FORMATION OF TUNGSTEN BRONZE-TYPE (BA6-3XSM8-YALYO54 (ALPHA=1+Y(2X)(ALPHA)TI18)36) SOLID-SOLUTIONS AND MICROWAVE DIELECTRIC-PROPERTIES/

The composition range of tungsten bronze-type Ba6-3xSm8+2xTi18O54 soli d solutions, which are excellent microwave dielectric resonators, has been extended to (Ba6-3xSm8+2x)(alpha)Ti18-yAlyO54(alpha=1+y/36) with the B-site substituted by Al. In this two-dimensional solid solution r egion, (Ba4.2Sm9.2)(alpha)Ti18-yAlyO54 (0 less than or equal to y less than or equal to 1.61), which includes the best end member compositio n (x=0.6) of Ba6-3xSm8+2xTi18O54 solid solutions, was selected for stu dy of solid solutions and their dielectric properties. In the whole re gion of the solid solution formula, tungsten bronze-type solid solutio ns have been formed and the dielectric constants, Q . f values and tau (f) have been measured. epsilon(r) and tau(f) decreased as the amount of substituted Al increased. The decrease in tau(f) with Al substituti on is expected to be especially large for dielectric materials with la rge positive tau f. These properties are discussed in terms of the str ucture.