Preparation And Optical Properties Of LaB₆ Low-E Thin Films By Magnetron Sputtering

LaB₆ nanoparticles have excellent barrier effect in the near-infrared band without sacrificing the transmittance in the visible band,It is an ideal choice for transparent thermal insulation materials.The magnetron sputtering method can solve the problem of introducing pollutants in the preparation of LaB₆ nanoparticles by mechanical grinding method,and can effectively prevent the agglomeration of nanoparticles as transparent heat insulation glass coating.However,there are other problems in the preparation of LaB₆ nanoparticle coating by magnetron sputtering.This experiment is to solve the problems of low crystallization and uncontrollable particle size uniformity of LaB₆ nanoparticle coating prepared by magnetron sputtering.The problem of low crystallization was solved by annealing process,and the size of LaB₆ nanoparticles was controlled by adding templates.The morphology and size of LaB₆nanoparticles were observed by FESEM and AFM.The crystallinity of the samples before and after annealing was detected by XRD.The chemical states of different elements in the samples were determined by XPS.The optical properties of samples with different morphologies were measured by UV-Vis-NIR spectrophotometer,and the influence of the morphologies of LaB₆ nanoparticles on the optical properties was analyzed.The results show that the crystallization of the sample is obviously improved after annealing,but the increase of the grain size reduces the near-infrared blocking performance.The particle size of LaB₆ nanoparticles can be effectively controlled by sputtering LaB₆after Ag templates is prepared by magnetron sputtering.By comparing the morphologies of different templates,it is found that when the substrate is heated at 150?and the thickness is2nm,the particle size of Ag templates is more uniform.After sputtering LaB₆ with the templates,the templates was removed by wet etching,and then annealed.After observing the morphology of the sample,it was found that the uneven particle size was improved.The UV-Vis-NIR spectrophotometer results show that the transmittance of LaB₆nanoparticles sputtered by the templates is up to 75%in the visible band,while the transmittance of the near infrared band is about 50%.Combined with the characterization of morphology,it is found that the improvement of optical properties is due to the control of the particle size of LaB₆ nanoparticles.Using the templates can effectively control the uniformity of the particle size of LaB₆ nanoparticles and keep the particle size at 40nm.By establishing the relationship between the morphology and optical properties of LaB₆ nanoparticles,the results show that the spherical like LaB₆ nanoparticles with the particle size of about 40 nm have the best optical properties.It is an ideal material for transparent thermal insulation coating because of its high barrier effect in near infrared band and high transmittance in visible band.