The effect of Gd, In, and Al substitution on magnetic and resonance properties in the system {Y
3-2x-aCa
2xGd
a} [Fe
2-zIn
z]- (Fe
3-x-yV
xAl
y)O
12is reported for

, and

. It is shown that compositions exist in this system that display improvements over conventional garnets in this respect to temperature stability and

-band resonance linewidth. The series Y
3-2xCa
2xFe
4.75-xV
xIn
0.25O
12is suggested as one such optimal series of compositions.