Direct Sintering Process for A5B4O15 (A=Ba, La; B=Ti, Sn, Nb) Microwave Dielectric Ceramics
| Autor: | Chi-Yang Liu, 劉冀陽 |
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| Rok vydání: | 2008 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 96 A5B4O15 (A=Ba, La; B=Ti, Sn, Nb) microwave dielectric ceramics prepared using a direct sintering process were investigated. The mixture of raw materials was pressed and sintered directly without any calcination stage involved. Effects of CuO addition were also studied. Ba2La3Ti3NbO15 (BLTN1) phase could be obtained after 2-6 h sintering at 1430-1500oC, BaLa2Ti3O10 phase was also found. Density of BLTN1 reached 6.08g/cm3 for 6 h sintering at 1500oC. The sintering temperature can be effectively reduced to 1350oC in BLTN1 ceramics with 2 wt％CuO additions (BLTN1C). BaLa2Ti3O10 and La2Ti2O7 phase were found in BLTN1C ceramics. Density of BLTN1C reached 6.22g/cm3 for 4 h sintering at 1430oC, and εr=42-50 was found. Single phase Ba3La2Ti2Nb2O15 (BLTN2) could be obtained after 2-6 h sintering at 1400-1470oC. Density reached 6.21g/cm3 for 6 h sintering at 1470oC. The sintering temperature can be effectively reduced to 1200oC in BLTN2 ceramics with 2 wt％CuO additions (BLTN2C). Dense BLTN2C of 6.29g/cm3 was obtained for 6 h sintering of 1270oC, and the properties εr=48-55 was found. Two phases Ba4LaTiNb3O15 and Ba4LaSnNb3O15 were found in Ba4La(Sn0.75Ti0.25)Nb3O15 (BLSTN) ceramics. Density reached 6.35g/cm3 for 4 h sintering at 1470oC. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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