| The property of solid-doped luminescence depends strongly on the structure of the solids.A series of Eu ions and Mn ions based spectra exploration focused on the impact of the crystal structure were studied in this work.This will serve as bases for improving the performance of luminescent materials and its applications in temperature sensing.The main research contents were as follows:As the introduction part,the first chapter introduced the definition,classification and characterization parameters of luminescence firstly.And then,the mechanism process of photoluminescence and the configuration coordinate model,energy transfer mechanism and temperature quenching were discussed.Lastly,the rare earth elements and transition metal elements commonly used in doped luminescence were introduced,and then the properties ofions,energy level structures of the rare earth elements and transition metal elements and the effects of the crystal field on the ions energy levels are presented.The second chapter presented a silicate solid solution material Ca2(1-x)Sr2xZnSi207 which could enhance the photoluminescence and afterglow luminescence of Eu2+ions via Ca/Sr solid solution.At first,we synthesized samples with different Ca/Sr ratios via high-temperature solid solution method,and confirmed the crystal phase of the samples by X-ray powder diffraction.Subsequently,a systematic study was carried out on the successfully synthesized sample:firstly,the luminescent center of the samples were verified by excitation and emission spectra to confirm that the luminescence of the sample was related to Eu2+.And then,the source of the afterglow of the sample was confirmed via the afterglow spectrum.From the afterglow decay curve,we estimated the long afterglow performance of each sample preliminary.Finally,we utilized the thermoluminescence curves to understand the distribution of the traps existed in the each samples.By fasten the doped concentration of Eu ions,we compared the solid solution ratios dependent photoluminescence spectra and found that the solid solution between the Ca and Sr could not only influence the peaks of Eu2+ emission,but also enhance the intensity of Eu2+emission significantly.The intensity of middle ratios was higher than one times of the samples before solid solution.By comparing the afterglow spectrum and afterglow decay curve of each solid solution ratio,the results showed that solid solution could also enhance the afterglow intensity of the samples.Combining the distribution of emission intensity and afterglow intensity with solid solution ratio,we discussed possible causes and situations.The experimental results indicated that proper solution would not only change the emission range of doped ions in the sample,but also promote its luminescence and afterglow ability.The third chapter mainly presented a Mn2+based green long afterglow material Ca14Zn6Ga10O35:Mn2+.After verifying the crystal phase of the samples synthesized by high-temperature solid solution method by XRD,we promoted a systematic study on a series of synthesized samples.The comparison of the emission spectra between the Mn single-doped sample and the Mn/Ge co-doped sample shown that a certain amount of Ge co-doped in CZGO could promote the reduction of Mn4+to Mn2+.By controlling the doping concentration of Mn,the best Mn concentration corresponding to the best Mn2+ emission was found.After analysising the linetype of the afterglow spectra of all samples,we determined that the luminescent center of green afterglow is Mn2+and located the Mn doping concentration corresponding to the best afterglow performance.After a comparative analysis of the afterglow decay curve and the thermoluminescence curve,we proposed a possible mechanism model to understand the photoluminescence and afterglow behavior.Based on the experiments in Chapter 3,we discussed the relationship between the concentration of Mn and the co-doped concentration of Ge and the reduction effect of Mn4+to Mn2+more detailedand explored the feasibility of the emission spectra fluorescence intensity ratio of Mn2+and Mn4+in temperature sensing.Afer analysising the variable temperature spectrum in the temperature range of 30-450 K,we confirmed that the intensity of anti-Stokes emission of Mn4+was positively correlated with temperature,and the emission intensity of Mn2+was generally negatively correlated with temperature.Among them,at low temperatures,Mn2+existed two emission parts:one is green and the other is orange,the orange part of the emission is almost completely thermally quenched when the temperature raised to near room temperature.After normalized the emission spectra,we fitted the integral intensity of the anti Stokes emission of Mn4+and the integral intensity ratio of the emission spectra of Mn2+ and Mn4+ with the temperature correlation,and then calculated the sensitivity of each method.The experimental results indicated that there existed four kind temperature sensing methods in CZGO:Mn.In Chapter 5,we explored four kind ? calcium phosphate based solid solution and its luminescent properties.First of all,we depicted the luminescent properties of the solid solutionsamples between Ca10Na(PO4)7 and Ca9Sc(PO4)7 samples with Eu2+doped as luminescent center.The results of emission spectra showed that different solid solution ratio could significantly affect the emission spectrum of Eu2+.After choosing the appropriate solid solution ratio,we verified the possibility of utilizing the samples to yield white light when co-doping Mn2+.And then,we provided a new type solid solution material which was formed Ca10Na(PO4)7 and Ca9Bi(PO4)7.We found that the emission spectrum of Eu2+from multi peak transformed to single peak when adding nearly same molar ratio of Bi and Na.According to the experimental results,we discussed this phenomenon in general.After that,we explored the solid solution of Ca10Na(PO4)7 and Ca9Al(PO4)7.The experimental results showed that the emission color of Eu2+could be adjusted when there existed a slight Na/Al solid solution.By controlling the doping concentration of Eu2+,we observed that the doping concentration of Eu2+could affect the sites occupation in the host.It was found that there existed energy transfer between Eu2+of different lattice sites after analysised the temperature dependent spectra.After choosen appropriate concentration of Eu2+ and appropriate solid solution ratio,we obtained the emission spectrasmiliar with the solar spectrum possessed a wide FWHW(full width at half maximum)with the width greater than 200 nm when co-doped Mn2+.At last,we investigated the solution of Ca9Y(VO4)7 and Ca9Y(PO4)7.When V ratio was small,meaning low concentration,V-O charge transfer luminescence could keep strong emission.We could adjust the distribution range of V-O emission at present viaadjusted the concentration of V slightly.With the Mn2+co-doped,we verified the white light properties of samples.Through the above four experiments,we explored the influence of solid solution on the luminescent properties,and verified the feasibility of single substrate white light through solid solution.At last,the main content of this thesis was summarized and the future development direction was looking forward. |
PDF Full Text Request