Search

Background Flaxseed (Linum usitatissimum L.) oil is an excellent functional oil containing various unsaturated fatty acids, mainly composed of linolenic acid, which is believed to have a variety of beneficial physiological and functional properties. However, the conversion efficiency of linolenic acid in the human body is low, and the research on flaxseed oil lacks a systematic review and evaluation. Scope and approach This review summarizes the research progress of flaxseed oil in recent years, including the main components, extraction and analysis methods of flaxseed oil; the main biological activities of flaxseed oil and its digestion, absorption, bioavailability and application in food; existing problems, possible solutions and prospects for future research. Key findings and conclusions Flaxseed oil is rich in alpha-linolenic acid (ALA) and other active ingredients, but the stability of ALA and its conversion to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in human body are very low. Improving the stability of ALA can promote its digestion and absorption in the gastrointestinal tract, thereby playing a beneficial role. The establishment of fat emulsion delivery system is an effective way to improve the stability and bioavailability of flaxseed oil. This review could benefit comprehensive understanding the value of flaxseed oil and promote its nutrition research and commercial product development.

Oil body (OB) is the lipid-storage organelle in oilseed, and its stability is crucial for oilseed processing. Herein, effects of roasting and boiling on the structure, stability, and in vitro lipid digestion of Camellia OB were studied. The interfacial structure and physical stability of the extracted OB were investigated by electrophoresis, confocal-Raman spectroscopy, zeta-potential, and surface hydrophobicity, etc. Boiling caused protein loss on the OB surfaces, forming a stable phospholipid interface, which resulted in coalescence of the droplets (d 100 μm) and negative ζ-potential (-3 ∼ -8 mV) values at a pH of 2.0. However, roasting partially denatured the proteins in the seeds, which were adsorbed on the OB surfaces. The random coil structure of interfacial protein increased to ∼20 % after thermal treatment. Besides, heating decreased the surface hydrophobicity of OB and improved lipid digestion. After boiling 60 min, the extent of lipolysis increased from 41.7 % (raw) to 57.4 %.

The objective of this study was to investigate the interaction between tannic acid (TA) and konjac glucomannan (KGM) with different molecular weight at different pHs,temperatures and urea concentration. The different molecular weight of KGM without change in primary structure were obtained by ultrasonic treatment. Turbidity titration showed that TA/KGM complexes could form at lower pH. The dynamic light scattering (DLS) and transmission electron microscopy (TEM) results indicated that the TA/KGM complexes assembled into large and uniform colloidal particles and would lead to precipitate with the increase of TA/KGM weight ratio. Isothermal titration calorimetry (ITC) results further revealed two-step binding behavior: the first stage corresponded to soluble complex formation, while the second stage represented aggregation between complexes. When the molecular increased, the transition of TA/KGM mass ratio between stage 1 and stage 2 changed from 3.5 to 3.0. KGM of higher molecular weight needed to bind more TA to move to the next stage. When the pH was 7 at 25 °C, the pH was 3.8 at 40 °C or urea addition, the ITC signal was completely abolished, the formation of complexes between KGM and TA was shown to be highly dependent on pH, temperature, urea concentration, suggesting the main driving force of TA-KGM complexes formation was hydrogen bond.

As a direct bandgap semiconductor, organic-inorganic lead halide perovskite (MAPbX3, MA = CH3NH3, X = Cl, Br, I) have been considered as promising materials for laser due to their excellent optoelectronic properties. The perovskite materials with 1D and 2D shapes were widely prepared and studied for Fabry-Perot mode and whispering-gallery-mode (WGM) microcavities, but cuboid-shape is rarely reported. In this work, we successfully fabricated single crystal cuboid-shaped MAPbBr3 perovskite with different morphologies, named microcuboid-MAPbBr3 (M-MAPbBr3) and multi-step-MAPbBr3 (MS-MAPbBr3), via solvothermal method. Furthermore, the as-prepared crystals’ excitonic recombination lifetime under different pumping energy density was studied by time-resolved photoluminescence (TRPL). Based on controllable morphology and remarkable lasing properties, these cuboid shaped single crystal perovskite could be a promising candidate for small laser, and other optoelectronic devices.

In nanophotonic energy storage, an energy conversion model is established for intrinsic nanophotonic energy storage (NPES) effects. Here we realize that the charge inhomogeneous distribution on the surface of upconversion nanoparticles (UCNPs) would persistently exist as well as the formation and migration of surface defects states despite of the compound component ratio, even following the stringent stoichiometric ratio. Our preliminary efforts on NPES effect has recognized from the recent published work by Chen et al. (2018) [4], in which the surface quantum confinement arose because of a recently found surface vacancy induced Coulomb states (SVIC) states. Further in-depth excavation on surface charge density distributions and defect orbitals of surface localized electrons and holes have affirmatively repeated the theory by Guerra et al. (2018) [32], and reflected the existence of surface defect states in both stoichiometric and non-stoichiometric compounds. Therefore, beyond the experimental trail-based multi-doping chemical modifications, we proposed that the surface electronic process for efficient NPES effect can be modulated by an intrinsic level-matching induced surface resonant quantum tunneling (LM-SRQT) in this work. The UCNP size-effect can be confirmed that simply might be not an influencing factor of dominating NPES effect while the surface degree of non-crystallizations indeed matters.

Recently, there has been an increasing research interest in the emerging fields of piezophotonics, which is the great interesting physics responsible for numbers of important technologies such as light source, smart sensor and mechanoelectronics. Piezophotonic effect is the coupling between the piezoelectric polarization and the photonic excitation in crystal that has a non-central symmetry. The strain-induced piezopotential can stimuli the photon emission without additional energy excitation such as light and electricity, which also offers great new opportunities of manipulating and fabrication of flexible optoelectronic devices. In this review, we will give a detailed description of the piezophotonic effect including its theoretical fundamental and practical applications. The piezophotonic light emission in doped ZnS CaZnOS, SrAl2O4 and LiNbO3 attract great interesting during the past years, and researchers have executed many scientific inquiries into flexible/stretchable optoelectronic devices. Until now, significant breakthroughs have been achieved on piezophotonic e-signature system, visible wearable electronic devices and multi-physical coupling devices. Certainly, rapid innovations in this field will be quite significant to the future of human life.

Protein fibrils are potential emulsifiers with a highly pH-dependent structure. Therefore, the influence of pH on the self-assemblies of whey protein isolate (WPI) fibrils was investigated through turbidity, transmission electron microscopy, and small-angle X-ray scattering tests. Next, the effects of fibril structure on the interfacial profiles and physical properties of stabilized Pickering emulsions were studied. With an increase in pH from 2.0 to 5.0, the cross-sectional radius of WPI fibrils increased from 1.87 ± 0.12 nm to 7.75 ± 0.33 nm, while with a further increase in pH to 7.0, the fibrils decreased to single strand. For all pH conditions, the WPI fibrils effectively absorbed at the oil-water interface. At pH 5.0, the contact angle of fibrils was the maximum (50.6°), and the diffusion rate was the fastest. The d4,3 values of the WPI fibril-stabilized Pickering emulsions were around 70–80 μm with no significant differences. Moreover, the Pickering emulsions stabilized by fibrils assembled at pH 5.0 showed a predominantly elastic gel-like behavior and high stability. This work clarifies the relationship between the structure of assembled WPI fibrils and their emulsifying properties, and it provides a theoretical basis for developing emulsion-based delivery systems.

The creations of photons in response to mechanical stimulus in a crystal that has noncentral symmetry are the great fundamental physics responsible for numbers of important technologies. The underlying mechanism and complete theory for a precise explanation of the mechanical-photonic energy conversion phenomena is vital important. We take commercial piezoelectric LiNbO3 matrics as the example to interpret the detail mechanisms of energy conversions for the photon-generation through a native point defects study. It was found the Frenkel and Schottky type complex pairs as well as the antisite pair defects acting as energy harvesting and migration centers, which are very easy to form and active. It does to be the extra deep electron or hole traps levels near the valence or conduction band edge, respectively. That is the substantial energy reduction via a spontaneous equilibrium transformation from the complementarily charged individuals into agglomerated complexes. Such energy gain for both two processes turns to be independent to the variations of synthesis chemical potentials. In addition, the complex defects actually form independent to the variations of the chemical potentials. This leads to a coupling and exchange effect by them to continuously collect and transport host charges along the path via localized states to the deep recombination levels. The initiating energy barrier is small which ambient thermal stimulation or quantum tunneling can accomplish. The native sensitizers such as VNb2O5, VLiNbO3, NbLi are also the energy conversion centers to non-radiative resonant energy transfer onto the activator center at the Oi to transfer the energy into photon emissions. A generalized energy conversion mechanism has been unraveled in this work. This gives a solid theoretical reference for developing the mechanical-photonic energy conversion materials.

Foaming behavior strongly depends on the structural characteristics of protein colloidal particles. These characteristics may be modified by means of changes in pH value or temperature. In this paper, the foaming and surface properties of gliadin nanoparticles (GNPs) treated by different pH values (3.0–5.8) and heat temperatures (25–70 °C) were investigated. First, decreasing of the pH value (from 5.8 to 3.0) is a process that pHs stay away from isoelectric point (pI∼6.5) of gliadin. Accordingly, zeta potential of GNPs, as indicator of surface charge, rose from +16.3 to +22.0 mV with decreasing the pH from 5.8 to 3.0. But the particle size of GNPs decreased slightly. Meanwhile, the foamability (FA) and foam stability (FS) of GNPs significantly decreased, evidenced by the slow initial adsorption rate and low viscoelastic modulus at the air/water interface. Heating induced a growth of GNPs particle size, however, the zeta potential remained unchanged. The FA and FS of GNPs after heat treated at different temperature values (25–70 °C) kept at the high values and the bubble size maintained the same level. FA and FS of heated GNPs were good enough to board the application of GNPs in the food processing. To compare the effect of pH and temperature on GNPs surface behavior, our results found that the zeta potential played leading role on the adsorption rate of GNPs onto the air/water interface instead of particle size and morphology. Besides, for the foaming properties of GNPs, sensitivity of pH and non-sensitivity of heating give an instructor for further applications.

The influences of the different structural flaxseed lignans on flaxseed oil (FO) emulsions during storage and digestion were investigated, focusing on their interfacial behavior. From perspective of interface, more than 60% of secoisolariciresinol (SECO) and the acidic hydrolysates of flaxseed lignan macromolecule (FLEH) were located on the interface of FO emulsions. It improved the stability of FO emulsions both during storage and digestion by inhibiting of free radical penetration and improving their targeted antioxidative activity. By comparison, the secoisolariciresinol diglucoside (SDG) and the alkaline hydrolysates of flaxseed lignan macromolecule (FLE) largely located in the aqueous and exerted lower antioxidative efficiency in emulsions. Moreover, SDG, SECO, FLE and FLEH slowed down the digestive rate of FO in emulsions, which might be due to flaxseed lignans inhibited the activity of digestive enzymes. These findings suggested that the different structural flaxseed lignans had the potential as antioxidants in emulsions during storage and digestion.

Multifunctional optical sensing devices are of decisive significance to the miniaturization and integration of optoelectronic devices. However, the development of stimuli responsive materials with multimode emission is still in the early stage, limiting the application of integrated optical sensing. Here, we report the multimode emission piezophotonic material fabricated by doping lanthanide ions into the quaternary piezoelectric semiconductor SrZnOS, achieving multimode emission under various stimulus/excitation sources (ultraviolet, near-infrared laser, X-ray, and force), due to its multifunctional optical properties. Particularly the mechanoluminescence has been realized covering both the visible and near-infrared spectral bands. Optical stress sensing was achieved by establishing a quantitative relationship between force and light conversion. Moreover, near-infrared mechanoluminescence can effectively resist the interference of ambient light. The temperature detection performance and the power-dependent color tunability of the sample were also evaluated for multifunctional applications. All the results indicate that the developed multifunctional optical materials with inherent multimode light-emitting characteristics have the potential in advanced optical sensing and anti-counterfeiting applications.

Piezoelectric semiconductor with optical, electrical and mechanical multifunctions has great potential applications in future optoelectronic devices. The rich properties and applications mainly encompass the intrinsic structures and their coupling effects. Here, we report that lanthanide ions doped piezoelectric semiconductor CaZnOS:Sm3+ showing strong red emission induced by dynamic mechanical stress. Under moderate mechanical load, the doped piezoelectric semiconductor exhibits strong visible red emission to the naked eyes even under the day light. A flexible dynamic pressure sensor device is fabricated based on the prepared CaZnOS:Sm3+ powders. The mechanical-induced emission properties of the device are investigated by the optical fiber spectrometer. The linear characteristic emissions are attributed to the 4G5/2→6H5/2 (566 nm), 4G5/2→6H7/2 (580–632 nm), 4G5/2→6H9/2 (653–673 nm) and 4G5/2→6H11/2 (712–735 nm) f–f transitions of Sm3+ ions. The integral emission intensity is proportional to the value of applied pressure. By using the linear relationship between integrated emission intensity and the dynamic pressure, the real-time pressure distribution is visualized and recorded. Our results highlight that the incorporation of lanthanide luminescent ions into piezoelectric semiconductors as smart materials could be applied into the flexible mechanical-optical sensor device without additional auxiliary power, which has great potential for promising applications such as mapping of personalized handwriting, smart display, and human machine interface.

Mechanoluminescenece (ML) is a dynamic luminescence phenomenon of materials under various mechanical stimulation. Impurity doped ZnS shows high ML repeatability without any needs for extra excitation sources, thus making it very promising in applications like stress sensing and battery-free new light source. Lots of progress has been made in the last decades, however, the reproducible ML (RML) mechanism is still unclear to explain some basic phenomena like how the electron is excited to conduction band when undergoing mechanical actions or how the excitation energy is transferred to the dopants so efficiently. Based on comparative study of photoluminescence (PL) and ML in Mn2+ doped ZnS prepared via melt-salt method, the RML energy routes in sphalerite ZnS: Mn2+ is proposed herein, and further, a general mechanism is supposed which could apply to other RML systems. The excitation of RML is possibly generated by electron transfer during bond rebuilding in plastic deformation while the highly efficient energy transfer is realized through hole and electron capture by the dopant. According to this mechanism, we provide some prospects for further optimization of RML performance as well as discovery of new RML materials.

Camellia oleifera seed oil contains nearly 80% oleic acid, which accounts for health-benefits, and it is stored in the subcellular oil bodies (OBs) organelles. To utilize C. oleifera OBs as a dietary supplement of unsaturated fatty acid, the physical properties need to be investigated. The physical stabilities of extracted OBs against ionic strength (0.01–1M) and temperature (30–90 °C) were evaluated via Turbiscan analysis and confocal microscope. The results showed that OBs extracted at alkaline conditions (pH 9.0–11) exhibited uniform dispersion. The surface charge of the OBs decreased dramatically with increasing NaCl content, and OBs droplet aggregation occurred under a NaCl concentration of 0.1 mol/L. Moreover, high temperature (up to 90 °C) had a positive effect on OBs stability. Overall, OBs extracted under alkaline pH were more stable than those extracted under neutral pH. Differences in the interfacial proteins of OBs extracted at the neutral and alkaline pHs were studied via sodium dodecyl sulfate-acrylamide gel electrophoresis (SDS-PAGE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Six types of oleosins, including Ole Ⅲ, the fragment of Ole Ⅱ, oleosin, Ole Ⅳ, Ole Ⅴ, and Ole Ⅰ, were found in the extracted membrane proteins. Oleosins and some coextracted endogenous proteins played a certain role in OBs stability.

In many revolutions of the cellulose based conductive materials, the most significant one was the developed material could be either directly used as a working electrode or used as the underlying substrate for the electrochemical deposition metal electrodes. In this work, an in situ polymerization of aniline monomer onto the porous structured cellulose scaffolds has been carried out, and then electrodeposition of Ag nanoparticles on the obtained conductive composites directly by using it as electrode. The Ag nanoparticles were deposited homogeneously on the matrix of polyaniline (PANI)/cellulose gels. The conductivity of PANI/cellulose nanocomposite gels containing Ag nanoparticles was increased to 0.94 SCm-1, which was higher than that of pure PANI/cellulose composites (3.45×10-2SCm-1). Furthermore, it could be used as electrode for the supercapacitors, and the highest specific capacitance of the cellulose/PANI/Ag aerogels was 217Fg-1. This approach offered a facile method for improving the electronic conductivity of native polymer nanohybrids, and suggested a new strategy for fabricating nanostructured polymer nanohybrids for application in energy storage.

The co-existence of polysaccharides and enzymes in the food matrix could form complexes that directly influence the catalytic efficacy of enzymes. This work investigated the self-assembly behaviors of α-amylase and charged polysaccharides and fabricated the α-amylase/polysaccharides complex coacervates. The results showed that the linear charge density of polysaccharides had a critical impact on the complex formation, structure, and enzyme protection under acidic conditions. At low pH, α-amylase formed compact and tight coacervates with the λ-carrageenan. However, α-amylase/pectin coacervates dissociated when the pH was lower than 3.0. The optimized binding ratio of α-amylase/λ-carrageenan was 12:1, and α-amylase/pectin was 4:1. Finally, the α-amylase/λ-carrageenan complex coacervates effectively immobilized the enzyme and almost 70% of enzyme activity remained in coacervates after exposure to pH3.0 for 1 h. This study demonstrates that the change in the linear charge density of polysaccharides could regulate the enzyme-catalyzed process in food processing by a simple and fine-controlled method.

To understand the influence of the degree of substitution (DS) of sodium carboxymethyl cellulose (CMC) and gliadin:CMC ratio on the surface and foaming behaviors of gliadin-CMC nanoparticles (G-CMC NPs) at pH 3, three DS (0.7–1.2) and four ratios (G:CMC~1:0.5–1:2) were investigated. Gliadin NPs with a pH of 3 were utilized as a control. Results showed that G-CMC NPs at all investigated DS and ratios possessed higher foamability and foam stability when compared to the control. This indicated that adding CMC to gliadin NP suspensions could greatly improve their foaming properties. G-CMC NPs with a DS of 0.7 and 0.9, had lower surface charge than G-CMC1.2 NPs, resulting in a weaker electrostatic repulsion, thus leading to faster adsorption kinetics and higher foamability. By increasing the G:CMC ratio from 1:0.5 to 1:2, the particle size gradually rose, and the zeta potential remained unchanged. At a ratio of 1:2, the highest foam stability was observed. This might be ascribed to the high continuous phase viscosity at this ratio, which could slow down the drainage rate and protect the bubbles against coalescence and disproportionation. It was worth mentioning that G-CMC NPs at all ratios exhibited impressive foamability (~220%) even at a very low concentration of G-CMC NPs (gliadin was fixed at 1 mg/mL). This implies that G-CMC NPs could act as a new efficient foaming agent, and based on its simple preparation, have the potential to be widely applied in foamed food.

Sensitivities of anthocyanins to pH and thermal treatment greatly limit their applications in food as the functional ingredients or natural pigments. Here, synergistic hydrogels formed by mixing konjac glucomannan (KGM) and xanthan gum (XG) were utilized to enhance the thermal stability of anthocyanins at various pH values (3.0, 6.0, and 9.0). Gels network was studied by combining the bulk-rheology and micro-rheology measurements. Interestingly, the thermo-induced anthocyanins degradation and the reconstructing of gel networks occurred simultaneously in KGM/XG hydrogels. Results showed that the gelling behavior of KGM/XG protected anthocyanins from thermo-exposure. That provides a promising strategy for stabilizing thermo-sensitive bioactive compounds in the thermo-induced gelling systems.

Pulsed electric field (PEF) could change the charge distribution of proteins and polysaccharides and affect their interactions and complexes aggregation, but those influences are not enough evaluated. Here, the effects of PEF on the complexes of α-amylase and pectin driven by electrostatic binding were studied. Changes in molecular conformation of α-amylase and assembly structure of α-amylase/pectin complexes were orderly assessed by fluorescence, FTIR, DSC, enzyme activities, particle size, ζ-potential, CLSM, and SEM. After PEF treatment (E~20 kV/cm, texp~1 ms, and 5 cycles), the intrinsic fluorescence of α-amylase was quenched, the content of β-sheet increased, enzyme activities lose almost 80%, and the denatured temperature increased. Ζeta-potential of α-amylase/pectin complexes did not change significantly, but the particle size rose gradually. The particle revolution of α-amylase/pectin complexes was recorded by Turbiscan, and the size growth model fit the Allometric function well. Finally, the complexes of α-amylase and pectin after PEF treatment tended to the branched, ring, or circles-like shape.

Currently, concentration-induced near-infrared upconversion quenching at highly doped levels of lanthanide ions poses a significant constraint for their practical applications. In this work, the fabricated Tm3+/Yb3+ codoped Na0.5Bi2.5Nb2O9 (NBN) materials with a layered structure exhibited a single-band near-infrared to near-infrared upconversion emission (808 nm emission, 980 nm excitation) with no obvious concentration quenching even with a higher Yb3+ content of 90 mol%, while maintaining excellent thermal stability. Meanwhile, the Tm3+/Yb3+ co-doped NBN materials showed strong visible-light absorption at 400-800 nm under the irradiation with sunlight (AM1.5), and the absorbed light can be released via a thermal stimulus, showing a typical photochromic reaction. The near-infrared upconversion emission intensity was effectively tuned after and before sunlight irradiation. This research provides a new strategy for designing high-efficiency near-infrared upconversion and visible photoresponsive oxides for near-infrared modulation, solar energy conversion, and other multifunctional applications.

A new Aurivillius oxide Na0.5Er0.5Bi4Ti4O15 (NEBT) was synthesized by conventional solid-state reaction and characterized by X-ray diffraction, scanning electron microscope, luminescent, dielectric, and piezoelectric measurements. The as-prepared NEBT ceramics showed a bright upconversion photoluminescence (UC) while simultaneously exhibited a piezoelectric characteristic. Under 980 nm radiation excitation, three emission bands located at green (532 nm, 556 nm) and red (671 nm) wavelength regions were obtained at room temperature. The fluorescence intensity ratio of two green emission bands (centered at 532,556 nm) was studied as a function of temperature in a range of 173–503 K. The maximum sensor sensitivity was found to be about 0.0017 K−1 (380 K). Dielectric property studies showed that NEBT had a phase transition from ferroelectric to paraelectric at around 665 °C. The annealing temperature dependence of piezoelectric d33 showed stably thermal piezoelectric properties of NEBT. As a multifunctional material, NEBT would be useful in sensor, future optical-electro integration devices.

High-performance, low-power and multifunction-integrated devices are crucial in emerging technologies. Herein, we demonstrate WS2/CsPbBr3 van der Waals heterostructure (vdWH) planar photodetectors combining the high mobility of mechanically exfoliated 2D WS2 nanoflakes with the remarkable optoelectronic properties of 1D single-crystalline CsPbBr3 nanowires and the strain-gated and strain-sensing characteristics induced by the piezo-phototronic effect. Owing to the effective charge carrier transfer and channel depletion originating from the appropriate energy band alignment, collaborative improvement of the photocurrent and dark current is realized, thus, an ultrahigh on/off ratio of 109.83 is achieved. The highest responsivity and detectivity at Vd = 2 V are 57.2 A W−1 and 1.36 × 1014 Jones, respectively. Even with a lower Vd of 0.5 V, decent performance is still obtained. Furthermore, the interfacial carrier transfer can be manipulated through the piezo-phototronic effect induced by CsPbBr3 monocrystal nanowires. Thus, when constructed on a flexible PEN substrate, the WS2/CsPbBr3 vdWH planar photodetector presents strain-gated photocurrent and responsivity, modulated by a factor of 11.3 with strain application, and a strain-sensing function is simultaneously realized due to the linear dependence of the photocurrent on strain. This unprecedented device design opens up a new avenue toward not only high-performance and low-power but also multifunction-integrated devices realized by the direct effect of mechanical inputs on charge carriers.

Ferroelectric oxides with optical, electrical and mechanical multifunctions have great potential applications in future optoelectronic devices. We examined the Er doped BaBi 4 Ti 4 O 15 (BBT) layered ferroelectric oxides and demonstrated that a certain amount of Er doped ceramic sample shows a bright up-conversion photoluminescence (UC) while simultaneously obtaining enhanced ferroelectric properties and increased Curie temperature ( T c ). The UC properties of doped BBT ceramics were investigated as functions of Er 3+ concentration and incident pump power. Green (557 nm) and red (670 nm) emission bands were obtained under 980 nm excitation at room temperature. Studies of dielectric constant and dielectric loss with different temperature indicated that introduction of Er increased the T c with relatively lower values of dielectric loss of BBT thus making this ceramic suitable for sensor applications at higher temperatures. Meanwhile, Er introduction improved the ceramic’s ferroelectric properties by increasing the remnant polarization making it suitable for effective ferroelectric devices. As a multifunctional material, Er doped BBT showed a great potential to be used in sensor, optical-electrical integration and coupling devices.

Pr 3+ doped CaBi 2 Ta 2 O 9 based bismuth layered-structure oxides were synthesized by a simple solid state reaction method. The photoluminescence properties of the samples were investigated by excitation and emission spectra. Photoluminescence excitation spectra show that the samples have broad blue excitation band located at 430–510 nm, which covers the emission wavelength of commercial blue light-emitting diode (LED) chips. Upon the excitation of 450 nm light, a novel red emission centered at 621 nm of Pr doped CaBi 2 Ta 2 O 9 makes it useful in the white LEDs. In addition, it was also found that the photoluminescence can been improved by partial substituting Sr for Ca. These Pr 3+ doped CaBi 2 Ta 2 O 9 based ferroelectrics could possibly be used as a multifunctional material for a wide range of applications, such as integrated electro-optical devices.

In this paper, Pr doped CaBi 4 Ti 4 O 15 ceramics were prepared by a traditional solid state method. Crystal structure and morphologies of the ceramics were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The photoluminescence properties of the samples were investigated by a spectrofluorometer. Three excitation bands are located at wide range of wavelength, which are 300–430 nm, 440–510 nm and 550–570 nm respectively. Upon the excitation of 494 nm light, the samples shows an emission peak centered at 614 nm, corresponding to 1 D 2 → 3 H 4 transition. A 614 nm red emission excited under the wave with long wavelength of Pr doped CaBi 4 Ti 4 O 15 makes it useful in the white LEDs. In addition, it is an intrinsic ferroelectric and piezoelectric material; the enhanced ferroelectric properties were obtained by Pr doping. As a multifunctional materials, Pr doped CaBi 4 Ti 4 O 15 may be useful in white LEDs, sensor, and optical-electro integration.

Single crystalline CdTe branched nanowires and well-aligned nanorod arrays were simultaneously synthesized by a simple chemical vapor deposition (CVD) technique. X-ray diffraction (XRD), scanning electronic microscopy (SEM), transmission electronic microscopy (TEM) and selected area electronic diffraction (SAED) were used to study the crystalline structure, composition and morphology of different samples. Vapor–liquid–solid (VLS) and vapor–solid (VS) processes were proposed for the formation of the CdTe branched nanowires and nanorod arrays, respectively. As-grown CdTe nanorod arrays show a strong red emission band centered at about 620 nm, which can be well fitted by two Gaussian curves centered at 610 nm and 635 nm, respectively.

Uniformly sized α-Fe2O3 hexagonal platelets were synthesized by a hydrothermal process using Fe(OH)3 suspension and large amount of NaOH. The reaction products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and a vibrating sample magnetometer (VSM). The results show that the hexagonal platelets are fine, monodisperse and consisting of single-crystals. The magnetic hysteresis (M–H) curve of the samples measured at room temperature indicates that the α-Fe2O3 micro-platelets exhibit ferromagnetic behaviors with relatively low coercivity.

This paper reports the growth of octahedral magnetic Fe 3 O 4 particles from iron powders via a simple alkaline hydrothermal process. The chemical compositions and morphologies of the as-grown Fe 3 O 4 particles were characterized by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), and scanning electron microscopy (SEM). Structure characterization showed that the phase structure of the prepared particles evolved from α-Fe to pure Fe 3 O 4 with increasing concentration of KOH, indicating the important role of KOH concentration on the formation of the magnetite octahedron. The magnetic properties of samples were also studied by means of a vibrating sample magnetometer (VSM). The pure magnetite Fe 3 O 4 octahedrons exhibited a relatively high saturation magnetization of 96.7 emu/g.

Ho3+/Yb3+ co-doped and Ho3+/Yb3+/Li+ tri-doped SrAl2O4 ceramics were prepared by the conventional solid-state reaction and their up-conversion (UC) luminescence was characterized. Strong green emission (556 nm) and weak red emission (664 nm) were observed under the excitation of 980 nm laser diode (LD) at room temperature. The up-conversion process is based on two-photon absorption. In Ho3+/Yb3+ co-doped SrAl2O4 ceramics, the UC intensity achieved its maximum as Yb3+ concentration was 20 mol% which was attributed to the energy transfer (ET) from Yb3+ to Ho3+. Furthermore, the UC green luminescence intensity was largely enhanced by about six times in Li+ doped SrAl2O4: Ho3+, Yb3+ ceramics and the related mechanisms have been discussed.