Abstract
Alumina-zirconia composites with ZrO{sub 2} contents up to 20% and negligible porosity were investigated at millimeter (mm) wavelengths to determine the changes appearing in the dielectric properties of pure alumina ceramics when unstabilized or partially stabilized ZrO{sub 2} is added to improve the mechanical strength. It is demonstrated that it essential to distinguish between the contributions of the monoclinic and the tetragonal phase of zirconia (m-ZrO{sub 2}, t-ZrO{sub 2}). Permittivity is raised with increasing content of either phases; the effective permittivity can be assessed by the rule of mixtures (Maxwell-Garnett formulation of the generalized Clasussius-Mossotti relation) using permittivity values of 10 for Al{sub 2}O{sub 3}, 14-21 for m-ZrO{sub 2} and 40-45 for t-ZrO{sub 2}. The permittivity data show only a small variation in the investigated range of 9-145 GHz. For the dielectric loss, there is evidence of a predominant contribution of m-ZrO{sub 2}; in addition, the marked increase in loss with frequency becomes sharper. The t-ZrO{sub 2}, which is responsible for strengthening, does not show any significant influence on losses. It is therefore concluded, that ZrO{sub 2} strengthening of alumina is feasible without affecting mm-wave losses at room temperature as long as the presence of m-ZrO{sub 2} is avoided.
Citation Formats
Molla, J, Heidinger, R, Ibarra, A, and Link, G.
Dielectric properties of alumina/zirconia composites at millimeter wavelengths; Propiedades dielectricas de compuestos de alumina/zircona a frequencias milimetricas.
Spain: N. p.,
1994.
Web.
Molla, J, Heidinger, R, Ibarra, A, & Link, G.
Dielectric properties of alumina/zirconia composites at millimeter wavelengths; Propiedades dielectricas de compuestos de alumina/zircona a frequencias milimetricas.
Spain.
Molla, J, Heidinger, R, Ibarra, A, and Link, G.
1994.
"Dielectric properties of alumina/zirconia composites at millimeter wavelengths; Propiedades dielectricas de compuestos de alumina/zircona a frequencias milimetricas."
Spain.
@misc{etde_10104701,
title = {Dielectric properties of alumina/zirconia composites at millimeter wavelengths; Propiedades dielectricas de compuestos de alumina/zircona a frequencias milimetricas}
author = {Molla, J, Heidinger, R, Ibarra, A, and Link, G}
abstractNote = {Alumina-zirconia composites with ZrO{sub 2} contents up to 20% and negligible porosity were investigated at millimeter (mm) wavelengths to determine the changes appearing in the dielectric properties of pure alumina ceramics when unstabilized or partially stabilized ZrO{sub 2} is added to improve the mechanical strength. It is demonstrated that it essential to distinguish between the contributions of the monoclinic and the tetragonal phase of zirconia (m-ZrO{sub 2}, t-ZrO{sub 2}). Permittivity is raised with increasing content of either phases; the effective permittivity can be assessed by the rule of mixtures (Maxwell-Garnett formulation of the generalized Clasussius-Mossotti relation) using permittivity values of 10 for Al{sub 2}O{sub 3}, 14-21 for m-ZrO{sub 2} and 40-45 for t-ZrO{sub 2}. The permittivity data show only a small variation in the investigated range of 9-145 GHz. For the dielectric loss, there is evidence of a predominant contribution of m-ZrO{sub 2}; in addition, the marked increase in loss with frequency becomes sharper. The t-ZrO{sub 2}, which is responsible for strengthening, does not show any significant influence on losses. It is therefore concluded, that ZrO{sub 2} strengthening of alumina is feasible without affecting mm-wave losses at room temperature as long as the presence of m-ZrO{sub 2} is avoided.}
place = {Spain}
year = {1994}
month = {Dec}
}
title = {Dielectric properties of alumina/zirconia composites at millimeter wavelengths; Propiedades dielectricas de compuestos de alumina/zircona a frequencias milimetricas}
author = {Molla, J, Heidinger, R, Ibarra, A, and Link, G}
abstractNote = {Alumina-zirconia composites with ZrO{sub 2} contents up to 20% and negligible porosity were investigated at millimeter (mm) wavelengths to determine the changes appearing in the dielectric properties of pure alumina ceramics when unstabilized or partially stabilized ZrO{sub 2} is added to improve the mechanical strength. It is demonstrated that it essential to distinguish between the contributions of the monoclinic and the tetragonal phase of zirconia (m-ZrO{sub 2}, t-ZrO{sub 2}). Permittivity is raised with increasing content of either phases; the effective permittivity can be assessed by the rule of mixtures (Maxwell-Garnett formulation of the generalized Clasussius-Mossotti relation) using permittivity values of 10 for Al{sub 2}O{sub 3}, 14-21 for m-ZrO{sub 2} and 40-45 for t-ZrO{sub 2}. The permittivity data show only a small variation in the investigated range of 9-145 GHz. For the dielectric loss, there is evidence of a predominant contribution of m-ZrO{sub 2}; in addition, the marked increase in loss with frequency becomes sharper. The t-ZrO{sub 2}, which is responsible for strengthening, does not show any significant influence on losses. It is therefore concluded, that ZrO{sub 2} strengthening of alumina is feasible without affecting mm-wave losses at room temperature as long as the presence of m-ZrO{sub 2} is avoided.}
place = {Spain}
year = {1994}
month = {Dec}
}