Chen Daqin, Zhou Yang, Wan Zhongyi, Ji Zhenguo, Huang Ping
College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310018, P. R. China.
Dalton Trans. 2015 Mar 28;44(12):5288-93. doi: 10.1039/c5dt00061k.
Yb(3+)/Ho(3+) activated glass ceramics containing β-YF3 nanocrystals were successfully fabricated. The green ((5)S2/(5)F4→(5)I8) upconversion emission is dominant in the glass ceramics and is about 160 times stronger than that of the precursor glass, resulting from the partition of lanthanide activators into a low-phonon-energy crystalline lattice and the subsequent low probability of multi-phonon nonradiative relaxation from the (5)S2/(5)F4 and (5)I6 states to the lower ones. Upon the introduction of Ce(3+) ions into nano-glass-ceramics, two efficient cross-relaxation processes between Ho(3+) and Ce(3+), i.e., Ho(3+):(5)S2/(5)F4 + Ce(3+):(2)F5/2→Ho(3+):(5)F5 + Ce(3+):(2)F7/2 and Ho(3+):(5)I6 + Ce(3+):(2)F5/2→Ho(3+):(5)I7 + Ce(3+):(2)F7/2, are demonstrated to greatly suppress the population of the green-emitting (5)S2/(5)F4 state and to enhance the population of the red-emitting (5)F5 one, leading to the intense single-band red UC radiation of Ho(3+).
成功制备了含有β-YF3纳米晶体的Yb(3+)/Ho(3+)激活的玻璃陶瓷。绿色（(5)S2/(5)F4→(5)I8）上转换发射在玻璃陶瓷中占主导地位，比前驱体玻璃强约160倍，这是由于镧系激活剂分配到低声子能量的晶格中，以及随后从(5)S2/(5)F4和(5)I6态到较低态的多声子非辐射弛豫概率较低。在纳米玻璃陶瓷中引入Ce(3+)离子后，Ho(3+)和Ce(3+)之间的两个有效交叉弛豫过程，即Ho(3+):(5)S2/(5)F4 + Ce(3+):(2)F5/2→Ho(3+):(5)F5 + Ce(3+):(2)F7/2和Ho(3+):(5)I6 + Ce(3+):(2)F5/2→Ho(3+):(5)I7 + Ce(3+):(2)F7/2，被证明能极大地抑制绿色发射(5)S2/(5)F4态的粒子数，并增加红色发射(5)F5态的粒子数，从而导致Ho(3+)强烈的单波段红色上转换辐射。
