Ceramic Target Research Articles

Ultrahigh Ferroelectric and Piezoelectric Properties in BiFeO3–BaTiO3 Epitaxial Films Near Morphotropic Phase Boundary

Ferroelectric solid solutions with composition near the morphotropic phase boundary (MPB) have gained extensive attention recently due to their excellent ferroelectric and piezoelectric properties. Here, we have demonstrated a strategy to realize the controllable preparation of BiFeO3-BaTiO3 (BF-BT) epitaxial films near the MPB. A series of high-quality BF-BT films were fabricated by pulsed laser deposition via adjusting oxygen partial pressure (PO2) using a BF-BT ceramic target. A continuous transition from rhombohedral to tetragonal phase was observed upon increasing PO2. Particularly, the film with a pure tetragonal phase exhibited a large remnant polarization of ∼90.6 μC/cm2, while excellent piezoelectric performance with an ultrahigh strain (∼0.48%) was obtained in the film with coexisting rhombohedral and tetragonal phases. The excellent ferroelectric and piezoelectric properties endow the BF-BT system near the MPB with great application prospects in lead-free electronic devices.

The study on the welded rate of bonding ZnO rotary target

The industrial grade ZnO ceramic rotary sputtering target was bonded by soldering technology based on indium solder. The scanning electron microscope (SEM) and ultrasonic flaw detection were used to study the influence of process parameters on the welded rate of the target and substrate. The study shows that the metallization of the ceramic inner surface greatly improved the wetting between the solder and ZnO target. In the process of the ultrasonic vibration gradually increasing from 5 KHz to 30 KHz, the welded rate first increased and then decreased, reaching the highest at 30 KHz. By designing the standard tooling, we researched the quantitative characterization of the bonding rate between target and substrate, and finally prepared a ZnO rotary target with a bonding rate greater than 95% and a single defect area of less than 1%.The ZnO film prepared by vacuum magnetron sputtering with bonding target has a uniform microstructure, and the transmittance in the infrared range reaches 97%, which has a very wide application prospect.

Analytical Study of the Penetration of Long Rod Projectiles with Conical and Blunt Nose in Normal and Oblique Ceramic Targets

The Mechanics of penetration investigate the interactions between projectiles and targets. The Mechanics of penetration were initially developed with military motives and were used in the design and manufacture of durable military vehicles, warships, protective vests, bulletproof panels, satellite protective equipment, nuclear reactor protection used. In this paper, the penetration of cylindrical and conical-nosed long rods projectiles in normal and the diagonally ceramic target is studied by analytically and numerical methods; And the Interface defeat e phenomenon, in which the projectile is eroded so that the material in the target surface is radial and outward flow. A comparison was also made between the oblique and normal penetration of long rods cylindrical and conical-nosed projectiles, which illustrates the importance of collision angles. The analytical relations related to the reduction of velocity and erosion of the projectile mass were investigated concerning the extraction time and kinetic energy loss of the projectile. Transition from the interface defeat phase to the penetration phase is also described in detail, and the variation of the critical speed suffering from the change in the angle of impact has been investigated. Each of the results of the analytical work and numerical simulations has been evaluated by experimental work carried out in previous studies and the comparison of the results shows the acceptable accuracy for the obtained relationships.

Defects-curated bipolar resistive switching and magnetism in CuxO films

Recently, the resistive switching (RS) and room-temperature ferromagnetism (RTFM) exhibited in copper oxide (CuxO) films and nanostructures have received extensive interest due to its promising application potential in various fields. Although there is consensus that these intriguing observations may have been resulting from structural defects, the exact type of defect responsible, however, still remains a matter of debate. In this study, we conduct systematic and comparative investigations on both RS and magnetic properties of CuxO films deposited under different atmospheric conditions using magnetron sputtering method with a single CuO ceramic target. X-ray diffraction and Raman spectroscopy show that the CuxO films deposited under O2 gas possesses a pure CuO phase, while the films deposited under N2 gas exhibit mixture of CuO and Cu2O phases. All films displayed bipolar RS characteristics, with the temperature dependence of current–voltage curves showing that the transport mechanisms of the low- and high-resistance states (LRS and HRS) are being governed by semiconductor-like ohmic conduction and space charge limited conduction, respectively. Interestingly, the pure-phased CuO thin film in both LRS and HRS states only displayed paramagnetic (PM) responses, whereas the CuO/Cu2O mixture film exhibited PM and PM + ferromagnetic (FM) behaviors in LRS and HRS, respectively. Detailed comparative analyses suggest that positive doubly charged oxygen vacancy (VO∙∙) curated conducting filaments may have dominated the bipolar RS, and electrons bound to VO∙∙ may further promote the FM coupling between neighboring Cu1+ and Cu2+ ions.

Influence of Al doping on crystal structure, optical, and photoluminescence characteristics of ZnGa2O4 films

Al-doped ZnGa2O4 (ZAGO) thin film phosphors were grown on the c-plane sapphire substrates by co-sputtering of ceramic ZnGa2O4 (ZGO) and metallic Al targets with the Al concentration in the range of 0–5.35%. A systematic investigation on the effects of Al dopant contents on the crystal structure and optical characteristics of ZAGO films has been conducted. First principle calculations were performed to investigate the preferable site of Al atoms in ZAGO supercell in detail. The high-crystalline nature of 1.65% ZAGO film was evidenced by X-ray diffraction patterns and transmission electron microscopy. Al doping revealed the enhanced bandgap of 5.32 eV for ZAGO films. The X-ray photoelectron spectroscopy was utilized in order to determine the chemical states as well as the stoichiometric Zn/Ga ratio in the ZAGO films. The crystallinity, optical, and photoluminescence (PL) characteristics of the ZAGO films are found strongly influenced by Al doping, O/(Zn + Ga + Al), and Zn/Ga ratio. The PL spectra exhibited the broad bands expanding from 380 to 600 nm with the peak located at 525 nm. The improved PL characteristics of ZAGO phosphors with trace Al (1.65%) demonstrate the promise of a relatively new semiconductor material system ZAGO for high-crystalline thin film phosphors.

Ternary-Oxides CuWO4/BiVO4/FeCoOx Films for Photoelectrochemical Water Oxidation: Insights into the Photoinduced Charge Transfer Pathway

Photoelectrochemical (PEC) water oxidation using semiconductor oxide films as a working electrode is an essential approach for investigating the effective utilization of sunlight and the production of green fuel. Herein, we report a ternary-oxides-based CuWO4/BiVO4/FeCoOx film deposited entirely by RF-magnetron sputtering using homemade ceramic targets. Our CuWO4/BiVO4 photoanode exhibits a significant photocurrent density of 0.82 mA/cm² at 1.23 V vs. RHE under AM 1.5G illumination, corresponding to a record > 380% increase to that of pure CuWO4 photoanode. To further boost the PEC performance, we deposited an ultrathin layer of amorphous FeCoOx cocatalyst, resulting in a triple CuWO4/BiVO4/FeCoOx heterojunction with a significant reduction in onset potential and a 500% increase in photocurrent density of pure CuWO4. Experimental studies and numeric computations were used to provide insights into the photoinduced charge carrier pathway across heterojunctions. Our results reveal noticeable interface potential barriers for charge carriers at the CuWO4/BiVO4 heterojunction, potentially lowering PEC efficiency without external potentials. Conversely, the deposition of the FeCoOx ultrathin layer over the CuWO4/BiVO4 heterojunction induces a - junction on the BiVO4/FeCoOx interface, which, when combined with the abundant FeCoOx oxygen vacancies, results in improved charge separation and transport, as well as enhanced photoelectrochemical stability. Our study provides a feasible strategy for producing photocatalytic heterojunctions systems and novel tools for investigating interface effects on photoinduced charge carrier pathways for PEC water splitting.

Study on the nucleation and growth of In2O3 powders for oxide ceramic targets

In this work, the precipitation nucleation and the growth mechanism during the preparation of In2O3 powders are studied in detail, laying a foundation for the preparation of high-quality In-based oxide target powders. The effects of ball milling, precipitation reaction temperature, and calcination treatment on the powder phase, particle size, particle shape, and crystallinity are explored. Moreover, the diffusion mechanism during the calcination process is analyzed. The results show that the ball milling process causes the In(OH)3 structure to transform from amorphous to crystalline, and the ball milling process can result in the agglomeration of precursor nanoparticles; the calcined powders also exhibit this behavior. The increase in the precipitation temperature of the precursor is beneficial for the refinement and homogenization of the In2O3 powder, but an abnormal grain growth occurs when the temperature is too high. In addition, at a calcination temperature of 350 °C, the In2O3 powder crystallization is incomplete, and In(OH)3 is observed in the powder. With the increase in the calcination temperature, the average grain size rapidly increases from 47.68 nm (700 °C) to 1250 nm (1400 °C). The dependence of the kinetic index of the growth process on the calcination temperature exhibits an opposite trend with respect to that of the growth rate. At a calcination temperature of 1050 °C, the kinetic index is the smallest (n = 3.96), and the activation energy increases suddenly, while the grain growth rate is the highest (the holding time increases from 1 to 7 h, and the grains grow by 61.64 %).

Generation of beam plasma near a dielectric target irradiated by a pulsed large-radius electron beam in the forevacuum pressure range

We have investigated generation of beam plasma near a dielectric (ceramic) target irradiated by a pulsed large-radius electron beam in the forevacuum pressure range 3–15 Pa. The electron beam was accelerated with voltage up to 8 kV. Under a certain threshold accelerating voltage increase in the plasma density was observed near the dielectric target as compared with beam plasma density without the target. A decrease in gas pressure leads to smaller value of this threshold voltage. The observed dependencies are apparently caused by two factors: secondary electrons being emitted from the ceramic target and charging of surface of the ceramic target by the e-beam. The secondary electrons, emitted from the ceramic target, provide “additional” ionization of the gas. The charge on the dielectric target surface creates a field that accelerates the slow secondary electrons, which provides an increase in plasma density near the ceramic target. The negative charge on the target slows down the beam electrons, and thus increases total ionization cross section of gas by electron impact. The value of negative charge on the dielectric surface increases with decreasing gas pressure.

Structure and properties of Mo–Hf–Si–B coatings obtained by magnetron sputtering using MoSiB/Hf mosaic target

Mo–Si–B and Mo–Hf–Si–B coatings were produced by magnetron sputtering of a MoSiB ceramic target equipped with 2 or 4 Hf segments. Their structure and composition were studied by scanning electron microscopy, energy dispersive spectro scopy, X-ray diffraction analysis, and Raman spectroscopy. Mechanical properties were determined by nanoindentation at a load of 4 N. The crack resistance of coatings was studied on a microhardness tester at loads of 0.25–1.0 N. The oxidation kinetics was studied at 1000 °C in air with a total exposure of 300 min. The heat resistance of coatings was determined as a result of short-term annealing at 1500 °C. Electrochemical tests were carried out by voltammetry in the 1N H2SO4 solution. The results showed that the Mo–Si–B coating and Mo–Hf–Si–B coating obtained using 2 Hf segments feature by a columnar structure. The use of 4Hf segments in coating deposition led to an increase in density and suppression of the undesirable columnar structure formation. It was shown that hafnium introduction into the coating composition increases the growth rate by 20% and reduces the grain size of the main component of the h-MoSi2 phase by an order of magnitude, while simultaneously promoting HfB2 formation. Maximum hardness (27 GPa), Young’s modulus (370 GPa) and elastic recovery (62 %) were achieved for the Mo-Si-B coating. The hardness of coatings obtained using 2 and 4 Hf segments decreases by 1.9 and 1.6 times, respectively. During the Mo–Si–B and Mo–Hf–Si–B (2Hf) coating microindentation, radial cracking was observed. The sample obtained with the maximum concentration of hafnium featured by the best crack resistance. Electrochemical tests showed that the corrosion resistance of coatings increases in the Mo–Hf–Si–B (2Hf) → Mo–Si–B → Mo–Hf–Si–B (4Hf) series. All coatings showed good oxidation resistance at 1000 and 1500 °C. However, coating delamination areas were observed on the surface of Mo–Si–B and Mo–Hf–Si–B (2Hf) samples. The Mo–Hf–Si–B (4Hf) coating showed a lower oxide layer thickness and better oxidation resistance due to the dense SiO2 + HfOх protective layer formation.

Performance and electrochemical evolution of (Zn0.4Ni0.6)0.95Li0.05O thin film for Li-ion storage electrode

To improve the electrochemical performance of thin films based on Zn0.4Ni0.6O (ZNO) solid solution compound (SSC), Li-decorated ZNO [(Zn0.4Ni0.6)0.95Li0.05O, ZNLO] SSC was designed in this work. ZNO and ZNLO nanostructured thin films were prepared by RF magnetron sputtering with related lab-made ceramic targets. Phase composition, element valences, microstructure, electrochemical properties and electrochemically-induced phase evolution of the thin films were investigated. The cells assembled with ZNLO thin films as electrode deliver high reversible specific capacity of 773 mAh g−1 at 200 mA g−1 after 200 cycles, which is extremely superior to that of the ZNO thin film (363 mAh g−1). ZNLO thin film shows a high rate performance with specific capacity of 511 mAh g−1 at 1000 mA g−1 even after 750 cycles. The electrochemically induced phase evolution was studied by transmission electron microscopy, and the results revealed that nearly complete redox conversions of Zn-Ni-O ↔ Ni/Zn and ZnO ↔ Zn took place in ZNLO thin films electrode. The high electrochemical performance owes to the enhanced electrical conductivity of thin film doped with Li-ion and nanostructured characteristics of thin film that provide high specific surface and redox conversion processes.

Oxygen-injection-dependent nonlinear absorption of MoS2 colloidal particles fabricated by laser ablation in liquid conditions

A series of colloidal solutions were obtained by pulsed laser ablation (PLA) of MoS2 ceramic target in water with varying ambient conditions. The results show that the oxygen-injection affects lowering the grain orientation of MoS2 and improving the monodispersion and plasmonic absorption at the range of 700–1200 nm. The nonlinear absorption (NLA) performance of the oxygen-injection samples is significantly enhanced with the increased oxygen compared with that of the non-oxygen-injection sample. Furthermore, the synergistic effects of electromagnetic enhancement and charge transfer were demonstrated to be the main reason for the improvement of NLA performance.

Laser Ablation of NiFe2O4 and CoFe2O4 Nanoparticles.

Pulsed laser ablation in liquids was utilized to prepare NiFe2O4 (NFO) and CoFe2O4 (CFO) nanoparticles from ceramic targets. The morphology, crystallinity, composition, and particle size distribution of the colloids were investigated. We were able to identify decomposition products formed during the laser ablation process in water. Attempts to fractionate the nanoparticles using the high-gradient magnetic separation method were performed. The nanoparticles with crystallite sizes in the range of 5–100 nm possess superparamagnetic behavior and approximately 20 Am2/kg magnetization at room temperature. Their ability to absorb light in the visible range makes them potential candidates for catalysis applications in chemical reactions and in biomedicine.

Failure and fragmentation of ceramic target with varying geometric configuration under ballistic impact

The failure and fragmentation of monolithic bare alumina 99.5% ceramic target and energy dissipation of steel 4340 projectile have been studied in a series of ballistic experiments carried out, with the incidence velocities in a range, 122–290 m/s. The velocity drop and energy dissipation increased with incidence velocity for 10 mm thick target with damage zone extended upon the whole area of rear face at higher velocities. The ballistic results obtained with the 10 mm thick target have been compared with the ballistic performance of the 5 mm thick target used in a previous study to explore the effects of target thickness on the failure mechanism. A model for the residual velocity of projectile after perforation of the single layered ceramic target has been developed based on the Lambert Jonas model by using the experimental data available for 5 mm and 10 mm thick alumina 99.5% target against 10.9 mm projectile. The residual velocities and damage patterns were reproduced with a reasonable amount of accuracy by a three-dimensional finite element model developed on commercial ABAQUS/CAE. The effect of obliquity and projectile diameter to target thickness ratio (D/T) on ballistic performance has been determined by the numerical simulation model with impact velocity in a range of 300–500 m/s. A spatial variation of ejected fragments velocity at different time steps was plotted to develop a velocity profile for the ceramic fragments coming out of the target. A semi-empirical model has been proposed for residual velocity after perforation of a monolithic ceramic target, relating to the incidence velocity and projectile diameter to target thickness ratio. The monolithic ceramic targets have been investigated for a comparative assessment of energy dissipation by the ceramic layer to eventually design an efficient front layer of a ceramic based composite armour in future studies.

Ion Composition of the Beam Plasma Generated by Electron-Beam Evaporation of Metals and Ceramic in the Forevacuum Range of Pressure

We present the results of measurements of the ion composition of the plasma generated by an accelerated electron beam in the forevacuum pressure range. It has been found that the main contribution to ionization processes comes from beam electrons. It has been shown that, during the electron-beam evaporation of metal or ceramic targets, the number of ions evaporated from the materials in the beam plasma significantly exceeds the number of ions produced from the residual atmosphere and admitted gases. Together, electron beams and beam-produced plasma can catalyze the processes of coatings deposition or modification of the surface layer of the samples.

Evaluation of Steel and Tungsten Carbide Cobalt (WC 8Co) 5.56 x 45 mm Caliber Projectile Penetration into Silicon Carbide (SiC) Experiment and Numerical Simulation

This study aims to evaluate WC-8Co as a substitution material in a standard steel core projectile commercially produced by PT Pindad (Persero). The enhanced performance of 5.56 x 45-millimeter ammunition after the addition of WC-8Co hard metal was evaluated in terms of penetration into a silicon carbide (SiC) target. Numerical simulations and analysis of the ballistic impact of WC-8Co on ceramic targets were verified by experimental data. The results show that front core substitution in SS109 bullets from steel (Pindad standard) to WC-8Co resulted in 1.5 times greater DoP. Although projectiles with steel (Pindad standard) as the front core have a muzzle velocity higher than those using WC-8Co, they have a lower kinetic energy than the latter. In addition, WC-8Co cemented carbides also displayed higher crater and residual velocity on SiC targets; around 1.8 and 1.3 times higher, respectively. These findings demonstrate the potential use of WC-8Co for development as front core material to improve the penetration of projectiles into ceramic armour.

In-Zn-Sn-O thin film based transistor with high-k HfO2 dielectric

Indium zinc tin oxide (IZTO) semiconducting thin films have been investigated as active channel layers for thin-film transistor (TFT) applications. The IZTO layer was deposited by radio frequency magnetron sputtering (RF-MS) using a sintered IZTO ceramic target with an In:Zn:Sn metal atomic ratio of 40:50:10 on the HfO2 layer either deposited using an atomic layer deposition (ALD) or RF-MS. The annealing treatments after IZTO and HfO2 film depositions were performed in air using a tube furnace and in an oxygen atmosphere using rapid thermal annealing at 400 °C, respectively. Optical transparency measured by UV-Vis spectroscopy showed that the HfO2 films deposited by either RF-MS or ALD were transparent in the visible region and had a similar band gap energy of about 4.9 eV. Electrical characteristics of IZTO based TFT were comparatively evaluated for the samples with IZTO/ALD or RF-MS HfO2/n++-Si structure. The IZTO TFT sample with 60 nm-thick HfO2 deposited by ALD had an on/off current ratio value of 7.0 × 106 and a field-effect mobility value of 6.2 cm2/Vs, which was superior to that with RF-MS deposited HfO2.

Electron-beam heating of ceramics to moderate temperature at fore-vacuum pressure

We have studied the electron-beam heating of ceramic targets (AlN, ZrO2, and Al2O3) in the fore-vacuum pressure range (2–5 Pa) to temperatures below their phase transformation temperatures (melting, evaporation; < 1700 0C). It is shown that in this temperature range, conductive heat transfer through the lower face plays a dominant role in the thermal balance of the ceramic target; heat transfer by thermal conduction through the gas, and by thermal radiation play no significant role in heat removal from the target. Mass-to-charge analysis of the ion composition of the beam plasma, generated by the electron beam itself, shows that even at these moderate temperatures, intense sublimation of low melting point volatile components of the ceramic target occurs. Depositing on the substrate surface, these components may negatively affect the coating parameters and properties. Our investigations indicate the necessity of taking special measures to minimize the effect of ceramic target volatile components prior to their intense evaporation during the deposition of protective and functional coatings.

The effect of RF plasma power on remote plasma sputtered AZO thin films

Aluminium-doped ZnO (AZO) thin films were deposited by remote plasma sputtering of a ZnO:Al2O3 98:2 wt% ceramic target in a pulsed DC configuration. The target power was kept constant at 445 W and the RF plasma power was varied between 0.5 and 2.5 kW. The as-deposited AZO thin films exhibited an optimum resistivity of 6.35 × 10−4 Ω·cm and optical transmittance of 92% at a RF plasma power of 1.5 kW. The thin film microstructure, chemical composition, and residual stress were investigated using SEM, RBS, XPS and XRD. Accurate determination of the chemical composition and correct interpretation of GIXRD data for AZO thin films are a particular focus of this work. The AZO layer thickness was 500–700 nm and Al content in the range of 2.3–3.0 at.%, determined by RBS. The AZO thin films exhibited a strong (002) preferential orientation and grain sizes between 70 and 110 nm. The (103) peak intensity enhancement in GIXRD is proven to be a result of the strong (002) preferential orientation and GIXRD geometrical configuration rather than a change in the crystallite orientation at the surface. XPS depth profiles show preferential sputtering of O and Al using a 500 eV Ar+ beam, which can be reduced, but not eradicated using an 8 keV Ar150+ beam. The preferential sputtering can be successfully modelled using the simulation software TRIDYN. A plasma power of 1.5 kW corresponds to a highly ionised plasma and various microstructural and compositional factors have all contributed to the optimum low resistivity occurring at this plasma power. The grain size exhibits a maximum in the 1.25–1.5 kW range and there is improved (002) orientation, minimising grain boundary scattering. The highest carrier concentration and mobility was observed at the plasma power of 1.5 kW which may be associated with the maximum in the aluminium doping concentration (3.0 at.%). The lowest residual stress is also observed at 1.5 kW.

Ferroelectricity Improvement in Ultra‐Thin Hf0.5Zr0.5O2Capacitors by the Insertion of a Ti Interfacial Layer

The effect at the nanoscale of a Ti interfacial layer on the performances of TiN/HfZrO/TiN capacitors is reported. Ferroelectric hafnium zirconium oxide (HZO) is synthesized by magnetron sputtering of a ceramic target. Titanium nitride top and bottom electrodes are grown by reactive magnetron sputtering. The insertion of an ultra‐thin Ti layer at the top electrode/HZO interface impacts the crystalline phase and the electrical properties of the ferroelectric HZO. Following post‐deposition annealing, the Ti layer is oxidized and becomes titanium oxide. Compositional and structural characterization is performed using glancing incidence X‐Ray diffraction and electron energy‐loss spectroscopy. The TiOzlayer is clearly distinguishable at the top electrode/HZO interface. Electrical characterization is conducted by positive‐up‐negative‐down (PUND) technique. The remnant polarization reaches a maximum value of for 6 nm thick HZO. The results are discussed in the framework of structural, compositional, and physical properties of the electrode/HZO interfaces and their effect on the electrical performances of thin HZO‐based junctions, which could subsequently be considered for the demonstration of synaptic learning mechanisms for neuromorphic applications.

Microstructure and properties of bilayered B4C-based ceramics

Bilayered B4C-based ceramics were obtained by hot-pressing. Microstructure, mechanical and ballistic properties of the bilayered ceramics were investigated. One layer was obtained upon addition of Ti and C to the hard B4C matrix, the newly formed TiB2 phase uniformly distributed in the matrix. The other layer included variable amounts of Ti3SiC2, equal to 10, 20, 30, 40 wt%, and the B4C-SiC matrix in a fixed weight ratio of 7:3. The amount of TiB2 and SiC phases, deriving from Ti3SiC2 decomposition upon sintering, increased with increasing the Ti3SiC2 content. The flexural strength and fracture toughness of bilayered ceramics both increased with increasing the Ti3SiC2 content from 10 to 40 wt%. Ballistic testing showed that the B4C-based ceramic target containing 30 wt% Ti3SiC2 broken into pieces upon being impacted by a 12.7 mm armor-piercing incendiary (API) projectile, and effectively consumed the bullet energy and protected the backing plate from serious damage.