Effect of BaCu(B 2 O 5 ) on the sintering temperature and microwave dielectric properties of Ba(Nd 0.8 Bi 0.2 ) 2 Ti 4 O
- PDF / 970,410 Bytes
- 4 Pages / 584.957 x 782.986 pts Page_size
- 55 Downloads / 232 Views
anfu Zhou Key Laboratory of New Processing Technology for Nonferrous Metal and Materials, Guilin University of Technology, Guilin 541004, China (Received 1 March 2010; accepted 27 May 2010)
The effect of BaCu(B2O5) (BCB) on the sintering temperature and microwave dielectric properties of Ba(Nd0.8Bi0.2)2Ti4O12 (BNBT) ceramics was investigated. The sintering temperature of the BNBT ceramics was significantly reduced from 1300 to 900 C. Due to adding BCB into Ba(Nd1–xBix)2Ti4O12, the temperature coefficient of resonant frequency can be adjusted to zero with BCB content increasing. Good microwave dielectric properties of quality factor (Qf) ¼ 2600 GHz, er ¼ 75, and tf ¼ 5 ppm/ C were obtained for BNBT with 7 wt% BCB sintered at 925 C for 2 h, which make it a potential candidate for low temperature cofired ceramics applications. I. INTRODUCTION
As the mobile radio communication networks developed, the microwave devices in communication systems must be miniaturized.1 To reduce the size of microwave devices, many dielectric materials such as the BaO– Ln2O3–TiO2 (Ln ¼ Nd, Sm, and La) ternary system, and their Bi-substituted systems were widely studied, due to their high-dielectric constants (>80) and low-dielectric losses.2,3 Most of the commercial microwave dielectric ceramics usually have a high sintering temperature (normally above 1300 C). Some materials (such as Bi2Mo2O9, etc.) have a low sintering temperature,4 but they have not been used to multilayer devices because of their reaction with Ag, which was used as the internal metallic electrode layers. Therefore, only the dielectrics with low sintering temperatures and compatibility with Ag can meet the performance and cost requirements for portable wireless applications by using low temperature cofired ceramics (LTCC) technology. For this purpose, low-melting glass additions or oxides for liquid phase sintering to lower the sintering temperatures of the dielectrics are lower in cost and easier to realize than others. Cheng et al.5 reported that BaNd2Ti4O12 ceramic was sintered at 950 C by using the BaO–B2O3–SiO2 (BBS) glass as additive and had er value of about 67 and quality factor (Qf) values of about 5000 GHz. Dernovsek et al.6 reported that BaNd2Ti4O12 ceramic with addition of B2O3–Bi2O3–SiO2–ZnO (BBSZ) glass was sintered at 900 C and had er ¼ 67, Q > 1000, and tf ¼ 4 ppm/ C at a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2010.0309
2380
http://journals.cambridge.org
J. Mater. Res., Vol. 25, No. 12, Dec 2010 Downloaded: 05 Dec 2014
a frequency of 6 GHz. Cho et al.7 reported that Ba (Nd0.8Bi0.2)2Ti4O12 (BNBT) ceramic with addition of a kind of lithium borosilicate glass Li2O–B2O3–SiO2– Al2O3 Qf of 2200 GHz, er of 68, and tf of 55 ppm/ C. CaO (LBSAC) was sintered at 900 C exhibited Qf of 2200 GHz, er of 68, and tf of 55 ppm/ C. It is well known that BaCu(B2O5) (BCB) addition often makes it possible to decrease the sintering temperature of many materials.8–13 Therefore, it is also possible that
Data Loading...
