Development of mechanoluminescence technique for impact studies

Chandra, B. P.

doi:10.1016/j.jlumin.2011.02.027

Cited by 63 publications

(34 citation statements)

References 40 publications

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“…7), the mechanical stimulation somehow has to reduce the depth of the trap, or has to provide an extra amount of energy which helps to overcome the thermal barrier associated with the trapped charges. The most recent model for ML emission, the piezoelectrically induced de-trapping model for piezoluminescence [15,16], ascribes the faster release of the trapped charges from trap B to the piezoelectric effect: (i) the application of pressure produces a piezoelectric field, which can be high near defects and activator ions, (ii) the piezoelectric field either lowers the depth of trap B or causes band bending, (iii) the decrease of trap-depth implies that less energy is needed to release the trapped electrons and causes a faster transfer of electrons from trap B to ionized europium ions (arrow 4 in Fig. 7) to form excited Eu 2+ ions in 4f 6 5d state, while band bending might cause direct tunneling from trap B to the Eu 2+ 4f 6 5d states or to trap A (arrow 6 in Fig.7), (iv) the de-excitation of the created Eu 2+ ions from 4f 6 5d to the 4f 7 ground state through emission of light causes an increase in afterglow, along with a faster decay, as observed for BaSi 2 O 2 N 2 :Eu.…”

Section: Discussionmentioning

confidence: 99%

“…The de-trapping in piezoluminescence, however, is induced by the pressure applied on the material. According to the piezoelectrically induced de-trapping model for piezoluminescence, proposed by Chandra et al [15,16], the applied pressure produces a piezoelectric field in the material which can reduce the trap depth or cause band bending. In the case of a decrease in trap depth, detrapping of trapped charge carriers can occur because of the lower energy barrier.…”

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confidence: 99%

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Mechanoluminescence in BaSi2O2N2:Eu

et al. 2012

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Mechanoluminescence (ML), a general term for the phenomenon in which light emission occurs during any mechanical action on a solid, can be divided roughly into two classes: destructive ML and non-destructive ML. For practical use in high-end applications (e.g. pressure sensors), materials with non-destructive ML properties are preferred. This paper reports on the strong non-destructive ML in BaSi 2 O 2 N 2 :Eu. When irradiated in advance with UV or blue light, this phosphor shows intense blue-green light emission upon mechanical stimulation such as friction or pressure. The ML has an emission band peaking at 498 nm, which is about 4 nm red-shifted compared to the steady state photoluminescence. The origin of the ML is discussed and related to the persistent luminescence of BaSi 2 O 2 N 2 :Eu. The same traps are responsible for both the phenomena.Based on the occurrence of ML in this phosphor, we were able to derive that the predominant crystallographic structure of BaSi 2 O 2 N 2 :Eu belongs to space group Cmc2 1 .

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Section: Discussionmentioning

confidence: 99%

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Mechanoluminescence in BaSi2O2N2:Eu

et al. 2012

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“…phosphors fractures. In these ML measurements, maximum ML intensity has been obtained for the 50 cm dropping height and ML intensity increases linearly with increases the falling height of the moving piston [46]. The ML intensity, which means peak ML intensity during forcing, strongly depended on the height the moving piston.…”

Section: Experimental Setup For Mechanoluminescence (Ml) Measurementmentioning

confidence: 91%

Enhanced luminescence performance of Sr2MgSi2O7:Eu2+ blue long persistence phosphor by co-doping with Ce3+ ions

Sahu

Bisen

Brahme

et al. 2015

J Mater Sci: Mater Electron

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A series of rare earth doped and co-doped distrontium magnesium di-silicate phosphors namely: Sr 2 MgSi 2 O 7 :Ce 3? , Sr 2 MgSi 2 O 7 :Eu 2? and Sr 2 MgSi 2 O 7 :Eu 2? , Ce 3? were prepared by the solid state reaction method. The crystal structures of sintered phosphors were an akermanite type structure which belongs to the tetragonal crystallography. The chemical compositions of sintered phosphors were confirmed by energy dispersive X-ray spectroscopy (EDS). Under the ultraviolet excitation, the emission spectra of both Sr 2 MgSi 2 O 7 :Eu 2? and Sr 2 MgSi 2 O 7 :Eu 2? , Ce 3? phosphors were composed of a broad band peaking at 460 nm, belonging to the broad emission band. When the Sr 2 MgSi 2 O 7 :Eu 2? phosphor is co-doped with Ce 3? ions, thermouminescence, photoluminescence, afterglow and mechanoluminescence (ML) intensity were strongly enhanced. The Sr 2 MgSi 2 O 7 :Eu 2? phosphor showed some afterglow with short persistence time. Ce 3? phosphors were proportionally increased with the increase of impact velocity, which suggests that these phosphors can be used as sensors to detect the stress of an object. Thus the present investigation indicates that the piezoelectricity is responsible to produce ML in prepared phosphors.

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“…Another peculiar phenomenon in this compound is mechanoluminescence. This type of luminescence is closely related to persistent luminescence and has been studied intensively in the framework of pressure sensing [8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Trapping and detrapping inSrAl2O4:Eu,Dypersistent phosphors: Influence of excitation wavelength and temperature

2014

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SrAl 2 O 4 :Eu,Dy is presumably the best known persistent luminescent phosphor. At room temperature, its green emission remains visible for hours after switching off the excitation. It is known that upon lowering the temperature of the phosphor a second photoluminescence emission band arises in the blue part of the visible spectrum, although its origin is still the subject of discussion. In this paper we thoroughly study the origin of both emission bands in SrAl 2 O 4 :Eu,Dy and we attribute this to europium ions substituting for the two different Sr sites in the phosphor's monoclinic host lattice. The photoluminescence properties, the thermal quenching behavior, and photoluminescence lifetime of both emission bands are investigated. A lanthanide energy level scheme is constructed for both sites. Using an integrated approach, i.e., combining charging, afterglow, and thermoluminescence measurements in the same run, we study the charging or trap filling processes in SrAl 2 O 4 :Eu,Dy upon excitation with site selective excitation wavelengths and at different temperatures. We show that trap filling is a thermally activated process when the green emitting center is excited at 435 nm.Furthermore, we also demonstrate that the distribution of filled traps after charging depends strongly on the excitation wavelength and thus on which Eu 2+ center has been excited. This suggests trapping of the electron close to the ionized Eu 2+ ion, without full delocalization to the conduction band during the trapping process. Finally, the quantum efficiency of the persistent luminescence is estimated at 65 (+/−10)%.

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Development of mechanoluminescence technique for impact studies

Cited by 63 publications

References 40 publications

Mechanoluminescence in BaSi2O2N2:Eu

Mechanoluminescence in BaSi2O2N2:Eu

Enhanced luminescence performance of Sr2MgSi2O7:Eu2+ blue long persistence phosphor by co-doping with Ce3+ ions

Trapping and detrapping inSrAl2O4:Eu,Dypersistent phosphors: Influence of excitation wavelength and temperature

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