Search

Ionic thermoelectric (i‐TE) gels can have a high thermopower, if the thermodiffusion of mobile cation/anion is decoupled, attracting increasing attentions. Herein, it is shown a high p‐type i‐TE thermopower of 41.8 mV K−1 in agarose‐based ionic thermoelectric gels of AG‐x Na:DBS (AG: agarose, Na:DBS: sodium dodecyl benzene sulfonate). The exclusively high thermopower is relative to the successfully decoupling the thermodiffusion of cation Na+ and anion DBS−. A unique porous structure is formed due to the micellization of the amphiphilic DBS− with the hydrophilic benzenesulfonic group attached to the hydrous agarose gel chains, while the hydrophobic alkyl chain point to the pore centers. As a result, the DBS− micelles are almost immobile as compared with Na+, which can be reconsidered as a part of the gel matrix. The work shines a light on decoupling of cation/anion thermodiffusion through tailoring the microstructure of the quasi‐solid i‐TE materials. [ABSTRACT FROM AUTHOR]

Scintillators with high light yield, spatial resolution, and detection sensitivity are desirable for X‐ray imaging. Howerer, it remains challenging to improve the light yield and radiation detection capability of alkali metal rare‐earth fluoride (ALnF4). Herein, a type of Cu2+ ion heterovalent co‐doped LiLuF4:Tb,Cu microcrystalline scintillation material with high light yield, persistent, and thermostimulated luminescence is obtained by defect engineering. The heterovalent codoping strategy not only increases the radioluminescence (RL) intensity, but also introduces more carrier traps in the material to enhance the long‐afterglow and thermoluminescence intensity of LiLuF4:Tb microcrystals. After doping of 3 mol% Cu2+ ions, the RL efficiency is increased by 88.61%, and the X‐ray detection limit of LiLuF4:Tb,Cu reaches 2.7928 nGy·s‒1. This detectivity is considerably lower than the medical imaging requirements (5.5 µGy·s‒1). Furthermore, a large‐area flexible scintillation film of dimensions 30 × 30 cm2 is prepared to achieve high spatial resolution X‐ray imaging of 22 LP mm−1@MTF(modulation transfer function) = 0.2. Besides, this flexible film enables X‐ray imaging of curved objects and stores optical information for >48 h. This work provides a paradigm for improving the RL intensity and X‐ray detection sensitivity of alkali rare‐earth fluorides by crystal defect engineering, and enriches X‐ray high resolution extended imaging applications. [ABSTRACT FROM AUTHOR]

MOFs have good potential for X-ray detection, but direct X-ray detection in single crystal form is rarely reported. In this work, we successfully synthesized Pb-TCPE, and the single crystal achieves a low detection limit and high detection sensitivity of 4812.6 μC Gyair−1 cm−2, which exhibits great potential for X-ray detection and imaging. [ABSTRACT FROM AUTHOR]

X-ray detectors based on scintillators are widely used in the fields of medical imaging, high-energy physics, geological exploration, and industrial detection. The development of scintillation materials with different characteristics has become the focus of considerable research interest. Herein, we report a facile hydrothermal synthesis of Gd- and Eu-codoped LiLuF4 microcrystals (MCs), which exhibit strong luminescence of Eu3+ ion characteristic emission, characterized by distinct red fluorescence emission. The research shows that Gd3+ co-doping effectively improved the sensitivity and light yield of LiLuF4:Eu MCs by regulating the proportion of co-doping ions. In addition, the detection limit is 140.72 nGy s−1 for LiLuF4:Eu,Gd MCs, approximately 39 times lower than the dose requirement of medical diagnosis. Based on LiLuF4:Eu,Gd MCs with the superior scintillation properties, a MC-composited film with 250 μm thickness was prepared by a direct coating method. The uniform and high-loading scintillation film exhibits outstanding imaging performance with a high spatial resolution of 14.8 LP mm−1, which confirms the application potential of X-ray imaging. [ABSTRACT FROM AUTHOR]

In recent years, the development of new scintillation materials with red and near-infrared light emission has had significant advantages based on the development of an avalanche photodiode with high quantum yield. This study used a hydrothermal method to synthesize rare-earth-doped Cs2NaScCl6 crystals, in which a red emission of Cs2NaScCl6:Sm was investigated with high X-ray sensitivity and low detection limit. In addition, a tunable wavelength range of radioluminescence can be achieved, in which a near-white light emission can be generated by precisely controlling the proportion of Sm3+ and Tb3+ doping concentrations. Meanwhile, a Cs2NaScCl6:7%Sm scintillation film has been successfully prepared by direct coating with a thickness of 150 μm, which achieves a spatial resolution of 11.9 lp mm−1 based on X-ray imaging experiments. Therefore, this perovskite material has shown potential application as an eco-friendly multifunctional imaging material. [ABSTRACT FROM AUTHOR]

Enhancing the thermoelectric transport properties of conductive polymer materials has been a long-term challenge, in spite of the success seen with molecular doping strategies. However, the strong coupling between the thermopower and the electrical conductivity limits thermoelectric performance. Here, we use polaron interfacial occupied entropy engineering to break through this intercoupling for a PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(4-styrenesulfonate)) thin film by using photochromic diarylethene (DAE) dopants coupled with UV-light modulation. With a 10-fold enhancement of the thermopower from 13.5 μV K−1 to 135.4 μV K−1 and almost unchanged electrical conductivity, the DAE-doped PEDOT:PSS thin film achieved an extremely high power factor of 521.28 μW m−1 K−2 from an original value of 6.78 μW m−1 K−2. The thermopower was positively correlated with the UV-light intensity but decreased with increasing temperature, indicating resonant coupling between the planar closed DAE molecule and PEDOT. Both the experiments and theoretical calculations consistently confirmed the formation of an interface state due to this resonant coupling. Interfacial entropy engineering of polarons could play a critical role in enhancing the thermoelectric performance of the organic film. [ABSTRACT FROM AUTHOR]

The thermoelectric figure of merit ZT bridges the efficiency and material parameters for a thermoelectric device operating under constant temperature of the hot‐ and cold‐source thermal boundary (Type‐I TB). However, many application scenarios fall under the constant heat‐in flux (qh) and constant cold‐source temperature (Tc) thermal boundary (Type‐II TB), for which a figure of merit is absent for more than half a century. This study aims to fill this gap and propose a figure of merit ZQD for the thermoelectric devices under the Type‐II TB condition, defined as ZQD=(ZTcZTc+1)(hκ)(qhTc)$Z{Q}_{\mathrm{D}} = ({\frac{{Z{T}_{\mathrm{c}}}}{{Z{T}_{\mathrm{c}} + 1}}})({\frac{h}{\kappa }})({\frac{{{q}_{\mathrm{h}}}}{{{T}_{\mathrm{c}}}}})$, where Z, h, and κ are the traditional figure of merit, leg height, and thermal conductivity, respectively. The effectiveness of ZQD is verified through both numerical calculations and experiments, which are more accurate and practical than ZT. Furthermore, a system‐level figure of merit ZQS is suggested after considering the external thermal resistance. Finally, optimization strategies for thermoelectric systems based on ZQS are proposed, showing a 30% enhancement in the efficiency. ZQD and ZQS are expected to be widely used in the thermoelectric field. [ABSTRACT FROM AUTHOR]

Eco‐friendly lead‐free organic–inorganic manganese halides (OIMHs) have attracted considerable attention in various optoelectronic applications because of their superior optical properties and flexible solution processibility. Herein, we report a novel pseudo‐2D layered OIMH (MTP)2MnBr4 (MTP: methyltriphenylphosphonium), which exhibits intense green emission under UV/blue or X‐ray excitation, with a near‐unity photoluminescence quantum yield, high resistance to thermal quenching (I150 °C=84.1 %) and good photochemical stability. These features enable (MTP)2MnBr4 as an efficient green phosphor for blue‐converted white light‐emitting diodes, demonstrating a commercial‐level luminous efficiency of 101 lm W−1 and a wide color gamut of 116 % NTSC. Moreover, these (MTP)2MnBr4 crystals showcase outstanding X‐ray scintillation properties, delivering a light yield of 67000 photon MeV−1, a detection limit of 82.4 nGy s−1, and a competitive spatial resolution of 6.2 lp mm−1 for X‐ray imaging. This work presents a new avenue for the exploration of eco‐friendly luminescent OIMHs towards multifunctional light‐emitting applications. [ABSTRACT FROM AUTHOR]

Eco‐friendly lead‐free organic–inorganic manganese halides (OIMHs) have attracted considerable attention in various optoelectronic applications because of their superior optical properties and flexible solution processibility. Herein, we report a novel pseudo‐2D layered OIMH (MTP)2MnBr4 (MTP: methyltriphenylphosphonium), which exhibits intense green emission under UV/blue or X‐ray excitation, with a near‐unity photoluminescence quantum yield, high resistance to thermal quenching (I150 °C=84.1 %) and good photochemical stability. These features enable (MTP)2MnBr4 as an efficient green phosphor for blue‐converted white light‐emitting diodes, demonstrating a commercial‐level luminous efficiency of 101 lm W−1 and a wide color gamut of 116 % NTSC. Moreover, these (MTP)2MnBr4 crystals showcase outstanding X‐ray scintillation properties, delivering a light yield of 67000 photon MeV−1, a detection limit of 82.4 nGy s−1, and a competitive spatial resolution of 6.2 lp mm−1 for X‐ray imaging. This work presents a new avenue for the exploration of eco‐friendly luminescent OIMHs towards multifunctional light‐emitting applications. [ABSTRACT FROM AUTHOR]

Currently, Faraday isolators and rotators for high‐power lasers are popular research topics; therefore, finding magneto‐optical materials with excellent Verdet constants and thermal properties is crucial. In this study, novel holmium scandium aluminum garnet (HoSAG) magneto‐optical ceramics were fabricated using vacuum sintering. This study improved the traditional ball milling method and pre‐synthesized powders with great sinterability after secondary ball milling and sieving. Different pre‐synthesis temperatures were found to have significant effects on the particle size and micromorphology of the synthesized powders. HoSAG ceramics with 0.05 wt% MgO sintering aid and held at 1700°C for 30 h reached a transmittance of 76.7% at 1550 nm. Meanwhile, HoSAG transparent ceramics maintain higher transmittance in the infrared region (>1500 nm) than terbium gallium garnet (TGG) crystals, indicating better application prospects. The Verdet constants of HoSAG magneto‐optical ceramics at 405, 532, 808, and 1064 nm were −421.5, −181.2, −65, and −32.3 rad T−1 m−1, respectively, which are slightly less than those of TGG magneto‐optical ceramics. Moreover, the thermal conductivity of HoSAG ceramics at 300.00 K was 4.89 W m−1 K−1, which is comparable to that of the TGG ceramics. [ABSTRACT FROM AUTHOR]

X‐ray flat‐panel detectors are widely used for nondestructive detection of internal information in medical radiography and industrial applications. However, a persisting challenge is the application of radiography on highly curved 3D objects to realize flexibility and information storage for the fabrication of flexible large‐area X‐ray detectors. This study demonstrates a halide‐based double perovskite Cs2Na0.9Ag0.1LuCl6:Dy3+ by a hydrothermal reaction. The as‐prepared crystals exhibit afterglow features through a co‐doping strategy of Dy3+ and Ag+ ions. The double perovskite material with doping modification exhibits excellent scintillation properties with high sensitivity, low detection limit, and high radiation stability. In addition, flexible scintillator detectors are fabricated with an area of 8.0 × 6.0 cm2 by the blade‐coating strategy, which has a high spatial resolution of 11.2 lp mm−1@MTF = 0.2. Based on the long afterglow properties, the Cs2Na0.9Ag0.1LuCl6:Dy3+ flexible film exhibits thermoluminescence after turning off the X‐ray, thereby having strong potential for X‐ray imaging of nonflat and irregular objects. [ABSTRACT FROM AUTHOR]

The current development direction of magneto-optical (MO) isolators involving miniaturisation and application in high-power lasers encounters difficulties in material application because preparing materials with excellent optical quality and a high Verdet constant remains a challenge. Herein, (Tb1−xCex)3Sc2Al3O12 (x = 0.001, 0.0025, 0.005, 0.01, 0.015, 0.02) MO ceramics with different doping concentrations were prepared by vacuum sintering. The phase structure, element distribution, microstructure, relative density, optical properties, surface properties and MO properties of the (Tb1−xCex)3Sc2Al3O12 ceramics were also characterised. Experimental characterisation reveals that the (Tb1−xCex)3Sc2Al3O12 ceramics have a pure Tb3Sc2Al3O12 (TSAG) phase and exhibit an excellent uniform element distribution. In addition, no secondary phase was detected in FESEM images with the increase in Ce concentration. However, a few small-sized residual pores, which remain entrapped in the Ce0.015TSAG and Ce0.02TSAG ceramics, can be observed. Moreover, all the obtained ceramics have good optical quality, and the in-line transmittances of the (Tb1−xCex)3Sc2Al3O12 ceramics at 1064 nm are 81.7%, 83.7%, 80.0%, 84.0%, 68.8% and 77.7%. The Verdet constant of the ceramics is optimised by Ce doping, and the Verdet constants of all the ceramics at the test wavelength are better than those of TSAG ceramic. The Verdet constant of the Ce0.01TSAG ceramic is still superior to that of the TSAG ceramic in the same temperature range. Finally, the extinction ratio values for the CexTSAG (x = 0.001, 0.0025, 0.005, 0.01) ceramics exceeded 40 dB. The Ce0.01TSAG ceramic shows the best optical transmittance, the highest magneto-optical FoM values and the highest Verdet constants. Thus, this ceramic can be used for a high-power laser in the visible and near-infrared regions in the future. [ABSTRACT FROM AUTHOR]

Semiconductor‐based X‐ray detectors with low detectable thresholds become critical in medical radiography applications. However, their performance is generally limited by intrinsic defects or unresolved issues of materials, and developing a novel scintillation semiconductor for low‐dose X‐ray detection is a highly urgent objective. Herein, a high‐quality rare‐earth iodate Tm(IO3)3 single crystal grown through low‐cost solution processing is reported with a wide bandgap of 4.1 eV and a large atomic number of 53.2. The roles of IO and TmO groups for charge transport in the Tm(IO3)3 are revealed with the structural difference between the [101] and [1¯01]$[{\bar{1}}01]$ crystal orientations. Based on anisotropic responses of material properties and detection performances, it is found that the [1¯01${\bar{1}}01$] orientation, the path with fewer IO groups, achieves a high resistivity of 1.02 × 1011 Ω cm. Consequently, a single‐crystal detector exhibits a low dark current and small baseline drifting due to the wide bandgap, high resistivity and less ion migration of Tm(IO3)3, resulting in a low detection limit of 85.2 nGyair s−1. An excellent X‐ray imaging performance with a high sensitivity of 4406.6 µC Gyair−1 cm−2 is also shown in the Tm(IO3)3 device. These findings provide a new material design perspective for high‐performance X‐ray imaging applications. [ABSTRACT FROM AUTHOR]

Scintillator glasses have the potential for X-ray imaging owing to their low production cost, controllable shape and size, and uniform ion-doping concentration. In this study, Tb3+-doped and Ce3+/Tb3+-co-doped oxyfluoride scintillator (C4T9) glass samples were fabricated by high-temperature melting and quenching. In addition, the luminescence properties of the glass samples and the discrepancy in the energy transfer mechanism between Ce3+ and Tb3+ under ultraviolet (UV) light and X-ray excitation were investigated. The C4T9 glass sample showed excellent integral scintillation efficiency of 84.1% for commercial Bi 4 Ge 3 O 12 (BGO) crystals. The spatial resolution of the C4T9 glass sample was higher than that of the commercial BGO crystal with 42.29 mGy s−1 X-ray irradiation, reaching 16 lp·mm−1. C4T9 glass is expected to become a key material in medical imaging, safety inspection, industrial inspection, and other fields. [ABSTRACT FROM AUTHOR]

Materials exhibiting mechanoluminescence (ML) are a class of smart materials capable of mechanical-to-light energy conversion. Thus, ML materials have been widely used in various electronic applications such as smart sensors, security systems, human–machine interfaces, and energy harvesting systems. Herein, we report a centrosymmetric ML semiconductor host material family MGa2S4 (M = Ca, Sr), which features in-layered structures constructed with unique distorted bi-tetrahedral [Ga2S2S4/2] lattice units. It exhibited similar structural characteristics to the well-known ML semiconductor host ZnS. Remarkably, the lanthanide ions of 5d → 4f transition-activated hosts showed sensitive and high ML luminance under natural lighting upon mechanical stimulation; thus, an efficient mechanical-to-light energy conversion of a self-powered display was achieved. Moreover, because of structural distortion and strain-gradient-induced electrical polarization in the ML host material upon mechanical stimulation, a ML mechanism based on the synergy effect between local electronic polarization and flexoelectricity was proposed. This study facilitates a deeper understanding of the relationship between the structure and underlying ML, and promotes further development of ML-material-based products and technologies. [ABSTRACT FROM AUTHOR]

Scintillators can convert high-energy rays into ultraviolet or visible light and are widely used in medical diagnosis, safety inspection, and industrial flaw detection. Nowadays, conventional scintillation materials have certain limitations, including the extreme synthesis conditions and complex synthesis process of bulk scintillators, as well as toxicity and poor stability of perovskite quantum dots (QDs). Fluoride has high stability and simple synthesis, which can effectively solve these problems. LiYbF4 has the advantages of a larger atomic number and density, and the synthesis of LiYbF4:Tb nanocrystals (NCs) exhibited good stability to thermal injection. X-ray tests showed that Tb3+-doped LiYbF4 NCs were more sensitive to X-rays than the commercial scintillator BGO, and the detection limit was 360 nGy s−1, which was 1/15 of the medical X-ray detection dose rate. Our self-made scintillation film with a load of 40 wt% and a thickness of 150 μm had excellent X-ray imaging capabilities with a spatial resolution of up to 20 LP mm−1 (MTF = 0.35), which shows great application potential in the X-ray imaging of biological and non-biological structures. [ABSTRACT FROM AUTHOR]

Lanthanide–organic frameworks (LnOFs) have been brought into focus due to their unique structure–function relevance, and have shown good application prospects in many fields. According to the characteristics of scintillating materials, we synthesized two isomorphic LnOFs with the lanthanides terbium and europium as emission centers: Tb(bmb)3·H2O (LnOF-1) and Eu(bmb)3·H2O (LnOF-2). Tb3+ and Eu3+ were used as X-ray absorption centers, and large conjugated organic ligands were used as energy transfer bridges, which can effectively convert X-rays into visible light. LnOF-1 and LnOF-2 show good X-ray scintillation performance and anti-radiation stability. At the same time, we prepared a LnOF-1 mixed matrix scintillating film by the physical deposition method for X-ray imaging experiments, and its spatial resolution can reach 9.5 lp mm−1@MTF20%. The excellent imaging application effect prospect makes the lanthanide–organic frameworks show development potential in the field of scintillating materials. [ABSTRACT FROM AUTHOR]

Novel Tb 3 Sc 2 Al 3 O 12 (TSAG) magneto-optical transparent ceramic was fabricated by vacuum sintering. The phase composition, microstructure, optical quality, thermal properties, and magneto-optical properties of TSAG ceramic were measured. It is shown that the increase in holding time has an effect on the grain size of TSAG ceramic. It is noted that TSAG35 ceramic presents the highest transmittance, corresponding to 81.5 % at the wavelength of 1064 nm. The thermal properties of TSAG ceramic are close to or superior to that of the reported TSAG and TGG crystals. The Verdet constant of TSAG ceramic is comparable to that of reported TSAG crystal, and 1.2 times that of TGG crystal. The results indicate that the novel TSAG ceramic is comparable to TSAG crystal in terms of magneto-optical properties and superior to TGG crystal, making it a candidate material for magneto-optical materials to be used in high-power lasers. [ABSTRACT FROM AUTHOR]

Magneto-optical materials with high Verdet constants at high extinction ratios are desirable for the Faraday isolators. However, current terbium-based crystals have encountered several issues, such as low Verdet constants (TGG crystals), difficult growth (TSAG crystals), and low utilization of raw materials, which limit the development of the Faraday isolators. Here, R 0.0025 TSAG (R= Pr, Ho, Dy, Eu) transparent ceramics are prepared. The ceramics exhibit high optical transparency above 74.0% in the 525–1565 nm range and a high relative density of 98.9%. In particular, the transmittance of R 0.0025 TSAG ceramics at 1064 nm is approximately 81.6%, 81.6%, 79.8%, and 80.6%, respectively. The Verdet constants of R 0.0025 TSAG ceramics at the measurement wavelength are greater than those of the TSAG ceramic. The compelling magneto-optical performance of the Dy 0.0025 TSAG ceramic includes a high Verdet constant of 161.8 ± 3 rad·m−1·T−1 at 635 nm. The Verdet constant of the Dy 0.0025 TSAG ceramic is still superior to that of TSAG ceramic in the same temperature range. The extinction ratios of the R 0.0025 TSAG (R= Pr, Ho, Dy) ceramics exceed 40 dB. The figure of merit points out the superior characteristics of R 0.0025 TSAG ceramics. Moreover, R 0.0025 TSAG (R= Pr, Ho, Dy) ceramics with a thickness above the centimeter level are successfully prepared. This work indicates that the Dy 0.0025 TSAG ceramic can promote the miniaturization of magneto-optical isolators and can be applied in high-power lasers. • (Tb 0.9975 R 0.0025) 3 Sc 2 Al 3 O 12 (R= Pr, Ho, Dy, Eu) transparent ceramics were synthesized and characterized. • The Verdet constants of R-TSAG ceramics at the measurement wavelength are greater than that of TSAG ceramic. • The values of extinction ratio for R-TSAG (R= Pr, Ho, Dy) ceramics exceed 40 dB. [ABSTRACT FROM AUTHOR]

Scintillators play a vital role in high-energy physics, medical imaging, security inspection, etc. Here, we designed and prepared a highly efficient scintillator of Ce,Tb-codoped LiLuF 4 , which was synthesized by a hydrothermal method using low-cost raw materials. The microcrystalline scintillator exhibits the strong luminescence of rare earth ion, which has a characteristic green fluorescence emission with a quantum yield of 71.59%. This material has a strong X-ray response, superior light output (16,509 ph/MeV), excellent ray cut-off capability and absolute stability. Based on micron-level powdered compounds, we used direct coating to manufacture a scintillation film with a size of 5.5 cm × 8.0 cm for X-ray imaging testing. The imaging test shows that the highly stable scintillation film not only has a spatial resolution capability of more than 10.0 LP/mm but also has great potential to be prepared as a flexible scintillator, which exhibited excellent performance as an potential scintillation detection material. Tetragonal LLF:Ce,Tb MCs exhibit bright and sensitive radioluminescence with the energy transfer process between rare earth ions, and its composite film can provide a decent spatial resolution for X-ray imaging applications. [Display omitted] • Lu element was used instead of Y element to improve the scintillation property of the material. • Ce ion sensitizing Tb ion strategy was adopted to improve the radiation light output of the material. • A large area scintillation film with transmittance of 79.92% was successfully prepared by direct coating method. • The spatial resolution of the scintillation film for radiation detection is more than 10.0 LP/mm. [ABSTRACT FROM AUTHOR]

Ce3+ or Tb3+ single-doped and Ce3+/Tb3+ co-doped oxyfluoride scintillation glass samples were prepared by high temperature melting method. The structures were analyzed by X-ray diffraction (XRD), the optical and luminescent properties were studied by transmittance, photoluminescence excitation, photoluminescence, X-ray excited luminescence (XEL) and fluorescence decay. The luminescence intensity in the Ce3+/5 mol% Tb3+ co-doped (CT5) glass sample under 304 nm light and X‐ray excitation is significantly enhanced compared to 5 mol% Tb3+ single-doped (T5) glass sample. The maximum integrated XEL intensity of CT5 glass sample is about 67% of the standard Bi 4 Ge 3 O 12 (BGO) crystal. Through the study of energy transfer mechanism, the results indicate that there is an energy transfer from Gd3+ ions or Ce3+ ions to Tb3+ ions. The lifetime of CT5 glass sample is 2.13 ms. The obtained results confirm that CT5 glass sample could be a promising scintillating material used in X-ray imaging. So we have demonstrated X-ray imaging using Ce3+/1–15 mol% Tb3+ co-doped (CT1-15) glass samples and confirmed they can reach a spatial resolution of 10.0 lp/mm. Further, the X-ray imaging effect of CT5 glass sample is the best, and the capability of CT5 glass sample for X-ray imaging application is confirmed. • Ce3+/Tb3+ co-doped oxyfluoride scintillation glass samples were successfully fabricated and characterized. • The scintillation mechanism and energy transfer mechanism in the Ce3+/Tb3+ co-doped glass samples were discussed. • The X-ray imaging experiments were carried out and proved the suitability of CT5 sample in X-ray imaging applications. [ABSTRACT FROM AUTHOR]