植物生长照明用La_(2)Mg_(4/3)Sb_(2/3)O_(6)∶Mn^(4+)红色荧光粉的制备及光谱特性

Preparation and Spectral Properties of La_(2)Mg_(4/3)Sb_(2/3)O_(6)∶Mn^(4+)Red Phosphor for Plant Growth Illumination

采用传统高温固相法制备了一系列La_(2)Mg_(4/3)Sb_(2/3-x)O_(6)∶xMn^(4+)红色荧光粉,并对其结构、形貌和光谱特性进行了研究。研究结果表明:La_(2)Mg_(4/3)Sb_(2/3)O_(6)与La_(2)Mg_(4/3)Nb_(2/3)O_(6)具有相同的双钙钛矿结构,Mn^(4+)掺杂对荧光粉的结构没有影响。La_(2)Mg_(4/3)Sb_(2/3-x)O_(6)∶xMn^(4+)荧光粉在360与510 nm处有两个较宽的激发峰,分别对应Mn^(4+)的^(4)A_(2g)→^(2)T_(2g)与^(4)A_(2g)→^(4)T_(2g)跃迁。在360 nm激发下,La_(2)Mg_(4/3)Sb_(2/3-x)O_(6)∶xMn^(4+)荧光粉在710 nm处呈现出较强的红光发射峰,对应Mn^(4+)的^(2)E_(g)→^(4)A_(2g)跃迁发射。Mn^(4+)在La_(2)Mg_(4/3)Sb_(2/3)O_(6)基质中的最佳掺杂浓度为0.004,此时的量子效率高达89.6%,色纯度为99%。根据激发光谱和发射光谱分析了Mn^(4+)在La_(2)Mg_(4/3)Sb_(2/3)O_(6)基质中的晶体场强,并计算了晶体场参数D_(q)、B和C。结合Mn^(4+)的位型坐标图分析了La_(2)Mg_(4/3)Sb_(2/3-x)O_(6)∶xMn^(4+)荧光粉的温度猝灭过程,计算得到其激活能为0.355 eV。最后,对比了La_(2)Mg_(4/3)Sb_(2/3-x)O_(6)∶xMn^(4+)荧光粉的发射光谱与植物光敏色素红外吸收型(P_(R))、远红外吸收型(P_(FR))的吸收光谱,并初步评估了其在LED植物照明领域的应用前景。

A series of La_(2)Mg_(4/3)Sb_(2/3-x)O_(6)∶xMn^(4+)red phosphors were prepared via traditional high-temperature solid-reaction method,and their structure,morphology and spectral properties were investigated.The results show that La_(2)Mg_(4/3)Sb_(2/3)O_(6)belongs to the double-perovskite structure as La_(2)Mg_(4/3)Nb_(2/3)O_(6)does,and the incorporation of Mn^(4+)has no influence on the structure of the phosphors.La_(2)Mg_(4/3)Sb_(2/3-x)O_(6)∶xMn^(4+)phosphor exhibits two broad excitation bands at 360 and 510 nm,corresponding to the^(4)A_(2g)→^(2)T_(2g)and^(4)A_(2g)→^(4)T_(2g)transitions of Mn^(4+)respectively.Upon 360 nm excitation,La_(2)Mg_(4/3)Sb_(2/3-x)O_(6)∶xMn^(4+)phosphor gives rise to a intense red emission band at 710 nm,which belongs to the^(2)E_(g)→^(4)A_(2g)transition of Mn^(4+).The optimal concentration of Mn^(4+)in La_(2)Mg_(4/3)Sb_(2/3)O_(6)host was determined to be 0.004,with quantum yield and color purity up to 89.6%and 99%,respectively.A crystal field analysis for Mn^(4+)in the La_(2)Mg_(4/3)Sb_(2/3)O_(6)matrix was conducted based on the excitation and emission spectra,and the crystal field parameters D_(q),B and C were calculated.The temperature quenching process of La_(2)Mg_(4/3)Sb_(2/3-x)O_(6)∶xMn^(4+)phosphor was analyzed with the configurational coordinate diagram of Mn^(4+),and the activation energy was calculated to be 0.355 eV.Finally,a comparison between the emission spectra of La_(2)Mg_(4/3)Sb_(2/3-x)O_(6)∶xMn^(4+)phosphor and the absorption spectra of phytochrome P_(R)and P_(FR)was provided,and the application prospect of La_(2)Mg_(4/3)Sb_(2/3-x)O_(6)∶xMn^(4+)phosphor in LED plant illumination was preliminarily evaluated.