【摘要】 利用金属硝酸盐和尿素的氧化还原反应,通过燃烧法在600℃的炉温下合成了蓝紫色长余辉发光材料CaA l2O4∶Eu2+,Nd3+。在金属硝酸盐溶液浓度不变的条件下,通过改变尿素与硝酸根的量的比,合成了多组长余辉材料样品。当尿素用量较少时,Eu3+不能完全被还原为Eu2+;随尿素用量增加,样品的Eu3+特征发射减弱,余辉初始亮度和持续时间均得到改善;当尿素的用量达到理论用量的5倍时,样品余辉特性最好,继续增加尿素用量,余辉亮度和持续时间反而下降。将燃烧法制备的各组样品用活性炭密封,在1 000℃条件下反应2 h,使Eu3+完全被还原为Eu2+,同时除去燃烧法反应不完全的杂质,可以一定程度提高材料的余辉发光性能。更多还原

【Abstract】 The afterglow phosphor CaAl₂O₄ ∶Eu²⁺,Nd³⁺ is prepared utilizing the redox reaction of respective metal nitrates and urea by combustion synthesis with ignition temperatures of 600 ℃.The X-ray diffraction（analysis） showed that it is coincident with the JCPDS Card（No.23-1036） and its crystal structure is CaAl₂O₄ which belongs to monoclinic phase and the crystal lattice constant is as follows: a=0.869 8 nm,b=0.809 2 nm,c=1.520 8 nm.With the invariable concentration of metallic ions nitrate,a series of phosphor samples were synthesized by altering the ratio of urea and nitrate.The emission spectra and excitation spectra of the phosphor were investigated.The excitation spectra of CaAl₂O₄ ∶Eu²⁺,Nd³⁺ showed a double peak broadband structure.The main peak located at 352 nm and a shoulder peak at 266 nm.The quantity of urea has obvious influence on the emission spectrum of CaAl₂O₄ ∶Eu²⁺,Nd³⁺.When the quantity of urea exceed double of theoretic quantity,adequate reducing gas produced in the process of combustion reaction benefit to the form of Eu²⁺ luminescent center,so emission spectra of CaAl₂O₄ ∶Eu²⁺,Nd³⁺ consist of characteristic broad band emission of Eu²⁺.Contrast this,inadequate reducing gas benefit to form of Eu³⁺ luminescent center,so when the quantity of urea less than double of theoretic quantity,the emission spectra exhibit characteristic narrowband emission of Eu³⁺.The samples are fired at 1 000 ℃ for 2 h in an active carbon atmosphere in order to deoxidize residual Eu³⁺ to Eu²⁺ and eliminate impurity brought by combustion synthesis.This is beneficial to promote the（performance） of luminescence.The decay curves of phosphor with different quantity of urea were measured.The change of urea’s quantity affected on the afterglow character of CaAl₂O₄ ∶Eu²⁺,Nd³⁺ distinctly and the optimal quantity of urea is（5 times） of theoretic quantity.When more urea was used in the experiment,the luminescent intensity will（decrease） and the lasting time will be shorten.更多还原