Abstract: Barium-strontium titanate (Ba_0.65Sr_0.35TiO₃) films doped with Ho³⁺(1mol%, 3mol%, 5mol%, 8mol%) were prepared by the sol-gel technique. The AFM, XRD, UV-Vis spectra and photoluminescence (PL) spectra of BST films were investigated. Results show that the lattice parameters of BST films increase when Ho³⁺ dopant increases from 1mol% to 3mol% then decrease with Ho³⁺ dopant from 3mol% to 8mol%. The lights centered at about 615, 650 and 750nm are corresponding to the transitions of ⁵F₃→⁵F₇, ⁵F₅→⁵F₈ and ⁵S₂, ⁵F₄→⁵F₇, respectively. The lifetime spectra of ⁵S₂, ⁵F₄ and three PL spectra above indicate that the luminescence intensity reach the maximum in 3mol% Ho³⁺ -doped BST films. The optimized Ho³⁺ dopant in BST films is 3mol%. The crossing relaxation mechanisms and site-substituting between H ³⁺ and Ba²⁺/Sr²⁺/Ti⁴⁺ are analyzed.

Key words: BST films, rare earth-doping, photoluminescence