Strong blue emission from Ti-doped crystals

Sato, Tokushi; Shirai, Masanobu; Tanaka, Kōichiro; Kawabe, Yutaka; Hanamura, Eiichi

doi:10.1016/j.jlumin.2004.12.016

Cited by 85 publications

(60 citation statements)

References 10 publications

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“…Since the blue emission of Ti 4þ ions is a characteristic emission of wide-gap hosts 7,8 stimulated through charge-transfer transitions, the corresponding assignment of the 420 nm (3 eV) luminescence band of sapphire has been the subject of many publications since the end of the last century. 1,3,4,[9][10][11][12][13][14] Another hypothesis attributes this band to the emission of F þ or F defect centers (an oxygen vacancy occupied by one or two electrons, respectively) ever-present in aluminum oxide.…”

Section: Introductionmentioning

confidence: 99%

Studies of concentration dependences in the luminescence of Ti-doped Al2O3

Mikhailik

Stefano

Henry

et al. 2011

Journal of Applied Physics

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The variation of luminescence and excitation spectra of titanium doped Al 2 O 3 for the concentration of Ti ranging from 10 to 1000 ppm was investigated using synchrotron radiation. In the lightly doped Al 2 O 3 -Ti (<100 ppm) samples we identified several emission bands. These are the emission of the excitons localized at Ti (290 nm), the emission due to F þ centers (325 nm), the band around 420 nm traditionally attributed to F center emission, and the luminescence of Ti 3þ ions at 720 nm. The emphasis in this study is on the clarification of the nature of the blue emission band in the samples with high concentration of Ti (!100 ppm), where the luminescence and excitation spectra of the blue emission exhibit noticeable variability. This is explained by a model of the luminescence process of Ti 4þ -F centers that includes the photoionization of Ti 3þ , the subsequent capture of electrons at F þ -centers, formation of excited F-centers and, finally, the emission of a blue photon. The quenching of the blue emission with increasing Ti concentration is interpreted in terms of competition between oxygen vacancies and Ti 4þ centers in the capture of the electron.

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Section: Introductionmentioning

confidence: 99%

Studies of concentration dependences in the luminescence of Ti-doped Al2O3

Mikhailik

Stefano

Henry

et al. 2011

Journal of Applied Physics

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“…Essays have been done since a long time to dope different oxides with Ti 3+ ions and difficulties are met to interpret the spectroscopic properties. As an example several authors have already studied Ti-doped spinel and we can mention at least two articles on this matter [9,10]. The main point is the presence of Ti 4+ ion (0.61 Å) in the host, which was already suspected in [6] and confirmed in [10] occupying the Al 3+ (0.54 Å) octahedral site.…”

Section: +mentioning

confidence: 83%

“…As an example several authors have already studied Ti-doped spinel and we can mention at least two articles on this matter [9,10]. The main point is the presence of Ti 4+ ion (0.61 Å) in the host, which was already suspected in [6] and confirmed in [10] occupying the Al 3+ (0.54 Å) octahedral site. Spin resonance measurement shows important result in MgAl 2 O 4 spinel samples grown under oxidizing atmosphere: Ti 4+ exists without any 3d electron as the electronic ground state [10].…”

Section: +mentioning

confidence: 83%

Optical properties of transition metal ion‐doped MgAl₂O₄ spinel for laser application

Jouini

Yoshikawa

Brenier

et al. 2007

Phys. Status Solidi (c)

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Ti and Mn-doped MgAl 2 O 4 spinel have been successfully grown by the micro-pulling-down method and spectroscopic properties have been investigated in view of the potential use as a short-wavelength tunable solid-state laser. Strong blue emission is observed from Ti-doped MgAl 2 O 4 and green emission from a Mn-doped one. The optimum conditions to obtain the strongest emission were studied by changing the doping concentration. These two broad emission bands around 455 nm for Ti (decay time of 5.7 µs) and 518 nm for Mn (decay time of 6.11 ms) were obtained by pumping in the UV region at 266 nm and 355 nm, respectively. Discussion is submitted to assign the origins of each type of fluorescence in spinel. Ni 2+ -doped crystal exhibits a broad absorption band at around 980 nm suitable for InGaAs laser diode pumping and a broad emission band in the near infrared with two decay times at 210 µs and 850 µs respectively and high quantum yields. 1 Introduction MgAl 2 O 4 spinel is a mixed oxide with high melting temperature at 2135 °C. It has a good thermal and mechanical properties, high hardness and low electrical loss. It can be easily activated by transition-metal ions like cobalt (Co 2+ ) or chromium (Cr 3+ ) for optical devices: with the saturable absorption in the eye-safe spectral range, Co 2+ -doped MgAl 2 O 4 crystals can be used as a media for passive Q-switch of lasers which operates in the spectral range of 1.3-1.6 µm, for example 1.32 µm Nd:YAG and 1.54 µm erbium glass lasers [1]. Cr 3+ -doped (MgO.nAl 2 O 3 ): stoichiometric (n = 1) or nonstoichiometric (n = 2.6) magnesium aluminate spinels have been well studied for tunable solid-state laser applications and fiber-optic thermometer [2,3]. Recently, we have reported the successfully growth of high quality 〈100〉 oriented undoped, Ti and Mn-doped spinel [4]. Strong blue emission was observed in the case of Ti-doped MgAl 2 O 4 under ultra-violet excitation upon the fourth harmonic Nd:YAG pulsed laser excitation [5]. First blue laser oscillation was obtained and optimization of the experimental conditions are under consideration. The present work is a continuation of an experimental series in which an extensive optical and chemical characterization was performed on Ti 3+ /Ti

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“…More oxygen vacancies would be introduced on doping, for example, if two Ti 3+ ions substituting two Si 4+ ions produce one oxygen vacancy for charge compensation. Although Ti doping could create more defect centers, the dopant ions may also play an important role on the luminescence through charge-transfer transitions [10]. It is known that the Ti doped phosphors usually exhibited characteristic luminescence bands centered at around 420 and 460 nm, due to charge-transfer transitions of Ti 4+ and Ti 3+ [10,11].…”

Section: Methodsmentioning

confidence: 99%

“…Although Ti doping could create more defect centers, the dopant ions may also play an important role on the luminescence through charge-transfer transitions [10]. It is known that the Ti doped phosphors usually exhibited characteristic luminescence bands centered at around 420 and 460 nm, due to charge-transfer transitions of Ti 4+ and Ti 3+ [10,11]. Thereby, the red shift of the emission spectrum can be explained by the superposition of these bands.…”

Section: Methodsmentioning

confidence: 99%

Photoluminescence of Titanium-Doped Zinc Orthosilicate Phosphor Gel Films

Tsai

et al. 2011

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. Titanium-doped zinc orthosilicate (α-Zn 2 SiO 4 :Ti) phosphor thin films were deposited on silicon wafer substrates by the sol-gel process. The crystallization processes and photoluminescence properties of the films were investigated. X-ray diffraction revealed that the dried films were amorphous and converted into single-phase willemite structure following annealed at 600 o C and above. Upon thermal annealing at 800 o -1000 o C, Ti-doped willemite thin films had the average crystallite sizes of 17~28 nm. The luminescence properties of phosphor films were characterized by excitation and emission spectra. Photoluminescence spectra of Ti-doped films exhibited prominent blue emission bands centered at 402 nm under an excitation wavelength of 225 nm. The emission intensity was dependent on the level of titanium doping, annealing temperature, and film thickness.

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Strong blue emission from Ti-doped crystals

Cited by 85 publications

References 10 publications

Studies of concentration dependences in the luminescence of Ti-doped Al2O3

Studies of concentration dependences in the luminescence of Ti-doped Al2O3

Optical properties of transition metal ion‐doped MgAl₂O₄ spinel for laser application

Photoluminescence of Titanium-Doped Zinc Orthosilicate Phosphor Gel Films

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Strong blue emission from Ti-doped crystals

Cited by 85 publications

References 10 publications

Studies of concentration dependences in the luminescence of Ti-doped Al2O3

Studies of concentration dependences in the luminescence of Ti-doped Al2O3

Optical properties of transition metal ion‐doped MgAl2O4 spinel for laser application

Photoluminescence of Titanium-Doped Zinc Orthosilicate Phosphor Gel Films

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Optical properties of transition metal ion‐doped MgAl₂O₄ spinel for laser application