Amorphous SiO2 Phase Research Articles

Silica Coating of Nickel–Iron Nanocomposite by Chemical Reduction Method

The study of magnetic nanostructures is interesting because of its applications. Some of them are the development of magnetic refrigerators, ferrofluids, drug delivery systems, fabrication of devices with giant magnetoresistance effects, and high-frequency transformers. The physical and chemical properties of metal changes due to silica coating. The interaction potential can be manipulated using surface coatings and also the particle shape can be controlled. Nanoparticles with a proper surface coating are of interest for several other applications in optoelectronic devices and in the biomedical field. Thus, developing a new synthetic route for these particles and investigating the stability of magnetic materials are of great importance. Silica coating improves the chemical stability and electrical resistivity of the material. In this study, Ni3Fe (core) nanoparticles were prepared and the silica shell for this core was synthesized. The as-prepared X-ray diffraction (XRD) patterns and 300∘C annealed sample of Ni3Fe/SiO2 shows a characteristic hump in the low angle range confirming the presence of amorphous cristobalite phase of SiO2. The size of the Ni3Fe cluster in the Ni3Fe/SiO2 composite was estimated to be 8[Formula: see text]nm and 9[Formula: see text]nm, respectively, for the as-prepared and annealed samples. Vibrating sample magnetometer (VSM) measurements show the Ni3Fe to silica ratio to be 59:41. A small decrease in the coercivity value, is probably due to morphological changes associated with the coating. Scanning electron microscope (SEM) studies of the as-prepared and annealed Ni3Fe/SiO2 powder particles are of flowerlike morphology and in agglomeration. The impedance spectra were found at room temperature for the as-prepared samples.

Porous Si/Ca-Si-O nanocomposite lithium storage materials by calciothermic reduction of Si with CaH2

Silicon monoxide (SiO)-based anode materials are one of the most intensively investigated class of materials for use as high-capacity anodes in lithium-ion batteries. However, their low initial Coulombic efficiency (ICE), resulting from the irreversible electrochemical reaction of the amorphous SiO2 (a-SiO2) phase in the SiO, restricts the wide-spread adoption of SiO-based anode materials in lithium-ion batteries. Pre-emptive formation of an irreversible phase that converts a-SiO2 to a non-reactive state with lithium prior to cell assembly has received much attention for enhancing ICE. However, this process has the drawback of not ensuring long-term cycle performance. Herein, the pre-emptive formation of irreversible phase combined with the high-energy mechanical milling (HEMM) process is proposed to simultaneously improve both the ICE and long-term cycle performance. The resulting porous Si/Ca-Si-O nanocomposite electrode exhibits an impressive ICE of 86.4 % and maintains 55 % of its capacity over 200 cycles. The key factor in the significant ICE improvement is the irreversible Ca-Si-O phase, which is formed by the calciothermic reduction of Si with CaH2. In addition, the microstructural changes induced by the HEMM process effectively mitigate the volume expansion of Si during cycling, resulting in improved long-term cycle stability.

Multilayer laminated Cu coil/CaO–Li2O–B2O3–SiO2 glass-ceramic preparation via a novel insulation packaging strategy for flat wire motor applications

A new insulation packaging strategy for the stator windings of flat wire motors based on LTCC technology was studied for the first time. The study aimed to replace traditional plastic packaging methods and avoid aging issues by fabricating a novel multilayer laminated Cu coil/CaO–Li2O–B2O3–SiO2 glass-ceramic structure. The analysis of the interface microstructure of the laminated structure revealed that the CaO–Li2O–B2O3–SiO2 glass-ceramic matrix consisted of a crystalline phase of CaSiO3 and an amorphous phase of SiO2. The interface between the Cu coil and CaO–Li2O–B2O3–SiO2 glass-ceramic exhibited good bonding with no formation of secondary phases. Additionally, the strong bonding between the Cu coil and CaO–Li2O–B2O3–SiO2 glass-ceramic was attributed to the diffusion of Cu atoms at the interface. The novel multilayer laminated structure based on LTCC technology proposed in this study can help achieve high-reliability insulation packaging for the stator windings of future high-power density and miniaturized flat wire motors.

Preparation of La2Zr2O7 composite SiO2 aerogels and their fiber-reinforced materials for thermal insulation applications

Lanthanum zirconate (La2Zr2O7) aerogel, with its unique pyrochlore structure, is extensively utilized in thermal insulation owing to its nanopore formation. Nevertheless, the single-phase La2Zr2O7 aerogels have drawbacks of being tough to mold, having a structure that can collapse at high temperatures. This study employed the epoxide sol-gel method to prepare mesoporous aerogels with complete shapes, low densities, and high specific surface areas consisting of La2Zr2O7 composite SiO2 (LZS). Meanwhile, the formed SiO2 amorphous phase can inhibit the growth of pyrochlore crystals and improve the thermal stability of the material. When the amount of SiO2 reached 10 % (LZS10), its density was 0.094+0.006 g/cm3, and the surface area was 88.7 m2/g with 24 % pore volume retention after heat treatment at 1000 °C, showing excellent heat resistance. Quartz fiber reinforced LZS10 aerogel composites (FLZS10) with a thickness of 5 mm were also prepared to study their thermal insulation properties in practical applications. Among them, FLZS10 exhibits a thermal conductivity of 0.057±0.002 W·m−1·K−1 after heat treatment at 1000 °C. When one side of FLZS10 is exposed to a flame at 1000 °C, the temperature of the opposite side is only 284.7 °C, indicating an outstanding thermal insulation performance.

Endothermic Dehydrogenation-Driven Preventive Magnesiation of Sio by Magnesium Hydride for High-Performance Sio-Based Lithium Storage Materials

Silicon monoxide (SiO)-based materials have gained much attention as high-capacity lithium storage materials because of their superior cycle performance. However, low initial Coulombic efficiency (ICE) of SiO derived from the irreversible electrochemical reaction of the amorphous SiO2 phase in SiO makes wide use of the SiO-based anode materials in lithium-ion batteries challenging. Magnesiation of SiO is one of the promising solutions to improve ICE of SiO-based anode materials. Here, we propose an endothermic dehydrogenation-driven magnesiation of SiO by employing MgH2 to improve both ICE and cycle performance. The resulting Si/Mg2SiO4 nanocomposite material showed much-improved ICE of 89.5% and long-term cycle performance for over 300 cycles compared to the homologue prepared by the magnesiation of SiO using Mg and pristine SiO. High-resolution transmission electron microscopy with thermogravimetry−differential scanning calorimetry revealed that the endothermic dehydrogenation of MgH2 mitigates the rapid temperature rise during magnesiation of SiO, thereby inhibiting the increase of Si domain size in the resulting Si/Mg2SiO4 nanocomposite. Detailed material characterization and electrochemical analysis of Si/Mg2SiO4 nanocomposite materials will be discussed in this presentation.

Synthesis and Characterization of Silicon–Carbon Powder and Its Resistance to Electron Irradiation

The issue of crystallization of silicon oxide at low temperatures is a topical issue for the electronics of the future. Organosilicon oligomers and polymers are “ideal” sources for obtaining ultrapure silicon ceramics and silicon nanoparticles. This paper presents the results of the synthesis of highly dispersed silicon-carbon powder from an organohydrosiloxane oligomer and the method for increasing its crystallinity at low temperatures. The diffraction pattern of the resulting powder corresponds to the amorphous–crystalline state of the components in this material, as evidenced by two intense and broadened amorphous halos in the region of Bragg angles 2θ = 7–11° and 18–25°. The resulting silicon–carbon powder was subjected to electron irradiation (E = 10 MeV; D = 106–107 Gy). This paper presents the data on the changes in powder properties via IR-Fourier spectroscopy, X-ray phase analysis, and scanning electron microscopy. Irradiation with fast electrons with an absorbed dose of 106 Gy leads to a slight crystallization of the amorphous SiO2 phase. An increase in the absorbed dose of fast electrons from D = 106 to D = 107 Gy leads to the opposite effect. An amorphization of silica is observed. This study showed the possibility of the crystallization of a silicon–carbon powder without a significant increase in temperature, acting only with electron irradiation. It is necessary to continue further research on expanding the boundaries of the optimal doses of absorbed radiation from fast electrons in order to achieve the maximum effect of the crystallization of silicon–carbon powder.

Interfacial reaction in Al2O3 fiber reinforced TiAl matrix composite

Al2O3 short fiber (containing 28 vol.% SiO2) reinforced TiAl matrix composite was prepared by spark plasma sintering (SPS). The interfacial reaction mechanism was clarified by thermodynamic and kinetic analyses. The main interfacial phase was Ti5Si3, originated from Ti element of TiAl matrix and Si element of Al2O3 fiber. The activation energy of interfacial layer was 285.1 kJ/mol. In addition, the matrix around the interfacial region was composed of γ-TiAl phase due to the consumption of Ti element in the process of interfacial reaction. However, the formation of mullite phase occurred in the heat-treated Al2O3 fiber and as-sintered composite due to the chemical reaction between γ-Al2O3 and amorphous SiO2 phases.

Growth characteristics of scanning micro-arc oxidation coating on Ti6Al4V alloy

ABSTRACT In this study, the ceramic coating was prepared on Ti6Al4V alloy by scanning micro-arc oxidation (SMAO). The growth features of SMAO coating were investigated by combining the voltage and discharge variation. The result shows that a higher working voltage is obtained during SMAO treatment owing to additional resistance from the electrolyte column. As the SMAO goes on, the discharge region moves to the electrolyte column edge, exhibiting an annular shape. The current density with Gaussian distribution is observed between the stainless-steel tube (cathode) and titanium substrate (anode), which causes the SMAO coating to show a higher thickness in the middle and lower on both sides. Similar to traditional MAO, the SMAO coating has an enhancement in the thickness, pore size and Si content with increasing oxidation time, but coating degradation occurs in the later stage of SMAO. The SMAO coating mainly consists of amorphous SiO2, rutile and anatase phases.

In-situ scanning transmission electron microscopy study of Al-amorphous SiO2 layer-SiC interface

Here, we present a comprehensive study on atomic-scale in-situ biasing/heating scanning transmission electron microscopy ((S)TEM) of Al-amorphous SiO2–SiC interface. The investigation includes electrical, chemical, and structural analysis of the interface at different temperatures (25–600 °C). The results show that at ~ 500 °C the electrical (three-orders of magnitude resistivity drop), chemical (dissolution of SiO2 amorphous layer), and microstructural features (e.g. formation of Al2O3, Si and Al4C3) of the interface start to change. According to the results, amorphous SiO2 dissolves in Al, leading to formation of α-Al2O3 and Si within the Al. In contrast, elemental interdiffusion (Al3+ ⇄ Si4+) between Al and SiC occurs resulting in formation of Al4C3. From the results, we can infer that reaction mechanism between Al and crystalline SiC is different with that between Al and SiO2 amorphous phase. It is believed that structural similarities between SiC and Al4C3 play an important role in paving the way for elemental interdiffusion.

Economical construction of spin coater for the fabrication of dielectric reflectors

Spin-coating is a versatile technique that utilizes only a few drops of the synthesized gel as an empirical method to fabricate the appropriate thin films. However, the economical design of a spin coater is always ground-breaking research. This paper reports the development of a spin coater using low-cost components such as SMPS, a brushless D.C. motor, and a proximity sensor. All of these components were contained in a stainless-steel unit and the entire equipment cost only 63 dollars, making it significantly less expensive than a standard one. The constructed spin coater was tested by fabricating three-and-five multilayer structures of TiO2/SiO2 with their respective sol–gel synthesized gels, and an X-ray diffraction (XRD) studies on the structures revealed a broad peak at 25°, confirming the existence of anatase TiO2 (titania) phase and non-crystalline amorphous phase of SiO2 (silica). Fourier transform infrared (FT-IR) spectroscopy endorsed the presence of titania and silica functional linkages by revealing vibrational bonds at 736 and 612 cm−1, respectively. Field emission scanning electron microscopy (FESEM) in cross-sectional mode on the three- and five-multilayer titania and silica structures evidenced the presence of titania and silica layers with intense (bright) and gloomy (dark) nature respectively. Finally, the reflectance study of the multilayer structures utilising ultraviolet–visible and near-infrared (UV–vis-NIR) spectroscopic showed 68 % and 100 % reflectance in the near-infrared region respectively, and demonstrated to be a dielectric reflector.

Endothermic Dehydrogenation-Driven Preventive Magnesiation of SiO for High-Performance Lithium Storage Materials.

Silicon monoxide (SiO)-based materials have gained much attention as high-capacity lithium storage materials based on their high capacity and stable capacity retention. However, low initial Coulombic efficiency associated with the irreversible electrochemical reaction of the amorphous SiO2 phase in SiO inhibits the wide usage of SiO-based anode materials for lithium-ion batteries. Magnesiation of SiO is one of the most promising solutions to improve the initial efficiency of SiO-based anode materials. Herein, we demonstrate that endothermic dehydrogenation-driven magnesiation of SiO employing MgH2 enhanced the initial Coulombic efficiency of 89.5% with much improved long-term cycle performance over 300 cycles compared to the homologue prepared by magnesiation of SiO with Mg and pristine SiO. High-resolution transmission electron microscopy with thermogravimetry-differential scanning calorimetry revealed that the endothermic dehydrogenation of MgH2 suppressed the sudden temperature rise during magnesiation of SiO, thereby inhibiting the coarsening of the active Si phase in the resulting Si/Mg2SiO4 nanocomposite.

Sulfuric Acid-Activated Silica Gel as a Potential Solid Acid Catalyst

The conversion of silica gels into sulfated silicas (SO4/SiO2) have been carried out. The sulfation process of the catalysts was carried out by impregnation of sulfuric acids at concentrations of 1; 2; and 3 M and calcination temperatures of 500, 600, and 700 °C. Sulfation with 2 M H2SO4 and calcination temperature of 600 °C (SS2-600) produced a catalyst with the highest acidity value (5.13 mmol NH3 g-1). XRD analysis showed the formation of amorphous SiO2 phase, whereas SSA analysis showed that the SS2-600 catalyst had a mesoporous structure with a surface area of 147.728 m2/g, a total pore volume of 0.25 mL/g and a pore diameter of 6.439 nm. Characterization results show that sulfated silica gels have potency as solid acid catalysts.

Transparent Dielectric TiO2/SiO2 Coatings for Thermal Shielding and Self-Cleaning Applications

The economical fabrication of one-dimensional dielectric reflectors using the hybrid sol-gel spin coating process is significant compared to sophisticated chemical and physical vapor deposition techniques. In this work, we opted for alternate layers of TiO2 and SiO2 films to fabricate near-infrared dielectric reflectors owing to their high refractive index contrast and easy tunability of the reflection window in the desired spectral range. X-ray diffraction (XRD) studies of the monolayer TiO2 and SiO2 confirmed the existence of anatase-TiO2 and amorphous-SiO2 phases, respectively. Spectroscopic ellipsometry investigation of TiO2 and SiO2 films revealed the refractive indices of 2.6 and 1.5, respectively. The field-emission scanning electron microscopy (FESEM) analyses evidenced the fabrication of 2.5 stacks/bilayers of TiO2/SiO2 (TiO2/SiO2)2.5S. The reflectance measurement demonstrated 100% reflection in the near-infrared region with its center wavelength of 833 nm. In addition, we have examined the water contact angle of various samples using the sessile drop technique, and 2.5 stacks-based reflector showed its lowest contact angle of 29.3o, which suggests its anti-fogging and self-cleaning applications.

Toward understanding the activation and hydration mechanisms of composite activated coal gangue geopolymer

The feasibility of coal gangue as primary cementitious material was experimentally investigated in this paper. An Orthogonal method was employed to investigate the optimum activation strategy for coal gangue-based geopolymer. Experiment parameters included the modulus of sodium silicate (M), alkali content (A), calcination temperature (T), holding time (H), and water-to-binder ratio (W/B). Meanwhile, the phase transitions, chemical compositions, and microstructure evolution were investigated by supplementary techniques, such as ESEM, XRD, and FTIR. Experimental results indicated that the hydration reactivity of coal gangue was markedly enhanced. And the formations of high contents of amorphous SiO2 and Al2O3 phases are the critical factors for the high reactivity, which highly depends on the proper calcination temperature and holding time. The hydration productions of alkali-activated coal gangue, mainly N-A-S-H gels, can rapidly precipitate around the unreacted particles and fill the existing cavities. Meanwhile, the average surface area, diameter, and porosity considerably declined with the hydration degree of geopolymer. In summary, coal gangue can be viewed as a new eco-friendly cementitious material via the proposed composite activation strategy.

Investigation of dye removal ability and reusability of green and sustainable silica and carbon-silica hybrid aerogels prepared from paddy waste ash

In this study, the paddy waste ash (PA) was utilized for producing carbon-silica hybrid (PCS) and silica (PS) aerogels. X-ray fluorescence (XRF) spectrometer analysis revealed a high silica content in PA. Crystalline SiO2-cristobalite structure was observed in the X-ray diffraction (XRD) patterns of PA. As expected, the PCS and PS samples exhibited an amorphous SiO2 phase. The pore enlargement and structural improvement after aerogel synthesis were determined using a N2 adsorption-desorption analysis. The specific surface area of the PCS and PS samples were found to be 519 and 652 m2/g, respectively. From the zeta potential results, the points of zero charge (pHPZC) of the samples were found below “2” except for the PCS sample (pHPZC = 2.08). In the first stage of the Remazol Turquoise GN (RTGN) adsorption experiments, the effect of initial pH (2–8) was examined for PA, PCS, and PS sorbents. The highest dye removal value of the PCS sorbent was 61% at pH = 2, while this value was 17.9% and 21.4% for PS and PA sorbents, respectively. The removal percentage curve exhibited a similar trend to the zeta potential curve of the samples. In the experiments conducted with different amounts of sorbents, the dye removal percentage increased with increasing amounts of sorbents. The experimental results and thermodynamic calculations showed that the RTGN adsorption onto PCS was an endothermic process. Pseudo-first order, pseudo-second order and intra-particle diffusion equations were applied to determine the adsorption kinetics of RTGN onto PCS, and it was found that the experimental data was well-fitted to the pseudo-second order kinetic model. The Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) adsorption isotherm models were used to define the adsorption mechanism of RTGN onto PCS. The Freundlich and Langmuir isotherm models were in agreement with our experimental data and it was concluded that RTGN adsorption on PCS surface occurred both as single layer and multi-layer, as well as took place on heterogeneous and homogeneous surfaces. Characterization analyses were conducted for the PCS sorbent after use to understand the structural changes after dye removal. The regeneration and reusability of the PCS sorbent were investigated and it was found that it preserved its initial removal ability by about 95% after four cycles. The dye removal percentage of PCS decreased by 28% after five cycles.

Diatomite – evaluation of physico-mechanical, chemical, mineralogical and thermal properties

Diatomite is one of the most intensively examined raw materials in the materials industry with a broad range of various applications. The diatomite sample, collected from Vitačevo plateau in the vicinity of Kavadarci, was fully characterized by means of physical-mechanical, chemical, XRPD, SEM, TEM, DTA/TGA and IR techniques. The physical-mechanical features pointed out to soft, light, white to gray rock with shell-like structure exhibiting compressive strength from 4.65–4.88 MPa in dry form, whereas the total porosity ranges 70–72% and the density is 2.06–2.09 g/cm3. The chemical analysis of the diatomite revealed that SiO2 content exceeds 91%. The results from the X-ray powder diffraction indicate predominant amorphous SiO2 phase associated with minor presence of crystalline quartz, muscovite, chlorites and plagioclase. The IR spectrum of the diatomite manifested characteristic bands for amorphous silica at 799 cm–1 and 1101 cm–1. DTA/TGA results display great thermal stability of the sample remaining amorphous up to 1050ºC whereas the SEM analysis determined the morphology, surface characteristics and the nanometric pores in the raw material. Thus, the studied diatomite is classified as a natural nanomaterial that is suitable for broad application in various construction materials, refractory ceramics, special oxide ceramics, and also finds potential use in filtering, adsorbent, catalysts, food and pharmaceutical industries.

Si Nanoparticles inside a Carbon Matrix As an Anode for Next Generation LIB

1. Introduction Lithium-ion batteries (LIB) are used in many applications such as cellular phones, mobile computers and electrical vehicles since they have high capacity and long cycle life. There is a continuing demand for advanced LIBs with higher energy density. However, graphite, conventional anode materials for commercial LIBs, are approaching their theoretical capacity limits. In this context, Si anodes have attracted much attention for the alternatives of graphite anodes because of their high capacity, low cost and environmental benignity. However, Si anodes suffer from drastic volume change and huge stress generation during the lithiation and delithiation process, which causes fracture of Si and deformation of the electrode. Such unfavorable phenomena arising from the severe volume change results in the poor cycle ability of Si anodes. These crucial problems hamper the direct utilization of Si anodes for next-generation LIBs.Amorphous SiO x (x<2) anodes have shown the cycle performance improvement since the amorphous structure and SiO2 phase serve as the buffer layer which suppresses the volume expansion during the lithiation delithiation process. However, the irreversible capacity of the first cycle is large due to the formation of inactive Li-Si-O phase from SiO2 phase. [1-2]Much research on composite anodes containing Si and graphite has been investigated, and improvement of the cycle performance of composite electrodes have been demonstrated. However, the amount of Si in the composite electrode is limited since there is a strong trade-off relationship between the capacity and the cycle performance in the composite electrode. [3-4]Recently, we have successfully synthesized Si nanoparticles inside a Carbon Matrix (SCM). Here, we show the electrochemical Li storage performance of SCM. 2. Experimental Synthesis of Si nanoparticles with Voids inside a Carbon Matrix (SCM) We synthesized SCM through chemical techniques. The cross-sectional SEM image of SCM is shown in Fig. 1. Si nanoparticles with voids inside the carbon matrix are observed. Electrode preparation SCM powder as active material, carbon powder as conductive additive and polyacrylate as binder at a mass ratio of 92:1:7 were mixed in water to form slurry. The slurry was coated onto Cu foil (10μm thickness) and dried at 90 ºC for 5 min, and then heated in vacuum at 100 ºC overnight. The electrode was punched into discs typically with a diameter of 13.8 mm. The weight of active material in the electrode is ranged from 3.0 to 4.0 mg. CR2032 cell preparation Coin type cell (CR2032) was assembled in the Ar-filled glove box. Li metal (Honjyou metal) was used as the counter electrode. Polypropylene was used as the separator. The liquid electrolyte used was 1.2 M LiPF6 in ethylene carbonate (EC)/diethyl carbonate (DEC) (1:1 vol %) with fluoroethylene carbonate (FEC) (2 vol %). 3. Results First charge –discharge curves of the SCM electrode with current rate of 0.1 C is shown in Fig. 2. During the first cycle, the electrode exhibited a reversible capacity of 680 mAhg-1 with an efficiency of 75.6 %. Cycle performance of the SCM electrode and shape of the SCM particle after cycling will be reported and discussed. 4. Reference [1] J. Yang et al. SiOx-based anodes for secondary lithium batteries. Solid State Ionics 152-153, 125-129 (2002).[2] M. N. Obrovac et al. Alloy Negative Electrodes for Li-Ion Batteries. Chem. Rev. 114, 11444−11502 (2014).[3] Y. liu et al. Silicon/carbon composites as anode materials for Li-ion batteries. Electrochem. Solid State Lett. 7 (10), A369-372 (2004).[4] U. Kasavajjula et al. Nano- and bulk-silicon-based insertion anodes for lithium-ion secondary cells. J. Power Sources 163, 1003-1039 (2007) Figure 1

Critical synthesis parameters of β-phase Zn2SiO4:Mn2+ phosphor and its metastability

The metastable β-phase Zn2SiO4:Mn2+ phosphor was successfully reproducible only under the following critical conditions: SiO2-rich stoichiometry, melting, and rapid cooling. The metastability of the β-phase was demonstrated through the phase transformation of the as-grown β-phase into the α-phase polymorph by reannealing and then slowly cooling. The β-phase showed yellow emission with a quantum efficiency of 65 %. The β-phase has less crystalline structure caged into amorphous SiO2 phase and the more widely diffused larger grain sizes like a hexagonal shape of a snowflake. It showed the less thermal quenching behavior due to its lower lattice vibration, as well as the longer decay time due to less Mn2+ pairs.

The electrochemical properties and reaction mechanism of orthorhombic Mn2SiO4 cathode for aqueous rechargeable zinc ion batteries

Manganese-based cathodes for aqueous rechargeable zinc ion batteries (ZIBS) are attracting extensive attention owing to high energy density, high safety of mild aqueous electrolyte, environmental friendly, facile battery assembly and low cost of sources materials. Here, a new manganese-based battery system for aqueous ZIBs by employed orthorhombic manganese silicate (Mn2SiO4) as cathode, Zn metal as anode, mild aqueous ZnSO4 + MnSO4 as electrolyte is reported for the first time. The Zn/Mn2SiO4 battery shows good Zn storage performance and can deliver reversible capacity of 154 mA h g−1 in the first cycle. Notably, the battery undergoes capacity deterioration in initial cycles, but exhibits superior cyclic stability after several cycles. A comprehensive study reveals the electrochemical reaction mechanism of this battery system is the irreversible phase transition from Mn2SiO4 to amorphous todorokite MnO2, amorphous SiO2 and crystalline phase occurs during the first charge, and followed by reversible conversion reaction between amorphous phase (todorokite MnO2 and SiO2) and crystalline phase (MnOOH, ZnxMnO2 and Zn2SiO4) in the subsequent cycles. Although the practical capacity and reaction mechanism needs to be clearly evaluated, this work could provide new insights into exploiting other advanced cathodes for aqueous rechargeable ZIBS.

Ru Underlayer Elimination for CoPt-Based Sputtered Tape With Perpendicular Recording Toward 330 TB per Cartridge Product

A sputtered tape that uses a CoPt-based granular recording layer was developed for practical application in the next generation of large-capacity magnetic tapes. 1) First, disk media were prepared by depositing films onto glass substrates using an inline disk sputter machine in which the substrates were stationary facing the target, and the ability to control the crystalline orientation, the magnetic isolation, and the magnetic anisotropy of the recording layer, which are the important functions of the underlayer, was investigated. As a result, it was found that the medium with Co60Cr40 (45 nm)/Co60Cr40-15 vol.% TiO2 (5 nm) as the underlayer has the same properties as the medium with the Ru underlayer. 2) Next, a sputtered magnetic tape with Co60Cr40 (25 nm)/Co60Cr40-SiO2 (25 nm) as the underlayer deposited on a polymer film was prepared using a roll-to-roll sputtering machine. The ability to control the crystalline orientation and magnetic isolation of the magnetic recording layer was evaluated, and from the results it was found that a magnetic film with a granular structure was formed on the sputtered magnetic tape in which the $c$ -axis of the magnetic crystal grains is oriented in the direction perpendicular to the film and the magnetic crystal grains are separated by the SiO2 amorphous phase. 3) Furthermore, when the recording properties of the sputtered magnetic tape with a Co60Cr40 (25 nm)/Co60Cr40-SiO2 (25 nm) underlayer were compared with those of a magnetic tape for a linear tape-open (LTO) format eighth-generation tape cartridge (LTO 8), it was confirmed that the broadband signal-to-noise ratio of the sputtered tape with a Co60Cr40/Co60Cr40-SiO2 underlayer is 4.2 dB higher than that of the LTO 8 tape at a linear density of 300 kfci.