山东蓝宝石的吸收光谱、ESR 和杂质分布

Absorption Spectra,ESR and Impurity Location for Shandong Sapphire

山东蓝宝石的吸收光谱由三部分组成:(1)在590～800nm 有一个强的宽带吸收,这是决定宝石颜色的主要吸收峰,可通过 Fe^(2+)→Ti^(4+)不同价态的电荷传输(IVCT)加以解释;(2)峰值分别在565nm 和447nm 的540～590nm 和421～476nm 吸收带是 Cr^(3+)在 O_h 场下基态~4A_2到~4T_2和~4T_1的跃迁;(3)峰值在373nm 和385nm 的363nm～394nm 吸收被归为于 O^(2-)→Fe^(2+)的电荷传输.与标准刚玉的红外吸收光谱比较,山东蓝宝石在1090cm^(-1)有一个新的吸收峰.晶体粉末电子顺磁共振谱证实 Cr^(3+)离子存在,Fe^(3+)和 Ti^(3+)的鉴别还需作进一步实验.平行于晶体 c 轴观察到六角形着色和生长区域,分散金属离子分布在(1010)面.

Absorption spectra of Shandong sapphire consists of three parts:1,A strong and broadabsorption band in 590～800nm,which determines the color,is explained through Fe^(2+)→Ti^(4+)intervalence charge transfers;2,540～590nm band peaked at 565nm,and 421～476mn bandpeaked at 447nm correspond to the transitions from ground state ~4A_2 to ~4T_2 and ~4T_1 of Cr^(3+)under O_h field,respectively;3,363～394nm absorption band peaked at 373nm and 385nm isattributed to O_^(2-)→Fe^(2+) charge transfers.Comparing with standard corundum there is a newinfrared peak at 1090cm^(-1).Cr^(3+) ion has been confirmed by ESR arising from powder,butthe determination of Fe^(3+) and Ti^(3+) needs studying further.Hexagonal color and growth zoneis observed parallel to the c-axis of this crystal,and dispersed metal ions are located at(1010)plane.