Oxide Crystals Research Articles

Plasma–induced rapid crystallization and surface engraving of amorphous TiOx(OH)y to enhance adsorption and photocatalytic activity

Herein, we highlight a facile, green, and controlled technique commonly known as plasma-liquid interaction for crystal growth, defect engineering, and surface modification of amorphous titanium oxide. Using a novel two-step procedure combining hydrolysis and plasma treatment, we have fabricated defect-enriched anatase TiO2 powder. Rapid crystallization of amorphous titanium oxide is observed due to the interaction of plasma-generated reactive species with the solvated material. However, prolonged treatment time decreases the material's crystallinity due to excess generation of oxygen vacancy defects (OVD) in the TiO2 lattice. The plasma treatment also engraves the material’s surface forming the porous structure, increasing the specific surface area to ∼46 %. At a higher treatment time, TiO2 nanoparticles are grown on the material’s surface. The dye adsorption of the material is quite rapid, and the performance depends on the material’s surface condition. This rapid adsorption speeds up the photo-degradation performance (up to ∼96 %) of the material. The presence of OVD increases the photocatalytic activity of the material. However, an excess amount of OVD quenches the activity. A comparative study between ambient air and argon plasma-assisted material modification for optimized adsorption and photocatalytic performance has been carried out.

Transparent Lead‐Free Ferroelectric (K, Na)NbO3 Single Crystal with Giant Second Harmonic Generation and Wide Mid‐Infrared Transparency Window

AbstractEnvironment‐friendly lead‐free potassium‐sodium niobate (KNN) has become one of the most extensively investigated ferroelectrics in the past decade, while high transparency KNN single crystal has never been realized yet. Here, a transparent KNN single crystal is successfully grown by the top seeded solution growth method. The KNN crystal possesses a very wide transmittance range of 0.37–8 µm, completely covering the important mid‐infrared atmospheric transparent window (3–5 µm). Noticeably, the KNN crystal exhibits the largest second‐harmonic generation efficiency (7.6× that of potassium‐titanyl phosphate (KTP)) with type‐I phase matchability under the fundamental wavelength of 1064 nm among all of the studied mid‐infrared oxide nonlinear optical crystals reported so far. This work demonstrates a novel mid‐infrared nonlinear optical oxide crystal with a giant second‐harmonic generation and wide transparency range, providing a new idea for the exploration of nonlinear oxide crystals.

Analytical Description of Concentration of Radiation Displacement Defects in Oxide Crystals as Function of Electrons or Neutrons Energy

Abstract The main purpose of this work is the description of dependence of the concentration of radiation displacements defects (RDD) induced by electrons and neutrons in garnets, perovskites, silicates, germanates, and tungsted bronzes type crystals (Y3Al5O12, Gd3Ga5O12, YAlO3, LiNbO3, Bi4Si3O12, Bi4Ge3O12, Ca0.28Ba0.72Nb2O6) on the energy of particles by analytical function. The dependences were determined on the basis of calculations made using the Monte-Carlo method realized in the Atom Collision Cascade Simulation program. The results of calculations show that the concentrations of RDD reduced to one impinging particle increased initially with the particles energy and they saturates for the electron and neutron energy above 3–36 MeV, depending on crystal, sublattice and kind of irradiation particle. A wide range of energies for which the concentration of RDD is independent of the energy of particles (neutrons, electrons) makes them potential materials for the dosimetry of high-energy particles. The comparison of the concentrations of RDD calculated for different sublattices as well as for the cases of electrons and neutrons is made. In the case of irradiation with electrons, the relative concentration of RDD of the oxygen sublattice strongly depends on the energy of electrons and the crystal and varies in the range of 10–90%. In the case of neutrons, the relative concentration of RDD of the oxygen sublattice does not depend on the neutron energy and is in the range of 66–84% depending on the crystal.

Brown Amphibole as Tracer of Tectono-Magmatic Evolution of the Atlantis Bank Oceanic Core Complex (IODP Hole U1473A)

Abstract Brown amphibole is a minor but common mineral component in lower oceanic crust. It is generally interpreted as products of migrating SiO2 and H2O-rich fluids or melts, which can be either residual melts from advanced magmatic differentiation of Mid-Ocean Ridge Basalt (MORB), or hydrothermal fluids including a seawater component. Within the lower oceanic crust exhumed at the Atlantis Bank Oceanic Core Complex, along the ultraslow Southwest Indian Ridge, brown amphibole is ubiquitous in all lithologies from olivine- to oxide-gabbros and diorites, including both undeformed and plastically deformed varieties. We here show the results of a systematic petrological study conceived to unravel the nature of the H2O-rich component recorded in brown amphiboles and document: (i) the evolution of migrating melts during the magmatic stage and (ii) different extents of melt-bearing deformation events recorded throughout the entire crustal transect. The low Cl contents and the light over heavy rare earth elements (LREE/HREE) ratios and high Ti contents in brown amphiboles indicate they crystallized from melts with a magmatic hydrous component. Consistently, their δ18O values are in equilibrium with Mid-Ocean Ridge Basalt (MORB) composition, except for diorite amphiboles that possibly record the local assimilation of altered minerals. In undeformed olivine gabbros, interstitial pargasite crystallized at hypersolidus conditions (~1000°C) from the melt residual after late stages of MORB differentiation. We speculate that before the olivine gabbro crystal mush reached fully solid state, some aliquots of residual melts were extracted and accumulated within discrete intervals. There, ferrobasaltic melts differentiated through the early crystallization of Fe-Ti oxides and clinopyroxene as liquidus phases, ultimately forming the oxide gabbros. This process promoted rapid Si enrichment and depletion in Fe, Ti, V in the residual melt, later extracted to form the crosscutting diorite veins. The mylonitic olivine gabbros record high-temperature plastic deformation (~900°C ± 50°C) under hypersolidus conditions, involving melts residual from previous crystallization of the gabbroic rock. Further solid-state plastic deformation led to substantial grain size reduction and, consequently, to an increase in porosity. This created pathways for subsequent melt focusing, which likely represent late-stage differentiated melts migrating throughout the lower crustal section. This study shows that brown amphibole in the Atlantis Bank lower oceanic crust is the crystallization product of melts residual from advanced magmatic differentiation, which are also locally involved in the plastic deformation events during crustal accretion.

33691 Prospective pilot evaluation in Fitzpatrick skin phototypes III to VI of a crystal-free brush-tip exfoliation device with variable vacuum pressure and skin infusion for hyperpigmentation

Unmet needs in skin of color include satisfactory long-term treatments for hyperpigmentation, whether primary or a sequela of various dermatoses. Surveys report that pigmentary disorders are the second most common dermatoses among African American patients consulting dermatologists, and that hyperpigmentation significantly impairs quality of life. This single-center, open-label pilot evaluation prospectively assessed safety, efficacy and tolerability in patients with Fitzpatrick skin phototypes III to VI of an FDA 510(k)-cleared crystal-free brush-tip exfoliation device with adjustable vacuum pressure and skin infusion containing 1% each of alpha-arbutin, glutathione, kojic acid plus azelaic acid; lactic acid; and salix alba bark extract. 23 female patients aged 26 to 71 with mild, moderate or severe facial hyperpigmentation received 3 to 6 treatments at 2 to 4 weekly intervals. Patients applied broad spectrum sunscreen daily. Three weeks after the third treatment, blinded assessment of standardized digital images found that all patients had improvements in skin tone, texture and brightness/radiance (≥2 points on 10-point scales), and 15 (65%) had ≥1 point improvement in pigmentation. Physician and patient GAIS scoring ranged from Improved to Very Much Improved. DQLI improved for 12 (52%). The procedure was well tolerated, with no significant adverse effects. Post-procedural erythema lasted 15 minutes to under 24 hours. All patients reported satisfaction with treatment and increased These pilot data show safety, efficacy and tolerability in skin of color. The ability to patient-tailor all procedural steps, including exfoliation depth, magnitude of vacuum pressure and infusion type, may confer benefits over conventional aluminum oxide crystal microdermabrasion.

Synthesis, Crystal Structures, and Nonlinear Optical Properties of Chalcone Doped by Titanium Dioxide Nanoparticles for Solar Cell Application

In this work, we investigate the effects of titanium dioxide (TiO2) nanoparticle percentages on the optical and electrical properties of 3-(4-(dimethyl-amino)phenyl)-1-phenyl-(2E)-propen-1-one (DAAP). In order to achieve thin films, DAAP was dissolved in acetone and doped with different ratios of TiO2. The pure and composite mixtures were spin-coated onto a glass substrate. We investigated the influence of TiO2 on XRD patterns, absorption, energy band gaps, refractive indices, sheet resistance, resistivity, and Hall coefficients. We used the XRD technique to study the structure of DAAP pre- and post-doping with TiO2 nanoparticles. It was evident from the XRD patterns that the composite transformed from an amorphous to a polycrystalline nature and behaved similarly to titanium oxide crystals. The pure sample exhibited an absorption band of 409 nm. With the addition of TiO2, the whole absorption spectrum shifted to the blue region. For example, with a dopant percentage of 15%, the spectrum shifted to a wavelength of 368 nm. The energy band gap values increased with a dopant concentration from 2.65 eV of pure DAAP to 2.91 eV of maximum dopant percentage (15%). The refractive index decreased to its lowest value of 2.47 with the increase in TiO2 concentration. The impact of increasing TiO2 percentage highly improved electrical characteristics by reducing the sheet resistance and resistivity to 905 k(Ω/sq) and 230 k on the (Ω · cm), respectively. An optimized DAAP doped with 15% TiO2 has been used as an n-type layer on a p-type monocrystalline silicon wafer (Si (111)) to fabricate η = 0.23% efficient solar cells. On the other hand, the amplified spontaneous emission (ASE) of the DAAP and dopant mixture was excited by the third harmonic generation (λex = 355 nm). The pure DAAP exhibits an ASE peak at 535 nm. The intensity decreased rapidly with increased dopant concentration, whereas the full width at half-maximum (FWHM) increased slightly.

Dynamic Observation of Anisotropic Chainlike Structures during Nonclassical Two-Step Nucleation in Solid-State Iron Oxide Crystallization.

The demonstration of the self-crystallization nucleation process from an amorphous precursor in a solid is crucial for understanding of interactions between atoms. We report a study of dynamic crystallization process of iron oxides by virtue of in situ measurement of transmission electron microscopy. At first, semiordered chainlike structures are observed with the increase of concentration, and when sufficient chains form, the crystalline lattice begins to grow. The two-step nucleation pathway has also been confirmed by performing a molecular dynamics simulation, where Lennard-Jones and magnetic dipole-dipole interaction potentials are both taken into account and take effect individually predominantly in different ranges of distance between atoms. Furthermore, the total free energy profile in the crystallization nucleation process is calculated to evidence the stabilization of intermediate state. This work advances our understanding of nonclassical nucleation theory.

Zinc Oxide Nanoparticles as Potential Delivery Carrier: Green Synthesis by Aspergillus niger Endophytic Fungus, Characterization, and In Vitro/In Vivo Antibacterial Activity.

We aimed to synthesize zinc oxide nanoparticles (ZnO NPs) using the endophytic fungal extract of Aspergillus niger. The prepared ZnO NPs were characterized, and their in vitro and in vivo antibacterial activity was investigated. Isolated endophytic fungus identification was carried out using 18S rRNA. A. niger endophytic fungal extract was employed for the green synthesis of ZnO NPs. The in vitro antibacterial activity of the prepared ZnO NPs was elucidated against Staphylococcus aureus using the broth microdilution method and quantitative real-time polymerase chain reaction (qRT-PCR). Additionally, the in vivo antibacterial activity was elucidated using a systemic infection model in mice. The biosynthesized ZnO NPs showed a maximum optical density at 380 nm with characteristic peaks on the Fourier-transform infrared spectrum. The X-ray diffraction pattern was highly matched with a standard platform of zinc oxide crystals. Energy-dispersive X-ray analysis confirmed that the main composition of nanoparticles was zinc and oxygen atoms. Scanning and transmission electron microscopies showed spherical geometry with a smooth surface. Zeta potential measurements (26.6 ± 0.56 mV) verified the adequate stability of ZnO NPs. Minimum inhibitory concentrations of ZnO NPs against S. aureus isolates ranged from 8 to 128 µg/mL. Additionally, ZnO NPs revealed antibiofilm activity, resulting in the downregulation of the tested biofilm genes in 29.17% of S. aureus isolates. Regarding the in vivo experiment, ZnO NPs reduced congestion and fibrosis in liver and spleen tissues. They also improved liver function, increased the survival rate, and significantly decreased inflammatory markers (p < 0.05). ZnO NPs synthesized by A. niger endophytic fungus revealed a promising in vivo and in vitro antibacterial action against S. aureus isolates.

Investigation on luminescence properties and energy transfer of Gd3+ and Sm3+-doped phosphate glass for solid-state lighting

The physical and optical properties of glasses for solid-state lighting applications are being investigated. The melt quenching procedure at 1200 °C was used to create the Gd3+ and Sm3+ ions using doped phosphate-based glasses. Gd2O3 and Sm2O3 concentrations increased density, according to the findings. For the alteration in the glass, the intensity of molar volume rose, indicating the establishment of a non-bridging oxygen (NBO) network. The absorption spectra migrated from 6H5/2, the ground state, to different states with wavelengths ranging from 300 to 1700 nm. When the energy transfer from the IH model is at its greatest at 11 mol% Gd3+ concentration, photoluminescence spectra exhibit four emission peaks ranging from 4G9/2 to 6H5/2, 6H7/2, 6H9/2, and 6H11/2, respectively. The maximum photoluminescence spectra intensity was 1 mol% of Sm2O3, which was compared to bismuth germanium oxide (Bi4Ge3O12; BGO) crystal at 10.33% by x-ray excitation. The color of orange emission is determined by the CIE 1931. The Judd-Ofelt (JO) parameter (Ωλ (λ = 2, 4, 6)) have been used by evaluated Judd-Ofelt theory and trend were Ω4 > Ω6 > Ω2. As a result, doped phosphate base glasses with Gd3+ and Sm3+ ions have property requirements, and cost-cutting production is the best option for solid-state lighting applications.

Upconversion luminescence enhancement of the ytterbium oxide with gold nanoparticles on anodized titanium surface

This paper presents a study of the cooperative luminescence (upconversion) process of Yb2O3 with gold nanoparticles on the anodized titanium surface. The luminescence of the samples was registered under two-photon excitation with using infrared laser (λ = 980 nm) and a quasi-continuous femtosecond laser (λ = 1030 nm). It was found that the quantum yield of luminescence in the presence of gold nanoparticles increases in 5.6 times fold as a result of non-radiative plasmon energy transfer. The constant of non-radiative dipole-dipole energy transfer was calculated with using the Förster model under the plasmon energy generation. It is also shown that under photoexcitation with wavelength of 980 nm at low temperatures (80 K), the intensity of upconversion luminescence increases according to the quadratic function of the excitation energy, which confirms the existence of upconversion luminescence generation by the mechanism of simultaneous energy transfer involving two Yb3+ ions in the oxide crystal.

The high-K calc-alkaline to shoshonitic volcanism of Limnos, Greece: implications for the geodynamic evolution of the northern Aegean

Genetic models for the formation of K-rich magmas in subduction-related settings range from partial melting of subduction-affected mantle sources to melting of crustal rocks depending on the local tectonic framework. The Miocene high-K calc-alkaline to shoshonitic rocks of Limnos Island reflect the magmatic activity in the northern Aegean, which migrated southwards in response to trench retreat and the collision of continental terranes in the Hellenic subduction system. New whole rock and mineral data of basaltic andesites, dacites and monzonites from Limnos indicate that the magmas underwent fractional crystallization of olivine, clinopyroxene, amphibole, apatite, and Fe-Ti oxides at 1100 to 700 °C and 0.5 to 0.1 GPa without significant assimilation of crustal rocks during the magma evolution. The strong enrichment of large ion lithophile elements and light rare-earth elements relative to depleted heavy rare earth and high-field strength elements points towards a mantle source that has been extensively hybridized by subducted sedimentary material. New Sr–Nd-Pb isotope data reveal a distinct isotopic composition of the Limnos rocks with high 207Pb/204Pb at low 206Pb/204Pb and 143Nd/144Nd ratios that is likely related to the subduction of the continental crustal succession of the Apulian block which was subducted prior to the onset of magmatism on Limnos. Partial melting models assuming a hybridized mantle source suggest that the primary melts of Limnos formed by melting of a phlogopite pyroxenite at melting degrees of 5 to 10%. Compositional differences between high-K calc-alkaline and shoshonitic magmas are explained by variable melting degrees and varying amounts of sediment supply to the mantle. The magmatic and tectonic evolution of Limnos island is typical for the Oligocene and Miocene volcanic centres of the migrating western Aegean arc front.

Femtosecond laser writing of waveguides in zinc oxide crystals: fabrication and mode modulation.

We report for the first time on optical waveguides in zinc oxide (ZnO) crystals fabricated by femtosecond laser direct writing. The confocal Raman microscopy under 488 nm laser excitation is used to investigate the micro-modifications of the laser irradiation, and guiding properties are studied via the end-face coupling at 632.8 nm. The mode modulation has been achieved by the adjustment of laser writing parameters. A minimum propagation loss of ∼6 dB/cm is obtained for the double-line waveguide structures. A Y-branch waveguide beam splitter is also fabricated, reaching a splitting ratio of nearly 1:1. The original optical properties in the guiding region have been well preserved, according to the confocal Raman investigation, which suggests potential applications of the ZnO waveguides for integrated photonics and nonlinear optics.

Electron Beam Transparent Boron Doped Diamond Electrodes for Combined Electrochemistry-Transmission Electron Microscopy.

The majority of carbon based transmission electron microscopy (TEM) platforms (grids) have a significant sp2 carbon component. Here, we report a top down fabrication technique for producing freestanding, robust, electron beam transparent and conductive sp3 carbon substrates from boron doped diamond (BDD) using an ion milling/polishing process. X-ray photoelectron spectroscopy and electrochemical measurements reveal the sp3 carbon character and advantageous electrochemical properties of a BDD electrode are retained during the milling process. TEM diffraction studies show a dominant (110) crystallographic orientation. Compared with conventional carbon TEM films on metal supports, the BDD-TEM electrodes offer superior thermal, mechanical and electrochemical stability properties. For the latter, no carbon loss is observed over a wide electrochemical potential range (up to 1.80 V vs RHE) under prolonged testing times (5 h) in acid (comparable with accelerated stress testing protocols). This result also highlights the use of BDD as a corrosion free electrocatalyst TEM support for fundamental studies, and in practical energy conversion applications. High magnification TEM imaging demonstrates resolution of isolated, single atoms on the BDD-TEM electrode during electrodeposition, due to the low background electron scattering of the BDD surface. Given the high thermal conductivity and stability of the BDD-TEM electrodes, in situ monitoring of thermally induced morphological changes is also possible, shown here for the thermally induced crystallization of amorphous electrodeposited manganese oxide to the electrochemically active γ-phase.

(Digital Presentation) Fabrication of Single-Crystal Layered Oxide Cathode through Variation on Heating Process

Since the announcement of a million-mile battery by Tesla, single-crystal processing of layered oxide cathode has received great attention recently. From single-crystal process, high Ni layered oxides with grain size in mm range tends to give better cycling performance due to better structural integrity against repeated charge/discharge cycles.However, during heating/calcination process of oxide/carbonates/nitrates powder compacts, it may involve decomposition, chemical reactions, diffusion, oxidation, sintering, grain-growth. For single-crystal process, the powder compacts need to be heated to higher temperatures (~950°C) for certain period of time. On the other hand, enough air/oxygen is need for Ni oxidation and better crystallization in Ni-rich layered structure. Therefore, it is important to investigate the processing of single-crystal Ni-rich layered oxide based on the sintering behavior, thermal gravimetric analysis, and phase transformation.Nevertheless, the lithiation/oxidation of Ni-containing oxides involves charge compensation resulted from defect reactions. As a result, the affected electrical, optical, structural, and electrochemical properties of layered oxides will be discussed based on defect chemistry consideration. The structural, microstructural and electrical properties of decomposed precursors and doped layered oxides will be examined using XRD, SEM and DC/AC impedance measurements. CV and charge/discharge tests from assembled coin cells will be used to evaluate electrochemical properties of single-crystal Ni-rich layered oxides.

Formation of Titanium Oxide on Nonmetal Substrates and the Coordination Structure of Titanium Ions in Molten Lif-KF

Electrodeposition of titanium materials on substrates is an important technique to improve and functionalize the surface properties. Especially electrodeposition of titanium and titanium oxide on a material that is an insulator. However, electrodeposition of an insulator on another insulator is considered to be difficult. If such deposition can be accomplished, it would have a variety of practical applications in both mechanical and electronic industries. We are thus proposing a new method for electrodeposition of titanium oxide on alumina substrates in LiF-KF with the addition of TiO2 and metal titanium. We have carried out the electrodeposition to test hypotheses on deposition of titanium oxide on the alumina surface by employing the three electrodes method in the molten salt. The nickel-wire in contact with alumina substrate was employed as a working electrode to grow titanium oxide on the substrate by the proposed electrochemical process. Titanium oxide deposition grew from the three-phase interface of nickel wire, molten salt and alumina substrate in a radial pattern. The growth rate of the deposition was controlled by adjusting the electrochemical parameters. We have also investigated the melt structure of LiF-KF with the addition of TiO2 and the addition of bulk titanium by combining high temperature Raman spectroscopic technique and density functional theory calculations. These results provide new insight into the growth process of titanium oxide crystals and possibly a new comprehensive plating procedure for titanium oxide on insulator substrates.

Thermal properties of single crystals of the low-positive thermal expansion material Al2W3O12

Investigations of the thermal conductivity and heat capacity of a monocrystalline sample Al2W3O12, along with computational investigations using density functional theory, reveal a complete picture of anisotropic thermoelastic properties of Al2W3O12, a low-positive thermal expansion material. The thermal conductivity at room temperature was essentially isotropic, with a directionally average value of 2.1 ± 0.2 W m−1 K−1, about twice the value reported for polycrystalline samples. The thermal conductivity shows a significant peak at about 20 K, and at 5 K corresponds to a phonon mean free path of about 2000 nm, much shorter than that of a typical high-quality oxide crystal with a more rigid framework. The flexible Al2W3O12 structure also gives rise to low-frequency modes, as evidenced by the high heat capacity in comparison with that of the constituent oxides. The thermal shock resistance figures of merit for moderate and severe thermal shock are both anisotropic, but high, with directionally average values of about 6500 W m−1 and 3300 K, respectively. An additional finding was that the phase transformation from the low-temperature monoclinic phase to the room-temperature orthorhombic phase shows considerable hysteresis and, evidenced by DSC on shards of single crystals, nucleation is a stochastic process.

Scintillation and photoluminescence investigations of Gd2MoB2O9: CeF3 phosphors

The CeF3 doped Gd2-xMoB2O9 phosphors (where x = 0.00, 0.25, 0.50 and 0.75 mol%) were synthesized by the conventional high-temperature solid-state reaction method at 900 °C for 12 h in air. DSC and TGA analysis executed to study the optimum temperature for sintering. The structural, photoluminescence and X-ray luminescence properties were investigated. The structure of the samples was analyzed by using X-ray diffractometer (XRD). The absorption spectra were analyzed and found that absorption edge increased with the increasing concentration of CeF3. The photoluminescence of phosphors shows the overlapping of excitation and emission peaks in the range of 300 nm–450 nm. These emission peak correspond to the 5d – 4f transitions of Ce3+ ion. The optimum concentration of CeF3 in these phosphors is 0.50 mol% corresponding to maximum emission intensity. The X-ray induced optical luminescence spectra showed a strong emission peak at 411 nm the concentration quenching at 0.75 mol%, which is as efficient as 54.4% compared with bismuth germanium oxide (BGO) crystal. The luminescence decay increased with the increment of CeF3 concentration. From the optical properties investigated, it was found that the phosphors performed a strong and fast luminescence signal which is appropriate for the development of scintillators in X-ray detector devices.

The Mechanism of Oxide Growth on Pure Aluminum in Ultra-High-Temperature Steam

A high-temperature water steam (H2O(g)) between 300 °C and 1000 °C reacted with the Al surface in this study. The Al surface states were characterized and analyzed using XRD °C, XPS, and SEM after and before the reaction, and the effects and mechanism of H2O(g) on the Al surface morphology and chemical composition were studied. The experiment showed that for an Al sheet reacting with H2O(g), its oxide layer morphology changed from nano-needle to flaky and granular oxides gradually with the rise of temperature, and finally the Al surface became porous as a whole. Its oxide crystals were amorphous and were determined to be aluminum oxide (Al2O3) using XPS. The needle-like oxide in the Al sheet surface tended to grow toward the surface, and no obviously inward oxidizing corrosion layer occurred in the aluminum substrate; the oxide layer between the oxide and Al sheet substrate was compact, and could effectively prevent the infiltration and corrosion of water molecules.

Plasma-enhanced atomic-layer-deposited indium oxide thin film using a DMION precursor within a wide process window

In this study, we developed a new liquid indium precursor, dimethyl[N-(tert-butyl)-2-methoxy-2-methylpropan-1-amine] indium (DMION), to deposit indium oxide films using the plasma-enhanced atomic layer deposition (PEALD) method. The indium oxide films were deposited using DMION and Ar/O2 plasma as the precursor and reactant, respectively, with relatively high growth per cycle (GPC, ∼1.2 Å/cycle) within a wide atomic layer deposition (ALD) window (35–300 °C). Impurities such as carbon and nitrogen were not detected regardless of the deposition temperature. The crystallinity of the films had a bixbyite cubic structure within the ALD window and facets could be controlled by deposition temperature modulation; (400) facets were dominant at low deposition temperatures (35 and 100 °C), whereas (222) facets were dominant at high deposition temperatures (200 and 300 °C). The dominant facets and orientations of the indium oxide crystal were maintained until 400 °C in the post-annealing process. The thin-film transistors (TFTs) using indium oxide deposited at 200 °C exhibited high field-effect (∼32.1 cm2/Vs) mobility with a reasonable threshold voltage (∼1.8 V) and subthreshold voltage swing (∼0.48 V/decade).

Investigation of dynamic mechanical properties and constitutive model of (010) plane of gallium oxide crystals under shock loading

In this study, ultraprecision processing performance of new-generation optoelectronic gallium oxide crystals is investigated. Based on material mechanics, Hopkinson rod test is carried out on (010) crystal plane of gallium oxide crystal. The destruction process of gallium oxide crystals was observed by high-speed photography and three-dimensional topography. Through this experiment, the dynamic mechanical properties of the (010) crystal plane of the gallium oxide crystal were tested, and the real stress-strain curves at different rates were obtained.The formation mechanism of fracture after crystal crushing was analyzed. It was found that the compressive strength and yield strength of gallium oxide crystals showed a significant plastic increase with the increase of the impact speed, while the plastic failure strain decreased with the increase of the impact speed. Furthermore, dynamic mechanical properties of (010) crystal plane of gallium oxide crystal are tested, and actual stress-strain curves are obtained. The fracture process of gallium oxide crystals is observed via high-speed photography. Formation mechanism of fractures is analyzed using three-dimensional topography. AlongsideCombined with the quasistatic indentation test, a set of Holmquist–Johnson–Cook constitutive models suitable for gallium oxide crystals is established. Based on obtained parameters, finite element software ABAQUS is used to numerically simulate nanoindentation test of gallium oxide crystals. By comparing numerically and experimentally obtained load-displacement curve data, validity of parameters of constitutive model is verified. It provides a certain guiding significance for the subsequent ultra-precision machining of gallium oxide crystals.