Maruyama N, Honma T, Komatsu T
Department of Materials Science and Technology, Nagaoka University of Technology, 1603-1 Kamitomioka-cho, Nagaoka, Japan.
J Chem Phys. 2008 May 14;128(18):184706. doi: 10.1063/1.2908231.
Transparent crystallized glasses consisting of nonlinear optical Ba(2)TiSi(2)O(8) nanocrystals are prepared in Eu(2)O(3)-, Nd(2)O(3)-, and Er(2)O(3)-doped 40BaO-20TiO(2)-40SiO(2) glasses by a conventional heat treatment method in order to clarify the optical properties of rare-earth (RE) ions in nanocrystals. The electronic polarizabilities of crystallized glasses are evaluated from the values of density and refractive index, and are found to decrease due to nanocrystallization, which indicates that the chemical bonding state in the crystallized glasses is more covalent compared to the precursor glasses. It is proposed from x-ray diffraction analyses and photoluminescence spectra of Eu(3+) ions that RE ions such as Nd(3+) and Eu(3+) are incorporated into Ba(2)TiSi(2)O(8) nanocrystals. The Judd-Ofelt parameters, Omega(t) (t=2, 4, and 6), of Nd(3+) and Er(3+) ions are evaluated from optical absorption spectra. It is observed that the Omega(2) parameter of Nd(3+) and Er(3+) increases largely due to nanocrystallization, suggesting that the site symmetry of Nd(3+) and Er(3+) ions in nanocrystallized glasses is largely distorted due to their incorporations into the Ba(2+) sites in Ba(2)TiSi(2)O(8) nanocrystals. The change in the Omega(4) and Omega(6) parameters due to nanocrystallization is small. It is proposed that nonlinear optical Ba(2)TiSi(2)O(8) nanocrystals including RE ions would have a high potential as active optical materials.
为了阐明纳米晶体中稀土（RE）离子的光学性质，采用传统热处理方法在掺有Eu₂O₃、Nd₂O₃和Er₂O₃的40BaO - 20TiO₂ - 40SiO₂玻璃中制备了由非线性光学Ba₂TiSi₂O₈纳米晶体组成的透明微晶玻璃。通过密度和折射率的值评估了微晶玻璃的电子极化率，发现由于纳米晶化其降低，这表明与前驱体玻璃相比，微晶玻璃中的化学键合状态更具共价性。从Eu³⁺离子的X射线衍射分析和光致发光光谱提出，Nd³⁺和Eu³⁺等RE离子被掺入Ba₂TiSi₂O₈纳米晶体中。从光吸收光谱评估了Nd³⁺和Er³⁺离子的Judd - Ofelt参数Ωt（t = 2、4和6）。观察到由于纳米晶化，Nd³⁺和Er³⁺的Ω2参数大幅增加，这表明Nd³⁺和Er³⁺离子在微晶玻璃中的位点对称性由于它们掺入Ba₂TiSi₂O₈纳米晶体中的Ba²⁺位点而大幅扭曲。纳米晶化导致的Ω4和Ω6参数变化很小。提出包含RE离子的非线性光学Ba₂TiSi₂O₈纳米晶体作为活性光学材料具有很高的潜力。
