Conseil à l’officine dans la prise en charge de l’asthme : comparaison des résultats obtenus en 1999 et 2009

(Mg1−xZnx)1.8Ti1.1O4 (x = 0.03–1.00) ceramics were prepared via the conventional solid-state method and their dielectric properties were investigated in the microwave frequency region. Formation of solid solutions was confirmed by the X-ray diffraction analysis, the EDX analysis, and the measured lattice parameters. A small amount of Zn substitution for Mg produced a large increase in Q × f due to a high packing fraction as well as a high relative density of the ceramics. By increasing x from 0.00 to 0.06, the Q × f of the specimen could be tremendously improved from 141,000 to a maximum of 210,700 GHz (at 10.52 GHz), demonstrating an unique potential for low-loss microwave applications. The τf values were found to retain in the range from −54.2 to −62.3 ppm/°C for all compositions because the resultant change of unit cell volume was small. Also, a remarkable lowering of the sintering temperature down to ∼300 °C was observed when Mg was totally substituted by Zn, thereby making it possible for low firing applications.