Abstract: A dielectric filter having a plurality of .lambda./4 coaxial dielectric resonators in stages, the resonator being filled with a dielectric material between its inner and outer conductors, comprising at least one stage in which the outer conductor of the .lambda./4 coaxial dielectric resonator is grounded via a capacitance or inductance. The dielectric filter is embodied as a low-pass filter, high-pass filter or a band-pass filter. As a result, by utilizing dielectric resonators having a desired resonant frequency, it is possible to readily achieve a dielectric filter having an attenuating pole in the neighborhood of the frequency passband and small in insertion loss.

Abstract: A method for preparing a PLZT ceramic having a composition represented by the following general formula:(Pb.sub.1-x La.sub.x)(Zr.sub.1-y Ti.sub.y).sub.1-0.25x O.sub.3(wherein x is a numerical value ranging from 0.01 to 0.3 and y is a numerical value ranging from 0.05 to 0.95) comprises the steps of preparing PLZT calcined powder from oxides of Pb, La, Zr and Ti or compounds which can be converted into these oxides through calcination as starting materials; mixing Sm.sub.2 O.sub.3 or Bi.sub.2 O.sub.3 as an auxiliary agent for sintering with the calcined powder; forming the resulting mixture into a molded product having a desired shape; and then subjecting the molded product to normal pressure calcination at a temperature ranging from 1,000 .degree. to 1,300 .degree. C. in an atmosphere comprising oxygen gas and vapor of Pb. The method can be easily practicable and makes it possible to prepare PLZT calcined powder capable of being easily sintered from a cheap raw material according to a dry method.

Abstract: A dielectric resonator to be advantageously used in 0.5-6 GHz band and having a large unloaded Q value, and adequate relative dielectric constant, a good stability of .tau..sub.f and a superior linearity of temperature characteristic of the resonance frequency, may be constituted by the dielectric porcelain composition expressed by the formula:Ba.sub.x Sr.sub.y Ca.sub.z (Zn.sub.1/3 Nb.sub.2/3).sub.1-t Ti.sub.t O.sub.3in which x+y+z=1, x is within the range of 0 to 0.5, y is within the range of 0.5 to 0.999, z is within the range of 0.001 to 0.20 and t is within the range of 0.001 to 0.25.

Abstract: A dielectric ceramic composition comprising oxides of strontium, zinc, niobium, and titanium, which is represented by the following composition formula;Sr.sub.1 (Zn.sub.1/3 Nb.sub.2/3).sub.1-x Ti.sub.x O.sub.3wherein Sr stands for strontium, Zn stands for zinc, Nb stands for niobium, Ti stands for titanium, O stands for oxygen, each suffix indicates the number of atoms, and x is a value larger than 0 but not larger than 0.5.This dielectric ceramic composition can be used not only as a dielectric resonator or a material thereof but also as a material of a dielectric substrate for a microwave IC or a dielectric adjusting rod.

Abstract: Benzene is catalytically oxidized in the vapor phase with oxygen in the presence of an alcohol to be converted to phenol. The catalyst used is represented by the formula: M.sub.a Ag.sub.b P.sub.c O.sub.d wherein M is selected from zinc, titanium, zirconium, tin, bismuth and vanadium, Ag is silver, P is phosphorus and O is oxygen, and a=1, b=0.005.about.5 and c=0 to 6. Phenol is obtained at an enhanced yield even though the catalytic oxidation is carried out at a relatively low temperature as compared with conventional catalytic oxidation processes.

Abstract: Disclosed is a water resistant catalyst for reducing nitrogen oxides with ammonia, which catalyst comprises barium sulfate and vanadium(IV)oxide sulfate which has peaks at 940 cm.sup.-1 and 510 cm.sup.-1 in an infrared absorption spectrum.