四種不同晶體結構錫酸鹽螢光體發光特性之研究

Abstract

本研究係以固態合成MSnO3 (M = Ca, Sr)、M2SnO4 (M = Mg, Sr, Ba)、Sr3Sn2O7與Y2Sn2O7等系列晶體結構不同的螢光體，藉還原及主體效應探討錫酸鹽自身活化特性以及摻雜Bi3+離子與稀土離子及過渡金屬離子之光致發光特性變化。 本研究發現Ca SnO3、M2SnO4 (M = Mg, Ba)與Sr3Sn2O7在紫外光激發下分別為發射綠、黃、黃與綠光之自身活化螢光體。除X光繞射之外，本論文尚使用光致發光光譜與色度座標進行錫酸鹽螢光體之特性鑑定。 Eu3+與Bi3+活化劑摻雜的Y2Sn2O7: R (R= Eu3+, Bi3+)主要發射紅與藍光，而本研究發現Eu3+, Pr3+與Sm3+激活的MSnO3與M2SnO4則發射紅、綠與橙紅光。其中Sr0.99Sm0.01SnO3光致發光光譜顯示Sm3+與Sm2+同時存在。但若以電荷補償(即Na+, Sm3+取代2Sr2+)則證實可以消除Sm2+之放射峰。 我們亦將探討:R (R= Eu3+, Pr3+, Sm3+, Dy3+, Tb3+, Bi3+)系列之發光並發現在270 nm紫外光激發Ca0.99Sm0.01SnO3可發射白光。此外，Eu3+ +與Sm3激活的Sr3Sn2O7與螢光體則分別發紅、綠與橘紅螢光，而Ba2(Sn,Ti)O4則呈現藍光，此應與之存在有關。 EPR實驗證據指出錫酸鹽中Sn4+易被水氧化，而形成[Sn4+O2-]錯合物，故必須善予保存。 本論文也探討氧缺陷與Ca SnO3、M2SnO4 (M = Mg, Ba)與Sr3Sn2O7相的發光光譜特性之相互關係。

The research is attempted to investigate the photoluminescent (PL) properties of unprecedented materials for phosphor applications. Phosphors with hosts of Y2Sn2O7, MSnO3 (M = Ca, Sr), M2SnO4 (M = Mg, Sr, Ba), and Sr3Sn2O7 crystallized in four different types of structure have been prepared by solid-state method, in which self-activated CaSnO3, M2SnO4 (M = Ba, Mg) and Sr3Sn2O7 phases were found to emit green, yellow, yellow, and green luminescence under ultraviolet excitation. In addition to X-ray diffraction, photoluminescence (PL) spectra, and chromaticity coordinates were used to characterize stannate phosphors. Rare-earth (R) activated Y2Sn2O7:R (R = Eu3+, Bi3+) phases were found to emit red and blue fluorescence, whereas SrSnO3:R and Sr2SnO4:R (R = Eu3+, Pr3+, Sm3+) were found to exhibit red, green and orange-red luminescence. In particular, both emissions attributed to Sm3+ and Sm2+ were observed in Sr0.99Sm0.01SnO3, however, the emission from Sm2+ can be suppressed by charge compensation effect, in which Na+ and Sm3+ substituting for two Sr2+ ions. The luminescence for R3+-doped CaSnO3:R (R = Eu, Pr, Sm, Tb, Dy, Bi) phases has also been investigated and, in particular, under excitation with ultraviolet of 270 nm CaSnO3:Sm3+ was found to emit white light which can be finely tuned by varying the Sm3+ contents. On the other hand, Eu3+ and Sm3+ activated Sr3Sn2O7 and Ba2SnO4 phases were found to emit red and orange red fluorescence, respectively, whereas Ti4+-activated Ba2SnO4 or Mg2SnO4 phase was found to emit blue light that was attributed to the presence of Sn2+ in the phosphor. The formation of [Sn4+O2-] complex has been confirmed by EPR spectra, which indicates the instability of Sn4+ in satnnate phosphors when exposed to humidity or water vapor. Furthermore, the correlation between the oxygen defects created by temperature-dependent hydrogen reduction and the PL spectra for CaSnO3 (M = Ca, Sr), M2SnO4 (M = Mg, Ba), and Sr3Sn2O7 phases was also investigated.