Synthesis of Complex Fluorides and Optical Properties of Doping Rare Earth Ions

本论文通过水热、溶剂热、高温固相以及单晶生长法合成了复合氟化物及部分稀土离子激活的氧化物。运用近年来兴起的温和水热和溶剂热法探索了MAIF5（M＝Ca、Sr、Ba）和LIMAIFa（M＝Ca、Sr）系列复合氟化物的合成条件。以水作为溶剂，合成了CaAIF、SrAIF、BaA作ICaAIF6和L诏rAI凡化合物，从起始反应物、反应温度、反应时间及酸度儿方面考察了几种化合物的合成条件。对于溶剂热反应，选择了五种不同的溶剂作为反应介质，分别为乙二醇、乙醇、甲苯、毗咙、四氢「臾喃。以乙二醇和甲苯为溶剂，可以合成SrAlF5和LiSrAlF6民复合氟化物，而乙醇、毗咙、四氢「归喃作为反应介质没有得到l；l标产物。在五种汽半剂中均不能合成CoAIF6、BaAlF5和LiCaAlF6复合氟化物。通过水热、高温固相以及单晶生民法介成了KMgF3:Eu体系。水热合成的产，物具有氧含员低、物相纯等优点，同时该伙合成的多移，体存在史多的色心。比较三种方法合成的KMgFa:EU的光谱，发现水热和单晶样品中除了6P7/2→8S7/2的线发则外，还明显出现址火峰位置位于420nm处的带发射。结合退火实验，相刃刁又热样品的带发射是由于色心所致，而单晶样l界，的带峰则源于晶体中存在的色心、和少量氧所致，但以色心为主。在高温样品中，只有特征的线发射，没有观察到类似的带发射。结合退火前后线带发射弧度的变化及色心激发谱和翻”．6P7/2-8S7/2发射潜的乘补程度，得出Eu3+→色心的能址传递。通过高温固相反应合成Gd，Eu单掺、双掺的KMgFa、BaLiF3、BaY2F8三种磷光体，考察了Gd2+，Eu2+的光学性质，发现了双掺体系中（Gd3+→Eu2+的能里传递以生象，分析了能墩传递方式，并计算了前两个体系中Gd3+→Eu2+能最传递儿率。考察了Pr内+ 在KMgF2、LiYF4、BaY2F8基质中的光谱情况，指认了发射峰所对应的跃迁光潜项，具体讨论了KMgFa:Pr3+激发潜中352nm处的宽带激发峰。考察了Pr3+的发射弧度在KMg1-xCaxF3体系中的咨隋况，发现随枷含嫩的增加，Pr3+的在各发射区的发射强度显著增弧，分析了可能的原因。此外本论文也通过旋转试域熔融法生长了Ca2MgSi2O2单晶，详细讨论了生长品体的彩响因索，并以该化合物为纂质，考察了Eu的掺杂行为。在空气氛围下，没有发生Eu3+→Eu2+的还原，而是形成Ca2Eu8Si6O26化合物，这借助X-ray粉末衍射、组分分析及光谱分析得到证实。In this dissertation, four methods: hydrothermal, solvothermal, high-temperature-solid-state method and single-crystal-growth method were used to synthesize complex fluorides and part of rare-earth-activated fluorides. By using recently arised mild hydrothermal and so I. vo thermal methods, we investigated the conditions for the synthesis of MAlF5(M=Ca Sr Ba) and LiMAlF6(M=Ca Sr) series. Using water as solvent, CuAJ.Fn-, SrAlF, BuAl Li.CaAllVfNL pound-were obtained. The optimum conditions for synthesizing the above-mentioned compounds were investigated by the aspects of the molar ratio of the starting materials, reactive temperature, reactive: 1 time and acidity. During the synthesis, pll values in the range of 3-5 had no obvious effects on the end products. For the solvothermal synthesis, five different solvents were tried: glycoi, ethanol, toluene, pyridine and tetrafuran. Using glycoi and toluene as reactive solvents, SrAlFB and LiSrA'IF,,compounds can be synthesized, but there was no expected products obtained when ethanol, pyridine and tetrafuran was used as solvents separately. For LiCaA11, compound, there was no product obtained in all these three solvents, which might be resulting from the lack of co-melting point of JJCaAlFf. Through hydrothenmil, high-temperature solid-state method and single-crystal-growth method, KMgF3: systems were synthesized. The products synthesized from hydrothermal. method have the advantages of lower-oxygen content and pure phase etc., meanwhile, the polycrystallines synthesized from this method had much more color centers. Comparing the KMgFJ: Eu spectra synthesized from these three kinds of methods, it can be seen that except the 6P7/2->RS7/2 line emission, there was another obvious band emission in hydrothermal and single-crystal samples, its maximum value lied at 420nm. Combining with the annealing experiment, it was proved that the band peak of the hydrothermal sample was caused by color centers, while that of the single-crystal-sample was from the existence of color center and small amount of oxygen, but color center was the main reason. In high-temperature sample, only the line emission was observed, no such band emission peaks. Together with the intensity change of the line and band emissions before and after annealing, also the overlapping between the color center excitation spectra and the emission spectra of Eu, the energy transfer from Eu to color center was concluded. Gd1, Eu2 single- and double-doping KMgF3, BaLiF3, BaY2Fs systems were synthesized through high-temperature solid state reaction. The optical properties of Gd and Eu in these three kinds of compounds were studied. The phenomena of energy transfer from Gd3+->Eu2+ were found, while the ways of energy transfer was analyzed and the probabilities of the energy transfer was calculated. we also investigated the spectra of Pra in KMgF3, LiYF4) BaY2Fs matrix, and the corresponding transition spectral terms of all the emission peaks were assigned. The unexpected peak observed in the excitation spectra of the KMgFa:Pr3+was discussed in detail. We also investigated the effect of the Pr ion spectra on Ca amount in KMgi-xCa,F3 system, and found that the omission intensity of the Pra ion was increased with the increasing of Ca-content in KMgi-xCaF3 matrix. The possible reason for that was analyzed. In addition, the single crystals of pure Ca2MgSi207 and doped with Eu were grown by the floating zone method. The effect of growth parameters on crystal quality vsa investigated in detail. No was confirmed by means of X-ray powder diffraction, composition analysis and photo-luminescence, whereas Ca2Eu8Si6O26 compound was formed by the combination Eu3+ with other elements in raw materials