Diamond Research Articles

A theoretical comparison of silicon and diamond in microdosimetry

Silicon and diamond are regarded as promising solid-state detectors for microdosimetry and have attracted considerable attention in recent years. However, their performance is slightly different due to the difference in physical qualities. In this work, we intend to compare their performance in microdosimetry theoretically from the aspect of tissue equivalence and electronic properties. The tissue equivalence study has shown that diamond exhibits better tissue equivalence than silicon due to the approximation of mean ionization/excitation potential to tissue. And the tissue equivalence of silicon is acceptable when the incident energy is low. In electronic properties comparison, the results indicate that the collection time in the diamond is shorter than that in silicon when aligned in the same configuration, and the current signal induced in CVD diamond is higher than in silicon at low electric fields. The current in natural diamond is greater than silicon at the low electric field only when the energy deposited in silicon and diamond is different. Since the microdosimeter is usually performed at low electric fields in microdosimetry to ensure low electronic noise, the electronic properties of high-quality CVD diamond are superior to silicon for microdosimetry applications. It seems that diamond, especially high-quality CVD diamond, exhibits better tissue equivalence and electronic properties than silicon in microdosimetry.

A Whale Tale

A Whale Tale Allegra Hyde (bio) The whale was already dead when it washed ashore. A massive sperm whale, its skin leathery and barnacled, its narrow jaw strutted with teeth. The whole town went down to the beach to see it: mothers and firefighters and stay-at-home dads and dead-beat dads and vacuum cleaner salespeople and endometriologists and dowagers and women of the night and diamond miners and fortune tellers and personal trainers. Children were bussed in from school. Prisoners from prison. Altogether, the townspeople encircled the creature, reaching forward to touch its gray-blue skin. People wept. People waved flags. People complained about not being able to barbecue because of health ordinances. More than anything, people wondered how the whale had died. A coroner-for-whales was summoned to conduct an autopsy. She began to cut the whale open right there on the beach, excavating through layers of blubber. Because it had taken her so long to arrive, however, and because it had started drizzling—and also because the work was gruesome—almost everyone went home before the procedure was complete. Everyone except for a few diehard protesters, local news reporters, police officers, orphans, and a man named Anders. Anders did not usually attend public spectacles such as this. He had merely been driving by on his way home from his job at a nonprofit for bicycle safety. He had ventured onto the beach because of the crowds and had stayed because of the whale. Or, more truthfully: Anders had stayed because it meant he could delay going home. And if he delayed going home, then he could delay returning to his longtime lover, Florian. And if he delayed returning to Florian, he could delay doing what he had promised himself he would do—which was end their relationship. The coroner-for-whales went about her work. She used a special saw to cut into the creature’s vast flank. She was aiming for its stomach, she told onlookers. She was getting close. Like everyone in the crowd, [End Page 44] Anders drew an anticipatory breath, though the sight of the whale disturbed him. Fins motionless. Glassy eyes staring at nothing. The bigness of the animal—the deadness of it, too—put a stone in his gut. Hard and round and heavy, the stone gave Anders the sinking sensation of foreboding. Or else: the foreboding came from what he planned to do when he got home. Anders loved Florian—or had loved him, early on in their seven-year relationship. Florian, who was all sparkles and beauty. Florian, with his sandy hair and sea-glass eyes. Florian, who was the son of a local witch/naturopath, who could whistle like the wind singing through trees, and who had at one time taken Anders’s breath away, but now took all of Anders’s money and time and energy, and who refused to get a job. “And we’re in!” The coroner tossed her saw aside and extended a gloved arm into the cavernous opening of the whale’s stomach. Anders felt the stone in his gut grow heavier. He had no business watching this creature be disemboweled. But his relationship with Florian was over—needed to be over—and he couldn’t yet bear to admit this to Florian’s face. So he pushed through the crowd to see what made the others yelp with surprise. The whale’s stomach was bursting with stuff. Human stuff. A wide-screen television. A wooden bed frame. Woolen socks, both matched and unmatched. Plastic fruit. A two-slice toaster. Several doilies—or so Anders guessed. Some items were hard to identify, covered as they were with the whale’s stomach slime. Next came a corduroy-upholstered couch. A set of collectible spoons from Midwest states. A rolltop desk. A pair of roller skates—which made Anders lean closer, since the skates were similar to a pair he’d just purchased. The couch, too, reminded him of the couch he owned, which he’d believed to be one of a kind. People grabbed items, inspected them, expressed their dismay and confusion. A reporter waved aloft a photo frame containing a...

Grassroots Research on Local Diamond Mining Impact Project

Grassroots Research on Local Diamond Mining Impact Project

Natural Diamond Council Report on Education in Retail Settings

Natural Diamond Council Report on Education in Retail Settings

Efficiency of ultrasonic burnishing effect on microhardness and microprofile of gate valve wedge surface made by SLM method of EOS PH-1 powder steel

To increase the wear resistance of the flat surfaces of the wedge of the DN20 PN160 gate valve made of EOS PH-1 stainless steel powder with a particle size from 20 to 50 μm by selective laser melting (SLM) on the EOSINT M280 machine, we studied the effect of post-processing by ultrasonic burnishing on the ULTRASONIC 20 machine with a tool with a natural diamond tip with a radius of 2 mm, oscillating with a frequency of 35 kHz and moving with a linear speed of 10 m/min under loading conditions with a static force of 400 N. We found that at feed rates of 0.04...0.08 mm/pass the greatest hardening of steel by 11—13 % relative to the initial microhardness of 430 HV0.05 before post-processing occurs at depths from 60 to 300 μm. Increasing the feed rate to 0.12 mm/pass ensures the formation of the maximum hardened zone in a thin surface layer with a microhardness of 489...502 HV 0.05 at a depth of 20 to 100 μm. Further increasing the feed rate to 0.2 mm/pass leads to a significant reduction to 440 HV 0.05 and microhardness instability at depths greater than 100 μm. The minimum value of the roughness parameters occurs at a feed rate of 0.06 mm/pass and is Ra = 57.67 nm. If we increase the feed rate to 0.12 mm/pass, the roughness increases to Ra = 176.44 nm and stabilizes at feed rates of 0.16 and 0.2 mm/pass. We plotted the Abbott-Firestone curves and histograms of the distribution of the wedge surface microprofile heights after post-processing at the investigated tool feed rates.

Izbor reagensa za modifikaciju spektralnih karakteristika slabo i anomalno luminescentnih dijamanata u procesu rendgenske separacije

The feasibility of targeted modification of the spectral properties of weakly and anomalously luminescent diamonds by modifying reagents containing luminophores based on sulfides and zinc orthosilicate, characterized by medium and low deviation of the luminescence signal from that of natural diamond. It was found that the hydrophobic treatment of inorganic luminophores with potassium butyl xanthate could increase the recovery of anomalous luminescent diamonds in the process of X-ray luminescence separation up to 80%. Organic collectors (optically transparent oil products with high extractability for luminophores and adhesion to diamonds) based on technical-grade diesel fuel and catalytically cracked heavy gas oil are recommended for the luminophorecontaining compositions. The feasibility of reducing the fixation of luminophores on the surface of kimberlite grains using sodium hexametaphosphate, sulfonol, carboxymethylcellulose and liquid glass was demonstrated. The application of these reagents in low-salinity water provides decreasing coating of kimberlite grains with luminophores while maintaining the required concentration of luminophores on the surface of diamonds. Semi-industrial tests with an LS-D-4-03N separator proved the possibility of complete recovery of weakly and anomalously luminescent diamonds after treatment of XRS tailings with the modifying reagents.

Increase of Wear and Heat Resistance of the AISI 304 Steel Surface Layer by Multi-Pass Nanostructuring Burnishing

The paper presents the results of experimental studies of the AISI 304 steel disc surface after finishing turning, electropolishing and nanostructuring burnishing after one and five passes of the tool with a natural diamond tip with a radius of 2 mm. It is shown that surface layer nanocrystallization provides for almost complete decomposition of austenite in a layer up to 100 µm thick, an increase in microhardness up to 400...450 HV0.025 and a 3.3-fold reduction in the wear intensity on hardened AISI 1045 steel under conditions of lubrication with industrial oil compared with electropolishing. The content of residual austenite in the surface layer is not more than 5% when the temperature rises to 400°C.

ODMR active bright sintered detonation nanodiamonds obtained without irradiation

We present the results of study the structure and composition of microcrystalline diamonds obtained by high-pressure high temperature sintering of detonation nanodiamond particles. Using optical detected magnetic resonance method, photoluminescence spectroscopy and Raman spectroscopy we found sintering of detonation nanodiamond significantly differ from initial detonation nanodiamonds and can be compared to high quality diamonds. Monocrystals of diamonds obtained by the method of oriented attachment have dimensions of up to tens of microns, possess the habitus of high-quality diamonds, and do not contain metal catalysts in the lattice structure. In those crystals, the presence of optically active nitrogen impurities in the crystal lattice is observed. In particular, there is a bright nitrogen-vacancy defects. They are characterized by optical detected magnetic resonance method, which shows that spin properties of the obtained single crystals correspond to high-quality natural diamonds and surpass synthetic diamonds obtained from graphite in the presence of metal catalysts, followed by irradiation and annealing to obtain nitrogen-vacancy defects optical defects in the diamond lattice. The presence of nitrogen-vacancy defects defects and the high-quality of the crystal structure of sintering of detonation nanodiamond allows us to consider them as potential candidates in quantum magnetometry. For this purpose, the possibility of a simple way to improve the AFM probe by fixing a microcrystalline sintering of detonation nanodiamond particle on its tip is demonstrated. Keywords: detonation nanodiamond, HPHT sintering, ODMR, single crystalline, photoluminescence, defects.

"Stealth Scripts": Ultrashort Pulse Laser Luminescent Microscale Encoding of Bulk Diamonds via Ultrafast Multi-Scale Atomistic Structural Transformations.

The ultrashort-laser photoexcitation and structural modification of buried atomistic optical impurity centers in crystalline diamonds are the key enabling processes in the fabrication of ultrasensitive robust spectroscopic probes of electrical, magnetic, stress, temperature fields, and single-photon nanophotonic devices, as well as in "stealth" luminescent nano/microscale encoding in natural diamonds for their commercial tracing. Despite recent remarkable advances in ultrashort-laser predetermined generation of primitive optical centers in diamonds even on the single-center level, the underlying multi-scale basic processes, rather similar to other semiconductors and dielectrics, are almost uncovered due to the multitude of the involved multi-scale ultrafast and spatially inhomogeneous optical, electronic, thermal, and structural elementary events. We enlighten non-linear wavelength-, polarization-, intensity-, pulsewidth-, and focusing-dependent photoexcitation and energy deposition mechanisms in diamonds, coupled to the propagation of ultrashort laser pulses and ultrafast off-focus energy transport by electron-hole plasma, transient plasma- and hot-phonon-induced stress generation and the resulting variety of diverse structural atomistic modifications in the diamond lattice. Our findings pave the way for new forthcoming groundbreaking experiments and comprehensive enlightening two-temperature and/or atomistic modeling both in diamonds and other semiconductor/dielectric materials, as well as innovative technological breakthroughs in the field of single-photon source fabrication and "stealth" luminescent nano/microencoding in bulk diamonds for their commercial tracing.

The Prospecting Value of the Fractional Granulometric Analysis in the Study of Diamond-Bearing Placers

The article presents the novel data of fractional granulometric testing on the Syuzevskaya diamond placer located in the northern part of the Chikman-Nyar depression. The geological section was studied to a depth of 42,0 m. 18 samples weighing up to 200 kg each were taken, selected sectionally at two-meter intervals and graded into 10 granulometric classes on the gamma-Baturin scale. The obtained results have important search value: 1) the curve of the debris distribution by size is typical for the mature alluvium of the foothill river; 2) the paleo river alluvium is formed by a high dynamics flow and is fairly well sorted by size, which is a favorable sign for the concentration of large diamonds and indicates a slight dilution with non-diamond-bearing detrital material; 3) the presence of a typical mature alluvium in the paleovally indicates a long time of its existence, which is also a favorable search sign for industrial diamond placers. The methodology and results of the study can be used at various stages of the exploration cycle for placer minerals, including diamonds, all over the world.

Experimental Study of Sulfur Solubility in Ca–Mg Carbonate Melt under P–T Parameters of Lithospheric Mantle

Abstract —Modeling the compositions, properties, and conditions of generation of natural agents of mantle metasomatism is one of the most topical subjects in experimental petrology. Particular attention is paid to the study of C- and S-bearing metasomatic agents and their role in the global carbon and sulfur cycles and in the processes of natural diamond formation. Experimental studies aimed at the estimation of sulfur solubility in carbonate melts under lithospheric mantle conditions were carried out on a multianvil high-pressure apparatus of the “split-sphere” type (BARS) in the carbonate–sulfur ((Mg,Ca)CO3–S) and carbonate–pyrite ((Mg,Ca)CO3–FeS2) systems at 6.3 GPa and 1050–1550 °C for 20–60 h. It has been experimentally established that the main processes occurring in the carbonate–sulfur system are the recrystallization of carbonate in a sulfur melt (1050–1350 °C) and the generation of a high-calcium carbonate melt with dissolved sulfur (5.0–6.5 wt.%) (1450–1550 °C) as well as graphite recrystallization and the initial stage of diamond growth (1550 °C) in this melt. The work demonstrates that the carbonate–pyrite interaction is accompanied by the recrystallization of carbonates and pyrite (1050–1250 °C) and the generation of two immiscible melts (sulfide one with dissolved oxygen and carbonate one with dissolved sulfur (1.7–2.5 wt.%) (1350–1550 °C)) along with the formation of graphite and the growth of diamond on seed crystals (1550 °C). It has been found that the solubility of sulfur in carbonate melts increases with temperature, which goes together with a decrease in CaO (±FeO) concentrations and an increase in MgO concentrations. The present study has shown for the first time that melts of alkaline-earth carbonates are capable of dissolving up to 6.5 wt.% sulfur and they are probable sulfur concentrators under the conditions of the lithospheric mantle.

Advanced Mapping of Optically-Blind and Optically-Active Nitrogen Chemical Impurities in Natural Diamonds

Natural diamonds with a rich variety of optically blind and optically active nitrogen impurity centers were explored at a nano/microscale on the surface and in bulk by a number of advanced chemical and structural analytical tools in order to achieve a comprehensive characterization by establishing enlightening links between their analysis results. First, novel compositional relationships were established between high-energy X-ray photoelectron spectroscopy (XPS) and low-energy Fourier-transform infrared vibrational spectroscopy (FT-IR) signals of nitrogen impurity defects acquired in the microscopy mode at the same positions of the diamond surface, indicating the verification XPS modality for qualitative and quantitative FT-IR analysis of high concentrations of nitrogen and other chemical impurity defects in diamond. Second, depth-dependent spatial distributions of diverse photoluminescence (PL)-active nitrogen defects were acquired in the confocal scanning mode in an octahedral diamond and then for the first time corrected to the related Raman signals of the carbon lattice to rule out artefacts of the confocal parameter and to reveal different micron-scale ontogenetic layers in the impurity distributions on its surface. Third, intriguing connections between local structural micro-scale defects (dislocation slip bands of plastic deformation zones) visualized by optical microscopy and Raman microspectroscopy, and related distributions of stress-sensitive PL-active nitrogen impurity defects in the proximity of these planes inside bulk diamonds were revealed. These findings demonstrate the broad instrumental opportunities for comprehensive in situ studies of the chemical, structural, and mechanical micro-features in diamonds, from the surface into bulk.

Historical diamond mine waste reveals carbon sequestration resource in kimberlite residue

Mined sub-aerially stored kimberlite provided a natural laboratory in which to examine the potential for carbon sequestration in ultramafic materials. A 15 cm hand sample of ∼50-year-old ‘cemented’ coarse residue deposit (CRD) collected from a cemented surface layer in the Cullinan Diamond Mine tailings in Gauteng, South Africa, demonstrated the encouraging effects of weathering on mineral carbonation of kimberlite. The examination of petrographic sections using light microscopy, X-ray fluorescence microscopy (XFM) and backscatter electron – energy dispersive spectroscopy demonstrated that weathering produced extensive, secondary Ca/Mg carbonates that acted as an inter-granular cement, increasing the competency of the CRD, i.e., producing a hand sample. Nearly every grain in the sample, including primary, un-weathered angular carbonate clasts were coated in secondary, μm- to mm-scale carbonate layers, which are interpreted as secondary materials. DNA analysis of an internal, aseptic sample of secondary carbonate revealed that the weathered kimberlite hosts a diverse microbiome consistent with soils, metal cycling and hydrocarbon degradation that was found within the secondary carbonate, interpreted as a biomaterial. The formation of secondary carbonate demonstrates that ‘waste kimberlite’ from diamond mining can serve as a resource for carbon sequestration.

Sand modification with a saponite clay suspension as a waste of the diamond mining industry

The results of the laboratory water permeability tests of a sand modified by a saponite clay fraction from the diamond mining industry waste are presented. The filtration of clay suspension through a landfill ground bed as a method of the additive enrichment is approved. The experimental apparatus consisted of the triaxial test chambers and semi-automatic devices for water and suspension supplying. The chambers excluded a sidewall leakage in the samples and provided required values of the vertical and horizontal stresses when measuring permeability. The samples of an alluvial fine sand and a sand mixed with 3 and 5 % a chalk and a dolomite were investigated. After preliminary saturation the rate of distilled water flow through the samples were determined at four values of hydraulic gradient. Then the filtration of a suspension containing up to 0.58-0.63 % clay particles was conducted. After that, the pore disks at the top of samples were washed by circulating water flow. At the last step of experiments the velocity of water flow was measured again at four values of hydraulic gradient. The experiments indicated that the modification of the sand by clogging the pores by the saponite clay fraction from a suspension flow is possible if a sand comprises the additives causing the aggregation of clay particles. The hydraulic conductivity of a sand with 3 % chalk decreased by 15-31 times, with 5 % - by 15-39 times at different values of relative compaction. The effect of a dolomite addition was not significant, the hydraulic conductivity decreased by a maximum of 14.3 times. To achieve the maximum depth of clogging, it is recommended to filtrate the suspension through a loose sand at a hydraulic gradient that provides a flow rate more than 3.5 m/day, after that, the sand layer should be compacted.

Air-thermal oxidation of diamond nanopowders obtained by the methods of mechanical grinding and detonation synthesis

In this work, using the methods of X-ray phase analysis, transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy, the features of the impact of annealing in air within the temperature range of t = 200÷÷550 °C on the morphology, elemental and phase composition, chemical state and structure of primary particles of nanopowders obtained by grinding natural diamond and the method of detonation synthesis are studied. It is shown that heat treatment in air at given values of temperature and heating time does not affect the elemental composition and atomic structure of primary particles of nanopowders obtained both by the methods of detonation synthesis (DND) and natural diamond grinding (PND). Using XPS, Raman spectroscopy, and transmission electron microscopy, it has been found that annealing in air within the temperature range of 400–550 °C results in the effective removal of amorphous and graphite-like carbon atoms in the sp2- and sp3-states from diamond nanopowders by oxidation with atmospheric oxygen. In the original DND nanopowder, containing about 33.2 % of non-diamond carbon atoms of the total number of carbon atoms, after annealing for 5 h at a temperature of 550 °C, the relative number of nondiamond carbon atoms in the sp2-state decreased to ~21.4 %. In this case, the increase in the relative number of carbon atoms in the sp3-state (in the lattice of the diamond core) and in the composition of oxygen-containing functional groups ranged from ~39.8 % to ~46.5 % and from ~27 % to ~32.1 %, respectively. In the PND nanopowder, which prior to annealing contains about 10.6 % of non-diamond carbon atoms in the sp2-state of the total number of carbon atoms, after annealing under the same conditions as the DND nanopowder, their relative number decreased to 7.1 %. The relative number of carbon atoms in the sp3-state increased from 72.9 % to 82.1 %, and the proportion of carbon atoms in the composition of oxygen-containing functional groups also slightly increased from 10.2 % to 10.8 %. It is demonstrated that the annealing of PND and DND nanopowders in air leads to a change in their color, they become lighter as a result of oxidation of non-diamond carbon by atmospheric oxygen. The maximum effect is observed at a temperature of 550 °C and an annealing time of 5 h. In this case, the weight loss of PND and DND nanopowders after annealing was 5.37 % and 21.09 %, respectively. The significant weight loss of DND nanopowder compared to PND is primarily caused by the high content of non-diamond carbon in the initial state and the high surface energy of primary particles due to their small size.

Nitrogen Structure Determination in Treated Fancy Diamonds via EPR Spectroscopy

Color induction in nitrogen-contaminated diamonds was carried out via various procedures that involve irradiation, thermal treatments (annealing), and more. These treatments affect vacancy defect production and atom orientation centers in the diamond lattice. Natural diamonds underwent color enhancement treatments in order to produce green, blue, and yellow fancy diamonds. The aim of this study was to follow the changes occurring during the treatment, mainly by EPR spectroscopy, which is the main source for the determination of the effect of paramagnetic centers (carbon-centered radicals) on the color centers produced via the treatments, but also via visual assessment, fluorescence, UV-vis, and FTIR spectroscopy. The results indicate that diamonds containing high levels of nitrogen contamination are associated with high carbon-centered radical concentrations. Four paramagnetic center structures (N1, N4, and P2/W21) were generated by the treatment. It is suggested that the N4 structure correlates with the formation of blue color centers, whereas yellow color centers are attributed to the presence of N1 species. While to produce blue and yellow colors, a thermal treatment is needed after irradiation, for treated green diamonds, no thermal treatment is needed (only irradiation).

Boron isotopes in blue diamond record seawater-derived fluids in the lower mantle

Boron is a quintessential crustal element but its conspicuous presence in diamond – a mantle mineral – raises questions about potential subduction pathways for boron and other volatiles. It has been a long-standing goal to characterize the isotopic composition of boron in blue, boron-bearing (Type IIb) diamonds to reveal its origin. Mineral inclusions indicate that Type IIb diamonds crystallize at transition zone to lower mantle depths, meaning that if the boron is subducted it would trace a pathway of volatile elements into the deep mantle. Here, using off-line laser ablation sampling, we present the first boron isotope compositions, along with trace element contents and carbon isotope compositions, of a suite of blue diamonds mainly sourced from the Cullinan diamond mine in South Africa. The ten analyzed blue diamonds have a wide range in δ11B, between −9.2 ± 2‰ and −0.5 ± 2‰, compared to the more restricted range for mid-ocean ridge basalts (−7.1 ± 0.9‰). Carbon isotope values for the blue diamonds range between −20.6 and −1.8‰, with a mode at −17‰, significantly more negative than the main mantle mode at −5‰. Combined, the boron and carbon isotope compositions require fluid input from subducted oceanic lithosphere down into deep mantle source regions of blue diamonds. This finding highlights a deep subduction pathway for volatiles to stoke the source regions of deeply-derived magmas.

Growth Pyramids of {110} Faces in Natural Diamonds

Growth Pyramids of {110} Faces in Natural Diamonds

Impact of artisanal small-scale (gold and diamond) mining activities on the Offin, Oda and Pra rivers in Southern Ghana, West Africa: A scientific response to public concern

The surface water systems of Ghana serve as a major source of drinking water, besides other multi-purpose benefit of hydro-electrical power generation and transportation. Thus, the dependence and benefits from such resources are of national interest. For instance, the Pra river of the South-Western surface water system of Ghana was a major consideration for a projected 5 billion m3 water demand in the year 2020 and “African Water Vision 2025”. In recent times, the colour state of the Pra river and similar surface water bodies of the Offin and Oda rivers has attracted intense public discussion. The prime issue relates to incessant illegal artisanal gold/diamond mining on or along these rivers. In order to assess the state of these rivers, water samples were taken, and analysed at the Council of Scientific and Industrial Research Laboratory (CSIR, Accra-Ghana) to investigate their physico-chemical quality. The research objective was to assess the extent of their water pollution by measuring physico-chemical parameters of turbidity, colour, pH and content of selected metals. A total of 18 preserved bottled samples [(5 from Offin river and 2 boreholes), 5 from Oda river and 5 from Pra river and 1 borehole)] were analysed, and results compared with portable water standards as defined by the WHO and CSIR (GS-175-1) of Ghana.Results on turbidity, colour, mercury and iron from the river and water samples generally exceed WHO or GS-175-1 limit. The Pra river recorded the most alarming result; range for turbidity (2,010 to 2,745 NTU), colour (3,000 to 4,500 Hz), total suspended solutes (2,240 to 2,570 mg/L) and total dissolved solutes (97.80–99.60 mg/L, excluding 319.00 to 25,440 mg/L). The Oda river shows lowest parameter values among the three rivers, as the areas have been dormant from illegal gold mining for 5 years. Current data suggests polluted river bodies and boreholes, and that none of these water resources meets the portable water consumption criteria unless treated prior to usage. As the current state of the water bodies may incur higher cost of water treatment or purification, an integrated water governance under Ghana's Ministry of Water Resource, Work and Housing, and the Minerals Commission and Environmental Protection Agency are recommended for the management of these valuable water resources.

Room-temperature bonding of GaN and diamond via a SiC layer

A GaN-on-diamond structure is the most promising candidate for improving the heat dissipation efficiency of GaN-based power devices. Room-temperature bonding of GaN and diamond is an efficient technique for fabricating this structure. However, it is extremely difficult to polish diamond to an average roughness (Ra) below 0.4 nm, especially for polycrystalline diamond. In this work, Room-temperature bonding of GaN and rough-surfaced diamond with a SiC layer was successfully achieved by a surface-activated bonding (SAB) method. The diamond surface’s initial Ra value was 0.768 nm, but after deposition of the SiC layer, the Ra decreased to 0.365 nm. The SiC layer formed at the as-bonded GaN/diamond interface was amorphous, with a thickness of about 7 nm. After annealing at 1000-°C, the amorphous SiC layer became polycrystalline, and its thickness increased to approximately 12 nm. These results indicate that the deposition of a SiC layer on diamond can efficiently lower the diamond surface’s roughness and thus facilitate room-temperature bonding.