Shivaram M, Nagabhushana H, Sharma S C, Prashantha S C, Daruka Prasad B, Dhananjaya N, Hari Krishna R, Nagabhushana B M, Shivakumara C, Chakradhar R P S
Jawaharlal Nehru Technological University, Anantapur 515002, A.P., India; Department of Physics, VV Puram College of Science, Bangalore 560 004, India.
Prof. CNR Rao, Centre for Advanced Materials, Tumkur University, Tumkur 572 103, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2014 Jul 15;128:891-901. doi: 10.1016/j.saa.2014.02.117. Epub 2014 Mar 15.
CaTiO3:Sm(3+) (1-11 mol%) nanophosphors were successfully synthesized by a low temperature solution combustion method [LCS]. The structural and morphological properties of the phosphors were studied by using Powder X-ray diffractometer (PXRD), Fourier transform infrared (FTIR), X-ray photo electron spectroscopy (XPS), scanning electron microscope (SEM) and transmission electron microscopy (TEM). TEM studies indicate that the size of the phosphor is ∼20-35 nm. Photoluminescence (PL) properties of Sm(3+) (1-11 mol%) doped CaTiO3 for NUV excitation (407 nm) was studied in order to investigate the possibility of its use in White light emitting diode (WLED) applications. The emission spectra consists of intra 4f transitions of Sm(3+), such as (4)G5/2→(6)H5/2 (561 nm), (4)G5/2→(6)H7/2 (601-611 nm), (4)G5/2→(6)H9/2 (648 nm) and (4)G5/2→(6)H11/2 (703 nm) respectively. Further, the emission at 601-611 nm show strong orange-red emission and can be applied to the orange-red emission of phosphor for the application for near ultra violet (NUV) excitation. Thermoluminescence (TL) of the samples irradiated with gamma source in the dose range 100-500 Gy was recorded at a heating rate of 5°Cs(-1). Two well resolved glow peaks at 164°C and 214°C along with shouldered peak at 186°C were recorded. TL intensity increases up to 300 Gy and thereafter, it decreases with further increase of dose. The kinetic parameters namely activation energy (E), frequency factor (s) and order of kinetics were estimated and results were discussed in detail.
采用低温溶液燃烧法（LCS）成功合成了CaTiO₃:Sm(³⁺)（1 - 11摩尔%）纳米磷光体。通过粉末X射线衍射仪（PXRD）、傅里叶变换红外光谱（FTIR）、X射线光电子能谱（XPS）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）研究了磷光体的结构和形态特性。透射电子显微镜研究表明磷光体的尺寸约为20 - 35纳米。为了研究其在白光发光二极管（WLED）应用中的可能性，研究了Sm(³⁺)（1 - 11摩尔%）掺杂的CaTiO₃在近紫外（NUV）激发（407纳米）下的光致发光（PL）特性。发射光谱由Sm(³⁺)的4f内跃迁组成，分别为(⁴)G₅/₂→(⁶)H₅/₂（561纳米）、(⁴)G₅/₂→(⁶)H₇/₂（601 - 611纳米）、(⁴)G₅/₂→(⁶)H₉/₂（648纳米）和(⁴)G₅/₂→(⁶)H₁₁/₂（703纳米）。此外，601 - 611纳米处的发射显示出强烈的橙红色发射，可用于近紫外（NUV）激发的磷光体的橙红色发射应用。以5°C s⁻¹的加热速率记录了在100 - 500 Gy剂量范围内用γ源辐照的样品的热释光（TL）。记录到在164°C和214°C处有两个分辨良好的发光峰以及在186°C处有一个肩峰。热释光强度在300 Gy时达到最大值，此后随着剂量的进一步增加而降低。估算了动力学参数，即活化能（E）、频率因子（s）和动力学级数，并详细讨论了结果。
