A new microwave dielectric ceramics based on the solid solution system between Ba(Ni 1/3 Nb 2/3 )O 3 and Ba(Zn 1/3 Nb 2/

  • PDF / 250,540 Bytes
  • 5 Pages / 612 x 792 pts (letter) Page_size
  • 79 Downloads / 222 Views

DOWNLOAD

REPORT


MATERIALS RESEARCH

Welcome

Comments

Help

A new microwave dielectric ceramics based on the solid solution system between Ba(Ni1//3 Nb2//3 )O3 and Ba(Zn1//3 Nb2//3 )O3 Seo-Yong Cho, Hyuk-Joon Youn, and Kug-Sun Hong Department of Inorganic Materials Engineering, Seoul National University, Seoul, Korea 151-742

In-Tae Kim and Yoon-Ho Kim Ceramics Division, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul, Korea (Received 3 August 1996; accepted 12 November 1996)

Microwave dielectric properties of the solid solution between Ba(Ni1/3 Nb2/3 )O3 and Ba(Zn1/3 Nb2/3 )O3 were investigated. Samples were prepared by the conventional mixed oxide method as well as the Pechini method. Sintered samples were analyzed using x-ray diffraction and scanning electron microscopy, and their microwave dielectric properties were measured by the post resonator method. The sample prepared by the Pechini method revealed excellent dielectric properties, i.e., permittivity of 35.6, quality factor of 5700 at 10 GHz, and very small temperature coefficient of resonant frequency. Order-disorder behavior of this solid solution system was found to depend on processing parameters. Variation in microwave dielectric properties was discussed in terms of the order-disorder behavior, chemical composition, mixture rule, etc.

I. INTRODUCTION

In recent years special attention was paid to dielectric materials used for microwave applications. These applications comprise of dielectric resonators, various types of filters, microstrip antennas, and waveguides.1, 2 A special name, i.e., microwave dielectric ceramics, was given for these materials, and they include complex perovskite compounds, (Zr, Sn)TiO4 , BaTi4 O9 , Ba2 Ti9 O20 , (Ba, Pb)O–Nd2 O3 –TiO2 , etc.3–5 The properties required for microwave dielectric ceramics are as follows: (i) Large permittivity, preferably larger than 15. (ii) Low dielectric loss, which means high quality factor, Q. This parameter is usually represented by Q ? F value, which is the product of quality factor and measuring frequency, because this product is independent on frequency at microwave domain.1 A Q ? F value greater than 5000 is required and a much higher value is preferred in most applications. (iii) Small temperature coefficient of resonant frequency stf d. A tf value in the range of 25 to 15 ppmy±C is generally required. These three parameters concerning the properties of microwave dielectrics are correlated to the size, frequency selectivity, and stability of a device, respectively. Within the last 10 years many workers have concentrated on complex perovskite compounds because these compounds exhibit a very high quality factor. In order to be a useful material its tf value must be small 1558

http://journals.cambridge.org

J. Mater. Res., Vol. 12, No. 6, Jun 1997

Downloaded: 19 Apr 2015

and controllable. In the case of Ba(Mg1/3 Ta2/3 )O3 and Ba(Zn1/3 Ta2/3 )O3 , no special attention on tf is necessary because their values are very close to 0 ppmy±C.6,7 In the case of Ba(Zn1/3 Nb2/3 )O3 (a

Data Loading...