本論文研究正極材料 LiMPO4 (M = Fe, Mn)單晶、粉末壓錠及奈 米顆粒的光譜性質。利用 x 光繞射能譜分析 LiMPO4樣品顆粒粒徑及 晶格常數、拉曼散射光譜分析其晶格微結構，橢圓偏光光譜分析其電 子結構。實驗結果歸納為以下五點結論：
第一，由 x 光繞射能譜分析得知，與 LiMPO4塊材比較，LiMPO4 奈米顆粒的晶格常數有些微變大。利用 x 光繞射能譜、電子掃描式顯 微鏡照片及聲子侷限模型擬合等方法，估算奈米顆粒粒徑大小，
LiFePO4約為 45 ~ 55 nm， LiMnPO4約為 25 ~ 35 nm。
第二，由室溫拉曼散射光譜分析得知，LiFePO4奈米顆粒之非晶 相層引起數個微弱拉曼峰。LiMPO4奈米顆粒拉曼峰普遍有紅移 (1 ~ 2 cm-1) 的趨勢，為聲子侷限效應導致。
第三，利用橢圓偏振光譜儀分析得知，LiFePO4的 4.5 eV 及 6.17 eV 吸收峰分別代表 Fe3d (t2g) →Fe3d (eg
) 及 O
2p→Fe3d (t2g)之電子躍遷，LiMnPO4 部分， 3.8 eV 及 6.4 eV 吸收峰代表 O2p→Mn3d (t2g) 及 O2p→Mn3d (eg) 之電子躍遷。
第四，我們利用 對 E 作圖，估算 LiFePO4單晶的能隙為 = 3.8 ± 0.1 eV， LiFePO4奈米顆粒之能隙值相較於單晶下降了約
0.35 eV，我們推測奈米化過程所產生的表面能 (surface energy)，提 供一部分電子躍遷至導帶所需要的能量。LiMnPO4粉末壓錠之直接能 隙約為 3.75 ± 0.1 eV， LiMnPO4奈米顆粒之能隙值比單晶上升了約 1.05 eV，我們認為與半導體在奈米尺寸時所產生的量子尺寸效應有 關。
第五，我們利用室溫拉曼散射光譜探討鋰的嵌入脫出是否對晶格 結構產生影響。發現 Li0.5FePO4奈米顆粒與 LiFePO4奈米顆粒之拉曼 峰位置大致相符，在 LiFePO4單晶與奈米顆粒的低溫拉曼散射光譜實 驗中，發現 LiFePO4 的拉曼峰參數在尼爾溫度附近無異常的溫度效 應。
未來，我們希望量測 LiFePO4單晶及奈米顆粒在充放電過程中的 拉曼散射光譜，了解該樣品在充放電過程中晶格微結構的變化。
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附錄
我們利用電腦程式 Mathematica 擬合聲子侷限模型，以下為相關 電腦程式: