Park Jung Hye, Kim Young Jin
J Nanosci Nanotechnol. 2014 Nov;14(11):8756-61. doi: 10.1166/jnn.2014.10004.
Ca2SiO4:Eu2+ powders were prepared by the sol-gel process using calcium nitrate hydrate, europium nitrate hydrate, and tetraethyl orthosilicate (TEOS). The effects of the amount of TEOS, firing temperatures, and the Eu2+ concentration on the structural and luminescence properties were investigated. The CaO impurity phase was produced and it strongly contributed to emission properties. The prepared powders were composed of irregular-shaped particles, square plates (CaO), and/or needle-shaped particles, depending on the amount of TEOS, while with excess TEOS content (1.2 M), Ca2SiO4:Eu2+ crystals were contained in the glass matrix. The photoluminescence excitation (PLE) spectra of the synthesized powders widely covered from 250 to 450 nm. The related PL emission spectra showed green emissions (- 510 nm), which resulted from two overlapped Gaussian emission bands centered at 502 and 550 nm assigned to the 4f(7)-4f(6)5d1 transitions of the Eu(II) and Eu(I) sites, respectively. Eu2+ ions were incorporated into CaO as well as Ca2SiO4, and thus the Eu2+ concentration in Ca2SiO4 was adjusted by the amount of the CaO phase in samples. As a result, the strongest green emission of Ca2SiO4:Eu2+ was obtained with 0.9 M TEOS.
采用水合硝酸钙、水合硝酸铕和正硅酸乙酯（TEOS）通过溶胶 - 凝胶法制备了Ca2SiO4:Eu2+粉末。研究了TEOS用量、焙烧温度和Eu2+浓度对结构和发光性能的影响。产生了CaO杂质相，它对发光性能有很大贡献。根据TEOS的用量，制备的粉末由不规则形状的颗粒、方形板（CaO）和/或针状颗粒组成，而当TEOS含量过量（1.2 M）时，玻璃基体中含有Ca2SiO4:Eu2+晶体。合成粉末的光致发光激发（PLE）光谱在250至450 nm范围内广泛覆盖。相关的PL发射光谱显示出绿色发射（- 510 nm），这是由分别位于502和550 nm处的两个重叠高斯发射带产生的，分别归属于Eu(II)和Eu(I)位点的4f(7)-4f(6)5d1跃迁。Eu2+离子既掺入到CaO中也掺入到Ca2SiO4中，因此通过样品中CaO相的量来调节Ca2SiO4中Eu2+的浓度。结果，当TEOS为0.9 M时获得了Ca2SiO4:Eu2+最强的绿色发射。
