Tb3+-doped CaNb2O6 (CaNb2O6:Tb3+) thin films were deposited on quartz substrates at a growth temperature of 300 °C using radio-frequency magnetron sputtering. The deposited thin films were annealed at several annealing temperatures for 20 min and characterized for their structural, morphological, and luminescent properties. The experimental results showed that the annealing temperature had a significant effect on the properties of the CaNb2O6:Tb3+ thin films. The crystalline structure of the as-grown CaNb2O6:Tb3+ thin films transformed from amorphous to crystalline after annealing at temperatures greater than or equal to 700 °C. The emission spectra of the thin films under excitation at 251 nm exhibited a dominant emission band at 546 nm arising from the 5D4 → 7F5 magnetic dipole transition of Tb3+ and three weak emission bands at 489, 586, and 620 nm, respectively. The intensity of the 5D4 → 7F5 (546 nm) magnetic dipole transition was greater than that of the 5D4 → 7F6 (489 nm) electrical dipole transition, indicating that the Tb3+ ions in the host crystal were located at sites with inversion symmetry. The average transmittance at wavelengths of 370~1,100 nm decreased from 86.8 % at 700 °C to 80.5 % at an annealing temperature of 1,000 °C, and a red shift was observed in the bandgap energy with increasing annealing temperature. These results suggest that the annealing temperature plays a crucial role in developing green light-emitting CaNb2O6:Tb3+ thin films for application in electroluminescent displays.

BaMoO4:Tb3+ phosphor powders were synthesized with different concentrations of Tb3+ ions using the solid-state reaction method. XRD patterns showed that all the phosphors, irrespective of the concentration of Tb3+ ions, had tetragonal systems with two main (112) and (004) diffraction peaks. The excitation spectra of the Tb3+-doped BaMoO4 phosphors consisted of an intense broad band centered at 290 nm in the range of 230-330 nm and two weak bands. The former broad band corresponded to the 4f8 →4f75d1 transition of Tb3+ ions; the latter two weak bands were ascribed to the 7F2→ 5D3 (471 nm) and 7F6→ 5D4 (492 nm) transitions of Tb3+. The main emission band, when excited at 290 nm, showed a strong green band at 550 nm arising from the 5D4→ 7F5 transition of Tb3+ ions. As the concentration of Tb3+ increased from 1 to 10 mol%, the intensities of all the emission lines gradually increased, approached maxima at 10 mol% of Tb3+ ions, and then showed a decreasing tendency with further increase in the Tb3+ ions due to the concentration quenching effect. The critical distance between neighboring Tb3+ ions for concentration quenching was calculated and found to be 12.3 Å, which indicates that dipoledipole interaction was the main mechanism for the concentration quenching of the 5D4→ 7F5 transition of Tb3+ in the BaMoO4:Tb3+ phosphors.

SrSnO3 phosphor powders were synthesized with two different contents of activator ions Eu3+ and Tb3+ using thesolid-state reaction method. The structural, morphological, and optical properties of the phosphors were investigated using X-ray diffractometry, field-emission scanning electron microscopy, and fluorescence spectrophotometry, respectively. All thephosphors showed a cubic structure, irrespective of the type and the content ratio of activator ions. For Eu3+-doped SrSnO3phosphors, the intensity of the 620nm red emission spectrum resulting from the 5D0→7F2 transition of Eu3+ was stronger thanthat of the 595nm orange emission signal due to the 5D0→7F1 transition in the range 0.01-0.05mol of Eu3+, but the ratio ofthe intensity was reversed in the range 0.10-0.20mol of Eu3+. The variation in the emission intensity indicates that the sitesymmetry of the Eu3+ ions around the host crystal was changed from non-inversion symmetry to inversion. For the Tb3+-dopedSrSnO3 phosphors under excitation at 281nm, one strong green emission band at 550nm and several weak bands wereobserved. These results suggest that the optimum red and green emission signals can be realized when the activator ion contentfor Eu3+- or Tb3+-doped SrSnO3 phosphors is 0.20mol and 0.15mol, respectively.

Green phosphors K2BaW2O8:Tb3+(1.0mol%) were synthesized by solid state reaction method. Differential thermalanalysis was applied to trace the reaction processes. Three endothermic values of 95, 706, and 1055oC correspond to the lossof absorbed water, the release of carbon dioxide, and the beginning of the melting point, respectively. The phase purity of thepowders was examined using powder X-ray diffraction(XRD). Two strong excitation bands in the wavelength region of 200-310nm were found to be due to the WO42− exciton transition and the 4f-5d transition of Tb3+ in K2BaW2O8. The excitationspectrum presents several lines in the range of 310-380nm; these are assigned to the 4f-4f transitions of the Tb3+ ion. The strongemission line at around 550nm, due to the 5D4→7F5 transition, is observed together with weak lines of the 5D4→7FJ(J=3,4, and 6) transitions. A broad emission band peaking at 530nm is observed at 10K, while it disappears at room temperature.The decay times of Tb3+ 5D4→7F5 emission are estimated to be 4.8 and 1.4ms, respectively, at 10 and 295 K; those of theWO42− exciton emissions are 22 and 0.92µs at 10 and 200K, respectively.

Tb3+ 이온이 첨가 된 NaCa(PO3)3 형광체의 여기 및 방출 스펙트럼 및 레이저 분광 측정을 통하여 형광특성을 조사 하였다. 고상법으로 NaCa(PO3)3:Tb3+ 형광체를 합성하였다. X선 회절측정(XRD)을 사용하여 형광체의 결정 구조 및 결정성을 분석하여 Tb3+ 이온이 30 mol%까지 첨가되어도 형광체의 결정구조가 NaCa(PO3)3의 결정상을 유지하였다. NaCa(PO3)3:Tb3+(0.01 - 30mol %)형광체의 여기 및 방출 스펙트럼과 형광의 감쇠곡선을 상온에서 측정 하였다. NaCa(PO3)3:Tb3+의 여기 스펙트럼에서 205 ~ 245 nm 영역에서 넓은 Tb3+의 4f – 5d 전이에 의한 f - d 밴드가 나타났다. NaCa(PO3)3:Tb3+의 방출 스펙트럼에서 5D4 → 7FJ 전이에 의한 강한 피크와 5D3 → 7FJ 전이에 약한 피크가 관찰 되었다. 방출 스펙트럼의 형광 강도와 형광의 수명시간 분석을 통하여 Tb3+ 이온 사이의 에너지 전이 및 교차 이완이 확인되었다.

본 연구에서 사용한 증감지 구성 물질은 Gd2O2S:Tb3+이고 Spectrometer를 이용하여 관전압 증가에 따른 형광특성을 분석하였다. 관전압에 증가에 따른 방출 형광을 측정한 결과 청색, 녹색, 적색에 해당하는 형광을 확인하였고, 그 중에서 녹색 형광에 해당하는 5D4 - 7F5의 형광이 가장 강하게 나타났다. 또한 50 kVp와 120 kVp의 형광량을 비교한 결과 50 kVp의 형광량은 120 kVp의 9.56%에 해당하는 형광만 방출하는 것으로 나타났다. Gd2O2S:Tb3+ 증감지를 이용한 X-선 촬영에서 100 kVp 이상의 높은 관전압을 사용 할 경우 필름에 도달하는 형광량과 강도가 급격히 증가하므로 적정농도의 영상을 획득하기위한 주의가 요구되어진다.