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The attenuation of slow shear acoustic waves in the (110) plane of tellurium dioxide (TeO2) crystals was investigated. The strong acoustic anisotropy of TeO2 crystals results in a non-uniform acoustic power distribution, which can introduce errors in conventional acousto-optic testing methods. In this study, we propose a general method to measure the acoustic power distribution along the propagation direction of acoustic waves in non-collinear acousto-optic tunable filters (AOTFs). Additionally, we analyze the errors introduced by the non-uniform acoustic field resulting from strong acoustic anisotropy in acousto-optic testing methods. The measurements were carried out for a crystal cutoff angle of 6.5° from the [110] axis, for the ultrasound frequency range from 40 to 140 MHz. The attenuation coefficients were determined and their quadratic dependence on ultrasound frequency was confirmed. [ABSTRACT FROM AUTHOR]

Monitoring the processes inside crystalline materials under their operating conditions is of great interest in optoelectronics and scientific instrumentation. Early defect detection ensures the proper functioning of multiple crystal-based devices. In this study, a combination of acoustic emission (AE) sensing and cross-polarization imaging is proposed for the fast characterization of the crystal's structure. For the experiments, tellurium dioxide (TeO2) crystal was chosen due to its wide use in acousto-optics. Studies were performed under uniaxial compression loading with a simultaneous acquisition of AE signals and four polarized optical images. An analysis of the temporal dependencies of the AE data and two-dimensional maps of the light depolarization features was carried out in order to establish quantitative criteria for irreversible damage initiation and crack-like defect formation. The obtained results reveal the polarization image patterns and the AE pulse duration alteration specific to these processes, and they open up new possibilities for non-destructively monitoring in real-time the structure of optically transparent crystals under their operating conditions. [ABSTRACT FROM AUTHOR]

Although the number of implants has increased gradually and consistently over the years to around one million per year globally, there is still far more potential for advancement in the field of dental implantology which is typically growing quickly. This study investigates the effect of nanofiller reinforcement high-performance polymer matrix to enhance mechanical and physical characteristics. Calcium silicate (CS)/Polyetherketoneketone (PEKK) biomedical composite (G0 as a control group) is reinforced with different weight percentages (G1-G4) of tellurium dioxide nanoparticles (TeO2 NPs) (n = 5). This research uses ethanol as a binder for mixing various weight percentages (wt%) of TeO2 NPs with CS/PEKK biomedical composite. The combination is then dried at 120°C in a forced convection oven before being put into special molds and compressed for 20 min Holding period at 310°C and 15 MPa. The composites were prepared via the compression molding technique. Morphological, mechanical, and physical characteristics were studied. The findings of this study suggested improvement in the interfacial interaction between TeO2 NPs (G1 and G2) and CS/PEKK bioactive composite resulting in better mechanical and physical properties, especially at 1 w% of TeO2 NPs (G2). [ABSTRACT FROM AUTHOR]

Herein, high‐k dielectric behavior of TeO2 thin films is investigated. The films are prepared using pulsed laser deposition on indium tin oxide (ITO)–glass substrates. Increasing the growth temperature has improved the surface roughness, transparency, and bandgap of the films. Films grown at 500 °C display nanocrystalline nature which is reflected in the increase of bandgap to 4.7 eV and is higher than the bulk value of α‐TeO2 (3.7 eV). The nanocrystalline TeO2 films in the metal–insulator–metal configuration show a stable high permittivity of ≈19 with low leakage current (J < 1 × 10−7 A cm−2) and good voltage stability (α = 509 ppm V−2). Field‐effect modulation is observed in the metal–oxide–semiconductor stack configuration with tellurium as a semiconductor. The study suggests nanocrystalline TeO2 as a low‐temperature processable high‐k material with high transparency for transistor applications. [ABSTRACT FROM AUTHOR]

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The attenuation of slow shear acoustic waves in the (110) plane of tellurium dioxide (TeO2) crystals was investigated. The strong acoustic anisotropy of TeO2 crystals results in a non-uniform acoustic power distribution, which can introduce errors in conventional acousto-optic testing methods. In this study, we propose a general method to measure the acoustic power distribution along the propagation direction of acoustic waves in non-collinear acousto-optic tunable filters (AOTFs). Additionally, we analyze the errors introduced by the non-uniform acoustic field resulting from strong acoustic anisotropy in acousto-optic testing methods. The measurements were carried out for a crystal cutoff angle of 6.5° from the [110] axis, for the ultrasound frequency range from 40 to 140 MHz. The attenuation coefficients were determined and their quadratic dependence on ultrasound frequency was confirmed.

Monitoring the processes inside crystalline materials under their operating conditions is of great interest in optoelectronics and scientific instrumentation. Early defect detection ensures the proper functioning of multiple crystal-based devices. In this study, a combination of acoustic emission (AE) sensing and cross-polarization imaging is proposed for the fast characterization of the crystal’s structure. For the experiments, tellurium dioxide (TeO2) crystal was chosen due to its wide use in acousto-optics. Studies were performed under uniaxial compression loading with a simultaneous acquisition of AE signals and four polarized optical images. An analysis of the temporal dependencies of the AE data and two-dimensional maps of the light depolarization features was carried out in order to establish quantitative criteria for irreversible damage initiation and crack-like defect formation. The obtained results reveal the polarization image patterns and the AE pulse duration alteration specific to these processes, and they open up new possibilities for non-destructively monitoring in real-time the structure of optically transparent crystals under their operating conditions.

The electrochemical reactions for the storage of Zn2+ while embracing more electron transfer is a foundation of the future high‐energy aqueous zinc batteries. Herein, we report a six‐electron transfer electrochemistry of nano‐sized TeO2/C (n‐TeO2/C) cathode by facilitating the reversible conversion of TeO2↔Te and Te↔ZnTe. Benefitting from the integrated conductive nanostructure and the proton‐rich environment in providing optimized electrochemical kinetics (facilitated Zn2+ uptake and high electronic conductivity) and feasible thermodynamic process (low Gibbs free energy change), the as‐prepared n‐TeO2/C with stable cycling performance exhibits a superior reversible capacity of over 800 mAh g−1 at 0.1 A g−1. A precise understanding of the reaction mechanism via ex situ and in situ characterizations presents that the reversible six‐electron transfer reaction is proton‐dependent, and a proton generating and consuming mechanism of three‐phase conversion n‐TeO2/C in the weakly acidic electrolyte is thoroughly revealed. [ABSTRACT FROM AUTHOR]

New glasses in the TeO2–Na6P6O18 system have been prepared, their thermal behavior has been studied by differential scanning calorimetry in the range 25–580°C, and their heat capacity has been determined as a function of temperature in the range 25–400°C. We have evaluated characteristics of the devitrification process and glassy state, obtained analytical representations of the glass transition temperature and the thermodynamic characteristics of the glasses as functions of their composition at 80°C, and carried out a comparative analysis of the results together with those for previously studied TeO2-based binary systems. Optical transmission of the glasses has been measured in the UV, visible, and IR spectral regions. We have demonstrated the possibility of doping the glasses with rare-earth oxides and studied luminescence properties of the glass with the composition 0.89TeO2–0.08Na6P6O18–0.03Nd2O3. [ABSTRACT FROM AUTHOR]

Tellurium dioxide is an ultra-wide bandgap semiconductor material playing a key role in optoelectronics. However, some of its physico-chemical properties such as the solid surface energy are still unknown. Indeed, the values available in the literature are scarce and contradictory. In this letter, the solid surface energy of tellurium dioxide (paratellurite) has been carefully determined to be 142 ± 7 mJ/m2. This was achieved by measuring the static contact angles made by various liquids (deionized water, ethylene glycol, mercury and Galinstan®) on top of a tellurium dioxide thin film, in a controlled environment. [ABSTRACT FROM AUTHOR]

It is necessary to simulate the thermodynamics of the Te/TeO2-CN-H2O systems to interpret the dissolution behaviour of elemental tellurium and tellurium dioxide in alkaline cyanide solutions. Below are the data employed to simulate the equilibrium diagrams presented in the article entitled “Dissolution behaviour of elemental tellurium and tellurium dioxide in alkaline cyanide solutions”. Most of the reactions are available in the Hydra database of MEDUSA© software along with their logarithms to the base 10 of the equilibrium constants (i.e., log K). However, it was complemented with the log K of some important reactions (e.g., which describes the formation of H2TeO3). Log K values were calculated form the ΔG°f reported in the scientific literature. The databases reported can be used to compare the equilibrium constant values, replicate the diagrams presented in the cited article, and simulate other aqueous systems (e.g., those employing alternative lixiviant agents as thiosulfate, thiourea, etc.).

Operation stability is the main challenge that current existing saturable absorbers (SAs) are facing. In this paper, we report on two low chemical activity saturable absorbers, the tellurium dioxide and antimony trioxide thin film, for stable femtosecond pulse generation in 2 μm region. The nonlinear absorption of two oxides at 2 μm was firstly revealed and the extraordinary mode-locking performance based on two oxides was demonstrated. The phase noise and amplitude noise were also measured and analyzed, and the integrated RMS relative intensity noise was found to be 0.0196% and 0.0218% for TeO2 thin film and Sb2O3 thin film respectively. Great thermal stability and long-term stability were also confirmed. Heating the oxides coated area in atmosphere for hours and the lasers still could be mode-locked. Compared to low dimensional materials, the oxides proposed in this paper could be more suitable for robust mode locking in harsh environment. The broadened working conditions tolerance also enables new applications for optical modulators. [ABSTRACT FROM AUTHOR]

We report observations of the Raman spectra of 10 keV hydrogen ion-implanted crystalline quartz, lithium niobate and tellurium dioxide over a wide range of ion fluences ( 10 14 – 10 18 protons/cm 2 ). We observe the emergence and growth of a new fluorescence feature in the Raman spectra (peaked at 1535 cm − 1 ) as a function of fluence in all three materials. When measured, the position and shape of this feature is nearly identical in each material. However, the appearance of this feature in tellurium dioxide has a slightly varied behaviour. Based on our observations, we suggest that this signal is due to the 557.7 nm photoluminescence of interstitial atomic O formed radiolytically. While interstitial molecular O2 has previously been observed in irradiated quartz, the presence of this atomic oxygen signature in proton-irradiated lithium niobate and tellurium dioxide has not been previously reported. Our results are important for the use of these materials, and other crystalline oxides, in charged particle (proton) radiation rich environments, such as those encountered by spaceborne instrumentation. [ABSTRACT FROM AUTHOR]

α-phase TeO 2 is a promising sensing material because of its unique ability to detect hydrogen gas. To investigate atomic-level mechanism on gas sensing of TeO 2 , the interaction between H 2 , NH 3 , SO 2 , CO 2 , H 2 S, CH 4 gases and TeO 2 are studied via first principles simulations. By the calculated adsorption energy, radial distribution function, band gap and charge transfer, TeO 2 shows a superior selective detection performance to hydrogen and it is consistent with experimental conclusion. The H–H bond of H 2 break after adsorption and a new H–O bond with length of 0.98 Å forms between TeO 2 and H 2. Moreover, the adsorption of H 2 causes an obvious increasing of DOS near the Fermi level, indicating a clear change in the electric conductivity. The calculated self-diffusion coefficients show that the diffusion of hydrogen molecule in TeO 2 is much easier than the other gases, suggesting a fast response of H 2 by TeO 2. This work provides a theoretical foundation for analysis and design of TeO 2 -based hydrogen sensor. Image 1 • For the first time, atomic sensing mechanism of TeO 2 towards H 2 gas is studied. • Predicted gases sensing behaviours of TeO 2 consist with experiments. • Detection of H 2 is related to formation of O–H bonds between H 2 and TeO 2. • Our analysis provides a basis for designing of TeO 2 -based gas sensor. [ABSTRACT FROM AUTHOR]

The gamma radiation induced optical properties of the tellurium dioxide films of thickness 1500 nm, deposited by thermal evaporation in the vacuum, were investigated. The dose dependences of the band gap and other optical parameters have been quantified from the transmittance spectra. The optical band gap decreases with the gamma radiation dose up to 400 Gy from 3.98 to 3.55 eV and increases beyond 400 Gy. Also, the refractive index and extinction coefficient increase appreciably with the gamma radiation dose up to 400 Gy and the two decrease beyond 400 Gy. This behavior of the optical properties is due to generation of the electronic localized states in the band gap and Urbach tail. The change in each of the optical properties due to gamma radiation can be an attractive idea for the TeO 2 film as photo-sensitive film-based dosimeter. The proposed material as dosimeter has minimum detectable effect on a dose range of 400 Gy, which is best suited for possible industrial applications such as food processing and sterilization. [ABSTRACT FROM AUTHOR]

Highlights • Temperature influences the acousto-optic interaction phase matching condition. • The phase matching frequency shift was measured in optical band from 440 to 1520 nm • The shift magnitude decreases with the optical wavelength growth. Abstract The temperature effect on the acousto-optic (AO) phase matching condition was examined both theoretically and experimentally on an example of wide-angle acousto-optic filter fabricated from tellurium dioxide crystal. It was shown that the AO crystal temperature variation changes the acoustic wave velocity that is involved into the AO interaction and shifts the phase matching frequency of AO diffraction. The AO phase matching frequency shift temperature coefficient was introduced, characterizing the magnitude of the frequency shift. The examination of frequency shift magnitude was carried for the optical wavelength band from 440 nm to 1.52 µm. It was shown that the temperature coefficient decreases with increasing the optical wavelength. A method was introduced that makes it possible to calculate the temperature shift coefficients for the real AO devices in a wide range of optical wavelengths. The coefficients obtained with the proposed method are in good agreement with the experimental data. Ultrasound attenuation was also examined in the given AO cell. Attenuation caused by the acoustic power absorption is the main mechanism leading to the appearance of the inhomogeneous temperature distribution inside the AO cell during the operation. [ABSTRACT FROM AUTHOR]

Keywords: Aqueous Zinc Batteries; Cathode; Electrochemistry; Six-Electron Transfer; Tellurium DioxideBatteries. Reversible six‐electron transfer cathode for aqueous zinc batteries is reported by Zhiqiang Zhu et al. in their Communication (e202312000)...By Zichao Yan; Junwei Li; Hongguang Liu; Hui Zhang; Shibo Xi and Zhiqiang ZhuReported by Author; Author; Author; Author; Author; Author [Extracted from the article]

Paratellurite, also known as α-tellurium dioxide, is a ceramic that is primarily employed for its interesting optical properties. However, this material’s crystal structure belongs to the 422 symmetry class that allows a unique piezoelectric behavior to manifest itself: deformation in pure face-shear. This means that crystal symmetry necessitates the piezoelectric tensor to have only a single non-zero coefficient, d123 = d14: such unique behavior has the potential to enable novel gyroscopic sensors and high-precision torsional microelectromechanical systems (MEMS) actuators, as pure face-shear can be used to induce pure torsion. Although α-TeO2 is one of the few known materials belonging to this symmetry class, considerable uncertainty in its single piezoelectric coefficient exists, with the few reported literature values ranging from 6.13 to 14.58 pC/N; this large uncertainty results from the difficulty in using conventional piezoelectric characterization techniques on paratellurite, limiting measurements to indirect methods. The novel applications that would be enabled by the adoption of this extraordinary material are frustrated by this lack of confidence in the literature. We therefore leverage, for the first time, a first-principles analytical physical model with electrochemical impedance spectroscopy (EIS) to determine, directly, the lone piezoelectric coefficient d123 = d14 = 7.92 pC/N.

In this study, tellurium (Te) nanostructures were synthesized via a facile sonochemical method by reducing TeCl 4 to Te under ultrasonic irradiation in methanol. Moreover, by carrying out the reaction in an alkaline environment TeO 2 nanoparticles were produced. According to our knowledge, it is the first time that without secondary reducing agent Te 4+ are reduced to Te. Also, the effects of ultrasonic power, irradiation time, solvent, and surfactant on the morphology and particle size of Te nanostructures were investigated. The obtained products were characterized by XRD, SEM, EDS, FT-IR and DRS. [ABSTRACT FROM AUTHOR]

As medical cyclotrons are becoming more abundant, 123I and 124I are getting more attention as alternatives to 131I for diagnostics of thyroid disease. Both 123I and 124I provide better diagnostics, deliver less dose to patients and both reduce the risk of thyroid stunning, facilitating subsequent therapy. Dry distillation of radioiodine from tellurium dioxide targets has become the standard approach to producing these radioiodines. Setting up such a production of radioiodine is associated with a lengthy optimization of the process and for this purpose natural tellurium is often used for economical reasons. In this paper, the distillation parameters are scrutinized to ensure optimal distillation temperature, in order to minimize time spent and prevent loss of expensive target material. It is further demonstrated how the individual iodine isotopes, produced from proton bombardment of natTe, will diffuse out of the target in a time dependent ratio. We believe the effect is due to the isotopes having their maximum cross section at different energies. The individual isotopes produced will thus have their highest concentration at different depths in the target. This results in individual mean diffusion lengths and diffusion times for the different isotopes.

A one-dimensional micro-structured tellurium (Te) microtube and tellurium dioxide (TeO2) microwire were successfully prepared by cold spray process in large scale by a facile approach of sprayed (Te), (TeO2) dry powder in an inert atmosphere using helium gas onto glass substrate. Tellurium and Tellurium dioxide were sprayed by heating carrier gas at (200,300,400 and 500 °C) and 2 MPa pressure on the glass substrate (100°C). Heat treatment was done under vacuum (0.0133mbar) for (30 min) at (200°C) for Te and (400°C) for TeO2.The prepared microtubes and microwire was examined by XRD, AFM and SEM. The result showed that the obtained microtubes and microwire were highly pure.

The synthesized 12Bi 2 O 3 – 8BaO–12ZnO-0.5CeO 2 -17.5SiO 2 - (50-x) B 2 O 3 - xTeO 2 glasses with x = 0, 10, 20, 30 and 40 mol% (coded BiTe-0 to BiTe-40) were investigated in terms of physical, structural, optical and mechanical properties to examine the influence of CeO 2 and TeO 2 on the heavy metal oxide (HMO) borosilicate network. Density values increased continuously with increasing TeO 2 concentration with BiTe-40 glass exhibiting maximum value of 5.0875 gcm−3. This property helped in enhancement of refractive index values from 1.769 for BiTe-0 to 1.942 for BiTe-40. Fourier transform infrared (FTIR) analysis of studied glasses revealed the presence of additional small peak at 683 cm−1 in BiTe-30 and BiTe-40 which confirmed the formation of stable TeO 4 units in the glass network. The deep brown colour of the glass existing due to bismuth's presence was nullified by CeO 2 and TeO 2 additives which improved transparency of the glass. Urbach analysis of these glasses led to optical bandgap variation between 3.27 eV and 2.73 eV for 0–40 mol% TeO 2 concentration. Makishima and Mackenzie model was utilized for evaluation of elastic property of the glasses, and Poisson's ratio ranging between 1.935 and 1.953 was obtained. Vickers micro-indentation test on the current glasses revealed decreasing microhardness from 4.116 to 4.076 GPa with TeO 2 variation from 0 to 40 mol% at 9.8 N load. Gamma radiation shielding parameters were determined using Phy-X/PSD software and it was found that BiTe-40 glass produce maximum MAC (mass attenuation co-efficient) values in high photon energy region 3.5–15 MeV. The present article also contains a detailed emphasis on behaviour of gamma radiation build-up factors at different incident photon energy and TeO 2 concentration. The increasing trend of exposure build up factor (EBF) was seen with increasing penetration depth inside the samples at all energies, indicating that glasses of larger thickness improve the escape probability of photons. Meanwhile, fast neutron removal cross-section (FNRCS) was highest for BiTe-10 sample (0.10118 cm−1) which also surpassed the value of ordinary concrete (0.093 cm−1). Overall, the present glass system bested other conventional shields available commercially in terms of gamma and neutron radiation shielding effectiveness. [Display omitted] • BiTe-40 glass exhibited maximum density value of 5.0875 g/cm3. • SPR peak of Bi vanished due to CeO 2 , reducing the melting temperature to 1100 °C. • Weaker Te–O bonds increased the brittleness of high tellurium glasses. • BiTe-40 is best ϒ-ray shielding glass with high Z eff and low EBF for energy < 1.5 MeV. • BiTe-10 glass gave highest FNRCS value of 0.1012 cm−1 compared to other glasses. [ABSTRACT FROM AUTHOR]

Epoxy nanocomposites were synthesized in the presence of hydroxyapatite with the aid of an ultrasonicator. In general, as the amount of hydroxyapatite increased from 0wt% to 10wt%, the mechanical properties of the hydroxyapatite-containing nanocomposite were enhanced. The mechanical properties of the nanocomposite were significantly enhanced by the simple addition of 10 wt% of hydroxyapatite. Specifically, the storage modulus of the 10 wt% hydroxyapatite-containing nanocompsote was 3.2GPa, which is 46% higher compared to that of the pristine epoxy nanocomposite. The glass transition temperature of hydroxyapatite-containing nanocomposites generally decreased by few degrees in Celsius. To investigate the effect of additives on the mechanical properties of the epoxy-based nanocomposite, nanocomposites were synthesized using both montmorillonite and tellurium dioxide instead of hydroxyapatite. Intrestingly, both additive-based nanocomposite materials resulted in an increase in the storage modulus while the glass transition temperature decreased. These results demonstrate that the addition of few wt% of all three additives (hydroxyapatite, montmorillonite, and tellurium dioxide) can enhance the mechanical properties of epoxy-based nanocomposites. [ABSTRACT FROM AUTHOR]

Thin films of Tellurium dioxide (TeO2) were investigated for γ-radiation dosimetry purposes. Samples were fabricated using thin film vapour deposition technique. Thin films of TeO2 were exposed to a 60Co γ-radiation source at a dose rate of 6 Gy/min at room temperature. Absorption spectra for TeO2 films were recorded and the values of the optical band gap and energies of the localized states for as-deposited and γ-irradiated samples were calculated. It was found that the optical band gap values were decreased as the radiation dose was increased. Samples with electrical contacts having a planar structure showed a linear increase in current values with the increase in radiation dose up to a certain dose level. The observed changes in both the optical and the electrical properties suggest that TeO2 thin film may be considered as an effective material for room temperature real time γ-radiation dosimetry.

The effects of gamma irradiation of various levels on the current-voltage characteristics for the (In2O3)0.1 (TeO2)0.9 thin films, prepared by thermal evaporation in vacuum, have been studied in detail. The current increases linearly with the gamma radiation dose up to certain dose and decreases thereafter. The sensitivity of these thin films, at different applied voltages in the range 0-4.8 V, has been found to be in the range 35-190 mA/cm2/Gy. Correspondingly, the minimum measurable dose has been found to be in the range 0.05-0.26 mGy. The values of the sensitivity are reasonably high in comparison to the commercially available gamma radiation dosimeters, revealing high scope for further developments. [ABSTRACT FROM AUTHOR]

The present article describes the development of an indigenous technology for large scale production of I based on the neutron irradiation of TeO target followed by the separation of I using dry distillation technique. In one batch, typically 180 g of natural TeO was irradiated for a period of 21 days in a thermal neutron flux of ~5 × 10 n cm s, which after chemical processing provided ~1.85 TBq (50 Ci) of I. The suitability of I for medical application was evaluated scrupulously in order to ensure compliance with stipulated pharmacopoeia requirement. [ABSTRACT FROM AUTHOR]