电荷补偿对Ba_(2)ZnGe_(2)O_(7)∶Bi^(3+)荧光粉发光性质的影响

Influence of charge compensation to the luminescence properties of Ba_(2)ZnGe_(2)O_(7)∶Bi^(3+)phosphor

采用高温固相法制备了2个系列的荧光粉样品:Ba_(2-x)ZnGe_(2)O_(7)∶xBi^(3+)(系列Ⅰ)和Ba1.994-yKyZnGe_(2)O_(7)∶0.006Bi^(3+)(系列Ⅱ)。X射线衍射(XRD)测试结果表明,少量Bi^(3+)、K^(+)的掺杂不会明显改变材料的物相结构。样品的荧光光谱测试结果表明,虽然2个系列样品的发光光谱都随组成成分变化有少量变化,但发光颜色基本上均为黄绿色。在358 nm的激发下,荧光粉的发射光谱呈现一个峰值在500 nm的宽发射带,归属于^(3)P_(1)→^(1)S_(0)能级跃迁。在500 nm监测下,荧光粉的最强激发峰位于358 nm,归属于^(1)S_(0)→^(3)P_(1)能级跃迁,此外还有一个位于320 nm的肩峰归属于O^(2-)-Bi^(3+)电荷转移带。系列Ⅰ样品的光谱数据结果指出,Bi^(3+)的最佳掺杂量x为0.006。在该基质中,Bi^(3+)掺杂取代Ba_(2+)属于不等价取代,会在晶格中产生Ba_(2+)空位或间隙O^(2-),对材料的发光强度产生负面影响。对此,采用K^(+)与Bi^(3+)协同掺杂起到电荷补偿的作用,填补Ba_(2+)空位或捕获间隙O^(2-)缺陷。空位被填补或间隙被捕获均减少了晶格畸变,从而使发光强度明显提高。系列Ⅱ样品的光谱数据表明,完全电荷补偿的荧光粉样品相比于没有掺K^(+)的样品,其发光强度提高了约2.5倍。

In this work,two series of phosphors were prepared using high-temperature solid-state reactions:Ba_(2-x)ZnGe_(2)O_(7)∶xBi^(3+)(seriesⅠ)and Ba1.994-yKyZnGe_(2)O_(7)∶0.006Bi^(3+)(seriesⅡ).X-ray diffraction(XRD)analysis demon-strated that the doping of a small amount of Bi^(3+)and K^(+)did not significantly change the phase structure of the mate-rial.The fluorescence spectra of the samples were obtained using a fluorescence spectrometer.The results indicated that the luminescence colors of both series remained yellow-green despite a slight variation in the luminescence spectra with changes in composition.Excitation at 358 nm led to the phosphor exhibiting a broad emission band with its peak at 500 nm,which corresponded to the energy level transition from^(3)P_(1)to^(1)S_(0).When monitoring at 500 nm,the strongest excitation peak occurred at 358 nm,representing the energy level transition from^(1)S_(0)to^(3)P_(1).Fur-thermore,a shoulder peak at 320 nm was observed,indicating a charge transfer band between O^(2-)and Bi^(3+).Analysis of the spectral data for seriesⅠsuggested that the optimal doping amount of Bi^(3+)was x=0.006.In this matrix,the substitution of Ba_(2+)by Bi^(3+)introduced an unequal substitution,leading to the generation of Ba_(2+)vacancies or intersti-tial O^(2-)within the lattice,which had a negative impact on the luminous intensity of the material.Co-doping with K^(+)acted as a charge compensator,effectively cancelling out the Ba_(2+)vacancies or interstitial O^(2-)by generating intersti-tial K^(+)or oxygen vacancies.Consequently,this process reduced lattice distortion and improved luminescent intensity.Further analysis of the spectral data for seriesⅡrevealed that the fully charge-compensated phosphor sample exhibited luminescent intensity about 2.5 times higher than that of the sample without K^(+)doping.