Study on La0.7Sr0.3MnO3 Nano-Crystalline Compounds and Microwave Dielectric Ceramic Processing
Date Issued
2005
Date
2005
Author(s)
Huang, Yu-Ching
DOI
zh-TW
Abstract
This research includes two parts. One is low calcining colossal magnetoresistance (CMR) material. The other is the processing of microwave dielectric ceramic for antenna and high K substrate. In the first part, we synthesized La0.7Sr0.3MnO3 (LSM) by three processes involving different precursor materials and compared their properties. We also fabricated thin films by those different precursor materials. Hydroxide based raw materials provide the lowest calcining temperature of LSM (500℃), the calcining temperature of acetylacetonate based raw materials and nitrate based raw materials are 800℃ and 900℃ respectively. The properties of nanocrystalline LSM compounds are different from those of the conventional CMR materials. The metal-insulator transition temperature of LSM is reduced with decreasing crystalline grain size, but its resistance value increases as reducing the crystalline grain size. The LSM synthesized from acetylacetonate based powders exhibit the largest MR ratio of 70% (at 90000Oe) with the smallest grain size among tried raw materials. The pin hole free thin film of LSM can also be prepared by nitrate based and hydroxide based raw materials by adding glycerol. The acetylacetonate basedd raw materials provided pin hole free film without glycerol.
In the second part studied the fabrication process of dielectric resonator antenna (DRA) model and high permittivity ceramic plate. We are able to make desired sizes and shapes of DRA model via cut-and-paste fabrication using Zn3Nb2O8 powder. The DRA model maintains the dielectric properties of Zn3Nb2¬O8. We have successfully fabricated high permittivity ceramic plates (~130) by process optimization and stress elimination using BZN powders.
Subjects
鑭鍶錳氧化物
薄膜
化學濕式法
共振天線
LSM thin film
sol-gel
antenna
high permittivity ceramic plate
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-94-R92527049-1.pdf
Size
23.53 KB
Format
Adobe PDF
Checksum
(MD5):49bc9d32bb35314ffd68c3aa57d2749f