Europium Tetrakis Dibenzoylmethide Triethylammonium Research Articles

Progress in Organic Triboluminescent EuD4TEA Crystal

AbstractOrganic triboluminescent (TL) crystals have attracted significant attention in recent years for their potential applications in various fields such as damage sensing in aerospace structures, cyanide detection in water, and radiation sensing. Europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA) is a class of organic TL crystals that have shown promising results in terms of sensitivity due to their high TL intensity, however, they exhibit thermal instability and fragility concerns. In this review, recent research progress on the development, characterizations, TL properties, and potential applications of EuD4TEA crystals in various fields, are summarized. The review will conclude with the current challenges of EuD4TEA crystals, such as fragility nature, thermal instability, and increasing cost of europium. Despite having challenges, EuD4TEA crystals have the potential for damage sensing in the structural composite.

Triboluminescence Phenomenon Based on the Metal Complex Compounds-A Short Review.

Triboluminescence (TL) is a phenomenon of light emission resulting from the mechanical force applied to a substance. Although TL has been observed for many ages, the radiation mechanism is still under investigation. One of the exemplary compounds which possesses triboluminescent properties are copper(I) thiocyanate bipyridine triphenylphosphine complex [Cu(NCS)(py)2(PPh3)], europium tetrakis dibenzoylmethide triethylammonium EuD4TEA, tris(bipyridine)ruthenium(II) chloride [Ru(bpy)3]Cl2, and bis(triphenylphosphine oxide)manganese(II) bromide Mn(Ph3PO)2Br2. Due to the effortless synthesis route and distinct photo- and triboluminescent properties, these compounds may be useful model substances for the research on the triboluminescence mechanism. The advance of TL studies may lead to the development of a new group of sensors based on force-responsive (mechanical stimuli) materials. This review constitutes a comprehensive theoretical study containing available information about the coordination of metal complex synthesis methodologies with their physical, chemical, and spectroscopic properties.

Measuring Important Properties of EuD4tea: A Material Solution looking for a Problem

Triboluminescence (TL) is the light emitted from a material when it undergoes fracture. While this unique phenomenon has been known for over 400 years, no theory has yet to predict whether a material will emit TL. However, this has not stopped scientists from coming up with many unique applications. One such application is the use as the active element for impact and damage sensors. Around the turn of the 21stcentury, researchers used TL to patent a sensor capable of discerning the locations of an impact. Their simple design involved coating a structure with a triboluminescent material or creating a composite triboluminescent object. A sensor would then be embedded within the structure or mounted on its surface. Impacts to the structure would produce light, which would be recorded and analyzed to determine the location. In addition, researchers proposed that several different triboluminescent materials could be used and arranged at various locations. The advantage is that when an impact takes place, its location could be determined by the wavelength emitted. For example, by placing two different triboluminescent materials at known distances from the detector, it is possible to determine the approximate location of the impact by measuring the emitted wavelength. Material property measurements such as triboluminescent yield and the prompt fluorescence decay time are important considerations for any luminescent material. TL emission has to be sufficiently bright, so that the light signal reaching from the point of fracture to the detector, through a fiber optics cable, is strong enough to be detected. The majority of the known triboluminescent materials do not emit light with sufficient intensity to allow detection with compact and inexpensive detectors. A few materials, such as Europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA), is bright enough to be seen in daylight and has more than twice the triboluminescent emission yield of zinc sulfide doped with manganese (ZnS:Mn) when subjected to low energy impacts. Research has also shown that adding specific dopants to EuD4TEAcan increase the triboluminescent emission yield by more than a factor of five over ZnS:Mn, which is often used as a basis for comparison.In fact, EuD4TEA has been found to be one of the brightest known TL materials and is a potential candidate for application as an impact sensor. The purpose of this presentation is to present results from recently completed light yield and prompt fluorescence decay time measurements for EuD4TEA. Emphasis will be placed on current efforts to utilize this data for a variety of potential applications to measure impacts in extreme environments. Basically, EuD4TEA is a material solution looking for a problem.

(Invited) Differences in Emission Properties for Triboluminescent EuD4tea Synthesized Using Both Europium Nitrate or Europium Acetate

Europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA) is one of the most intense triboluminescent (TL) materials currently known. Some time ago, the authors reported that the triboluminescent yield was increased by 82% by changing the starting europium salt from europium chloride to europium nitrate. Unfortunately, europium nitrate has been classified as a hazardous material that cannot be shipped by air, which limits the availability of manufacturers and increases the cost. In an effort to further reduce the synthesis cost of EuD4TEA, we explore the effects of europium acetate on the triboluminescent properties of EuD4TEA by comparing the triboluminescent yield. The photoluminescent spectra as well as crystal structure using an optical microscope will also be explored

Using Exotic Materials like EuD4TEA to Monitor Damage and Radiation Exposure in Extreme Environments

In recent years, luminescent materials have been proposed for use as smart sensors to measure structural damage and to monitor radiation fluence. To sense structural damage using triboluminescence, appropriate materials are embedded in a composite host structure for various applications, such as crew launch or exploration vehicles. When the damage occurs in the host structure, it leads to the fracture of the triboluminescent crystals resulting in light emission. This process provides a real-time warning that structural damage has occurred. The TL emission of the candidate material has to be sufficiently bright, so that the light signal reaching from the point of fracture to the detector, through a fiber optics cable, is strong enough to be detected. The majority of the known triboluminescent materials do not emit light with sufficient intensity to allow detection with compact and inexpensive detectors. Over the past 40 years, some materials have been reported with TL of sufficient intensity for the light emission to be easily observed with the naked eye. Out of these triboluminescent materials, only few could satisfy the above criterion. Europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA), one of the brightest known TL materials and is a potential candidate for application to this type of hybrid smart sensor in extreme environments. Ionizing radiation in the extreme environment of space poses a significant challenge to future human and robotic exploration missions. To be used in space, any intelligent sensor material must also be resistant to ionizing radiation. Sources and types of such radiation include galactic and solar electrons and protons, x-rays, ultraviolet light, and magnetically trapped charged particles in radiation belts. While much research has been devoted to characterizing material degradation due to electron exposure, surprisingly little work seems to have been done on proton damage. Research has shown that proton bombardment in the keV to MeV range, like that occurring in space, reduces the intensity of fluorescence. Thus, proton irradiation will likely reduce the ability of a candidate smart material to emit fluorescence. Practical space-based sensors based on luminescence will depend heavily upon research investigating the resistance of these materials to ionizing radiation and the ability to anneal or self-heal from damage caused by such radiation. In 1951, Birks and Black showed experimentally that the fluorescence efficiency of anthracene bombarded by alphas varies with total fluence (N) as (I/I0) = 1/(1 + AN), where I is the luminescence yield, I0 is the initial luminescence yield, and A is a constant. The half brightness fluence (N1/2) is a material figure of merit and is defined as the reciprocal of A. Broser and Kallmann developed a similar relationship to the Birks and Black equation for inorganic phosphors irradiated using alpha particles. From 1990 to the present, we have found that the Birks and Black relation describes the reduction in emission yield for every tested luminescent material except lead phosphate glass due to proton irradiation. These results indicate that radiation produced quenching centers compete with emission centers for absorbed energy. Recently, the N1/2 for EuD4TEA irradiated with 3 MeV protons was measured to be about 3 x 1010 mm-2. Conversely, ZnS:Mn compounds tested were found to have N1/2 values for 3 MeV protons that are nearly one thousand times larger (~1013 mm-2). According to Tribble, a spacecraft at 1 AU from the Sun will receive a 1 MeV proton fluence of less than 1011 mm-2 from a large solar event. Likewise, 1 MeV proton fluences in the Earth’s radiation belts and the Earth-Moon-Sun Lagrange points will be even less than the 1011 mm-2 value from large solar events. For this reason, EuD4TEA might be a candidate sensor material to monitor large-scale solar events for astronauts in vehicles flying in near earth space. Since their N1/2 values are larger, ZnS:Mn compounds are more suited for use as sensors in higher radiation environments or for very long duration space missions. The purpose of this presentation is to present results from all research completed in this area. Particular emphasis will be placed on synthesizing EuD4TEA material as well as the design and construction of a 1U CubeSat payload that will orbit the Earth carrying an innovative first generation sensor to monitor radiation fluence. This flight experiment is a natural outgrowth of earlier ground based radiation exposure measurements that will be used to determine if EuD4TEA-based materials can be used as a real-time structural damage and/or radiation sensor for applications in space or other extreme environments.

Potential of Using EuD4tea for Space-Based Damage and Radiation Sensors

In recent years, luminescent materials have been proposed as active elements for smart sensors to measure structural damage using triboluminescence (TL) and to monitor radiation fluence. To sense structural damage, these materials are embedded in a composite host structure for various applications, such as crew launch or exploration vehicles. When the damage/fracture occurs in the host composite structure, it will lead to the fracture of the TL crystals resulting in light emission. This will provide a warning, in real time, that structural damage has occurred. The TL emission of the candidate material has to be sufficiently bright, so that the light signal reaching from the point of fracture to the detector, through a fiber optics cable, is strong enough to be detected. The majority of the known TL materials do not emit light with sufficient intensity to allow detection with compact and inexpensive detectors. Over the past 40 years, some materials have been reported that TL with sufficient intensity for the light emission to be easily observed with the naked eye. Out of these TL materials, only few could satisfy the above criterion. Europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA), one of the brightest known TL materials and is a potential candidate for application to this type of hybrid smart sensor. Space radiation poses a significant challenge to human and robotic exploration missions to deep space. To be used in space, any intelligent sensor material must also be resistant to ionizing radiation. Sources and types of such radiation include galactic and solar electrons and protons, x-rays, ultraviolet light, and magnetically trapped charged particles in radiation belts. While much research has been devoted to characterizing material degradation due to electron exposure, surprisingly little work seems to have been done on proton damage. Research has shown that proton bombardment in the keV to MeV range, like that occurring in space, reduces the intensity of fluorescence. Thus, proton irradiation will likely reduce the ability of a candidate smart material to emit fluorescence. Practical space-based sensors based on luminescence will depend heavily upon research investigating the resistance of these materials to ionizing radiation and the ability to anneal or self-heal from damage caused by such radiation. In 1951, Birks and Black showed experimentally that the fluorescence efficiency of anthracene bombarded by alphas varies with total fluence (N) as (I/I0) = 1/(1 + AN), where I is the luminescence yield, I0 is the initial luminescence yield, and A is a constant. The half brightness fluence (N1/2) is a material figure of merit and is defined as the reciprocal of A. Broser and Kallmann developed a similar relationship to the Birks and Black equation for inorganic phosphors irradiated using alpha particles. From 1990 to the present, we have found that the Birks and Black relation describes the reduction in emission yield for every tested luminescent material except lead phosphate glass due to proton irradiation. These results indicate that radiation produced quenching centers compete with emission centers for absorbed energy. Recently, we measured the N1/2 for EuD4TEA irradiated with 3 MeV protons to be about 3 x 1010 mm-2. Conversely, ZnS:Mn compounds tested were found to have N1/2 values for 3 MeV protons that are nearly one thousand times larger (~1013 mm-2). According to Tribble, a spacecraft at 1 AU from the Sun will receive a 1 MeV proton fluence of less than 1011 mm-2 from a large solar event. Likewise, 1 MeV proton fluences in the Earth’s radiation belts and the Earth-Moon-Sun Lagrange points will be even less than the 1011 mm-2 value from large solar events. For this reason, EuD4TEA might be a candidate sensor material to monitor large-scale solar events for astronauts in vehicles flying in near earth space. Since their N1/2 values are larger, ZnS:Mn compounds are more suited for use as sensors in higher radiation environments or for very long duration space missions. Late this year, a 1U CubeSat payload will be placed in Earth orbit carrying an innovative first generation EuD4TEA sensor that will be used to monitor radiation fluence. This flight experiment is a natural outgrowth of earlier ground based radiation exposure measurements. The purpose of this presentation is to present results from research completed in this area from 1990 to present. Particular emphasis will be placed on recent TL and radiation exposure measurements using EuD4TEA. This groundbreaking research can be used to help determine if EuD4TEA-based materials can be used as a real-time structural damage and/or radiation sensor for space applications.

Smart phone assisted detection and quantification of cyanide in drinking water by paper based sensing platform

An organometallic dye, europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA) and gold nanoparticles (Au NPs) impregnated paper based sensor platform have been utilized for development of fluorescence turn-on cyanide assay in aqueous media. The ordinary filter paper with 6μ m pore size were employed as solid support that facilitates impregnation of EuD4TEA and gold nanoparticles and provides durability. Detection mechanism relying on two processes (i) dissolution of gold nanoparticles causing fluorescence recovery and (ii) ligand exchange of triethyl amine with CN group stimulating cyanide specific fluorescence enhancement. The paper platform exhibit naked eye distinguishable color transition upon CN− addition from 10−2 to 10−12M. To standardize the methodology a homemade image processing algorithm has been developed that enabling calibration of color change and quantify CN− concentration. The described algorithm is applicable to Android smart phones and facilitate transforming these devices into a quantitative cyanide detector. The overall methodology provides instrument free cyanide detection and therefore rapid control of water quality and safety at off-field conditions.

Europium Tetrakis Dibenzoylmethide Triethylammonium: Synthesis, Additives, and Applications Review

There are a number of techniques currently being used for damage detection and monitoring of civil, aerospace, and military structures and aircraft. However, the major drawbacks of the current techniques are that they do not provide in-situ and distributed sensing. Wiedemann and Schmidt defined triboluminescence (TL) as the emission of light produced by mechanical action. In recent years, triboluminescent materials have been proposed for use as the active element in smart structural sensors. To sense damage, these materials would be embedded into the structure. If damage occurs to this structure, the embedded triboluminescent material would give off visible light. This light could be transferred by lightweight fiber optics or wireless detector to a computer-based detection system to warn occupants in real time that a significant impact event has occurred. In addition, the triboluminescent based sensor could allow for real-time monitoring of both the magnitude and location of damage to the host structure. One of the brightest TL materials currently known is europium tetrakis dibenzoylmethide triethylammonium EuD4TEA.Since 2011, the authors have delved into the feasibility of enhancing the properties of EuD4TEA by (a) modifying the synthesis process and (b) determining the reproducibility of the synthetic procedure by measuring the batch variation error. Further, the study evaluated the possible techniques that can be incorporated in to the synthesis technique to enhance the TL property by (i) introducing various inorganic and organic dopants; (ii) optimizing dopant concentration; (iii) studying solvents effects on TL property; and (iv) evaluating the effects of ionizing radiation on TL properties. In addition, this research developed a simple apparatus for the measurement of TL properties in the laboratory using a two-fold technique consisting of measuring TL intensity and/or spectral characterization. This enabled for the determination of a unique decay time for a particular compound. In addition, impact studies have been conducted to correlate the impact energy (velocity) with TL emission, thus allowinga system to detect and evaluate the magnitude of the impacts. The spectra of these compounds have been analyzed in detail to investigate the cause of luminescence and designate the transitional energy levels for each of the peaks. The effect of introducing EuD4TEA into poly(methyl methacrylate) and its impact on the TL emission spectra were determined for sensor applications. This poster will provide a review of the important results of this research.

Using Luminescent Materials As the Active Component for Multipurpose Sensors

Environmental severity poses a significant challenge for Earth-based defense applications as well as human and/or robotic space missions. Past research has shown that luminescent materials can be used to measure exposure to ionizing radiation, temperature, and impact/pressure differential in adverse environments. In 1951, Birks and Black showed experimentally that the luminescent efficiency of anthracene bombarded by alphas varies with total fluence (N) as (I/I0) = 1/(1 + AN), where I is the luminescence yield, I0 is the initial yield, and A is a constant [ref. 1-2]. The half brightness (N1/2) is defined as the fluence that reduce the emission light yield to half and is equal to is the inverse of A[ref. 3]. Broser and Kallmann developed a similar relationship to the Birks and Black equation for inorganic phosphors irradiated using alpha particles [ref. 4]. From 1990 to the present, I found that the Birks and Black relation describes the reduction in light emission yield for every tested luminescent material except lead phosphate glass due to proton irradiation [ref. 5]. These results indicate that radiation produced quenching centers compete with emission for absorbed energy. For the last forty years, Allison et al. has shown that phosphor thermometry can be used to measure the temperature of moving or rotating surfaces under adverse conditions [ref. 6]. For the last decade, Fontenot and Hollerman et al. have concentrated on measuring the relative triboluminescent emission yields from inorganic zinc sulfide/similar compounds and new organic materials like europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA). Triboluminescence is produced when crystals of certain luminescent materials are stressed or broken. It was found that the ZnS compounds doped with Mn, Cu, and Pb had the largest measured triboluminescent emission yield of inorganic compounds [ref. 6]. The red emission luminescence from EuD4TEA can be seen in bright daylight with the naked eye [ref. 5]. Over the past few years, Fontenot et al. has optimized the synthesis process by making it more efficient and cheaper, discovered that it is possible to combine EuD4TEA with polymers such as poly(methyl methacrylate) (PMMA), and investigated the effects of various dopants such as dimethyl methylphosphonate (DMMP), dibutyl phosphate (DBP), dysprosium, samarium, and uranium [ref. 5]. To date, DBP is the best dopant creating nearly a six-fold increase in triboluminescent yield when compared to the original method [ref. 6]. The purpose of this presentation is to give an overview of my research in this area that show it is possible to use the same luminescent materials as the active element in multipurpose sensors. Particular emphasis will be placed on recent measurements made on some of these materials.

Effects of Water on the Triboluminescent Properties of Europium Tetrakis Dibenzoylmethide Triethylammonium

Europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA) is one of the most intense triboluminescent (TL) materials currently known. The authors have reported in 2011, that the intensity of emission can be enhanced by changing the starting europium salt from europium chloride to europium nitrate by 82%. While investigating the impact of solvents on the intensity of light emission, the authors in 2012, demonstrated that replacing anhydrous ethanol with laboratory grade ethanol showed no change in the observed TL results. However, changing the solvent from ethanol to acetone resulted in faster precipitation of the compound, and slow crystallization yielded larger crystals with higher intensity of triboluminescence. As a result of this research, this paper investigates the effect of solvent dilution using deionized water on the triboluminescent properties of EuD4TEA.

Synthesis conditions of europium tetrakis dibenzoylmethide triethylammonium crystals

Europium tetrakis dibenzoylmethide triethylammonium crystals are highly triboluminescent, indicating possible use in structural health monitoring. This work investigates the effect of synthesis conditions on crystalline yield and morphology of this material. Less solvent yields more material, but may cause striations in crystal faces. No statistical effect on triboluminescent yield was recorded. Scanning electron microscopy shows crystal size varies from 30–400 μm based on synthesis conditions.

Magnesium tetrakis dibenzoylmethide triethylammonium: A novel blue emitting phosphor

Triboluminescence (TL) is the emission of cold light that is created when materials are fractured. Europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA) is one of the brightest triboluminescent materials that exist. However, due to the rising cost of europium, it is becoming very expensive to synthesize. As such, we have begun investigating other elements that can possibly replace europium as the luminescent center. After ruling out other lanthanides, we turned our attention to the alkaline earth metals. This paper will explore the luminescent properties of a new novel blue emitting phosphor: magnesium tetrakis dibenzoylmethide triethylammonium.

Measurement of the triboluminescent properties for europium and samarium tetrakis dibenzoylmethide triethylammonium

Triboluminescence (TL) is the emission of cold light that is created when materials are fractured. Europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA) is one of the brightest triboluminescent materials that exist. In 2010, efforts began to introduce additives to the synthesis to increase the triboluminescent yield of EuD4TEA. To date, this research has increased the overall emission yield of EuD4TEA by nearly two fold. This paper explores the effects of adding samarium to EuD4TEA. The effects of this additive on the decay time and photoluminescent emission spectra are reported. In addition, the effects of europium on samarium tetrakis dibenzoylmethide triethylammonium are also determined. The effects of europium on the decay time and photoluminescent emission spectra are also reported. Results will show that both additives have an adverse effect on the triboluminescent emission yield. Open image in new window

Effects of added dibutyl phosphate on the luminescent properties of europium tetrakis dibenzoylmethide triethylammonium

Since 2003, the authors have been pushing the boundaries on a special type of functional material, i.e., a material that gives off light when it is stressed, strained, and/or fractured. This unique class of materials has been proposed for the active element of impact sensors, earthquake detectors, and stress sensors. However, in order for this concept to go from the lab to real world applications, the light emission from these functional materials must be bright such that inexpensive light detectors can be used. One of the brightest materials found thus far is europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA). This material has an emission so bright that it can be observed in daylight. In 2013, the authors discovered that the addition of dimethyl methylphosphonate (DMMP) increased the light emission two fold. As a result, a search for similar compounds was conducted to determine if the emission can be increased further. This paper explores the effects of dibutyl phosphate (DBP) on EuD4TEA. The effects of DBP on the triboluminescence, photoluminescence, and crystal structure of EuD4TEA will be determined. This paper will show that DBP has an even greater effect on the properties of EuD4TEA than DMMP.

Cover Picture: Cryst. Res. Technol. 5/2012

AbstractThe cover picture shows doped europium tetrakis dibenzoylmethide triethylammonium crystals illuminated with: (left) Standard room light, and (right) Ultraviolet light. (see pages 573–578) (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Cylindrical conical gears with line contact. (in German) : I. Szekely, Rev. Roumaine Sci. Tech., Ser.Mecan. Appl., 10 (1) (1965) 217–228

An organometallic dye, europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA) and gold nanoparticles (Au NPs) impregnated paper based sensor platform have been utilized for development of fluorescence turn-on cyanide assay in aqueous media. The ordinary filter paper with 6 μ m pore size were employed as solid support that facilitates impregnation of EuD4TEA and gold nanoparticles and provides durability. Detection mechanism relying on two processes (i) dissolution of gold nanoparticles causing fluorescence recovery and (ii) ligand exchange of triethyl amine with CN group stimulating cyanide specific fluorescence enhancement. The paper platform exhibit naked eye distinguishable color transition upon CN− addition from 10−2 to 10−12 M. To standardize the methodology a homemade image processing algorithm has been developed that enabling calibration of color change and quantify CN− concentration. The described algorithm is applicable to Android smart phones and facilitate transforming these devices into a quantitative cyanide detector. The overall methodology provides instrument free cyanide detection and therefore rapid control of water quality and safety at off-field conditions.