| Summary: | 碩士 === 國立成功大學 === 電機工程學系 === 86 === CaO-Li2O-Sm2O3-TiO2為一新的微波介電陶瓷材料，據文獻指出，其在微
波頻帶下具有很高之介電係數： r＝105，惟Q值與頻率- 溫度穩定性皆不
甚理想： f‧Q = 4640 GHz ，共振頻率下之溫度係數tf 為 +13 ppm/℃
，本實驗即針對以上缺點提出改進方案。首先，加入適量之BaCO3於上述
系統中，並相對提高Sm2O3、TiO2之含量，將在系統中另外形成具高Q特性
之BaO-Sm2O3-TiO2 ( f‧Q = 10000~11000 GHz)，而使此系統成為一個二
相系統。經由實際之量測，由於BaO-Sm2O3-TiO2之生成，Q值將獲得顯著
之改善，而擁有如下之特性： r＝95.5，f‧Q = 7580 GHz，tf = -5.9
ppm實驗中另外將部分的Sm以Nd取代，以求進一步改善其特性，當取代量
為1/6時可得到一最佳之微波介電特性：er = 101，f‧Q = 7300 GHz，tf
= +1.5 ppm/℃，此時成分間之莫耳比例如下：CaO : BaO : Li2O : Sm2
O3 : Nd2O3 : TiO2 = 14 : 4 : 8 : 10 : 2 : 62。
CaO-Li2O-Sm2O3-TiO2 is a lately developed microwave dielectric
material. It had been reported to have microwave dielectric
properties as follow: er = 105, f‧Q = 4640 GHz, and tf = +13
ppm/℃. Obviously, the dielectric constant of this system is
rather high in microwave range, however, poor Q value and
temperature coefficient will certainly block it from microwave
application. In this work, the improvement of the microwave
properties of the CaO-Li2O-Sm2O3-TiO2 system was inves-tigated.
It was found that byIn addition, even better properties were
obtained by partially re-placing Sm with Nd. With a composition
of CaO : BaO : Li2O : Sm2O3 : Nd2O3 : TiO2 = 14: 4: 8: 10: 2:
62, excellent microwave dielectric properties was obtained: er =
101, f‧Q = 7300 GHz, and good temperature stability for the
resonant frequency (tf = +1.5 ppm/℃) at 4.5 GHz.
|
|---|
