DIELECTRIC-CONSTANTS OF YTTRIUM AND RARE-EARTH GARNETS, THE POLARIZABILITY OF GALLIUM OXIDE, AND THE OXIDE ADDITIVITY RULE

The dielectric constants (κ') and dielectric loss values of 10 rare-earth gallium garnets and 1 rare-earth aluminum garnet were measured at 1 MHz using a two-terminal method with empirically determined edge corrections. The results are: κ'(Dy3Al5O1 2)=11.07±0.05; κ'(Ho3Ga5O 12) =12.38±0.05; κ'(Dy3Ga 5O12)=12.36±0.06; κ'(Tb 3Ga5O12) =12.40 ±0.03; κ'(Gd3Ga5O12) =12.18±0.10; κ'(Eu3Ga5O1 2) =12.46±0.05; κ'(Sm3Ga5O 12) =12.55±0.03; κ'(Nd3Ga 5O12) =12.59±0.12; κ'(Y 3Sc2Ga3O12) =12.94±0.03; κ'(Sm3Sc2Ga3O 12) =13.67±0.04; and κ'(La 2.66Lu2.66Ga2.66O12) =14.40±0.03. The dielectric polarizability of Ga2O3 derived from the dielectric constants of these and other Ga compounds is 8.80±0.14 Å3. The agreement between measured dielectric polarizabilities as determined from the Clausius-Mosotti equation and those calculated from the sum of oxide polarizabilities according to αD(mineral) =ΣαD (oxides) for six aluminum garnets and twelve gallium garnets is ∼1%.