Effects of Ion Substitution on Microwave Dielectric Characteristics Including the Pressure Dependence of Capacitance

1.Effects of A-site Alkaline-Earth Substitution of Perovskite Oxide on Microwave Dielectric CharacteristicsThe main systems studied were as follows：(A I D21-x II D2A‘I D2)ZrO I D23 I D 2.(A D 21-x D 2 A‘i D 2 x D 2)(Mg D 21/3 D 2 Ta D 22/3 D 2)O D 23 D 2，(A D 21-x D 2 A’I D 2 x D 2)(Zn D 21/3 D 2 Ta D 22/3 D 2)O I D 23 D 2(AA‘=Ba，Sr，Ca)and further(Ba I D21-x ii D 2 A‘I D 2 x D 2)(B I D 21/2 I D 2 B’I D 21/2 I D 2 O I D 23 I D 2(A‘=Ca，Sr B=Y，Nd：B’=Nb，Ta)。Followings are summaries of this subtitle.That is，systematic differences are noted in the order of differences of ionic radii of the two alkaline-earth ions for the(Ba I D21-x I D2 Ca I D2)，(Ba I D 21-x I D 2 Sr I D2)，and(Sr I D 21-x D 2 Ca D 2 x D 2)substitution systems.Dielectric constants increase sharp with x to have respective peak values at around the limit compositions of isomorphism substitutions of Ba by Ca for all systems studied.Further，and dielectric losses also increase sharp to have plateaus.2。Pressure Dependence of CapacitancePressure Dependences of Capacitance were measured for pellets of the(Ba I D21-x II D2 Ca I D2)(Mg I D21/3 D 2 Ta I D 22/3 ii D2)O I D 23 D 2 system up to 1.5 Gpa from room temperature to 200℃.Capacitance decrease inclinations with pressure are sharper in an order of dielectric constant of the pellet.3。Elastic Properties and Dielectric PropertiesElastic parameters were evaluated by an acoustic method for ceramics of the(Ba-D21-x-D2Ca-D2x-D2)(Mg-D21/3-D2Ta-D22/3-D2)O-D23-D2 system to find following relations。(1)The decrease in Young‘s modulus-mechanical softening-is correlated well with the increase in dielectric constant-dielectric softening。(2)A marked similarity is found between shear modulus and fQ for their composition dependences。

1. Effects of A-site Alkaline-Earth Substitution of Perovskite Oxide on Microwave Dielectric CharacteristicsThe main systems studied were as follows : (AィイD21-xィエD2A'ィイD2xィエD2)ZrOィイD23ィエD2. (AィイD21-xィエD2A'ィイD2xィエD2)(MgィイD21/3ィエD2TaィイD22/3ィエD2)OィイD23ィエD2, (AィイD21-xィエD2A'ィイD2xィエD2)(ZnィイD21/3ィエD2TaィイD22/3ィエD2)OィイD23ィエD2 (AA' = Ba, Sr, Ca) and further (BaィイD21-xィエD2A'ィイD2xィエD2)(BィイD21/2ィエD2B'ィイD21/2ィエD2OィイD23ィエD2 (A'=Ca, Sr B=Y,Nd : B'=Nb, Ta). Followings are summaries of this subtitle. That is, systematic differences are noted in the order of differences of ionic radii of the two alkaline-earth ions for the (BaィイD21-xィエD2CaィイD2xィエD2), (BaィイD21-xィエD2SrィイD2xィエD2), and (SrィイD21-xィエD2CaィイD2xィエD2) substitution systems. Dielectric constants increase sharp with x to have respective peak values at around the limit compositions of isomorphism substitutions of Ba by Ca for all systems studied. Further, and dielectric losses also increase sharp to have plateaus.2. Pressure Dependence of CapacitancePressure Dependences of Capacitance were measured for pellets of the (BaィイD21-xィエD2CaィイD2xィエD2)(MgィイD21/3ィエD2TaィイD22/3ィエD2)OィイD23ィエD2 system up to 1.5 Gpa from room temperature to 200℃. Capacitance decrease inclinations with pressure are sharper in an order of dielectric constant of the pellet.3. Elastic Properties and Dielectric PropertiesElastic parameters were evaluated by an acoustic method for ceramics of the (BaィイD21-xィエD2CaィイD2xィエD2)(MgィイD21/3ィエD2TaィイD22/3ィエD2)OィイD23ィエD2 system to find following relations. (1) The decrease in Young's modulus - mechanical softening - is correlated well with the increase in dielectric constant - dielectric softening. (2) A marked similarity is found between shear modulus and fQ for their composition dependences.