title: Structure, charge transfer bands and photoluminescence of nanocrystals tetragonal and monoclinic ZrO2:Eu.
abstract: Eu(3+)-doped tetragonal and monoclinic ZrO2 (called t-ZrO2:Eu and m-ZrO2:Eu, respectively) nanoparticles were prepared using the Pechini sol-gel process. The samples were characterized via X-ray diffraction (XRD) and field-emission-scanning electron microscopy (FE-SEM), and with photoluminescence spectra. The influences of the Eu3+ concentration and the fired temperature on the crystal phase composition of the tetragonal and monoclinic ZrO2:Eu were reported. The typical interesting photoluminescence (PL) properties of the t-ZrO2:Eu and m-ZrO2:Eu nanoparticles were presented. In the t-ZrO2:Eu and m-ZrO2:Eu, the main emission peaks were at 607 and 615 nm, respectively, both of which originated from the 5D0-7F2 transition. The excitation band of the t-ZrO2:Eu powder with a lower Eu3+ doping concentration that was obtained at a low temperature (450 degrees C) consisted of a broad band of 230-500 nm. Both broad excitation bands in the t-ZrO2:Eu and m-ZrO2:Eu were ascribed to the O(2-) - Eu3+ charge transfer (CT) transition. The reason was discussed based on the relationship between the CT energy and its crystal structure. The CT energy of m-ZrO2:Eu is higher than that of t-ZrO2:Eu. A detailed chemical bond analysis was performed to explore the CT energy difference between t-ZrO2: Eu and m-ZrO2:Eu.
authors: Department of Physics, Pukyong National University, Busan 608-737, Republic of Korea.
authors: Ling
authors: L
authors: Li
authors: Hyun Kyoung
authors: HK
authors: Yang
authors: Byung Kee
authors: BK
authors: Moon
authors: Byung Chun
authors: BC
authors: Choi
authors: Jung Hyun
authors: JH
authors: Jeong
authors: Ki-Wan
authors: KW
authors: Jang
authors: Ho Sueb
authors: HS
authors: Lee
authors: Soung Soo
authors: SS
authors: Yi