Optical Investigation of Sm doped ZrO 2

physica status solidi (c), 2014

Journal of Non-Crystalline Solids, 2008

We obtained samarium-doped zirconia using two different routes. In one, atomic layer deposited thin crystalline films were doped by using ion implantation; this sample was mainly monoclinic. The other method, the skull-melting technique, yielded polycrystalline bulk zirconia containing both monoclinic and tetragonal phases of ZrO 2 . Thorough photoluminescence (PL) measurements of Sm emission in these materials were performed using pulsed laser excitation at 405, 320 and 230 nm, respectively corresponding to direct, defect-related and host-sensitized excitation. Both samples exhibited well-resolved emission series of Sm 3+ . In general, the recorded spectra may be considered as superpositions of two different sets of lines attributable to Sm 3+ centers in different crystalline phases of ZrO 2 . These results have been confirmed by time-resolved measurements, which also suggest that all emission lines originate from a common initial state ( 4 G 5/2 ) with a lifetime of about 1 ms. As expected, the host-mediated excitation leads to a prolonged decay profile attributed to the retarded energy transfer from host to guest.

Journal of Luminescence, 2011

The studies of ZrO 2 and yttrium stabilized ZrO 2 nanocrystals luminescence as well as yttrium stabilized single crystal luminescence and induced absorption showed that the intrinsic defects are responsible for luminescence at room temperature. These defects form a quasi-continuum of states in ZrO 2 band gap and are the origin of the luminescence spectrum dependence on the excitation energy. Luminescence centers are oxygen vacancies related but not the vacancies themselves. At room temperature, in ZrO 2 , deep traps for electrons and holes exist. The oxygen vacancies are proposed to be the traps for electrons.

Optical Materials, 2005

Strong visible emission under UV (320 nm) and IR (967 nm) excitation on ZrO 2 :Sm 3+ and ZrO 2 :Er 3+ nanophosphors were obtained and the concentration effect on the luminescence and crystalline structure is reported. Experimental results shows that phase composition depend on the ion concentration. The visible emission obtained under UV excitation is produced by the transitions 4 G 5/2 ! 6 H 5/2,7/2,9/2 of Sm 3+ through a non-radiative energy transfer process from the host to the active ion. Energy transfer and quenching effect due to ion concentration was confirmed by measuring the fluorescence decay time. Green (545 nm) and red (680 nm) emissions bands were observed under IR excitation troughs an upconversion process. It was proved that visible emission for both nanophosphor could be tuned by controlling the ion concentration. The nature of this behavior is discussed taking into account the phase composition for ZrO 2 :Sm 3+ and two photon absorption and cross-relaxation process was considered for ZrO 2 :Er 3+ nanophosphor.

Chemistry of Materials, 2021

The present article is a thorough quantum mechanics investigation based on DFT method targeting the opto-electronic properties of the m-ZrO 2 material issuing from the presence of defects. Herein, we conclude that the luminescence observed around 477 nm (∼2.60 eV) corresponds to the charge transfer between Ti Zr and oxygen atoms (i.e., Ti 3+ + O-→ Ti 4+ + O 2-), and not from oxygen vacancies or d-d transitions at Ti 3+ sites. Namely, based on constrained DFT calculations, an emission at 2.61 eV (475 nm) was calculated that matches perfectly with experiments (around 2.60 eV / 477 nm). Moreover, in order to demonstrate the propensity of the ZrO 2 host lattice to entrap titanium, intrinsic and extrinsic point defect formation energies on m-ZrO 2 were computed.

Optical Materials, 2002

Pure and rare earth doped zirconium oxide was prepared by the sol–gel process and annealed at 1000 °C to stabilize the monoclinic phase. Thermoluminescence (TL) and photoluminescence (PL) under Gamma and UV irradiation were performed. A single TL peak was present at 135 °C under gamma irradiation, whereas under UV irradiation the TL presented two peaks at 62 and 130 °C. The PL of pure and rare earth doped samples was also characterized. The experimental spectra suggest the presence of energy transfer processes between the dopant (Sm3+) and the host (ZrO2).

Physical Chemistry Chemical Physics, 2012

Pure and europium (Eu 3+ ) doped ZrO 2 synthesized by an oil-in-water microemulsion reaction method were investigated by in situ and ex situ X-ray diffraction (XRD), ex situ Raman spectroscopy, high-resolution transmission electron microscopy (HRTEM), steady state and time-resolved photoluminescence (PL) spectroscopies. Based on the Raman spectra excited at three different wavelengths i.e. 488, 514 and 633 nm and measured in the spectral range of 150-4000 cm À1 the correlation between the phonon spectra of ZrO 2 and luminescence of europium is clearly evidenced. The PL investigations span a variety of steady-state and time resolved measurements recorded either after direct excitation of the Eu 3+ f-f transitions or indirect excitation into UV charge-transfer bands. After annealing at 500 1C, the overall Eu 3+ emission is dominated by Eu 3+ located in tetragonal symmetry lattice sites with a crystal-field splitting of the 5 D 0 -7 F 1 emission of 20 cm À1 . Annealing of ZrO 2 at 1000 1C leads to a superposition of Eu 3+ emissions from tetragonal and monoclinic lattice sites with monoclinic crystal-field splitting of 200 cm À1 for the 5 D 0 -7 F 1 transition. At all temperatures, a non-negligible amorphous/disordered content is also measured and determined to be of monoclinic nature. It was found that the evolutions with calcination temperature of the average PL lifetimes corresponding to europium emission in the tetragonal and monoclinic sites and the monoclinic phase content of the Eu 3+ doped ZrO 2 samples follow a similar trend. By use of specific excitation conditions, the distribution of europium on the amorphous/disordered surface or ordered/crystalline sites can be identified and related to the phase content of zirconia. The role of zirconia host as a sensitizer for the europium PL is also discussed in both tetragonal and monoclinic phases.

The Journal of Physical Chemistry C, 2012

The local structure of europium doped and impregnated ZrO 2 in the amorphous state and during crystallization is investigated by in situ X-ray diffraction and in situ Raman, high-resolution transmission electron microscopy (HRTEM) and time-resolved photoluminescence spectroscopy. From Raman spectra excited at three different wavelengths (λ ex = 488, 514, and 633 nm), both phonon modes of ZrO 2 and photoluminescence (PL) corresponding to europium electronic transitions were investigated. In the assynthetized state, samples were X-ray and Raman amorphous with few tetragonal (also monoclinic) crystallites being observed under HRTEM microscopy. In situ XRD patterns show that all samples crystallize in the tetragonal phase around 450°C. The time-resolved PL spectra of europium doped and impregnated ZrO 2 show spectral dynamics with time delay after lamp/laser pulse which is assigned to the coexistence of the different amorphous and crystalline components or unreacted europium precursor. From in situ Raman spectra, crystallization was detected at 300−350°C, monitoring for the characteristic tetragonal-like 5 D 0 − 7 F 2 emission of europium at 606 nm. The ratio of tetragonal to amorphous emission increased abruptly from ca. 2−4% at 300−400°C to almost 25% at 400−450°C, whereas at 500°C the emission is mostly tetragonal. A similar trend was found with the ex situ calcined samples, but relative strong tetragonal emission was observed at lower temperature in the range of 350 to 400°C.

Optical Materials Express, 2012

Non-doped as well as titanium and lutetium doped zirconia (ZrO 2) materials were synthesized via the sol-gel method and structurally characterized with X-ray powder diffraction. The addition of Ti in the zirconia lattice does not change the crystalline structure whilst the Lu doping introduces a small fraction of the tetragonal phase. The UV excitation results in a bright white-blue luminescence at ca. 500 nm for all the materials which emission could be assigned to the Ti 3+ e g  t 2g transition. The persistent luminescence originates from the same Ti 3+ center. The thermoluminescence data shows a well-defined though rather similar defect structures for all the zirconia materials. The kinetics of persistent luminescence was probed with the isothermal decay curve analyses which indicated significant retrapping. The short duration of persistent luminescence was attributed to the quasi-continuum distribution of the traps and to the possibility of shallow traps even below the room temperature.