Visible up-conversion emissions at 435, 545, 580, 675 and 690 nm and 437, 547, 575 and 675 nm have been obtained from BaTiO3 doped with 4 % Ho3+ ions in two different forms of the prepared samples, powder and thin film, under 808 nm laser diode excitation emissions. Combined with the energy level structure of Ho3+ ions and the kinetics of the visible emissions, the up-conversion mechanism has been analyzed and explained. The blue, green and red emissions of both samples have been attributed to the ground state-directed transition from 5F1, 5S2 and 5F5 states, respectively, which are populated through excited state absorption on 808 nm excitation. Nano-structure pure barium titanate and doped with different concentrations of Ho3+ ions in the form of powder and thin films have been prepared by so-gel technique, using barium acetate (Ba(CH3CHOO)2) and titanium isopropoxide (Ti((CH3)2CHO)4) as precursors. The thin films were prepared by spin-coating sol-gel method. The as-grown thin film and powders were found to be amorphous, which crystallized to the tetragonal phase after synthesization at 750 °C in air for 30 minutes. The crystallite size of thin film and powder samples both doped with 4 % Ho3+ ions, were found to be equal to 11 and 16 nm, respectively.Uzbudom laserskom diodom na 808 nm postigli smo emisije u vidljivom području na 435, 545, 580, 675 i 690 nm, te na 437, 547, 575 and 675 nm, u BaTiO3 punjenom s 4 % Ho3+ iona u uzorcima dvaju oblika, prahu i tankom sloju. Uzimajući u obzir stanja iona Ho3+ i kinetiku emisije fotona, analizirali smo i objasnili mehanizam uzbude naviše. Emisije oba uzorka u plavom, zelenom i crvenom području pripisuju se prijelazima u osnovno stanje sa stanja 5F1, 5S2 odn. 5F5 koja se pune apsorpcijom fotona 808 nm u višim stanjima Ho3+ iona. Metodom sol-gel pripremili smo nanostrukturni čist barijum titanat i barijum titanat punjen s dvjema koncentracijama Ho3+ iona, kao prah i kao tanke slojeve. Rabili smo barijum acetat (Ba(CH3CHOO)2) i titanijev izopropoksid (Ti((CH3)2CHO)4) za njihovu pripremu. Tanke smo slojeve dobivali centrifugiranjem sol-gela. Svježe pripremljeni tanki slojevi i prah su amorfni, ali se kristaliziraju zagrijavanjem na 750 ◦C u zraku tijekom 30 minuta. Veličina kristalita u tankom sloju i prahu, svaki punjen s 4 % Ho3+ iona, iznosi 11 odn. 16 nm
