Magnetic and Microwave Properties of Calcium Vanadium-Substituted Garnets

Polycrystalline ferrimagnetic pentavalent vanadium garnet compositions conforming to the general formula {Y3−2xCa2x} [Fe2] (Fe3−xVx) O12 for x equal 0 to 1.5 were investigated and evaluated along with the ``yttrium-rare-earth-free'' garnets of the system {Bi3−2yCa2y} [Fe2] (Fe3−yVy) O12 for y equal 0.75 to 1.5. Single crystals of the latter system have been investigated for 1.0<y≦1.4. Magnetic and microwave properties are reported. In the (Bi-Y)CaVIG compounds, 4πMs values from 1780 G to zero are covered. Linewidths increased approximately as M−1 for values of x=0 to 1; for x>1.0 to 1.5, linewidth values are 100 to 200 Oe. In the BiCaVIG compounds, the linewidths are higher (500 Oe) for values of y<1.0 and approximately 200 Oe for 1.0<y≦1.5. Dielectric constants (X band) for these compounds varied from 29 to 13 for y=0.75 to y=1.5, respectively. Compositions in both systems were prepared possessing dielectric loss tangents (X band) as low as 0.0001. The temperature characteristics of these vanadium garnets are compared to the more widely used yttrium aluminum and yttrium gadolinium iron garnets. Single-crystal samples (y=1.33, 4πMs=500 G) were prepared possessing measured linewidths at C band of 1.0 Oe.