Formation Of Hexagonal Structure Research Articles

Investigation of electrical, dielectric, magnetic and electrochemical characteristics of a BaFe12O19/Co0.5Zn0.5Fe2O4 nanocomposite

BaFe12O19 (barium ferrite, i.e., BaF) nanoparticles, Co0.5Zn0.5Fe2O4 (cobalt zinc ferrite, i.e, CZF) nanoparticles and their nanocomposite were synthesized for the investigation of electrical, magnetic, dielectric, and electrochemical properties. The X-ray diffraction (XRD) pattern revealed the formation of hexagonal structure for BaF nanoparticles and cubic structure for CZF nanoparticles with crystallite size of 32.44 nm and 31.30 nm, respectively. Whereas, for nanocomposite, the crystallite size obtained is 34.21 nm were shifting of peaks revealed the formation of nanocomposite. The Fourier transform Infrared (FTIR) spectra revealed the presence of metal-oxygen vibrational peaks for all the samples. The dielectric data revealed the increase in dielectric constant of nanocomposite as compared to pristine CZF whereas, loss reduced for nanocomposite significantly. Single semicircle in Nyquist plot for all the samples revealed the contribution of grain resistance in impedance. The hysteresis loop showed the increase in specific saturation magnetization from 16.963 emu/g to 21.305 emu/g for nanocomposite when compared with pristine BaF. Whereas specific remnant magnetization increased to 10.305 emu/g for nanocomposites. The electrochemical properties presented by Cyclic voltammetry showed the presence of cathodic and anodic peaks which revealed the presence of redox reaction in all samples. The specific capacitance calculated for all samples at different scan rate revealed that a nanocomposite showed highest Cs value 16.43 F/g at 25 mV, whereas it increased to 27.01 F/g, 35.93 F/g and 38.87 F/g with the increase in scan rate to 50 mV, 75 mV and 100 mV, respectively.

Sustained electromagnetic parameters of barium ferrite and epoxy nanocomposites for patch antenna miniaturization over GHz frequency range

Herein, we synthesized BaFe12O19 and BaFe12O19: Epoxy (50:50) nanocomposite using the co-precipitation method. X-ray Diffraction (XRD) pattern confirmed the formation of hexagonal structure where the crystallite size is 27.3 nm. The Field Emission Scanning Electron Microscopy (FESEM) showed the formation of hexagonal grains and Energy Dispersive X-ray Spectroscopy (EDX) confirmed the purity of the sample. Transmission Electron Microscopy (TEM) showed the crystallite size of 34 ± 2 nm for BaF nanoparticles and 42 ± 2 nm for Ba-Epoxy nano composites. The values of ε′ is found within the range of 6.2–6 for BaF and 4.5–4 for BaF: Epoxy over the whole frequency range. In addition, the value of real part of permeability μ′ are 1.9–1.2 and 1.4–1 for BaF and BaF: Epoxy, respectively. The ac conductivity is observed to remain constant till 0.6×109 Hz and 0.2×109 Hz frequency for BaF and BaF: Epoxy, respectively.

Study on the homogeneity of tilted dendritic structures in single crystal superalloys

Dendrites play a crucial role in the microstructure of single crystal superalloys, predominantly developing along the [001] orientation. The mechanical performance is greatly influenced by the uniform distribution of dendrites. During the solidification process, we frequently observe instances of dendrites deviating from the [001] orientation, resulting in tilted structures. These deviations give rise to both aligned and misaligned arrays within the transverse section. The study comprehensively examines the homogeneity of tilted dendritic structures. As solidification progresses, new dendrites within the aligned array tend to maintain a hexagonal structure. Simultaneously, the remaining metastable structures gradually transition into hexagonal structures. In contrast, various polygons mutually transform in misaligned array, resulting in a dynamic adjustment of their proportions. Consequently, the aligned array exhibits a higher proportion of hexagonal structures and a more uniform dendrite spacing compared to the misaligned array. Within the transitional region, an increase in heptagonal structures leads to heightened non-uniformity in dendrite spacing. The predominance of hexagonal structures can be attributed to their more uniform solute distribution, facilitated by the characteristics of the aligned array, which promote hexagonal structure formation by adjusting the solute field distribution. On the other hand, due to the random positioning of dendrites in the misaligned array, various stacking structures coexist in dynamic equilibrium. The research reveals an intrinsic relationship between macroscopic array patterns, stacking structures, dendrite spacing, and microscopic solute distribution. These findings provide a theoretical foundation for the production of high-quality single crystal dendritic structures and offer insights into their influence on material properties.

Citrate precursor route for Y3+ substituted M-type Ba-hexaferrite: Synthesis, the effect of doping on structural, optical, magnetic and anti-bacterial properties

Herein, citrate precursor technology has been used in the lab to create BaYxFe12-xO19, where x = 0.0, 0.1 and 0.2. Fourier Transform Infrared and UV spectroscopy and Powder X-ray Diffraction have all been utilized to determine the structure and to confirm the phase formation.XRD confirmed the formation of hexagonal structure where lattice parameters a and c decreased from 5.88 Å to 5.81 Å and 23.19 Å to 23.17 Å, respectively, with the increase in doping concentration.Tauc plot facilitate with the values of energy gap for all the prepared samples, which is in decreasing order with increase in doping concentration for 4.48 eV–4.38 eV. An increase in magnetization value from 8.77 emu/g - 26.22 emu/g for doping of Y from x = 0.0–0.20 has been observed from magnetization versus magnetic field data taken from vibrating sample magnetometer. The main objective of this work is to study the antibacterial activity of the Y doped BaFe12O19 against gram positive Staphylococcus aureusas well as gram negative bacteria Escherichia coli. All the prepared samples have shown the antimicrobial effect at all the concentration with MIC value ranging from 0.55 to 0.80 mg/ml.Thus, the present study explores the potential applications of Y-doped Barium hexaferrites in biomedical applications.

Synthesis, structure, thermal, magnetic, dielectric properties of Ce3+ doped M-type SrFe12O19 and electrochemical determination of L-cysteine

• Nanostructured Sr (1-x) Ce x Fe 12 O 19 nanoferrites were prepared by auto combustion method with dual fuel (Urea and glycine). • The dielectric properties of all the samples have been measured using LCR meter at room temperature and electrochemical studies was using by cyclic voltammetry at RT. • The XRD patterns and IR spectra confirmed the formation of hexagonal structure. • The dielectric parameters decreases while AC conductivity increases with frequency. At a particular frequency, the dielectric constant, dielectric loss real part and imaginary part of impedance increases, attain maximum, then begins to decrease with increase in composition. • The SrHF’s/GCE electrode showed impressive results including increased sensitivity, limit of detection, higher concentration range, stability, and reproducibility properties. Cerium substituted SrFe 12 O 19 with the nano composition of Sr (1-x) Ce x Fe 12 O 19 ( x = 0.00, 0.01, 0.05 and 0.09) have been prepared using auto-combustion technique with dual fuel. The PXRD images confirmed a single-phase hexagonal crystalline structure similar to a magnetoplumbhite for all samples. Fourier transform infra-red spectroscopy (FT-IR), field emission-scanning electron spectroscopy (FE-SEM), elemental mapping (EDS) were used to examine for the structure and morphology of the samples. The temperature dependent hexagonal phase formation and percentage weight loss was studied by thermogravimetric and differential thermal analysis (TG-DTA). Vibrating sample magnetometer (VSM) analysis confirmed that M-SrHF’s are hard magnetic in nature and super paramagnetic, these are measured at room temperature. It was found that, with the increase of the dopant Ce 3+ in strontium ferrites, the values of saturation magnetization (M S ), remanence magnetization (Mr), coercivity (H C ) and magnetic parameters of strontium ferrites decrease. The electrochemical behavior of the SrHF’s electrode and the electro-oxidation of L-cysteine was investigated using of cyclic voltammetry (CV). The best voltammetric response has been observed for a SrHF’s electrode in buffer solution at pH of 7.0 with an acquisition and scan rate of 50 mV s − 1 . The dielectric properties are measured in LCR meter and described based on the Maxwell–Wagner’s two layer model. The electron hopping between Sr 2+ and Sr 3+ , as well as Fe 3+ and Fe 2+ ions on B-sites, drives the conduction mechanism in these ferrites, these nano hexaferrites which shows its suitability in various technological applications.

Enhanced the Cu2+ doping on the structural, optical and electrical properties of zinc oxide (ZnO) nanoparticles for electronic device applications

Zinc oxide (ZnO) and Cu doped ZnO Nano particles (NP's) were synthesized through chemical route (sol gel & Co-precipitation) to reveal their structural, electrical and optical properties. The synthesized NP's have been characterized by X-Ray diffraction (XRD), Fourier transform infrared rays (FTIR) spectroscopy, Ultra violet visible (UV–V) spectroscopy and impedance spectrometry techniques. XRD pattern revealed the formation of hexagonal structure of ZnO NP's. However size variation of ZnO NP's was observed with addition of Cu contents. SEM analysis revealed that nanorods have been made due to Cu doping in ZnO NP's. FTIR spectroscopy determined the presence of Cu contents in the synthesized samples while UV-technique shown the absorption peaks in the range of 200–800 nm range. The band gap energy decreases with increasing Cu content was observed. The microwave dielectric properties (i.e. relative permittivity & tangent loss) of the Cu doped samples were observed to be decrease with resonant frequency.

Hexagonal structures in 2D Navier–Stokes flows

Geometric structures naturally appear in fluid motions. One of the best-known examples is Saturn’s Hexagon, the huge cloud pattern at the level of Saturn’s north pole, remarkable both for the regularity of its shape and its stability during the past decades. In this article, we will address the spontaneous formation of hexagonal structures in planar viscous flows, in the classical setting of Leray’s solutions of the Navier–Stokes equations. Our analysis also makes evidence of the isotropic character of the energy density of the fluid for sufficiently localized 2D flows in the far field: it implies, in particular, that fluid particles of such flows are nowhere at rest at large distances.

Study on the structural and electrical transport properties of YMn0.9Cr0.1O3

In this work, the structural, micro-structural, dielectric, AC conductivity of rare earth manganite YMn0.9Cr0.1O3 have been reported. The compound is synthesized by sol–gel auto-combustion route. The X-ray diffraction study confirms the formation of hexagonal structure along with the onset of few orthorhombic peaks. The morphological study using scanning electron micrographs shows homogeneous distribution of particles with average particle size of 185 nm. Raman spectroscopy shows the A1Raman scattering line at ∼ 676 cm−1to be much stronger than the other Raman modes. The nature of frequency dependence of dielectric constant has been described by Maxwell-Wagner model. The frequency dependence of the conductivity at different temperatures as described by Jonscher’s plot suggests that the conduction phenomenon in the material obeys the correlated barrier hopping (CBH) model. The activation energy of the intrinsic charge carriers has been calculated by using the Arrhenius equation at different frequencies.

Synthesis and characterization of ZnSe nanorods by coprecipitation method

The present work includes, the synthesis of zinc selenide (ZnSe) nanorods (NRs) using co-precipitation method and characterizations. The ZnSe (NRs) were synthesized using Zn (CH3COOH)2·2H2O and Na2SeO3 as precursors and N2H4·H2O as the reducing agent. The prepared sample were analysed by X-ray diffraction (XRD), transmission electron microscopic technique (TEM), photo luminescence (PL) and UV–Visible spectroscopic techniques. The XRD analysis confirms the formation of hexagonal structure of ZnSe NRs of dimensions; diameter ranges of 90 nm to 170 nm and length 750 nm. TEM micrographs confirm the formation of nanorods. UV–visible absorption spectroscopy was used to determine the optical band gap of ZnSe NRs. The strong and broad absorption band was observed in the wavelength region 320 nm to 470 nm which is corresponding to the band gap of ZnSe nanorods. The PL spectra shows emissions at 543 nm,655 nm,761 nm and corresponding chromaticity diagram indicates that the material emits blue light, it is found suitable for blue LEDs for clinical use and other optoelectronic devices.

Structural, photoluminescence and Judd-Ofelt analysis of red-emitting Eu3+ doped strontium hexa-aluminate nanophosphors for lighting application

In this paper, the structural and luminescence properties of Eu 3+ - doped SrAl 12 O 19 nanophosphors are discussed. A series of SrAl 12 O 19 :xEu 3+ (x = 0.5, 1, 1.5, 2 and 2.5 mol %) nanophosphors were prepared using urea assisted-combustion synthesis method. The elemental and phase identification were performed by X-ray diffraction. The peak positions in the X-ray diffraction pattern have confirmed the formation of hexagonal structure. The vibration of oxide bonds and the formation of the molecules were confirmed from FTIR spectra. The surface morphology and particle size distribution are estimated using Field Emission-Scanning Electron Microscopy (FE-SEM), High Resolution-Transmission Electron Microscopy (HR-TEM). The optical properties of prepared nanophosphors series are studied using photoluminescence spectra and UV–visible spectra analysis. The refractive index of the optimized concentration of nanophosphor is estimated using Herve and Vandamme relation. Further, Judd-Ofelt analysis was performed on photoluminescence emission spectra. The potential application of synthesized nanophosphors in light-emitting devices (LED) is verified using photometry analysis on obtained emission spectra. The obtained CCT number confirmed that these phosphors are useful as a red color LED. • Red-emitting Eu 3+ -doped strontium hexa-aluminate nanophosphors are synthesized using combustion synthesis method. • The luminescence intensities of nanophosphors are strongly depending on Eu 3+ -concentration. • A detail Jud-Oflet analysis is performed on the nanophosphors. • The estimated CCT values showed that these phosphors are used for warm lighting application.

Structural, surface morphology and radiation shielding properties of barium ferrite powder

In this study, Barium ferrite (BaFe12O19) was prepared in powder form using the sol-gel method. Next, structural, surface morphology, and radiation shielding properties of Barium ferrite compound were determined using experimental and simulation methods. The structural and surface morphology were characterised using x-ray diffraction (XRD) and the scanning electron microscope (SEM). The formation of hexagonal structure has been verified by XRD patterns for synthesised pure BaFe12O19. The amplitude of XRD peaks declines as the FWHM rises, indicating that crystallinity has degraded and crystallite size has decreased. SEM images provide accurate representations of surfaces. The topography of the surface is characterized by the presence of several spherical granules. Additionally, the mean diameter of the spherical granules was determined to be approximately 30 nm using the histogram. Moreover, FLUKA simulation code was used to calculate some radiation shielding parameters such as linear attenuation coefficients (4.639, 0.554, 0.336 and 0.2013 cm−1), mass attenuation coefficients (0.8787, 0.1049, 0.0686 and 0.0381 cm2 g−1), half value layers (0.1494, 1.2512, 2.0629 and 3.4434 cm) and mean free path values (0.21554, 1.8051, 2.9762and 4.9677 cm) against 0.81, 0.356, 0.911 and 2.614 MeV photon energies, respectively. The results showed that synthesized Barium ferrite has good surface renditions and distinguished spherical granules along with promising gamma-ray attenuation properties.

Growth of ZnSnO nano structures for thermopower applications by thermal evaporation with and without oxygen precursor

In this manuscript, we have reported the crystal quality control of ZnSnO nanostructures during thermal evaporation growth in the presence and absence of oxygen gas during the growth process. To test this hypothesis, we have prepared two set of samples by evaporating Zn and tin powders (5:1 ratio) on Si substrate under similar growth conditions. But one set of samples was prepared in the presence of oxygen gas with a flow rate of 100sccm while other set of samples was grown under the absence of oxygen gas. Structural study revealed the formation of hexagonal structures of ZnSnO for both sets of samples while the Raman spectroscopy also supported the XRD data. But the observed morphology (SEM images) showed the different behavior of samples i. e porous structure of the samples grown using oxygen precursor while the nano-needle shape morphology was observed for the sample grown without oxygen. Thermo power measurements demonstrated that sample grown using oxygen precursor possess the highest value of Seebeck voltage along with other thermoelectric parameters when we compared with the samples grown without the presence of oxygen gas. The highest thermo power ability was related to the formation of porous structures which is a major cause of mobility enhancement.

Dielectric study of ZnO nanorods synthesized by thermal decomposition method

ZnO nanorods were prepared by well-known thermal decomposition method. Nanorods were synthesized with two different annealing temperature 300 °Cand 500 °C. Prepared samples were characterized with different characterization methods. X-ray diffraction (XRD) results confirmed the formation of hexagonal structure of ZnO. Field emission scanning electron microscope (FESEM) images show formation of ZnO nanorods with different size and shape. Dielectric study also investigated for prepared samples. Dielectric study indicated that sample ‘500’ gives high dielectric constant in low frequency region. Nyquist plots showed reducing of grain boundaries with increasing annealing temperature.

Temperature dependent photoluminescence in Sol-gel derived Ce doped ZnO nanoparticles

Abstract Undoped and Ce-doped ZnO nanoparticles (NPs) were prepared by sol–gel method. FTIR spectra demonstrated distinct characteristic absorption peaks at 520 and 528 cm−1 which correspond to Zn-O stretching mode, eventually confirming formation of ZnO. Other peaks corresponding to Zn-O-Zn antisymmetric vibrations at 628 and 668 cm−1 were also observed. UV–Vis transmission spectra showed absorption dips at 365 and 370 nm respectively for undoped and Ce doped ZnO and corresponding band gap values were estimated to be 3.32 and 3.28 eV. This redshift of band gap is due to the formation of a shallow levels inside the band gap. Photoluminescence (PL) emission spectra of NPs contained two major peaks one in UV and the other in the visible (blue) region. Their intensities monotonously rose and acquired substantially higher values with temperature lowering from 27⁰C to −10⁰C. The morphological study revealed the formation of hexagonal structures by Ce doping in ZnO. The study suggests the possibility of designing a temperature sensor using Ce doped ZnO also its potential use in organic photovoltaics.

Doping Effect and Microstructure Behavior of Rare-Earth Element Cerium (Ce+3) in Barium Hexaferrite (BaCexFe12-xO19) Nanoparticles

Cerium substituted BaM hexaferrites BaCexFe12-xO19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) nano crystallites were synthesized via Sol-gel method. The x-ray diffraction (XRD) patterns were analyzed by Rietveld refinement which confirms the formation of hexagonal structure. The crystalline size was calculated by Debye Scherrer method, W–H method and SSP method. The lattice constant ? found to decrease, this was due to the octahedral site replacing a large radius of Ce3+ ion with a smaller radius Fe3+ ion, While the lattice constant c found increase. The x-ray density observed increases with increasing Ce3+ concentration. Fourier transform infrared spectroscopy (FTIR) confirmed the two frequency bands n1 tetrahedral site and n2 octahedral site in a range between 400–620 cm-1. Impedance analyzer was used to investigate the dielectric properties in a range of 1 MHz – 3 GHz following Maxwell Wagner model. Dielectric constant showed decreasing trend while dielectric loss showed dispersive behavior by increasing frequency and same was that with tangent loss, such behavior was due to Koop's phenomenological theory. AC conductivity exhibits a plane behavior in a low frequency, while dispersive in high frequency. Such behavior was due to grain effect at high frequency. Impedance showed continuous action at high frequency, which is attributed to the release of space charges. The real and imaginary modulus showed variation by increasing frequency, which was due to the occurrence of relaxation phenomenon. As per dielectric research, these ferrites can be utilized in high frequency devices, microwave technologies, and semiconductor devices.

Zinc Oxide Nanorod Electrolyte–Insulator– Semiconductor Sensor for Enhanced 2-Methoxyethanol Selectivity

In this work, we demonstrate 2-methoxyethanol-sensitive ZnO nanorods based on electrolyte–insulator–semiconductor (EIS) structure. The hydrothermal method is employed to synthesize the ZnO nanorods on Si substrate. The structural, morphological, compositional, and optical features of ZnO nanorods are analyzed, confirming the formation of hexagonal structure in ZnO nanorods. We investigate the sensing performance of EIS-based ZnO nanorods for the detection of various organic solvents (2-methoxyethanol, ethanol, and methanol) at various concentrations. As a chemical sensor, these EIS-based ZnO nanorods are capable of generating a different exposure response to 2-methoxyethanol than to methanol than to ethanol. The highest sensitivity, stability, and reproducibility are with respect to 2-methoxyethanol, making the ZnO nanorods prepared here a promising sensing membrane for 2-methoxyethanol.

Morphological exploration of chemical vapor–deposited P-doped ZnO nanorods for efficient photoelectrochemical water splitting

Photoelectrochemical (PEC) water splitting is beneficial and has received attractive attention due to a greater potential to generate hydrogen and oxygen from water by using plentiful solar light to solve the problem of energy crisis. Various active semiconductor materials are used in PEC water splitting applications. Nevertheless, in past decades, most of the researchers suggested that titanium oxide (TiO2) is the best photoanode for this type of applications. Now, Zinc oxide (ZnO) is considered a perfect substitution to TiO2 due to its comparable energy band structure and superior photogenerated electron transfer rate. In this study, bare and phosphorous-doped ZnO nanorods were successfully developed on fluorine-doped tin oxide-coated glass (FTO) substrate by chemical vapor deposition. X-ray diffraction (XRD) pattern authenticated hexagonal structure formation with strong diffraction peak of (101), which showed that ZnO nanorods were perfectly developed along c axis. The optical and morphological properties were analyzed by UV–Vis and scanning electron microscopy images. The energy-dispersive X-ray spectra demonstrated that doping agent phosphorous was present in ZnO nanorods. The PEC properties of the developed ZnO nanorods were further investigated and obtained results suggested that a small amount of phosphorous-doped ZnO nanorods enhances their PEC performance.

Ball-like nickel hydroxide nanoparticles: Electro-synthesis, characterization, and application

Ball-like nickel hydroxide nanostructures were synthesized using electro-crystallization method. The synthesis was carried out in an electrolytic cell containing two nickel electrodes, and an aqueous solution of C4H12Cl as supporting electrolyte. The effect of applied voltage on morphology, structure, and magnetic properties of the products were studied using XRD, FT-IR, SEM/EDX, TEM, and VSM. The XRD patterns confirm the formation of hexagonal structure of Ni(OH)2 without any impurities. Based on FT-IR results the amine molecules present at the surface of particles. The SEM images show that the products have ball-like shape. Each nickel hydroxide ball composed of the small nanoparticles. The mean particle size increases from ∼9 nm to ∼50 nm by increasing the applied voltage from 8 V to 26 V. The ability of electro-synthesized nickel hydroxide nanostructures on removal of cobalt and cadmium from laboratory water and real water of Khorram-rood, Seimareh, and Kashkan rivers in Iran, has been investigated. The AAS data show that the removal efficiency of heavy metals from real water is higher than laboratory water. Based on these results we could successfully remove 100 % of cadmium and 85.8 % of cobalt from real water samples.

Structural, Optical, and Electrical Studies of Sonochemically Synthesized CuS Nanoparticles

In this study, we reported facile sonochemical synthesis of CuS nanoparticles by using CuCl2 and Na2S in aqueous medium without using any organic solvent and surfactant. Structural characterization of synthesized product using X-ray diffraction study revealed the formation of hexagonal structure of CuS in covellite phase. Crystallite size of ~13 and ~11 nm were determined using Debye–Scherrer and Williamson–Hall methods, respectively. Field emission scanning electron microscopy micrographs revealed the particulate morphology of CuS nanostructures. The optical properties of CuS nanoparticles were investigated by ultra violet and visible (UV-Vis), photoluminescence (PL), and Fourier transform infrared spectroscopy. The band gap was calculated by Tauc’s relation and found to be 3 eV. The PL spectrum showed a strong green emission at wavelength 505 nm. The electrical conductivity of CuS nanoparticles was found to be in semiconducting range, i.e. 550 S/cm. Impedance analysis of CuS nanoparticles revealed 7.55 MHz as the resonant frequency.

Investigation of magnetic and dielectric properties of Agx-substituted Co0.05−x Zn0.95O dilute magnetic semiconductor prepared by co-precipitation method

A series of Agx-substituted Co0.05−x Zn0.95O (x = 0.00–0.05) nanoparticles calcined at 700 °C have been synthesized using a simple co-precipitation technique. The prepared nanoparticles have been analyzed for their structural, optical, magnetic, and dielectric properties using X-ray diffractometer, Fourier infrared spectroscopy, UV–visible spectroscopy, vibrating sample magnetometer, and inductor capacitor and resistor meter, respectively. The XRD results verify the formation of pure hexagonal wurtzite structure. FTIR spectra show a band at 439 cm−1 that is the characteristic stretching band of Zn–O which also confirms the formation of hexagonal structure. The band-gap energy decreases as the concentration of Ag increases except for samples with concentration x = 0.01 and x = 0.03. VSM results reveal that nanoparticles exhibit ferromagnetism at room temperature. The dielectric constant and tangent loss decreases with increasing frequency. However, the a.c. conductivity increases with increasing frequency. The prepared nanoparticles can be used in a variety of applications such as optoelectronic, memory, and microelectronic devices.