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Transitions between different oligomeric states of membrane proteins are essential for proper cellular functions. However, the quantification of their oligomeric states in cells is technically challenging. Here we developed a new method to quantify oligomeric state(s) of highly expressed membrane proteins using the probability density function of molecule density ( PDF

In this work, the ultraviolet light-emitting diodes (UV-LEDs) at 380 nm were grown on patterned sapphire substrate (PSS) by atmospheric pressure metal organic chemical vapor deposition (AP-MOCVD). A sputtered AlN nucleation layer was utilized on the PSS to enhance the quality of the epitaxial layer. By using high-resolution X-ray diffraction, the full-width at half-maximum of the rocking curve shows that the UV-LEDs with sputtered AlN nucleation layer had better crystalline quality when compared to conventional GaN nucleation samples. From the scanning electron microscope (SEM) and transmission electron microscopy (TEM) images, it can be observed that the tip and sidewall portion of the pattern was smooth using the sputtered AlN nucleation layer. The threading dislocation densities (TDDs) are reduced from 6×10 7 cm −2 to 2.5×10 7 cm −2 at the interface between the u-GaN layers for conventional and AlN PSS devices, respectively. As a result, a much higher light output power was achieved. The light output power at an injection current of 20 mA was enhanced by 30%. Further photoluminescence (PL) measurement and numerical simulation confirm that this increase of output power can be attributed to the improvement of material quality and light extraction.

A novel multi-layer stacking capacitive type microphone is designed in this study based on theoretical analysis and numerical simulations, while fabricated via two standard stable silicon-based MEMS processes—PolyMUMPs and SOIMUMPs. The adoption of two standardized processes helps greatly to increase yield rate. The sensitivity of the microphone is first determined by an analytical model based on an equivalent circuit, which is followed by finite element (FEM) analyses on the capacitance value, static pull-in voltage and dynamic characteristics. Based on the developed analytical model, varied dimensions of the microphone are optimized and then the performance is validated by analytical simulations. In the next step, micro-fabrication of the microphone is accomplished using two standard processes, PolyMUMPs and SOIMUMPs provided by MEMSCAP. Experiments are conducted to acquire the information of pull-in voltage for safe operation and frequency response in sensitivity for performance evaluation. In the static case, experimental results show a good agreement with the analytical results with 90 Mpa residual stress assumed. As for dynamic validation, the frequency response is measured in an anechoic room adopting the exciting frequency as the audible range from 100–10 kHz. The measured sensitivity is as around 0.78 and 1.7 mV/Pa from 100 to 10 kHz, under the biases of 2 and 4.5 V, respectively. Within the audible frequency range, the proposed device maintains the loss as less as 2.7 dB (ref. to V/Pa), under 3 dB—the commonly acceptable drop within audible frequency range.

This work proposes design, optimization and validation of a new two degree-of-freedom (DOF) rotational optical image stabilizer (OIS) that is suitable for installing into a mobile-phone-camera. This OIS differs from the previous designs since it stabilizes the lens holder directly by two-DOF translational mechanisms that are actuated by voice coil motors. The work can be divided into three main parts: (1) designs of mechanism and genetic algorithm (GA) optimization of magnetic field, (2) establishments of the dynamic model and equation of motions (EOM) of a dual-axis rotational structure, and (3) realizations of a sliding mode control (SMC) controller with fine performance. The dynamic of the dual-axis rotational OIS system has been analyzed and the EOM has been derived. Based on the Lagrange’s method, the motions of the OIS have been modeled through considering kinetic energy and electromagnetic torques. In the last part, the theory of SMC is applied, and the associated simulations are conducted. Based on the simulation results, the SMC controller is forged with the assistances from MATLAB pre-simulation and tested by a microprocessor module. After a series of experiments and verifications, the prototype of the novel OIS is finally accomplished with satisfactory performance of vibration reduction.

Internal quantum efficiency (IQE) of InGaN/GaN UV LEDs with patterned sapphire substrates (PSS) was investigated using electroluminescence (EL) and photoluminescence (PL) methods. The physical mechanisms that affect temperature-dependent EL efficiency as a function of injected carrier density were deduced. In order to reduce the density of non-radiative recombination centers to improve quantum efficiency, improvement of crystal quality and reduction in the number of defects are necessary. PSS LEDs showed better EL characteristics than non-PSS LEDs because of the improved epitaxial quality. Contrary to PL IQE, EL IQE was significantly affected by carrier injection efficiency, especially at low temperature when high bias voltage was applied to the p–n junction.

This study presents design, analysis and experiment of a miniaturized rotary generator in size of 10 times 10 times 2 mm3 and its compact energy harvest circuit chip. The designed generator consists of patterned planar copper coils and a multipolar hard magnet ring made of NdFeB. To perform modeling, a harmonic-like magnetic field model along the circumferential path of each magnetic pole is assumed with the assistance from measured peak magnetic flux densities. This is followed by the application of Faraday's law to predict generated electromotive forces (EMFs) in terms of the relative rotational speed between the magnet ring and coils. The genetic algorithm (GA) is next applied to optimize the critical dimensions of the miniaturized generator. The theoretical model of this power microgenerator is evaluated and compared with experimental results, and it is found that the analytical simulation shows a good agreement with the experimental results. The optimized generator offers 4.5 V and 7.23 mW in root mean square (rms) at 10 000 r/min. With microgenerator successfully fabricated, a novel energy harvest circuit employing Dickson charge pump is designed and fabricated via the 0.35-mum process offered by National Chip Implementation Center (CIC) of Taiwan. This charge pump circuit owns the merit of almost-zero thresholds of employed metal-oxide-semiconductor (MOS) transistors, enabling the conversion of low-power alternating current (ac) signals by the microgenerator to direct current (dc) ones.

This study aims to perform the micro-/nano-machining with an atomic force microscopy (AFM) tip in a scanning electron microscope (SEM) via run-to-run (R2R) controller and digital image feedbacks. The R2R is assisted by the technique of exponentially weighted moving average (EWMA). This ''EWMA feedback'' controller is a popular R2R control scheme, which primarily uses data from past process runs to adjust settings for the next run. On the other hand, the digital images are obtained by using the wavelet transform and binarization in order to recognize machining results, and then return feedback of the digital image information to the controller; finally obtain the next input data for the actuating controller to achieve the targeted machining precision. The experimental results for preliminary machining in micro-level indicate that the EWMA controller based on image feedbacks performs with satisfactory results at reducing the process variation, particularly at the first few production runs, thereby making it possible to further reduce the bias and bring the process output closer to its target as soon as the process begins to operate. It is seen that the proposed EWMA controller with digital image feedbacks is easy to implement and provides a good approximation to the optimal variable discount factor, which can reduce the error of the machining process from initial 40% without control to 0.7% with the proposed R2R. More importantly, such a reduction can be achieved at no loss of long-term stability. With sure precision of AFM, the aforementioned resulted micro-machining precision can easily be extended to nano-levels. Therefore, this study demonstrates a successful micro-/nano-machining operation in the environment of a SEM, by employing the designed R2R controller with digital image feedbacks.

The objective of the study is to design and construct an in situ inspection machine that would be used to evaluate the dynamic performance of the small-scaled hydrodynamic journal bearings used often for data-storage devices. To this end, novel design ideas of using a high-stiffness air bearing and suspending the test bearing by the specially-designed fixture frame are first proposed, which are accompanied by the special requirements in the manufacturing precisions for various dimensions and geometry characteristics of the components of the experiment system. The capacitor-type sensors, including two custom-mades are next utilized to measure the motions of the spindle and bearing. Finally, a calculating algorithm for deriving performance parameters of the test bearing are proposed, which is intended primarily to estimate rotor stiffness coefficients, load capacity, and eccentricity ratio to determine if the test bearing meet the dynamic performance expected by the original design.

The objective of this study is to design an intelligent control servo scheme for the three-axis optical pickups employed in the next-generation optical disc drives. The three-axis pickup owns the capability to move the lens holder in three directions of focusing, tracking and tilting, which is required particularly for higher data-density optical disks and precision measuring instruments to annihilate non-zero lens tilting. The intelligent controller utilizes a commercially often-used double phase-lead compensator equipped with the capability of auto-tuning on control parameters. In this way, the model uncertainty of the pickups caused by manufacturing tolerance and the coupling between three different DOFs of the three-axis pickup can be overcome to render desired precision data-reading. In the initial stage of the study, Lagrange’s equations are employed to derive equations of motion for the lens holder. A double-lead controller equipped with a fuzzy logic parameter tuning algorithm is then designed to perform dynamic decoupling and forge control efforts toward the goals of precision tracking, focusing and zero tilting simultaneously. Along with the controller, a genetic algorithm is developed to search the optimal designed parameters of previously designed auto-tuning algorithm. Finally, the experiments are conducted to show the effectiveness of the controller. With validated performance, the designed intelligent controller is ready to be employed for the next-generation optical disc drives.

This study presents the optimal design for the resonator beam profile of a bimodal ultrasonic motor via finite element modeling and Taguchi experimental design method. General design goals of an ultrasonic motor are to maximize the output power while restraining the contact force in order to extend component lives. To achieve the aforementioned goals, based on recent studies, beam profile design could play an important role because geometric variants of profile lead to substantial changes in the output power of the motor and simultaneously affect the contact force significantly. To investigate the effect of various profiles on the performance of the ultrasonic motor, the dynamic equations of motion are first formulated by utilizing an extended Hamilton’s principle and the method of the Lagrange multiplier. The method of finite element modeling is meanwhile used to approximate the governing partial differential equations by a discrete, finite degree-of-freedom system. With the beam outer profile parametrized by cubic splines in terms of locations of two intercepts, the Taguchi experimental design method is finally applied based on the simulated dynamics of the derived finite system to distill generic design guidelines for beam profile of the ultrasonic motor. It is found that a general paraboliclike profile for beam outer shape is best suited for maximizing output power, while a vaselike profile leads to the worst performance.

Recent design trends for modern mobile phones are evolving to be miniaturized and versatile sounds in quality. To these ends, a microspeaker with a corrugated diaphragm is employed to broaden the sound frequency range. Due to the fact that diaphragm corrugation and air closures were not considered in any past studies, this study presents comprehensive modeling with the consideration of diaphragm corrugations and air closures. It starts with the modeling on the subsystems of the voice coil motor (VCM) in the speaker. The magnetic field of the VCM is modeled by one set of finite elements, while the corrugated diaphragm is modeled by another set of finite elements. In addition, the air closures above or below the diaphragm are modeled by the third group of finite elements based on basic acoustics. Simulations are conducted with and without air closures. It is found that: 1) the speaker with 45deg corrugation exhibits overall higher (better) sound pressure levels (SPLs), while 2) the 75deg corrugation leads to unsatisfied, low SPLs below 1 kHz and two undesired antiresonances at higher frequencies. The theoretical findings are successfully validated by experiments

Spatially-resolved electroluminescence (EL) images in the triple-junction InGaP/InGaAs/Ge solar cell have been investigated to demonstrate the subcell coupling effect. Upon irradiating the infrared light with an energy below bandgap of the active layer in the top subcell, but above that in the middle subcell, the EL of the top subcell quenches. By analysis of EL intensity as a function of irradiation level, it is found that the coupled p-n junction structure and the photovoltaic effect are responsible for the observed EL quenching. With optical coupling and photoswitching effects in the multi-junction diode, a concept of infrared image sensors is proposed.

Nonradiative energy transfer from an InGaN quantum well to Ag nanoparticles is unambiguously demonstrated by the time-resolved photoluminescence. The distance dependence of the energy transfer rate is found to be proportional to 1/d(3), in good agreement with the prediction of the dipole interaction calculated from the Joule losses in acceptors. The maximum energy-transfer efficiency of this energy transfer system can be as high as 83%.

A novel cone-shaped lens cap for High Brightness Light Emitting Diodes (HB-LEDs) is proposed for improving brightness and high uniformity of the direct LED Backlight Units (BLUs) for large area LCD-TVs. Combining the designed lens cap with red, green and blue (RGB) chips on a Metal Core Printed Circuit Board (MCPCB), the LED module with the proposed cap is able to provide a compact white light source with unique features such as instant color variability and lower power usage, etc [1] [2]. The cone shape of the proposed lens cap is designed to emit only a small portion of light upward along the optical axis of the lens, while most of the light rays to the sides, providing a uniform luminance distribution and the high brightness on the backlight. In addition, a small, local square reflective box is designed and coupled to enclose the proposed LED module[3] [4] [5], the inner surfaces of which are attached with reflective films to increase the level of light mixing in the larger, global reflector box. With the structure of the LED module well designed, the placement of the LED modules in the BLU is next optimized via the method of optimization algorithm (OA). In the process of OA executions, the locations of the LED modules are the design factors to be optimized with chosen enclosure dimensions and number of LEDs to maximize brightness and uniformity of the entire BLU. Moreover, in the OA process, the software TRACEPRO is utilized to compute brightness and uniformity of the BLU with certain combination of the aforementioned design and control parameters considered. With the theoretically-optimized placement of the LED modules in hand, experiments based on a realistic BLU built in the laboratory are conducted to verify the performance of the proposed LED module and associated optimized locations. The results indeed identify the attributes of the BLU, which make it possible to achieve excellent backlight performance using a direct illumination approach from the light source of "Cone-Shaped Lens Cap of LEDs".

This study is dedicated to perform nonlinear asymptotic analysis based on the continuous thin plate model of MEMS capacitive sensor/actuator in order to predict the pull-in voltages/positions more precisely than past works. In these past studies, only discrete models without residual stress were considered. A sensor/actuator is considered in structure of two parallel electrostatically-charged flexible square plates — one thin plate in persistent vibrations to reflect external pressure and another thick plate in relative still as the backplate. The dynamic model in the form of the partial differential equation for the parallel plates is first established based on the balance among plate flexibility, residual stress and electrostatic forces. Assuming harmonic deflection for the vibrating plate clamped on boundaries, Galerkin method is used to decompose the established system p.d.e. into discrete modal equations. Solving the discrete modal equations, plate deflection can be obtained. The pull-in position is next solved from the condition that as the pull-in occurs the electrostatic attraction force on the deflected plate exceeds the elastic restoring force by the deflected plate. It is found from analysis results for some case study that the pull-in position is 1.66 μm with air gap of 3.75 μm. This predicted pull-in position is smaller than the predict position from past works, two-thirds of the gap. In addition to theoretical analysis, experiments are also conducted to verify the correctness of the established model.Copyright © 2005 by ASME

The study is aimed to perform dynamic modeling of the part-feeder powered by piezoelectric actuation. This part-feeder consists mainly of a horizontal platform vibrated by a pair of parallel piezoelectric beams. The parts to be transported on the platform march forward owing to their intermittent impacts on the platform. The dynamic modeling technique used herein is essentially the Rayleigh-Ritz method, which first incorporates material properties and constitutive equations of the piezoelectric materials, and then captures the complex dynamics of the parallel-beam piezo-feeder by three lower-order assumed modes in the transverse direction of the vibrating beams. With the three approximated assumed modes in hand, the system dynamics is then represented by three coupled discrete equations of motion. Based on these equations, displacement and velocity of the platform can be approximately obtained. Based on the approximated motions of the platform, the marching speed of the parts with intermittent impacts on the platform can be predicted. Numerical computations are conducted to acquire the estimated marching speed of the parts, along with the experimental study. The comparison between the theoretical predicted transporting speed of the part and the experiment counterparts.

The effect of metabolites from the indigenous Acidithiobacillus thiooxidans and temperature on the bioleaching of cadmium from soil was investigated in the present study. Bioleaching was found to be more effective than chemical leaching of cadmium. The metabolite, mainly sulfuric acid, which was shown to be growth-associated in the exponential phase, plays a major role in bioleaching. The maximum amount of cadmium leached was obtained after 8 days of precultivation when cells were directly involved in the leaching process. It indicates that cells in the exponential growth phase exhibit higher activity toward bioleaching. In contrast, the maximum amount of cadmium leached and the maximum initial rate for bioleaching were reached after 16 days of precultivation when only metabolites were involved in the bioleaching process. It implies that higher sulfuric acid concentration results in higher leaching efficiency. In addition, higher temperature leads to higher leaching efficiency. The optimal operation condition for bioleaching was determined to be a two-stage process: The first stage involves the precultivation of the indigenous A. thiooxidans at 30°C for 8 days followed by 20 minutes of centrifugation to discard cells. The second stage involves the bioleaching with the subsequent supernatant at 50°C. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 638–645, 2003.

We have studied the characteristics of efficiency droop in GaN-based light emitting diodes (LEDs) with different kinds of insertion layers (ILs) between the multiple quantum wells (MQWs) layer and n-GaN layer. By using low-temperature (LT) (780 °C) n-GaN as IL, the efficiency droop behavior can be alleviated from 54% in reference LED to 36% from the maximum value at low injection current to 200 mA, which is much smaller than that of 49% in LED with InGaN/GaN short-period superlattices layer. The polarization field in MQWs is found to be smallest in LED with InGaN/GaN SPS layer. However, the V-shape defect density, about 5.3×108 cm−2, in its MQWs region is much higher than that value of 2.9×108 cm−2 in LED with LT n-GaN layer, which will lead to higher defect-related tunneling leakage of carriers. Therefore, we can mainly assign this alleviation of efficiency droop to the reduction of dislocation density in MQWs region rather than the decrease of polarization field.

This study develops a continuous model to analyze the 'pull-in' effect in the circular micro-plates used in capacitive-type micro-electro-mechanical systems (MEMS) sensors, actuators and microphones. In developing the model, the governing equation of motion of the deformed plate is established in the form of a partial different equation (PDE) which is then decomposed using the Galerkin method to create a coupled set of modal ordinary differential equations. By considering the first-order deflection mode only and using a fifth-order Taylor series expansion of the electrostatic force, closed-form solutions are obtained for both the position and the voltage of the static pull-in event. Applying an energy balance method and a finite-order approximation method, the solutions are then obtained for the position and voltage of the dynamic pull-in event. The theoretical results obtained for the pull-in phenomena are verified based on the comparison to available experimental data, and also numerically using a finite element analysis (FEA) approach. In general, the results indicate that the ratio of the dynamic to static pull-in voltages is approximately 92%. However, when the squeezed-film effect induced by the air gap between the two plates is taken into account, the value of this ratio increases slightly as a result of considering a higher dynamic pull-in voltage.

A-plane InxGa1−xN/GaN (x = 0.09, 0.14, 0.24, and 0.3) multiple-quantum-wells (MQWs) samples, with a well width of about 4.5 nm, were achieved by utilizing r-plane sapphire substrates. Optical quality was investigated by means of photoluminescence (PL), cathodoluminescence, and time resolved PL measurements (TRPL). Two distinguishable emission peaks were examined from the low temperature PL spectra, where the high- and low-energy peaks were ascribed to quantum wells and localized states, respectively. Due to an increase in the localized energy states and absence of quantum confined Stark effect, the quantum efficiency was increased with increasing indium composition up to 24%. As the indium composition reached 30%, however, pronounced deterioration in luminescence efficiency was observed. The phenomenon could be attributed to the high defect densities in the MQWs resulted from the increased accumulation of strain between the InGaN well and GaN barrier. This argument was verified from the much shorter carrier lifetime at 15 K and smaller activation energy for In0.3Ga0.7N/GaN MQWs. In addition, the polarization-dependent PL revealed that the degree of polarization decreased with increasing indium compositions because of the enhancement of zero-dimensional nature of the localizing centers. Our detailed investigations indicate that the indium content in a-plane InGaN/GaN MQWs not only has an influence on optical performance, but is also important for further application of nitride semiconductors.

Pressure-induced resonant Raman scattering is adopted to analyze the zone-center optical phonon modes and crystal characteristics of Zn1−xMnxTe (0≦x≦0.26) thin films. The pressure (Pt) at which the semiconducting undergoes a transition to the metallic phase declines as a function of Mn concentration (x) according to the formula Pt(x)=15.7−25.4x+19.0x2 (GPa). Pressure-dependent longitudinal and transverse optical phonon frequencies and the calculated mode Gruneisen parameters were adopted to investigate the influence of Mn2+ ions on the iconicity. The experimental results indicate that the manganese ions tend to increase the iconicity of ZnTe under ambient conditions, whereas an external hydrostatic pressure tends to reduce the iconicity and the bond length of Zn1−xMnxTe.

A novel miniaturized optical image stabilizer (OIS) is proposed, which is installed inside the limited inner space of a mobile phone. The relation between the VCM electromagnetic force inside the OIS and the applied voltage is first established via an equivalent circuit and further validated by a finite element model. Various dimensions of the VCMs are optimized by a genetic algorithm (GA) to maximize sensitivities and also achieving high uniformity of the magnetic flux intensity.

This study proposes a new miniaturized autofocusing mechanism and an intelligent autofocusing algorithm with digital images as feedbacks. An actuation scheme for autofocusing is fostered via (1) capturing image by a complementary metal-oxide semiconductor sensor array, (2) evaluating the clearness of images by the well-known method of discrete cosine transformation (DCT), and (3) actuating the lens in the designed mechanism to the best-focusing position estimated by a neural network (NN), assisted by a genetic algorithm (GA).

Effects of Co content on the magnetic properties and microstructure of melt-spun [(Fe1−xCox)0.675Pt0.325]84B16 (x=0–0.5) and [(Fe1−yCoy)0.725Pt0.275]85B15 (y=0 and 0.3) nanocomposite ribbons have been investigated. The substitution of Co for Fe in [(Fe1−xCox)0.675Pt0.325]84B16 ribbons enhances the coercivity (Hci) from 7.5kOe for x=0to10kOe for x=0.3, due to the formation of ordered L10-(Fe,Co)Pt phase with higher anisotropy field. The effect of Co substitution for Fe in [(Fe1−yCoy)0.725Pt0.275]85B15 series ribbons is similar to that in [(Fe1−xCox)0.675Pt0.325]84B16 system. Interestingly, larger magnetization could be obtained by decreasing the boron and Pt content simultaneously. Moreover, L10-(Fe,Co)Pt phase provides [(Fe0.7Co0.3)0.725Pt0.275]85B15 ribbons sufficient high coercivity Hci=5.4kOe, resulting in a remarkable enhancement of energy product from 10.0MGOe for Co-free ribbons to 15.7MGOe for ribbons with y=0.3.

The vibrational, electronic, and crystalline properties of n-type chlorine-doped ZnSe (ZnSe:Cl) layers with a carrier concentration from 8.2×1015 to 1.8×1018 cm−3 are studied by Raman spectroscopy. The spectral line shapes of the longitudinal-optical-phonon and plasmon coupling mode are analyzed using the Raman scattering efficiency and the dielectric function to obtain the electron densities and mobility. The splitting of the transverse-optical (TO) phonon and the redshift of the chlorine-related impurity vibration mode are clearly observed when pressure is applied. The semiconductor-to-metal phase transition pressure of ZnSe:Cl layers declines as the carrier concentration increases, indicating that n-type doping reduces crystal stability. Additionally, the pressure-induced weakening of the longitudinal-optical-phonon-plasmon coupling efficiency suggests that pressure tends to degrade the n-type characteristic of ZnSe:Cl because of the emergence of the new deep donorlike state.

Magnetic properties, phase evolution, and microstructure of melt spun SmCo7−xHfxCy (x=0–0.5; y=0–0.14) ribbons via direct quenching have been investigated. For SmCo7−xHfx series ribbons, proper volume fraction of Hf is effective to stabilize and increase the magnetocrystalline anisotropy field of the TbCu7-type structure. Accordingly, the optimal magnetic properties of Br=6.4kG, Hci=7.3kOe, and (BH)max=8.7MGOe could be obtained for x=0.1. Furthermore, a slight C addition to above alloys is helpful in refining the grain size of the ribbons from 100–400nm for C-free to 10–80nm for C-containing samples. As a result, the magnetic properties are further improved to Br=6.9kG, Hci=11.8kOe, and (BH)max=10.6MGOe for SmCo6.8Hf0.2C0.12 nanocomposite ribbons.

The effect of Au content on the magnetic properties and microstructure of melt spun (FePt)100−xAux (x=0–40) ribbons have been investigated. X-ray diffraction and thermal magnetic analysis results indicate that Au-rich phase coexists with ordered L10-FePt(Au) phase in ternary FePtAu ribbons after an isothermal annealing. Meanwhile, the Curie temperature of L10-FePt(Au) phase in annealed (FePt)100−xAux (x=0–40) ribbons is almost unchanged, revealing that higher volume fraction of Au addition does not modify the composition of the L10-FePt(Au) phase. All the Au containing ribbons exhibit a completely isolated L10-FePt(Au) granular structure, and the grain size is effectively decreased with the increase of Au content. As a result, the intrinsic coercivity (Hci) of the ribbons increases substantially from 2.1kOe for binary FePt to 19.5kOe for (FePt)60Au40.

Magnetic properties, microstructure, and phase evolution of (Ce1−xPrx)9.5Febal.CoyTi2B10 (x=0–1 and y=0, 2.5) nanocomposites have been investigated. A progressive substitution of Pr for Ce enhances the remanence (Br), intrinsic coercivity (Hci), and maximum energy product [(BH)max] of the ribbons effectively. In addition, the Curie temperature of 2:14:1 phase also increases with increasing Pr concentration. For Co-free (Ce1−xPrx)9.5Febal.Ti2B10 ribbons, magnetically hard 2:14:1 phase and two soft phases, α-Fe and Fe3B, are found in the ribbons with x=0, 0.3, 0.4, and 0.7, while Fe3B phase disappears in the ribbons with x=1. On the other hand, the value of Br, (BH)max, temperature coefficient α, and Curie temperature of 2:14:1 and α-Fe are improved with a slight substitution of 2.5 at. % Co for Fe. The magnetic properties of Br=8.5kG, Hci=7.5kOe, (BH)max=13.5MGOe, α=−0.185%∕°C, and β=−0.54%∕°C can be achieved in (Ce0.5Pr0.5)9.5Febal.Co2.5Ti2B10 nanocomposites.

Magnetic aftereffect and surface magnetic domain structure of (Fe0.675Pt0.325)100−xBx(x=12–20) nanocomposites have been investigated for correlating with their corresponding phases and magnetic properties. Exchange-coupling effect between grains is present for all the studied ribbons as evidenced by Henkel plot. The volume fraction of magnetically soft phases decreases with increasing B concentration from x=12 to x=18. It leads to the reduction in the activation volume of the reverse domain. Among all samples, the (Fe0.675Pt0.325)82B18 ribbon having the highest intrinsic coercivity (Hci) exhibits minimum value in activation volume V=1.1×10−18cm3, because it possesses the least volume fraction of the magnetic soft phases, i.e., Fe2B or Fe3B phases. Magnetic force microscopy studies reveal the magnetic domain structures of the ribbons, confirming the existence of strong exchange coupling between magnetic grains.

Phase evolution, microstructure, and magnetic properties of melt-spun Pr9FebalTixB11−yCy (x=0, 2.5, and 4, y=0–11) ribbons have been investigated. For Pr9FebalTixB11−yCy series ribbons, addition of Ti suppresses the formation of metastable Pr2Fe23B3 phase and ensures the existence of a large amount of magnetically hard Pr2Fe14B phase in the ribbons. However, the increase of C substitution in the Pr9FebalTi2.5B11−yCy (y=0–5.5) ribbons diminishes the Br, Hci, and (BH)max monotonically, which comes from the increase of volume fraction of Pr2Fe17Cz and α-Fe phases and the rapid decrease of the 2:14:1 phase. Only in the higher Ti content Pr9FebalTi4B11−yCy ribbons, a slight C addition cannot only form the Pr2Fe14(B,C) phase but also refine the grain size, giving rise to the improvement of magnetic properties. The optimal properties of Br=9.4kG, Hci=11.1kOe, (BH)max=18.0MGOe, α=−0.207%∕°C, and β=−0.612%∕°C are achieved in Pr9FebalTi4B10.5C0.5 nanocomposites.

The phase evolution, microstructure, and magnetic properties of melt-spun Pr11Febal.B8−xCx (x=0–8) and Pr11Febal.Co10B6C2 nanocomposites have been investigated. Summarizing the results of x-ray diffraction and thermal magnetic analysis for Pr11Febal.B8−xCx series ribbons, magnetically soft Fe3B and α‐Fe phases are found to coexist with magnetically hard 2:14:1 phase for carbon-free (x=0) ribbons; three phases, namely, 2:14:1, Pr2Fe17Cy, and α‐Fe, appear for x=2–6, while 2:14:1 phase is almost not formed in Pr11Febal.C8 ribbons. The optimal magnetic properties of Br=9.4kG, Hci=9.3kOe, and (BH)max=17.3MGOe are obtained in Pr11Febal.B6C2. Substitution of 10at.% Co for Fe in Pr11Febal.B6C2 ribbons refines the grain size of the existing 2:14:1, Pr2Fe17Cy, and α‐(Fe,Co) phases and enhances the magnetic properties of the ribbons to Br=9.8kG, Hci=10.4kOe, (BH)max=19.0MGOe.