia, guarantor), Dusan GALUSEK (703 Slovakia), Jozef RÁHEĽ (703 Slovakia, belonging to the institution) and Pavol ŠAJGALÍK (703 Slovakia)

Edition

Ceramics International, Elsevier, 2012, 0272-8842

Other information

Language

English

Type of outcome

Článek v odborném periodiku

Field of Study

20504 Ceramics

Country of publisher

United Kingdom of Great Britain and Northern Ireland

Confidentiality degree

není předmětem státního či obchodního tajemství

Impact factor

Impact factor: 1.789

RIV identification code

RIV/00216224:14310/12:00064286

Organization unit

Faculty of Science

DOI

http://dx.doi.org/10.1016/j.ceramint.2012.01.020

UT WoS

000303634900031

Keywords in English

Tape casting; Loss tangent; Alumina; Dopants

Abstract

V originále

Polycrystalline aluminas with various concentrations of oxide dopants CaO, MgO, and TiO2, ranging from 0.05 wt.% to 5 wt.% (3 wt.% in case of MgO), as well as pure alumina references were prepared by tape casting of aqueous suspensions and sintered in air at 1600 degrees C for 4 h for applications as low dielectric loss electroceramics. Loss tangents were measured at room temperature in the frequency range between 1 and 100 kHz as the key parameter for the intended application. The values of loss tangents of doped materials were influenced by the concentration of dopants. The addition of 0.5 and 5 wt.% of TiO2 and 3 wt.% of MgO decreased the value of loss tangent in the whole frequency range. The addition of these dopants eliminated abnormal grain growth and decreased the amount of residual porosity. By doing so, the dopants compensated the negative influence of process impurities and decreased the loss tangent values. The cations (Ti4+) with high solubility in the Al2O3 crystal lattice were preferably built into the grain boundary glass, thus efficiently reducing the concentration of polarizable defects in corundum matrix; the formation of vitreous phase had a positive effect on the value of loss tangent in TiO2 doped samples. The increased values of loss tangent were related to lower density of prepared materials, and the presence of residual porosity. Other contributing factors were especially the formation of calcium-containing secondary crystalline phases, and the increased concentration of lattice defects due to incorporation of atoms with different valencies to alumina crystal lattice. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Citovat

CHOVANEC, Jozef, Dusan GALUSEK, Jozef RÁHEĽ and Pavol ŠAJGALÍK. Low loss alumina dielectrics by aqueous tape casting: The influence of composition on the loss tangent. Ceramics International. Elsevier, 2012, vol. 38, No 5, p. 3747-3755. ISSN 0272-8842. Available from: https://dx.doi.org/10.1016/j.ceramint.2012.01.020.

@article{1090574,
   author = {Chovanec, Jozef and Galusek, Dusan and Ráheľ, Jozef and Šajgalík, Pavol},
   article_number = {5},
   doi = {http://dx.doi.org/10.1016/j.ceramint.2012.01.020},
   keywords = {Tape casting; Loss tangent; Alumina; Dopants},
   language = {eng},
   issn = {0272-8842},
   journal = {Ceramics International},
   title = {Low loss alumina dielectrics by aqueous tape casting: The influence of composition on the loss tangent},
   volume = {38},
   year = {2012}
}

TY  - JOUR
ID  - 1090574
AU  - Chovanec, Jozef - Galusek, Dusan - Ráheľ, Jozef - Šajgalík, Pavol
PY  - 2012
TI  - Low loss alumina dielectrics by aqueous tape casting: The influence of composition on the loss tangent
JF  - Ceramics International
VL  - 38
IS  - 5
SP  - 3747-3755
EP  - 3747-3755
PB  - Elsevier
SN  - 02728842
KW  - Tape casting
KW  - Loss tangent
KW  - Alumina
KW  - Dopants
N2  - Polycrystalline aluminas with various concentrations of oxide dopants CaO, MgO, and TiO2, ranging from 0.05 wt.% to 5 wt.% (3 wt.% in case of MgO), as well as pure alumina references were prepared by tape casting of aqueous suspensions and sintered in air at 1600 degrees C for 4 h for applications as low dielectric loss electroceramics. Loss tangents were measured at room temperature in the frequency range between 1 and 100 kHz as the key parameter for the intended application. The values of loss tangents of doped materials were influenced by the concentration of dopants. The addition of 0.5 and 5 wt.% of TiO2 and 3 wt.% of MgO decreased the value of loss tangent in the whole frequency range. The addition of these dopants eliminated abnormal grain growth and decreased the amount of residual porosity. By doing so, the dopants compensated the negative influence of process impurities and decreased the loss tangent values. The cations (Ti4+) with high solubility in the Al2O3 crystal lattice were preferably built into the grain boundary glass, thus efficiently reducing the concentration of polarizable defects in corundum matrix; the formation of vitreous phase had a positive effect on the value of loss tangent in TiO2 doped samples. The increased values of loss tangent were related to lower density of prepared materials, and the presence of residual porosity. Other contributing factors were especially the formation of calcium-containing secondary crystalline phases, and the increased concentration of lattice defects due to incorporation of atoms with different valencies to alumina crystal lattice. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
ER  -

CHOVANEC, Jozef, Dusan GALUSEK, Jozef RÁHEĽ and Pavol ŠAJGALÍK. Low loss alumina dielectrics by aqueous tape casting: The influence of composition on the loss tangent. \textit{Ceramics International}. Elsevier, 2012, vol.~38, No~5, p.~3747-3755. ISSN~0272-8842. Available from: https://dx.doi.org/10.1016/j.ceramint.2012.01.020.

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