製程參數對於錳鋅亞鐵鹽電性磁性及微觀結構的影響

Abstract

這篇論文探討製程參數對於錳鋅亞鐵鹽之電性磁性及微觀結構的影響，並 找出製造錳鋅亞鐵鹽的最佳製程。發現以二氧化錳/氧化鋅/三氧化二鐵為 原始材料的亞鐵鹽有最大電阻率(室溫直流電阻率大約是百萬級)和最小介 電損耗，而以碳酸錳/氧化鋅/三氧化二鐵為原始材料的亞鐵鹽有最大介電 常數(低頻介電常數大約是百萬級)。在所有的製程參數中，控制冷卻速率 和燒結時的氧分壓是最重要的。初導磁率會隨著冷卻速率的增加而上昇。 當氧分壓降低時，初導磁率和介電常數會隨之增加。 "氣氛燒結"可以用 來改善燒結過程中的鋅損耗，使用氣氛燒結，百分比理論密度有明顯的改 善。除此之外，也提供在不同溫度範圍下的導電機制。在低溫範圍是由鐵 離子的電子交換主導，高溫時是鐵離子和錳離子共同主導其導電機制。 This thesis deals with the influences of process parameters on the electrical, magnetic properties and microstructure of Mn-Zn ferrites, and try to find out the best process method for making ferrites. It is found out that the raw materials of MnO2/ ZnO/Fe2O3 is characterized for its high dc-resistivity and low loss and MnCO3/ZnO/Fe2O3 is characterized for its high dielectric constant. The most important parameters among all the process parameters for making ferrite are the cooling rate and sintering oxygen partial pressure. The initial permeability increases as the cooling rate increases. Initial permeability and dielectric constant increases as the oxygen content decreases. " Atmosphere sintering " was provided to solve the zinc loss during sintering. The percent theoretical density can be improved (72%→85%). Besides, the conduction mechanisms in different temperature range were also provided. It is believed that the conduction mechanisms for low temperatures (25℃-150 ℃) is attributed to the electron transport between Fe2+ and Fe3+ ions. While at high temperatures (150℃-400℃), charge transport between Mn2+ and Mn3+ also plays into effect.