Structure Of Amorphous Phase Research Articles

Enhanced Electrochemical Catalysis: Hydrogen Evolution Using Bimetallic Sulfides on Nickel Foam.

Hydrogen is considered clean energy with broad application prospects for the 21st century, and water electrolysis plays a crucial role in hydrogen production. However, economic limitations and large overpotential values hinder its development. In this study, we deposited nickel (Ni), iron (Fe), and sulfur (S) onto nickel foam (NF) using the constant potential method to form the Ni-S-Fe/NF catalyst, which exhibited an exceptionally low overpotential (31 mV) at a current density of -10 mA cm-2, and a Tafel slope of 75.1 mV dec-1 in 1 M sodium hydroxide. It showed a minor charge resistance (1.256 Ω). The amorphous phase structure and optimized catalyst composition promoted outstanding hydrogen evolution activity. This work offers valuable perspectives on the industrial application of hydrogen production.

Enhanced OER electrocatalyst performance by sulfur doping trimetallic compounds hybrid catalyst supported on reduced graphene oxide

Hydrogen evolution by electrolysis of water is an effective method to solve the energy problem, but the catalyst of oxygen evolution reaction is an effective measure to solve the slow kinetics of hydrogen production from electrolytic water. Therefore, an efficient electrocatalyst for oxygen evolution reaction is urgently needed to find. The Co-based trimetallic oxides has been prepared by using isopropyl alcohol and propan-1,3-diol as hydrothermal reaction environment and annealing at high temperature can enrich the types of active core materials of the catalyst. The sulphuration process forms the core-shell structures of crystalline and amorphous phases, and the heterogeneous interface between the crystalline and amorphous structures optimizes the electronic structure. Meanwhile, due to its excellent physical and chemical properties, not only does rGO provide a conductive substrate and promote carrier migration and high current response, but also effectively inhibits the aggregation of nanoparticles, so that the catalyst nanoparticles are uniformly dispersed and the active center is fully exposed, providing a way for oxygen release in the OER process. When Fe0.3Ni1Co2/S-C has been used as electrocatalytic for OER, the overpotential and Tafel slope were as low as 276 mV and 52.2 mV·dec−1 at 10 mA·cm−2 current density. With many improvements on transition metal catalysts, transition metal catalysts may be quickly replaced precious metal catalysts for large-scale use in electrolytic water.

Surface-engineered TiO2 nanoparticles incorporated Chitosan polymer membrane for seawater desalination: Fabrication, characterization, and performance evaluation

The effect of surface coating over titanium dioxide nanoparticles (TiO2-NPs) incorporated with chitosan (TiO2-NPs/chitosan) was evaluated as a reverse osmosis membrane (RO) for enhanced performance on seawater desalination. The impact of surface coating on the chitosan membrane performance in seawater reverse osmosis (SWRO) was investigated by altering the mass of TiO2-NPs (0.25 g and 0.5 g) used for the surface coating RO membrane. TiO2-NPs were applied to the membranes using a surface coating technique and dried to create a sturdy polymer structure. The characteristic of fabricated membranes shows the function group reflects on organic compounds from /chitosan membranes polymer (–OH, -CH, C=O, C-O-C, -CH3, C-O, and NH2). In addition, TiO2-NPs are expressed in the wavenumber range of 850-500 cm-1, which characterizes the presence of Ti-O-Ti bonds. Morphological and crystal analyses of TiO2-NPs incorporated in chitosan membrane show significantly smaller pores formed because TiO2-NPs are essential in the high permeability performance under the amorphous phase structure. Also, the high performance of fabricated membranes was evaluated against water flux and salt. Adding TiO2-NPs can decrease the water flux value by 23 L m-2 h-1 and increase salt rejection by 52.94%. In optimized pH, the seawater desalination had efficient recovery.

Structural, optical and mechanical properties of Ti-doped Ta2O5 films for PV glass covers

Ti doped Ta2O5 thin films (TTO) with uniform thickness were prepared on photovoltaic glass substrates by DC and RF magnetron co-sputtering with different target powers. The surface morphology and microstructure of the films were characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM). The composition of the films was analyzed by X-ray photoelectron spectroscopy. The optical parameters of the films were measured by UV–visible spectrophotometer. The hardness and Young 's modulus of the coating were tested by nanoindentation. XPS analysis shows that the main components of TTO films are TiO2 and Ta2O5. SEM and AFM results show that the surface of the TTO film is smooth and flat, with uniform elemental distribution and nanometer roughness. The SEM cross-sectional morphology shows that the TTO film presents a dense columnar structure growth. The TEM results show that the TTO films do not show bright diffraction rings and mainly exhibit an amorphous phase structure dominated by Ta2O5. The optical test results show that the maximum transmittance of TTO film can reach 94.59 %. The transmittance of TTO films shows a decreasing trend with increasing sputtering power of the target, while the opposite is true for reflectance and refractive index. The optical band gap of the TTO films is between 4.12 eV and 4.42 eV. The mechanical test results show that the hardness of the TTO film can reach up to 9.53 Gpa. The hardness of TTO film increases with the increase of target power. The H/E and H3/E2 values indicate that Ti doped Ta2O5 films are favourable for improving the resistance to plastic deformation of the films. Comprehensive analyses show that Ti doped Ta2O5 films can have both excellent optical and mechanical properties. TTO films can provide a valuable reference for the study of PV glass protective layer.

(AlCrMoTiNi)1-XNX high entropy ceramic with high hardness and toughness prepared by co-filtered cathodic vacuum arc deposition

High entropy ceramic (HEC) coatings have become candidates for new protective coating due to their high strength. However, the hardness - toughness balance of the ceramic coatings is still a difficult problem to solve. The strong nitride forming elements Al, Ti, Cr, Mo, and the non-nitride forming element Ni were selected as the components of the (AlCrMoTiNi)1-XNX HEC coatings to regulate the hardness and toughness. When x = 0 and 0.29, the composite structure of amorphous and metallic Ni phase is observed in these coatings. When x = 0.37, 0.40, and 0.45, the phase structure changes to the composite structure of nanoscale face-centered cubic (FCC) phase, metallic Ni, and amorphous phase. When x = 0.45, the maximum hardness of the HEC coating is 31.25 GPa, and it also has high toughness with a KIC value of 3.25 MPa m1/2. The HEC coating with high hardness and toughness also presents excellent wear resistance and corrosion resistance. Therefore, the (AlCrMoTiNi)0.55N0.45 HEC coating has potential as a protective coating applied in various areas.

Defect control and optical performance of yttrium orthovanadate nanocrystals via a facile pH-sensitive synthesis

Nanocrystalline YVO4 powders have been synthesized via a facile co-precipitation method, which has been investigated over the wide pH range from 4 to 13. XRD patterns indicated that the phase structure purity of the precipitation is influenced by the pH value. The reaction mechanism of YVO4 crystal was suggested to illustrate the development stages beginning with precipitates to form impure amorphous phase structures such as amorphous yttrium polyvanadate and hydrous Y(OH)3. SEM and TEM techniques were performed to observe the changes of the morphology and size by adjusting the pH conditions after YVO4 nanocrystals were sintered under ambient conditions at 600 °C for 2 h. Luminescence properties showed that the self-activated emission of YVO4 matrix material shows an obvious peak at 486 nm in the 400–650 nm wavelength range, attributing to the charge transfer in the vanadate groups. With decreasing the pH value, the diffuse reflectance spectra of YVO4 nanocrystals demonstrated that the energy gap Eg showed a red-shift trend mainly ascribed to the oxygen vacancies. Moreover, the luminescence emission intensity of YVO4 nanocrystals increases obviously after sintering treatment, which can be explained by the sintering-induced grain growth and improved surface band bending due to the dehydration or the removal of carbonate species. The findings of this study could provide new insights into the understanding of the reaction mechanism of YVO4 crystal with variable optical band gap and offer an opportunity for realizing tunable optical performance by defect structure regulation for laser and optoelectronics applications.

Femtosecond laser modification of vanadium dioxide for color display applications

Vanadium dioxide (VO2) has been one of the most significant functional materials for its prominent property change during phase transition. Here the modulation in crystallinity and morphology of VO2 thin film is achieved by femtosecond laser direct writing. Both the local crystallization from an amorphous phase and self-organized periodical structures are generated due to the well-controlled femtosecond laser energy deposition and controlled accumulation. The dynamic evolution of either the volumetric or surface nano-/micro-structure depends strongly on the femtosecond laser conditions, revealed by changes of the Raman bands and reflectance spectra at visible wavelengths. Based on the distinguishable color display performance of differently processed regions, a four-color-level image has been drawn on a VO2 thin film. This work proposes an elaborate “annealing by light” and optical property modulation method for the VO2, paving the way to producing complex integrated multi-functional devices for color display and data storage.

Microstructure evolution and mechanical properties of Al doped ta-C films prepared by filtered cathodic vacuum arc

Al-doped tetrahedral amorphous carbon (ta-C) films were prepared by filtered cathodic vacuum arc technique. Effect of Al content on the structure and properties of the ta-C film were systematically investigated. Results showed that Al content in films increased from 0 to 39.5 at. % as the Al target current altered from 0 to 2 A. Without Al doping, ta-C film mainly presented amorphous characteristic with disordered arrangement and compact structure. With a small amount of Al doping, the film maintained the amorphous phase structure, and Al atoms mainly existed in the carbon tetrahedral interstitial space in the form of solid solution. At high Al doping content, the formed Al nanoparticles embedded in the carbon matrix network. Meanwhile, the addition of Al could promote the graphitization of films. The residual stress of ta-C films decreased gradually with increase of Al content. Furthermore, the hardness and elastic modulus of films also decreased with increasing Al content. That's ascribed to the reduction of residual stress and graphitization of the carbon structure. In addition, the ta-C film with Al addition could effectively improve the friction and wear properties of films at both room and high temperature. The friction coefficient decreased with the increase of Al content at room temperature (RT). At 400 °C, the film containing 7.6 at. % Al obtained the lowest friction coefficient and wear rate, corresponding to the values of 0.29 and 12.3 × 10−8 mm3/N⋅m, respectively.

Growth mode and characterizations of electrodeposited Re thick films from aqueous solutions with additives on Cu (110) + (311) substrates

Rhenium (Re) thick films were electrodeposited on copper (Cu) substrates with (110) + (311) texture from aqueous solutions with additives of 2 g l−1 gelatin, 1 mM sodium lauryl sulfate, and 1 mM vanillin. The microstructure and morphology of the films with different thickness values were characterized by scanning electron microscopy and atomic force microcopy. The chemical composition and the crystallographic structure of the films were identified by energy dispersive spectroscopy and x-ray diffraction, respectively. Re thick films were obtained due to the synergistic effect of additives. The additives had a significant influence on electrodeposition of the films. The microstructure and growth mode of Re films were influenced by surface topography and orientation texture of the substrate. The deposition rate was about 0.064 mg min−1. Re thin films adhered well to the substrate with no evidence of delamination and cracking. However, the Re thick film was not stable, fine microcracks were present, and even delamination occurred in vacuum condition due to large residual stress in the deposits or the shrinkage from decomposition of Re hydrides in the vacuum environment. Re films consisted of an amorphous phase structure. The Re film had a high hardness of 349 ± 15 VHN and exhibited a Stranski–Krastanov growth mode.

Structural characteristics of radiation‐amorphized ZrSiO4:U,Th according to Raman spectroscopy of Boson peak

AbstractThe structure of the amorphous fraction and the tensile‐compressive stresses in amorphous‐crystalline radiation‐damaged zircon ZrSiO:U,Th depending on radiation dose and temperature (8–350 K) are investigated according to Raman spectroscopy of Boson peak for the first time. The Boson peak at 60–70 cm−1 associated with localized phonon states in the amorphous fraction ( ) is recorded at low temperatures ( K) for samples with and over the entire temperature range 8–350 K for . The wider localized states distribution in the latter case is considered as a sign of the amorphous phase structure evolution with an increase in radiation dose. The estimates of an atomic correlation radius based on the Ioffe–Regel criterion are similar to those in glasses, nm. The monotonic increase in value during heating of zircon with is governed by thermal expansion of the percolating amorphous fraction. The nonmonotonic variations of the value in zircon with is determined by the stresses in the amorphous fraction due to the mismatch in thermal expansion coefficient (CTE) and elastic moduli of the amorphous and crystalline phases depending on temperature; a change in the sign of the crystalline fraction CTE at 30 K is assumed. The Boson peak disappearance at 100 K in zircon with during heating conforms to with the violation of the phonon localization as a consequence of amorphous fraction contraction and partial ordering. The data obtained are important for predicting the thermal and mechanical properties of heterogeneous radiation‐damaged materials and nanocomposites.

Study of Structural, Mechanical, and Corrosion Resistance of a Nanocomposite CrSiN/CrN/Cr Coating Deposited on AZ31: Effects of Deposition Time

To improve the surface properties of Mg alloys and expand the applications of CrN-based materials, composite CrSiN coatings consisting of amorphous Si3N4 and nano CrN phases have been prepared on AZ31 based on the theory of fine grain strengthening and multigrain boundaries. The effect of the thickness of the coating on the structure and properties was investigated. The microstructure was studied by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The mechanical properties, adhesion properties, and corrosion resistance were investigated using a nanoindentater, scratch testers, and electrochemical workstations. The results show that the coating consists of a face-centered cubic CrN phase, that Si3N4 is not found in the diffraction pattern, and that the HRTEM images show a composite structure of amorphous and nanocrystalline phases. With the increase in deposition time (thickness), the surface roughness decreases, the defects disappear, and the interface has no visible defects. Moreover, the hardness and elastic modulus of the coating increase, corrosion resistance improves, adhesion performance first increases and then decreases. The adhesion between coating and substrate reaches the maximum when sputtering time is 50 min, which corresponds to the CrSiN thickness of 0.79 μm.

Magnetic and structural properties of nanocomposite permanent magnet produced from crystallization of Pr4Fe67Nb4Cu2Zr1B22 alloy

Present research work narrates synthesis, structural, thermal and magnetic characteristics of Pr4Fe67Nb4Cu2Zr1B22 nanocomposite magnets. Amorphous Pr4Fe67Nb4Cu2Zr1B22 rods were produced through injection casting technique and permanent magnetic characteristics were obtained by one-step annealing the amorphous rods. XRD analysis elucidated that as-cast rods have amorphous phase structure and annealed magnets have tetragonal Pr2Fe14B hard phase, cubic structural α-Fe phase and tetragonal Fe3B soft phase. Optimal annealed magnet composed of 63% Pr2Fe14B hard phase, 26% α-Fe and 11% Fe3B soft phases with mean grain sizes around 51.6 ± 1 nm for Pr2Fe14B, 25.4 ± 2 nm for α-Fe and 21.5 ± 2 nm for Fe3B phases. Microscopic and atomic probe studies showed that the annealed magnet consists of Pr2Fe14B, α-Fe, Fe3B nanosized grains interlinked with thin grain boundaries. Henkel curve evidenced the existence of inter-grain exchange coupling between magnetic nanophase grains. Magnetic hysteresis measurements revealed that Pr4Fe67Nb4Cu2Zr1B22 nanocomposite magnet yielded maximum magnetic characteristics such as coercivity Hc of 382 kA/m, remanence Br of 0.70 T and maximum energy product (BH)max of 64.2 kJ/m3 with rare earth to iron ratio 4:67.

Metastable phase separation and duplex metallic glass formation of liquid Zr<sub>35</sub>Al<sub>23</sub>Ni<sub>22</sub>Gd<sub>20</sub> alloy

Duplex metallic glass with two amorphous phases has been extensively investigated for desirable strength and plasticity. In this paper, the metastable phase separation and dual amorphous phase formation of liquid Zr<sub>35</sub>Al<sub>23</sub>Ni<sub>22</sub>Gd<sub>20</sub> alloy under substantial undercooling condition and rapid cooling condition are studied by drop tube technology. The equilibrium solidification structure consists of three crystalline phases, while the critical undercooling temperature of metastable phase separation is determined to be 516 K (0.37<i>T</i><sub>L</sub>). The separated Zr-rich liquid phase undergoes amorphous transition and becomes amorphous AM-Zr phase with the composition of Zr<sub>45</sub>Ni<sub>23</sub>Al<sub>23</sub>Gd<sub>9</sub> when alloy undercooling is increased to 624 K (0.45<i>T</i><sub>L</sub>). After that, the Gd-rich liquid phase forms amorphous AM-Gd phase with the composition of Gd<sub>39</sub>Al<sub>22</sub>Ni<sub>20</sub>Zr<sub>19</sub> at larger undercooling of 714 K (0.52<i>T</i><sub>L</sub>). With the increase of liquid undercooling and cooling rate, the kinetic mechanism of metastable phase separation changes from nucleation and growth type to spinodal decomposition type, and consequently the microstructure of dual amorphous phases transforms from a spherical morphology to a reticular structure. The average hardness and Young’s modulus, which are influenced by free volume, phase volume fraction and structure of dual amorphous phases, exhibit a complex variation of first increasing and then decreasing with the decrease of alloy droplet size. The formation of dual amorphous phases is in favor of the energy dissipation and the generation of multiple shear bands during mechanical compression, which improves the plasticity for this kind of amorphous alloy.

The role of amorphous ZIF in ZIF-8 crystallization kinetics and morphology

Understanding the composition and structure of amorphous precursor phases is fundamental for elucidating two-step crystallization mechanisms and designing shape- and size-controlled nanomaterials. However, that understanding is largely lacking for metal–organic framework compounds despite their growing significance as functional materials. Here, we report the crystallization of zeolite imidazolate frameworks-8 (ZIF-8, Zn(C4H5N2)2) via an amorphous ZIF (am-ZIF) solid precursor phase with a rough stoichiometric composition of Zn(C4H5N2)1.78(C4H6N2)0.17(CH3COO)0.22. The formation of am-ZIF is attributed to the incomplete deprotonation of 2-Methylimidazole (HmIm) and the involvement of the hydrogen bond between CH3COO– and –HN, which can further transform into the dense Dia(Zn) structure with a diamondoid crystal topology in pure water. Taking am-ZIF as a precursor, the tunable dissolution and recrystallization kinetics of am-ZIF into ZIF-8, due to the addition of EtOH and CTAB, allows the selective fabrication of dodecahedral, cubic, and hollow ZIF-8. Overall, an in-depth understanding of the differences in composition and structure of am-ZIF from ZIF-8 and the resulting crystallization kinetics suggests a novel approach to designing metal–organic frameworks with controlled crystal morphology.

Comparative study on mechanical and tribological properties of Cr–Al–N and Cr–Al–O coatings deposited by cathodic arc evaporation

A comparative study was performed for (Cr1−xAlx)2O3 and (Cr1−xAlx)N coatings with different Al contents (x = 0, 0.5, and 0.7) concerning structural, mechanical, and tribological properties. The composition-dependent phase structure was found for Cr–Al–O coatings, where higher Al content promotes a mixed structure of cubic and minor amorphous phases. Moreover, the mixed-phase structure results in lower indentation hardness, ∼27 GPa, and residual compressive stress, ∼ −4 GPa, as compared to Cr2O3 and Cr–Al–N coatings. Besides, (Cr0.5Al0.5)2O3 and (Cr0.3Al0.7)2O3 show worse wear resistance with a wear rate higher than 1.0 × 10−5 mm3/N·m at 200 − 600 °C due to reduced hardness and lower residual stress. A higher bias potential of −150 V induces higher compressive residual stress and hardness, which is beneficial to the high-temperature wear resistance of Cr–Al–O coatings.

Long-term aging of CVD grown 2D-MoS2 nanosheets in ambient environment

A chemically vapor deposited MoS2 nanosheets (NSs) is aged in the laboratory at ambient and at 40% average humidity for ~36 months. Nanorods of few microns in length and few nanometers in diameter are found to grow from the MoS2 seeds. They have been growing as a result of the chemical reaction between the MoS2 NSs and ambient O2 and moisture, they exhibit an amorphous phase structure in the stoichiometric form of MoO3. Density functional theory simulations further reveal the role of H2O and O2 in the transformation of the MoS2 NSs. The adsorption energy of O2 molecules on the MoS2 sites is Ead = −1.09 eV as compared to lowest absolute Ead = −0.10 eV of H2O indicating the favorable adsorption of O2 and subsequent Mo oxidation. This study provides valuable insight into the aging phenomenon of MoS2 exposed to O2 and moisture which might limit their application.

Enhanced linear and nonlinear optical properties of erbium/ytterbium lead phosphate glass by gamma irradiation for optoelectronics applications

Herein, this study intends to reveal the impact of gamma irradiation on the structural, linear, and nonlinear optical characteristics of 47P2O5−23Na2O−6Al2O3−22PbO−0.5Er2O3−1.5Yb2O3 glass. The Er/Yb-doped lead phosphate glass samples were produced using the traditional melt quenching procedure and then treated to different doses of gamma irradiation (0, 20, 50, and 100) kGy. The amorphous phase structure of the Er/Yb-doped lead phosphate glass samples was verified through XRD patterns. Also, the shift of the FTIR peaks due to the change in bond angles, and the change in the bond length of the P–O–P bridges means the glass network stability against radiation. With increasing irradiation dosages, the energy gap dropped from 4.11 eV to 3.42 eV and then enhanced to 3.48 at 100 kGy. At the same time, the Urbach energy enhanced from 10.23 eV to 37.03 eV. The oscillator energy Eo was found between 1.55 and 1.62 eV. Also, the dispersion energy Ed varied between 2.11 eV at 100 kGy and 2.71 eV at the dose of 50 kGy. The percentage of free carrier ions to effective mass (N/m*) is in the range (4.82–8.66) × 1047 cm3/g. Besides, the lattice dielectric constant ({varepsilon }_{l}) increased from 5.54 to 6.63 as the gamma dosages increased. Furthermore, increasing gamma doses up to 50 kGy promotes susceptibility, which subsequently declines at 100 kGy, suggesting that increasing gamma doses over 50 kGy weakens polarizability potential. While the increasing gamma doses up to 50 kGy reduces the nonlinear refractive index and then improves at 100 kGy. Overall, the nonlinear and linear research revealed that Er/Yb lead phosphate glass is being used as a promising material for gain media and optical amplifiers.

Effect of heat-treatment temperature and borohydride concentration on corrosion behaviour of ENB coating

Electroless Ni-B (ENB) alloy coatings are extensively used due to their good tribological, physical, electrical and mechanical properties. The behaviour of coatings generally depends on the concentration of bath parameters, heat-treatment temperature, as well as heat-treatment duration. The current study was carried out to deposit coatings over steel specimens with various NaBH4 concentrations and heat-treated at various temperatures to study the significance of NaBH4 concentration as well as heat-treatment temperature on corrosion resistance of the Ni-B coatings. Ni-B coatings were heat-treated for an hour at different temperatures for example, 350°C, 450°C and 550°C. Electrochemical impedance spectroscopy (EIS) and Potentiodynamic polarization (PDP) test methods were employed to analyse the corrosion behaviour of the as-deposited as well as heat-treated coatings. The tests were conducted against a corrosive environment consisting of 3.5% NaCl solution. It was observed that the as-deposited coatings with low boron content exhibit a mixture of amorphous and nanocrystalline structures. The same gradually becomes amorphous with the rise in sodium borohydride concentration. The increase in boron content with sodium borohydride concentration in the coating bath led to the transformation of phase structure. This amorphous phase structure of as-deposited coatings further transforms into a crystalline structure upon heat treatment. This crystallinity increases with heat-treatment temperature. The as-deposited coatings show cauliflower-like surface morphology at all concentrations of NaBH4 but the same becomes a coarse-grained structure with clustered aggregates leading to a rough surface. The as-deposited coatings show better corrosion resistance behaviour compared to heat-treated ones, especially at the higher temperature.

Effective tri-metal and dual-doped catalyst for oxygen evolution reaction: Amorphous Co-Mn-Ni-P-B-O nanoparticles

Developing high-performance oxygen evolution reaction (OER) electrocatalysts is essential because OER is critical in metal-air battery and water splitting due to its slow kinetics. Therefore, OER catalysts are challenging for many researchers. In this study, an OER catalyst is synthesized using a simple, low-cost method. It has attractive features such as an amorphous phase and nano-sized structure, fabrication using three transition metals, and dual-doping using phosphorus (P) and boron (B). Dual-metal (CNPBO, CMPBO, NMPBO) and single-doped (CMNBO) comparison groups are prepared to confirm the efficiency of these features. The use of three transition metals and dual-doping causes metal-metal bonds to weaken, allowing the electrons to move more freely. Accordingly, synthesized Co-Mn-Ni-P-B-O nanoparticles exhibit outstanding intrinsic catalytic performance. The overpotential for j10 and the Tafel slope decreased 1.59 V and 62 mV/dec compared with the dual-metal samples (1.64 V and 96 mV/dec).

Controlling the crystallinity of HfO2 thin film using the surface energy-driven phase stabilization and template effect

Phase transition of HfO2 thin film has been investigated to demonstrate desirable electrical properties, such as high dielectric constant or ferroelectricity, however, the most of results exhibited a limitation on enhancing the crystallinity because of employing dopant. In this study, the crystallization behavior in the thin film was investigated in the intrinsic and extrinsic aspects. In the laminated structure, highly crystallized tetragonal phased HfO2 was obtained by controlling the layer thickness and adapting the template effect for intrinsic and extrinsic crystallization, respectively, without using dopant. Moreover, by the phase composition analysis, the dielectric constant of various crystal structures of HfO2 thin film, tetragonal, monoclinic, and amorphous phases, were revealed using the data obtained from the real deposited thin film by atomic layer deposition process, not from the theoretical calculation.