CeMgAl11O19-SrAl12O19固溶体和CeMgAl11O19-SrMgAl10O17固溶体在稀土和碱土复合六角铝酸盐体系中的光谱学性质研究

本文研究CeMSAl11O19-SrAl12O19和CeMeAl11O19-SrMgAl10O17体系固溶体的发光性质。发现在CeMgAl11O19-SrAl12O19体系中,能形成完全的固溶体,随着SrAl12O19含量的增加,晶胞常数a线性地减小,c保持不变,Ce3+的Nephelauxetic效应和晶场强度减弱,Ce3+最低5d激发带边能量呈指数形式变化,Ce3+的发射能量线性地高移。在CeMgAl11O19-SrMgAl10O17体系中,不能形成完全的固溶体。固溶体终端组成大约为0.3CeMgAl11O19-0.1SrMgAl10O17。在这种固溶体中,晶胞常数α和c则随SrMgAl10O17含量分别线性地减小和增大。样品制备中添加H3BO3,引起固溶体晶僻特性改变,大大提高Ce3+的发光强度。但当H3BO3量超过0.4(摩尔比)时,硼将进入晶格,反而减弱Ce3+的发光。

SPECTROSCOPIC PROPERTIES OF CeMgAl11O19-SrAl12O19 and CeMgAl11O19-SrMgAl10O17 SOLID SOLUTIONS IN RARE EARTHS AND ALKALINE EARTHS DOUBLE HEXALUMINATES SYSTEMS

The systems of CeMgAl11O19-SrAl12O19 and CeMgAl12O19-SrMgAl10O17 were studied. In CeMgAl12O19-SrAl12O19, complete solid solutions were observed and the positions of the lower d-band edge and emission peak of Ce3+ shifted to higher energy while the cell of the solid solutions contracted as a result of decrease of the parameter a as the concentration of SrAl12O19 increased. Furthermore, both the Nephelauxetic effect and the crystal field intensity of Ce3+ decreased with increasing SrAl12O19 concentration. Except for 0.9 CeMgAl12O19-0.1 SrAl12O19, the emission position of Ce3+ in energy increased linearly with increasing SrAl12O19 content, which could be accounted for by power development fashion of the relation E=Q [1-(z/4)l/z 10-ar] (see ref. [6]). For 0.1 CeMgAl12O19-0.9 SrAl12O19,the deviation of the emission peak of Ce3+ from the straight line position could be due to a small Stokes shift for the compound. For CeMgAl12O19-SrMgAl10O17, solid solutions were observed only when SrMgAl10O17 content was within 70%.In the solid solutions,the emission peak energy of Ce3+ increased linearly,and the cell parameters a and c decreased and increased respectively with increasing SrMgAl10O17 concentration. For 0.1 CeMgAl12O19-0.9 SrMgAl10O17, two phases were found with SrMgAl10O17 as the primary phase and a magnetoplumbite-type Ce-and Si-double hexaluminate as the second phase, The emission of Ce3+ in the mixed phases originated probably from the latter compound.The intensity of Ce3+ emission in solid solutions was considerably enhanced by adding H3BO3 to starting materials. But the Ce3+ emission would reversely decrease if the quantity of H3BO3 was too high. It was found that the change of crystal habit of solid solutions by H3BO3 and the substitution of B for Al in the compounds were responsible for the observations.