Modified bismuth-substituted synthetic garnets for electronic applications

Abstract

Embodiments disclosed herein include methods of modifying synthetic garnets used in RF applications to reduce or eliminate Yttrium or other rare earth metals in the garnets without adversely affecting the magnetic properties of the material. Some embodiments include substituting Bismuth for some of the Yttrium on the dodecahedral sites and introducing one or more high valency ions to the octahedral and tetrahedral sites. Calcium may also be added to the dodecahedral sites for valency compensation induced by the high valency ions, which could effectively displace all or most of the Yttrium (Y) in microwave device garnets. The modified synthetic garnets with substituted Yttrium (Y) can be used in various microwave magnetic devices such as circulators, isolators and resonators.

1 . (canceled) 
     
     
         2 . A modified synthetic garnet having a composition represented by the formula Bi x Y 3-x-0.35 Ca 0.35 Zr 0.35 Fe 4.65 O 12 , x being between 0.5 and 1.0, bismuth being substituted for yttrium on a dodecahedral site, zirconium being substituted for iron on an octahedral site, and calcium being added to a dodecahedral site to replace yttrium and balance charges with zirconium. 
     
     
         3 . The modified synthetic garnet of  claim 2  wherein x is between 0.6 and 0.8. 
     
     
         4 . The modified synthetic garnet of  claim 3  wherein x is 0.5. 
     
     
         5 . A method of manufacturing a bismuth-modified synthetic garnet, the method comprising:
 providing a material include oxides, carbonates, or a combination thereof;   forming a composition represented by the formula Bi x Y 3-x-0.35 Ca 0.35 Zr 0.35 Fe 4.65 O 12 , x being between 0.5 and 1.0, bismuth being substituted for yttrium on a dodecahedral site, zirconium being substituted for iron on an octahedral site, and calcium being added to the dodecahedral site to replace yttrium and balance charges with zirconium.   
     
     
         6 . The method of  claim 5  wherein x is between 0.6 and 0.8. 
     
     
         7 . The method of  claim 5  wherein x is 0.5. 
     
     
         8 . The method of  claim 5  further including forming an electronic device from the composition. 
     
     
         9 . The method of  claim 5  further including:
 blending the material to form a mixture; 
 drying the mixture; 
 sieving the dried mixture; 
 calcining the sieved mixture; 
 milling the calcined material into particle sizes of about 0.5 micron to 10 micron; 
 spray drying the milled material to form granules; 
 pressing the granules; and 
 calcining the pressed granules to form the composition. 
 
     
     
         10 . The method of  claim 9  wherein drying is at a temperature between 100-400° C. 
     
     
         11 . The method of  claim 9  wherein milling is performed in a vibratory mill, an attrition mill, or a jet mill. 
     
     
         12 . The method of  claim 9  wherein calcining the pressed granules is at a temperature between 850-1000° C. 
     
     
         13 . The method of  claim 9  wherein calcining the sieved mixture is at a temperature between 100-400° C. 
     
     
         14 . The method of  claim 13  wherein calcining the sieved mixture is at a temperature between 900-950° C. 
     
     
         15 . An electronic device incorporating a synthetic garnet having a composition represented by the formula Bi x Y 3-x-0.35 Ca 0.35 Zr 0.35 Fe 4.65 O 12 , x being between 0.5 and 1.0, bismuth being substituted for yttrium on a dodecahedral site, zirconium being substituted for iron on an octahedral site, and calcium being added to the dodecahedral site to replace yttrium and balance charges with zirconium. 
     
     
         16 . The electronic device of  claim 15  wherein x is between 0.6 and 0.8. 
     
     
         17 . The electronic device of  claim 15  wherein x is 0.5. 
     
     
         18 . The electronic device of  claim 15  wherein the device is an isolator. 
     
     
         19 . The electronic device of  claim 15  wherein the device is a circulator. 
     
     
         20 . The electronic device of  claim 15  wherein the device is configured for magnetic microwave applications. 
     
     
         21 . The electronic device of  claim 15  wherein the device is incorporated into a cellular base station.