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The annealing treatment plays a crucial role in tailoring the properties of synthetic diamond materials, especially those doped with various elements in order to form specific color centers like nitrogen-vacancy (NV), silicon-vacancy (Si-V), germanium-vacancy (Ge-V), etc. This study delves into the annealing of 175 μm-thick Ge-doped polycrystalline diamond (PCD) films grown by microwave plasma-assisted chemical vapor deposition (MPCVD). Large-area PCD plate was cut into smaller equivalent 5 × 5 mm2 pieces, which were separately subjected to annealing in microwave plasma in H 2 atmosphere, to annealing in vacuum or to annealing under high-pressure high-temperature conditions (HPHT, 5.9 GPa, 2000 °C). The structure, phase composition and photoluminescence (PL) of samples before and after various annealing processes were investigated. All applied types of annealing enhance both the Si-V and Ge-V lines in PL at room temperature. Increasing annealing temperature leads to gradual decrease of full widths at half-maxima (FWHM) of diamond Raman peak (1332.5 cm−1), as well as Si-V (738 nm) and Ge-V (602 nm) PL peaks. In addition, the limitations for each type of annealing are established. The obtained results are crucial for the design of CVD-grown Ge-doped and Si-doped PCD materials that can be used for applications in photonics such as single photon sources, biomarkers, as well as for the fabrication of optical diamond thermometers. [Display omitted] • Ge-doped PCD film was grown by MPCVD and cut into series of equivalent samples. • Different samples were subjected to different types of annealing: in H 2 plasma, in vacuum, and in HPHT conditions. • The annealing resulted in lowering FWHM of Raman, XRD and PL peaks of samples. [ABSTRACT FROM AUTHOR]

Boron doped diamond (BDD) has been widely used in various electrochemical fields, due to its unique physical and chemical properties. However, the investigation of the electrochemistry of bi-element incorporated diamond, especially the variation of surface components after nitrogen incorporation into BDD and the corresponding electron transfer of inner-sphere and outer-sphere redox probes is still lacking. Here, the electrochemistry of nitrogen and boron bi-element incorporated diamond (NBD) is thus investigated in both inner and outer redox systems, namely in [Fe(CN) 6 ]3-/4- and [Ru(NH 3) 6 ]3+/2+ solutions. On the NBD electrode, enhanced electrochemical responses are achieved for both outer- and inner-sphere redox reactions. Such enhancement originates from the enrichment of C O groups and the increased amount of sp2 species in the NBD film. Moreover, the nitrogen and boron atoms incorporated in diamond modulate the surface polarities and the electronic states of diamond. Based on the enhanced and stable capacitance of the NBD electrode, its electrochemical energy applications are explored by assembling its supercapacitor as a case study. This work reveals the influence of sp2 species and oxygen-contained function group on the electrochemistry of bi-element incorporated diamond films and reveals their potential electrochemical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

A series of Dy3+ doped aluminoborosilicate glasses with general formula 20SiO 2 -(40-x) B 2 O 3 –10Al 2 O 3 –20NaF 2 –10ZnO-xDy 2 O 3 (x = 0, 0.1, 0.5, 1.0. 1.5, 2.0 and 2.5 mol %) were prepared by melt-quenching method. The FTIR analysis confirms the presence of stretching and bending vibrations of BO 4 , BO 3 and SiO 4 units in the prepared glasses. DTA results show that Tg is decreasing with addition of Dy3+ ions in the glass system. Theoretically calculated mechanical properties such as elastic modulus, bulk modulus, shear modulus and Poisson's ratio suggest the increase in mechanical stability of glasses with dysprosium addition. Also experimental analysis carried out using Vicker's microhardness suggests glass stability with applied loads. Absorption spectrum shows twelve bands that exist due to transition from 6H 15/2 level to different excited levels. Nephelauxetic ratio and bonding parameter calculated shows decreasing ionicity of glasses with increase in Dy3+ ions. Judd-Oflet parameter calculated for all the glasses follow the trend Ω 6 > Ω 4 > Ω 4. Luminescence study shows three emission peaks having transitions from 4F 9/2 → 6H 15/2 (blue), 4F 9/2 → 6H 13/2 (yellow) and 4F 9/2 → 6H 11/2 (red). Radiative parameters calculated suggest higher stimulated emission cross-section for present glasses having 4F 9/2 → 6H 13/2 transition. The decay measurement for all the glass samples were recorded with an excitation at 350 nm and monitoring emission at 575 nm corresponding to the 4F 9/2 → 6H 13/2 transition and decay curves were fitted to bi-exponential fit. The CIE colour chromaticity coordinates were determined using CIE chromaticity diagram and the values were found to be in close proximity with the standard white light (0.33. 0.33) for all the glasses. Further colour correlated temperature values were found to lie in the near bright white region with CCT around ~4000 K. • Various concentrations of Dy3+-doped SiO 2 –B 2 O 3 –Al 2 O 3 –NaF–ZnO glasses were synthesized. • Mechanical properties of these glasses were studied along with experimental analysis. • Optical bandgap and Urbach energy of these glasses were calculated. • Energy transfer mechanism and radiative parameters were studied. • All Dy3+- doped glasses CIE (x, y), and CCT values represent the bright white light region. [ABSTRACT FROM AUTHOR]

Transparent 10BaO-20ZnO-20LiF-(50- x) B 2 O 3 - x Er 2 O 3 glasses with x = 0, 0.1, 0.5, 0.7 and 1 mol % were synthesized using melt-quench method. Their amorphous nature was confirmed from X-Ray Diffraction (XRD). The glasses were irradiated with 3 kGy gamma dose, among which the sample with 0.7 mol % Er 2 O 3 doping showed the highest integrated thermoluminescence (TL) intensity. The dose-response was evaluated by irradiating the sample with 0.25- 30 kGy gamma doses. The highest integrated TL intensity was obtained at 3 kGy dose. Fourier Transform Infrared (FTIR) spectra of the 0.7 mol % Er 2 O 3 doped glass after 3 kGy gamma irradiation predicted the creation of new bonds and rise in the Non-Bridging Oxygens. UV–Vis–NIR absorption spectra recorded after 3 kGy gamma irradiation accounted for the formation of color centers due to an increase in the total absorption of the glass, a decrease in the bandgap and an increase in the Urbach energy. The sample exhibited good linearity in the 0.25 to 3 kGy range with high sensitivity of 27021 counts g-1kGy-1 and a minimum detectable dose of 0.201 kGy. TL signal faded by just 4% after a week of storage. The annealing condition for reusability and the effective atomic number of the glass were examined. Trap parameters like activation energy, frequency factor and lifetime, determined using Computerized Glow Curve Deconvolution (CGCD) and Chen's peak shape methods supported the low fading of the sample. Overall, the remarkable TL dosimetry characteristics present the usefulness of the titled glass system in radiation processing of food products and high-dose (0.25 to 3 kGy) gamma environment. [ABSTRACT FROM AUTHOR]

Continuous mode delivery of medical oxygen from oxygen concentrators and oxygen cylinders leads to wastage of precious medical oxygen during exhalation and rest phases of the respiratory cycle. Pulse mode oxygen delivery can address the stated problem, however, it is required to determine the number of oxygen release pulses and the exact instant of inhalation or exhalation. Herein we report the design and development of an intelligent pulsed mode respiratory device- "RESPIPulse," which is capable of delivering oxygen bolus by automatically sensing the inhalation and exhalation instances from body mount surface electromyography (sEMG) electrodes without manual intervention or settings. The device comprises a set of miniature single-channel sEMG electrodes, an embedded machine-learning algorithm, a normally open solenoid valve, an airflow sensor, and necessary driving electronics. The solenoid valve opens or closes depending on the muscular inhalation or exhalation effort determined from the sEMG signals, thus preventing the wastage of respiratory oxygen. The sEMG signals are subjected to envelop extraction followed by feature extraction. Performances of k-nearest neighbor (kNN), support vector regression (SVR), and random forests (RF) regressors are initially tested in Python IDE to identify the best learning algorithm that is deployed in the microcontroller for determination of the instances of inhalation and exhalation. Trials are conducted on 20 healthy subjects and 10 dyspnea-affected patients. Based on the computed performance measures and evaluation time, the kNN algorithm estimates the respiratory instances more accurately than the other two algorithms. A significant amount of oxygen savings, ranging between 35.48–82.35%, is obtained using the RESPIPulse device which is much higher than the pulse mode delivery devices employing manual settings exhibiting maximum conservation of 48.2%. [Display omitted] • Automated pulsed mode oxygen delivery device based on sEMG and airflow is developed. • The device can save up to 82% of medical oxygen. • The device acts as oxygen conservation system. [ABSTRACT FROM AUTHOR]

Diamond-based X-ray luminescent composites are robust materials to be used in synchrotrons and free-electron lasers to detect and visualize high-intensity X-ray beams. Such composites consist of luminescent rare-earth (RE) particles embedded into an X-ray transparent diamond matrix. In this work, polycrystalline diamond composites with embedded particles of EuF 3 , SrF 2 :Eu and YAG:Ce were grown by microwave plasma CVD using diamond seeds with an average particle size difference of two orders of magnitude: from 5 nm up to 500 nm, with positive and negative zeta potentials. The structure, phase composition, and luminescent characteristics of the resulting composite films were investigated and analyzed. We found that various particle types can be better-suited for different composites, and the exact seeding should be selected on the case-by-case basis. The direct comparison of various diamond-based composites, grown in the identical CVD conditions but with various luminescent powders, show that YAG:Ce particles in diamond allow achieving a brighter photoluminescence (PL) in comparison to Eu-based fluorides. However, the set of fluoride powders doped with Eu3+ ions allow obtaining unusually narrow (FWHM = 0.9 nm) and intensive line near 611 nm in PL spectra, which might be better-suited for detection and characterization applications rather than a broad peak of Ce with FWHM ≈ 120 nm. [Display omitted] [ABSTRACT FROM AUTHOR]

The impact of plasma inhomogeneity on the sp 2 content of thin film (∼micron) boron doped diamond (BDD) electrodes, grown using microwave chemical vapour deposition (MW-CVD) under different methane (CH 4 ) concentrations (1% and 5%), is investigated. The sp 2 surface content (critical for interpreting electrochemical data) is comparatively assessed using a variety of electrochemical measurements: capacitance; solvent window analysis and quinone surface coverage. For all growths, distinctive regions containing appreciably differing amounts of sp 2 carbon are identified, across the wafer. For example, on the 1% CH 4 wafer, some areas exhibit electrochemical signatures indicative of high quality, minimal sp 2 content BDD, whereas others show regions comprising significant sp 2 carbon. Note Raman microscopy was unable to identify these variations. On the 5% CH 4 wafer, no region was found to contain minimal levels of sp 2 carbon. Changes in sp 2 content across the BDD films indicates spatial variations in parameters such as temperature, methane and atomic hydrogen concentrations during growth, in this case linked directly to the use of a commonly employed multi-moded (overmoded) chamber for MW-CVD BDD synthesis, operated under low power density conditions. Varying sp 2 levels can have significant impact on the resulting electrochemical behaviour of the BDD. [ABSTRACT FROM AUTHOR]

• AuNPs-rGO@3-D printed Ag electrodes as enzyme free blood urea sensor. • PoC handheld device for instant urea quantification in human blood. • Sensor response current 5 times higher, high sensitivity of 183 µA/mM/cm2. • Plausible reaction mechanism for urea oxidation is reported. Herein we report a novel electrochemical sensing chip and a point-of-care device (PoC) for enzyme-free electrochemical detection of urea in human blood. The electrochemical sensing chip was developed by 3-D printing of conductive Ag ink and subsequent electrodeposition of AuNP-rGO nanocomposite. Material characterization of the sensing chip was conducted to find a plausible mechanism for the electrochemical reaction with urea. Subsequently, the response with varying concentrations of urea in solution and human blood samples was tested. High peak response current (~5 times than that of the highest reported value), low impedance, rapid sensor fabrication procedure, high selectivity towards urea, excellent linear response (R2 = 0.99), high sensitivity of 183 μA mM−1 cm−2, the fast response indicated by high diffusion coefficient, the limit of detection of 0.1 µM, tested shelf life of more than 6 months and recovery rate of >99% ensured the application of the developed sensor chip towards PoC urea detection test kit. A PoC device housing an electronic circuitry following the principles of linear sweep voltammetry and compatible with a sensing chip was developed. A maximum percentage error of 4.86% and maximum RSD of 3.63% confirmed the use of the PoC device for rapid urea measurements in human blood. [ABSTRACT FROM AUTHOR]

• LA works as eco-friendly corrosion inhibitor to mitigate corrosion of steel rebar. • LA adsorbed through the formation of Zwitterion-Cl-Fe complex onto steel rebar. • 0.115 M LA with 0.17 M NaCl in pore solution performed excellent. • LA remains in the passive film which protect the steel rebar from corrosion. • Schematic shows the adsorption of inhibitor molecules onto the steel rebar surface. In the present study, different amounts of L-arginine (LA) i.e. Zwitterion have been used as an eco-friendly corrosion inhibitor to study its effect on the mitigation of the steel rebars corrosion in 0.17 M NaCl added simulated concrete pore (SP) solution. Potentiodynamic polarization, open circuit potential (OCP), and electrochemical impedance spectroscopy (EIS) have been used to understand the corrosion kinetics and mechanism for the formation of passive film at steel rebar/solution interface with exposure periods. The characterization of passive films after 144 h of exposures were performed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Cl− ions help in the formation of Zwitterion-(Cl)-Fe complex in the presence of LA containing solution which led to stabilize the passive film resulting improvement in polarization resistance (R p). The steel rebar exposed to 0.115 M LA containing SP + 0.17 M NaCl solution exhibited around 96% inhibition efficiency after 144 h of exposure. Raman spectroscopy of passive film reveals adsorption of LA and formation of goethite and maghemite. A schematic has been proposed to derive the adsorption mechanism of LA in the presence of Cl− ions and form Zwitterion-(Cl)-Fe complex, therefore, enhanced corrosion resistance was observed. [ABSTRACT FROM AUTHOR]

Multi-layered polycrystalline diamond (PCD) films were synthesized using microwave plasma-assisted chemical vapor deposition (CVD) with periodical addition (injections) of N 2 gas to the standard CH 4 -H 2 gas mixture. The aim of such an approach was to reduce the roughness of the films while preserving the overall high quality and phase purity of the PCD material. The thicknesses of the films were in the range of 5 to 51 μm, while the number of layers was from 1 to 15. The introduction of even the smallest amount of nitrogen leads to a significant (more than 2-fold) increase in the growth rate of PCD films. Optimized injection regimes allowed the reduction of the relative roughness (S q /thickness) of the PCD films by more than 3 times in comparison with standard microcrystalline diamond film grown under similar conditions without N 2 addition. The proposed method of periodic injection of N 2 during growth restricted the formation of continuous NCD layers, which improved the overall sp3/sp2 ratio in comparison with standard multi-layered MCD/NCD materials. The obtained multi-layered PCD materials with reduced roughness may be used for the formation of protective and hard covers, optical coatings, electrochemical and thermal management applications. The multi-layered PCD films were synthesized in a microwave plasma CVD in regimes with short-term periodic N 2 injections in CH 4 -H 2 process gas; the average growth rate is doubled owing to the pulsed nitrogen injection, while the surface roughness is reduced by more than 3 times in comparison with a standard (no N 2 injection) microcrystalline film. [Display omitted] • Multi-layered PCD films are grown by microwave plasma CVD with short-term periodic N 2 injections. • Surface roughness is reduced by 3 times in comparison with a standard single-layer film. • Average growth rate is doubled owing to the pulsed nitrogen injection. [ABSTRACT FROM AUTHOR]

• Broad absorption band observed around 465nm was due to Surface Plasmon Resonance (SPR), responsible for dark brown colour of Bi added samples • There was drastic decrease in MAC and Z eff values in the lower gamma energy range (0.015-3 MeV) because of dominance of the PE absorption process • MAC graph had K-absorption edges due to Bi3+ and Ba2+ ions at 0.1 MeV and 0.04 MeV • Bi-15 sample exhibited lowest HVL, TVL and MFP among the fabricated glasses, indicating the minimum thickness requirement for shielding ϒ-rays. • TL intensity dropped on adding Bi 2 O 3 (5 mol%) to the network initially and on further addition (10 mol%) there was rise in the intensity. Image, graphical abstract With the main intention of developing a transparent radiation shielding as well as a gamma dosimetric material, a series a heavy metal oxide borosilicate glass of composition (60-x) B 2 O 3 - 20SiO 2 - xBi 2 O 3 - 10ZnO- 10BaO with x = 0, 5, 10, 15 mol% was prepared by melt- quench technique. The glasses obtained were all transparent, except Bi-15 sample which is opaque and black in colour. The darkening is due to thermal reduction of Bi3+ ions, which is clearly indicated by absorption band around 377nm. XRD patterns showed the absence of crystalline peaks even in the opaque Bi-15 sample, confirming the glassy nature of all glasses. Furthermore, the structural changes in the glasses were confirmed with density measurement and FTIR studies. The Vickers hardness test done on transparent samples proved their higher mechanical strength, along with the theoretical calculation of elastic constants. The detailed analysis of gamma and neutron radiation shielding parameters for all the glasses was done using Photon Shielding and Dosimetry (PSD) software. The results suggested that the ϒ-ray shielding capacity increased, whereas the neutron attenuation ability decreased with the successive addition of Bi 2 O 3. The opacity of Bi-15 can create problem in certain applications where transparency is needed. In order to assess the possibility of transparent glasses to be used as gamma dosimeter, they were irradiated with gamma rays of 1.25 MeV and thermoluminescence (TL) glow curves were recorded. An interesting behaviour of quenching of TL intensity for initial addition and enhancement of TL intensity for further addition of Bi 2 O 3 was observed. The linearity of the dose- response curve for Bi-10 sample in two regions of gamma doses 100 Gy-3 kGy and 5- 50 kGy, showcased the chances of Bi-10 sample to be used as TL dosimeter for both low and high doses. [ABSTRACT FROM AUTHOR]

Color centers are promising single-photon emitters owing to their operation at room temperature and high photostability. In particular, using nanodiamonds as a host material is of interest for sensing and metrology. Furthermore, being a solid-state system allows for incorporation to photonic systems to tune both the emission intensity and photoluminescence spectrum and therefore adapt the individual color center to desired properties. We show successful coupling of a single nanodiamond hosting silicon-vacancy color centers to a plasmonic double bowtie antenna structure. To predict the spectrum of the coupled system, the photoluminescence spectrum of the SiV centers was measured before the coupling process and convoluted with the antenna resonance spectrum. After transferring the nanodiamond to the antenna the combined spectrum was measured again. The measurement agrees well with the calculated prediction of the coupled system and therefore confirms successful coupling., (Creative Commons Attribution license.)

Peripheral ameloblastoma is a rare, benign, slow-growing odontogenic neoplasm prevalent in the mandible. It originates from the odontogenic epithelium and its remnants, and its histological characteristics are identical to those of intraosseous ameloblastoma. It is less aggressive and invasive than its intraosseous variety, with a low recurrence rate. This report vividly portrays a rare case of peripheral ameloblastoma in a young male patient, detailing its clinical and surgical presentation. It effectively underscores the importance of considering peripheral ameloblastoma in the differential diagnosis of exophytic gingival lesions., Competing Interests: Human subjects: Consent for treatment and open access publication was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Chattopadhyay et al.)

2D MXenes have been used as electrochemical sensor materials, but their output current signal remains weak in point of care (PoC) settings. To address this issue, here we report a novel MXene-supported cobalt-MOF-based nanocomposite, which is used with a carbon black (CB) ink and 3-D printed as the CoMOF-MXene@CB layered electrode structure for the development of a sensor electrode and a PoC chip for electrochemical detection of blood creatinine with an enhanced current range, specificity, and sensitivity. The limit of detection (LOD) and sensitivity of the fabricated sensor were found to be 0.005 μM and 1.1 μA μM -1 cm -2 , which are 44 times lower and 32 times enhanced, respectively, as compared to the existing literature report (LOD 0.22 μM and sensitivity 0.034 μA μM -1 ) for creatinine sensing in PoC settings. The sensor exhibited an excellent linear sensor response ranging from 10 to 800 μM and good reproducibility, stability, and selectivity with significant accuracy. These characteristics helped the sensor to accurately determine the creatinine levels in real human serum samples.

Micro-hotplate structures are increasingly being investigated for use in a host of applications ranging from broadband infra-red sources within absorption-based gas sensors to in situ heater stages for ultra-high-resolution imaging. With devices usually fabricated from a conductive electrode placed on top of a freestanding radiator element, coefficient of thermal expansion (CTE) mismatches between layers and electro-migration within the heating element typically lead to failure upon exceeding temperatures of 1600 K. In an attempt to mitigate such issues, a series of hotplates of varying geometry have been fabricated from a single layer of mechanically robust, high thermal conductivity, and low CTE boron-doped polycrystalline diamond. Upon testing under high vacuum conditions and characterization of the emission spectra, the resulting devices are shown to exhibit a grey-body like emission response and reach temperatures vastly in excess of conventional geometries of up to 2731 K at applied powers of ⩽100 mW. Characterization of the thermalization time meanwhile demonstrates rapid millisecond response times, while Raman spectroscopy reveals the performance of the devices is dictated by cumulative graphitization at elevated temperatures. As such, both diamond and sp 2 carbon are shown to be promising materials for the fabrication of next-generation micro-hotplates., (© 2023 The Authors. Small published by Wiley-VCH GmbH.)

The high thermal conductivity of polycrystalline diamond makes it ideally suited for thermal management solutions for gallium nitride (GaN) devices, with a diamond layer grown on an aluminum nitride (AlN) interlayer atop the GaN stack. However, this application is limited by the thermal barrier at the interface between diamond and substrate, which has been associated with the transition region formed in the initial phases of growth. In this work, in situ spectroscopic ellipsometry (SE) is employed to monitor early-stage microwave plasma-enhanced chemical vapor deposition diamond growth on AlN. An optical model was developed from ex situ spectra and applied to spectra taken in situ during growth. Coalescence of separate islands into a single film was marked by a reduction in bulk void fraction prior to a spike in sp 2 fraction due to grain boundary formation. Parameters determined by the SE model were corroborated using Raman spectroscopy and atomic force microscopy., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

We report the experimental evidence of the Imbert-Fedorov (IF) shift in monolayer M o S 2 for a fundamental Gaussian beam. Using Jones vector formalism, we have shown a novel, to the best of our knowledge, pathway to apply the quantum weak measurement technique for easy and accurate determination of the IF shift. We have revealed the dependence of IF shift over a large range of angles of incidence along with the mode of polarization of the incident light. Our experimental findings via the weak value amplification scheme are in good agreement with the theoretical analysis. The present method is a general one and can also be implemented for other materials to observe such tiny transverse shifts.

Lauric acid (LA) has been recommended as economic, eco-friendly, and commercially viable materials to be used as phase change materials (PCMs). Nevertheless, there is lack of optimized parameters to produce microencapsulated PCMs with good performance. In this study, different amounts of LA have been chosen as core materials while tetraethyl orthosilicate (TEOS) as the precursor solution to form silicon dioxide (SiO 2 ) shell. The pH of precursor solution was kept at 2.5 for all composition of microencapsulated LA. The synthesized microencapsulated LA/SiO 2 has been characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM). The SEM and TEM confirm the microencapsulation of LA with SiO 2 . Thermogravimetric analysis (TGA) revealed better thermal stability of microencapsulated LA/SiO 2 compared to pure LA. PCM with 50% LA i.e. LAPC-6 exhibited the highest encapsulation efficiency (96.50%) and encapsulation ratio (96.15%) through Differential scanning calorimetry (DSC) as well as good thermal reliability even after 30th cycle of heating and cooling process., (© 2021. The Author(s).)

This paper reports the crystallization kinetics of (Cu 60 Zr 25 Ti 15 ) 99.3 Nb 0.7 bulk metallic glass under isothermal conditions. Differential scanning calorimetry (DSC) has been employed for isothermal annealing at ten different temperatures prior to the onset of crystallization (T o ) temperature. X-ray diffraction and transmission electron microscopy have been used to confirm the amorphous structure of the as cast sample. Crystallized volume fractions (x) are calculated from the exothermic peaks of DSC scans. Crystallized volume fractions (x) against time show sigmoidal type of curves as well as the curves become steeper at higher annealing temperatures. Continuous heating transformation diagram has been simulated to understand the stability of the bulk metallic glass. Crystallization kinetics parameters are calculated using Arrhenius and Johnson-Mehl-Avrami equations. Activation energy (E a ) and Avrami exponential factor (n) have exhibited strong correlation with crystallized volume fraction (x). The average activation energy for isothermal crystallization is found to be 330 ± 30 kJ/mol by Arrhenius equation. Nucleation activation energy (E nucleation ) is found to be higher than that of growth activation energy (E growth ). The Avrami exponential factor (n) indicates about the diffusion controlled mechanism of the nucleation and three-dimensional growth.

Microwave dielectric loss tangent measurements are demonstrated as a method for quantifying trace sp 2 -hybridized carbon impurities in sub-micron diamond powders. Appropriate test samples are prepared by vacuum annealing at temperatures from 600 to 1200 °C to vary the sp 2 /sp 3 carbon ratio through partial surface graphitization. Microwave permittivity measurements are compared with those obtained using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and electron energy loss spectroscopy (EELS). The average particle size remains constant (verified by scanning electron microscopy) to decouple any geometric dielectric effects from the microwave measurements. After annealing, a small increase in sp 2 carbon was identified from the XPS C 1s and Auger spectra, the EELS σ* peak in the C 1s spectra, and the D and G bands in Raman spectroscopy, although a quantifiable diamond to G-band peak ratio was unobtainable. Surface hydrogenation was also evidenced in the Raman and XPS O 1s data. Microwave cavity perturbation measurements show that the dielectric loss tangent increases with increasing sp 2 bonding, with the most pertinent finding being that these values correlate with other measurements and that trace concentrations of sp 2 carbon as small as 5% can be detected., Competing Interests: The authors declare no competing financial interest.

With the retention of many of the unrivaled properties of bulk diamond but in thin-film form, nanocrystalline diamond (NCD) has applications ranging from micro-/nano-electromechanical systems to tribological coatings. However, with Young's modulus, transparency, and thermal conductivity of films all dependent on the grain size and nondiamond content, compositional and structural analysis of the initial stages of diamond growth is required to optimize growth. Spectroscopic ellipsometry (SE) has therefore been applied to the characterization of 25-75 nm thick NCD samples atop nanodiamond-seeded silicon with a clear distinction between the nucleation and bulk growth regimes discernable. The resulting presence of an interfacial carbide and peak in nondiamond carbon content upon coalescence is correlated with Raman spectroscopy, whereas the surface roughness and microstructure are in accordance with values provided by atomic force microscopy. As such, SE is demonstrated to be a powerful technique for the characterization of the initial stages of growth and hence the optimization of seeding and nucleation within films to yield high-quality NCD., Competing Interests: The authors declare no competing financial interest.