【摘要】 研究了掺镁掺铁铌酸锂晶体的紫外、可见及红外光谱 ,首次发现当掺镁量超过通常所说的阈值 (第一阀值 )时 ,Fe3+ 离子和部分Fe2 + 离子的晶格占位由锂位变为铌位 ,但仍有部分Fe2 + 离子留在锂位 .晶体缺陷化学分析表明 ,继续增加掺镁量 ,占锂位的Fe2 + 离子数将逐渐减少 ;当掺镁量达到另一个适当的值 (第二阀值 )时 ,全部Fe2 + 都占铌位 ,晶体的抗光折变能力空前提高 ,这种现象称作双阈值效应 .更多还原

【Abstract】 The ultraviolet-visible and infrared absorption spectra of Fe 2O 3 and MgO co-doped lithium niobate (LiNbO 3) crystals were studied. It was found that some Fe 2+ ions were still in Li-sites though Fe 3+ ions changed their site occupation from Li-sites to Nb-sites while the doping concentration of MgO was above the threshold (the first threshold). Defect chemical analysis shows that the amount of Fe 2+ ions will decrease as the doping concentration of Mg increases, and when the doping concentration reaches a suitable value (the second threshold) all Fe 2+ ions in Li-sites will diminish. It is expected that LiNbO 3 crystal doped with the second threshold will have an excellent ability to resist laser induced optical damage. This phenomenon is called as double thresholds effect.更多还原