采用高温固相法制备了一系列黄橙光荧光粉Sr_(9)Mg_(1.5)(PO_(4))_(7-x)(BO_(3))_(x):0.05Eu^(2+)(SMPB_(x)O:Eu^(2+),x=0~0.6)和Sr_(9-2 y)Ca_(y)Ba_(y)Mg_(1.5)(PO_(4))_(7):0.05Eu^(2+)(SC_(y)B_(y)MPO:Eu^(2+),y=0~1.0),并对其发光...采用高温固相法制备了一系列黄橙光荧光粉Sr_(9)Mg_(1.5)(PO_(4))_(7-x)(BO_(3))_(x):0.05Eu^(2+)(SMPB_(x)O:Eu^(2+),x=0~0.6)和Sr_(9-2 y)Ca_(y)Ba_(y)Mg_(1.5)(PO_(4))_(7):0.05Eu^(2+)(SC_(y)B_(y)MPO:Eu^(2+),y=0~1.0),并对其发光性能的调控进行了研究。所得荧光粉可以被蓝光和近紫外光有效激发,并发射黄橙光(450~800 nm)。随着(BO_(3))^(3-)与Ca^(2+)-Ba^(2+)共掺浓度的改变,可以调节Eu^(2+)发光中心在Sr31、Sr1和Sr32格位中的选择性占据,从而改变SMPB_(x)O:Eu^(2+)和SC y B y MPO:Eu^(2+)的发射光谱。因此,固定激发波长,改变(BO_(3))3-或Ca^(2+)-Ba^(2+)共掺浓度可以实现对SMPB_(x)O:Eu^(2+)(x=0.2~0.6)和SC_(y)B_(y)MPO:Eu^(2+)(y=0.25~1.0)发光颜色的调控。另外,SMPB_(x)O:Eu^(2+)和SC_(y)B_(y)MPO:Eu^(2+)的发光颜色也可以通过改变激发波长来进行调控。此外,(BO_(3))^(3-)掺杂与Ca^(2+)-Ba^(2+)共掺均可以明显提高荧光粉的热稳定性。在100℃下,SMPB_(x)O:Eu^(2+)(x=0.2~0.6)和SC_(y)B_(y)MPO:Eu^(2+)(y=0.25~1.0)样品的发光强度均可达到其各自初始强度的60%以上。展开更多
Dendritic coarsening in AI-2mol%Si alloy during isothermal solidification at 880K was investigated by phase field modeling. Three coarsening mechanisms operate in the alloy： （a） melting of small dendrite arms; （b...Dendritic coarsening in AI-2mol%Si alloy during isothermal solidification at 880K was investigated by phase field modeling. Three coarsening mechanisms operate in the alloy： （a） melting of small dendrite arms; （b） coalescence of dendrites near the tips leading to the entrapment of liquid droplets; （c） smoothing of dendrites. Dendrite melting is found to be dominant in the stage of dendritic growth, whereas coalescence of dendrites and smoothing of dendrites are dominant during isothermal holding. The simulated results provide a better understanding of dendrite coarsening during isothermal solidification.展开更多
文摘采用高温固相法制备了一系列黄橙光荧光粉Sr_(9)Mg_(1.5)(PO_(4))_(7-x)(BO_(3))_(x):0.05Eu^(2+)(SMPB_(x)O:Eu^(2+),x=0~0.6)和Sr_(9-2 y)Ca_(y)Ba_(y)Mg_(1.5)(PO_(4))_(7):0.05Eu^(2+)(SC_(y)B_(y)MPO:Eu^(2+),y=0~1.0),并对其发光性能的调控进行了研究。所得荧光粉可以被蓝光和近紫外光有效激发,并发射黄橙光(450~800 nm)。随着(BO_(3))^(3-)与Ca^(2+)-Ba^(2+)共掺浓度的改变,可以调节Eu^(2+)发光中心在Sr31、Sr1和Sr32格位中的选择性占据,从而改变SMPB_(x)O:Eu^(2+)和SC y B y MPO:Eu^(2+)的发射光谱。因此,固定激发波长,改变(BO_(3))3-或Ca^(2+)-Ba^(2+)共掺浓度可以实现对SMPB_(x)O:Eu^(2+)(x=0.2~0.6)和SC_(y)B_(y)MPO:Eu^(2+)(y=0.25~1.0)发光颜色的调控。另外,SMPB_(x)O:Eu^(2+)和SC_(y)B_(y)MPO:Eu^(2+)的发光颜色也可以通过改变激发波长来进行调控。此外,(BO_(3))^(3-)掺杂与Ca^(2+)-Ba^(2+)共掺均可以明显提高荧光粉的热稳定性。在100℃下,SMPB_(x)O:Eu^(2+)(x=0.2~0.6)和SC_(y)B_(y)MPO:Eu^(2+)(y=0.25~1.0)样品的发光强度均可达到其各自初始强度的60%以上。
基金financially supported by the Natural Science Foundation of Liaoning Province(20092061 and 20102189)
文摘Dendritic coarsening in AI-2mol%Si alloy during isothermal solidification at 880K was investigated by phase field modeling. Three coarsening mechanisms operate in the alloy： （a） melting of small dendrite arms; （b） coalescence of dendrites near the tips leading to the entrapment of liquid droplets; （c） smoothing of dendrites. Dendrite melting is found to be dominant in the stage of dendritic growth, whereas coalescence of dendrites and smoothing of dendrites are dominant during isothermal holding. The simulated results provide a better understanding of dendrite coarsening during isothermal solidification.
