Photoluminescence of gold-doped (Zn, Cd)S mixed phosphors

Tiwari, Sanjay; Mishra, Shikha; Chandra, B. P.

doi:10.1007/bf02747243

Cited by 5 publications

(3 citation statements)

References 15 publications

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“…It is well-known that an AC-EL device electrically behaves as an RC equivalent circuit. 26 When the sheet resistance increases, the emission intensity will decrease due to lower exciting electric eld on the EL phosphor. 21 When NH 3 molecules are adsorbed on the PEDOT:PSS surface by physisorption, the holes of PEDOT:PSS interact with the electron-donating NH 3 molecules.…”

Section: Resultsmentioning

confidence: 99%

Flexible alternating current electroluminescent ammonia gas sensor

et al. 2017

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In this work, the fabrication and performance of flexible alternating current electroluminescent (AC-EL) devices for ammonia (NH 3 ) detection at room temperature are presented for the first time. The AC-EL gas sensor was fabricated by the screen-printing of a ZnS:Cu,Cl phosphor and PEDOT:PSS sensing layers. The effects of parameters including applied voltage, excitation frequency and waveform on light emission and luminance intensity of the AC-EL gas sensor were systematically investigated. From gassensing characterization, the AC-EL gas sensor exhibited very high selectivity and a linear response to NH 3 in the concentration range of 100-1000 ppm at room temperature. A sensing mechanism of the EL gas sensor was proposed based on the resistance change of the PEDOT:PSS sensing layer via a chargetransfer process.

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Section: Resultsmentioning

confidence: 99%

Flexible alternating current electroluminescent ammonia gas sensor

et al. 2017

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“…The preparation of phosphors was carried out following the conventional technique reported earlier (Tiwari et al 1994). The (Zn, Cd)S:Au, CI phosphors (hexagonal) and (Zn, Cd)S:Au, C1 phosphors (cubic) were prepared by firing for 1 h in nitrogen atmosphere at 1100°C and 900°C respectively.…”

Section: Methodsmentioning

confidence: 99%

Preparation and characterization of gold doped (Zn, Cd)S mixed phosphors for mechano-optical transducers

Tiwari¹,

Tiwari

Sahu³

et al. 1995

Bull. Mater. Sci.

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When mechanically excited, initially the ML intensity increases, attains a maximum value and then decreases with time. The total M L intensity I r initially increases with the impact velocity V o of piston and attains a saturation value for higher values of V o and follows o and 1/ are constants. The ML intensity is the relation /.r=l°exp(-V/V o) where I T maximum for 20% CdS contents in the (Zn, Cd)S phosphors due to increase in hardness which may in turn increase the fracture stress and subsequently the piezoelectric field strength. The wavelength corresponding to the peak of both the ML and PL spectra shift towards longer wavelength with increasing CdS contents. Some models are discussed and it is concluded that the impulsive deformation of these phosphors may be due to piezoelectrification of newly created surfaces. The similarity of M L spectra with EL and PL spectra suggests that although the excitation processes are different, emission process is governed by the states of similar nature.

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“…3 It has been shown that by varying the zinc to cadmium ratio, fine tuning of the wavelength of the photoluminescent emission band can be achieved. [2][3][4][5][6] A major requirement for the purpose of this work was to move the emission peak of the phosphor sufficiently far into the infra-red region so that visible light emission was minimized resulting from the high energy side of the band was minimized, whilst maintaining sufficient intensity at infrared wavelengths which could be detectable by night vision systems.…”

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confidence: 99%

ZnCdS:Cu,Al,Cl: A Near Infra-Red Emissive Family of Phosphors for Marking, Coding, and Identification

Silver

Marsh

Fern

et al. 2017

ECS J. Solid State Sci. Technol.

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Zn 1-x Cd x :Cu 0.03% ,Cl (where x = 0.5-0.9) infrared emitting phosphors have been synthesized by an aqueous thermal decomposition method. The aim was to developing infrared emitting phosphors for coding, marking, and identification applications. The phosphors were characterized by, X-ray powder diffraction, scanning electron microscopy and photoluminescence spectroscopy. The emission band at 1000 nm was sufficiently far into the infrared region that visible emission was minimized. Co-doping Zn 1-x Cd x S:Cu 0.03% with Al 3+ increased the infrared emission intensity to over twice that of the equivalent Zn 0.3 Cd 0.7 S:Cu 0.03% phosphor (with no Al 3+ ion co-doping), with the highest intensity being found for the phosphor composition Zn 0.1 Cd 0.9 S:Cu 0.03%, Al 0.03% . It is shown herein that the inclusion of Al 3+ into the phosphors causes the formation of cells with smaller cell volume, and it is suggested that this is the prerequisite for the improved photoluminescent properties. Finally we have shown herein that these infrared emitting powder phosphors are thus able to meet marking and coding requirements, especially in low light and poor visibility. Although the uses of phosphors are widespread in modern technologies and they are common in the display and lighting industries where products find applications in both domestic and commercial applications, their use in other areas is less widely appreciated. Such uses include:-on postage stamps to help letter sorting, on currency and bank notes for secrecy/authenticity, thermometry, luminescent paints and glow in the dark toys. In addition there are a number of military applications.Recently the wide availability of near-ultraviolet light and visible light emitting diodes (LEDs) and laser diodes in addition to infrared emitting systems has made the remote excitation of infrared emitting phosphors a practical possibility. Infrared emitting powder phosphors have the potential to meet marking and coding requirements, especially in low light and poor visibility.The advantages of IR emitting powder phosphors are:-1) That they can be easily deposited by conventional techniques to form large areas, if required, either by simple settling techniques, or by inclusion in a binder suitable for screen or ink-jet printing (the binder of course must be transparent over the required spectral range). 2) Such deposited powder layers, depending on their thickness and particle size and particle morphology etc., can be used in a transmission or a reflective mode with suitable UV or visible excitation sources.The ease of fabrication and the wide excitation spectra of the phosphors as well as their efficiencies facilitate a wide range of potential applications, including the following as preliminary examples: a) For use in coding/marking systems as simple IR sensitive markers. b) For improved marking/detection in conjunction with night vision systems.The origins of the green luminescence in ZnS:Cu phosphors (where Cu is introduced as a dopant into the ZnS lattice) has been attribute...

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Photoluminescence of gold-doped (Zn, Cd)S mixed phosphors

Cited by 5 publications

References 15 publications

Flexible alternating current electroluminescent ammonia gas sensor

Flexible alternating current electroluminescent ammonia gas sensor

Preparation and characterization of gold doped (Zn, Cd)S mixed phosphors for mechano-optical transducers

ZnCdS:Cu,Al,Cl: A Near Infra-Red Emissive Family of Phosphors for Marking, Coding, and Identification

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