Abstract: Ceramics resulting from the oxide system barium oxide-rare earth oxide-titanium oxide have been found to exhibit an isotropy with respect to electrical properties such as the temperature coefficient of frequency at the first resonant frequency, dielectric constant, and, to some extent, the loss factor, Q. Such anisotropy effects reproducibility in fabricating ceramic articles for use in the microwave region and in the performance of these articles. Isotropic ceramics from the same ternary oxide system can be made by compacting non-nucleated powders followed by the usual sintering of the green compact. Anisotropic bulk ceramic workpieces can be machined to reproducibiy afford ceramic articles with the appropriate value of the electrical property in question by measuring the components of the electrical property along the three principal axes of the workpiece, and then determining the angles between the principal axes necessary to give a resultant having the preselected value.

Abstract: The present invention is directed to a ceramic composition comprising at least three of the four phases BaTi.sub.4 O.sub.9, Ba.sub.2 Ti.sub.9, BaZn.sub.2 Ti.sub.4 O.sub.11 and Ba.sub.3 Nb.sub.4 Ti.sub.4 O.sub.21 (i.e., the phases BT.sub.4 ss, BZ.sub.2 T.sub.9 ss BZ.sub.2 T.sub.4 and BNbT). The ceramic composition may further comprise the phase Ba.sub.3 Ta.sub.4 Ti.sub.4 O.sub.21 (BTaT). The ceramic compositions have an excellent combination of electrical characteristics including Q value at the frequencies of interest for dielectric resonators, the dielectric constant and the T.sub.f value and are well adapted for use as electrical components in equipment operating at microwave frequencies such cellular communications equipment.

Abstract: Ceramic composition comprising oxides of the elements Ba, Ti, Zn, and Me where Me is Nb or Nb and Ta, the mole ratios of the elements relative to Ba being:3.8.ltoreq.Ti.ltoreq.4.50.1.ltoreq.Zn.ltoreq.1.00.05.ltoreq.Me.ltoreq.0.3and the composition containing at least one crystal structure of BaTi.sub.4 O.sub.9 and BaTi.sub.9 O.sub.20. The ceramic compositions have an excellent combination of electrical characteristics including Q value at the frequencies of interest for dielectric resonators, the dielectric constant and the T.sub.f value and are well adapted for use as electrical components in equipment operating at microwave frequencies such cellular communications equipment.

Abstract: An assembly including a ceramic insert and a surrounding dielectric filler in a ferrite or garnet toroid is disclosed, wherein a void is provided into which the dielectric filler can expand, such as by the formation of a temporary layer of liner material on an outer surface of the ceramic insert, or on the liner surface of the toroid, or on both. The ceramic insert is inserted into the toroid, and then the void between the ceramic insert and the toroid is filled with a dielectric heat-curable composition. Then the filled assembly is heated to an elevated temperature to burn out said liner. The liner material burns at a temperature of about 100.degree. F to a temperature which is at least 20.degree. F below the curing temperature of the dielectric heat-curable composition, and preferably the liner burns at a temperature below about 300.degree. F, to leave essentially no ash adversely affecting the resulting assembly.