Study on the Structure and Photoluminescence of Ho~(3+)-doped BST Films

Barium-strontium titanate(Ba_(0.65)Sr_(0.35)TiO_3)films doped with Ho~(3+)(1mol%,3mol%,5mol% 8mol%)were prepared by the sol-gel technique.The AFM,XRD,UV-Vis spectra and photolumines- cence(PL)spectra of BST films were investigated.Results show that the lattice parameters of BST films increase when Ho~(3+)dopant increases from 1mol% to 3mol% then decrease with Ho~(3+)dopant from 3mol% to 8mol%.The lights centered at about 615,650 and 750nm are corresponding to the transitions of ~5F_3→~5F_7,~5F_5→~5F_8 and ~5S_2,~5F_4→~5F_7,respectively.The lifetime spectra of ~5S_2,~5F_4 and three PL spectra above indicate that the luminescence intensity reach the maximum in 3mol% Ho~(3+)-doped BST films.The optimized Ho~(3+)dopant in BST films is 3mol%.The crossing relaxation mechanisms and site-substituting between Ho~(3+)and Ba~(2+)/Sr~(2+)/Ti~(4+)are analyzed.