In this work, planar-heterojunction organic phototransistors (OPT) have been constructed from solution process, by combining a semiconducting diketopyrrolopyrrole polymer PDVT-10 and a novel carbon nanomaterial- carbon quantum dots (CQDs). The PDVT-10/CQDs planar heterojunction films, possessing the optical properties of both PDVT-10 and CQDs, reveal strong optical absorption in a wide spectral region from ultra-violet to near infra-red. Compared with pristine PDVT-10 phototransistors, such planar-heterojunction OPTs exhibit a remarkably higher performance on broad-spectrum photo-detection, with a photoresponsivity of 2.6×10⁴ A/W, a specific detectivity of 2.4×10¹³ Jones, and maximum light sensitivity higher than 10⁴ under the 450-nm laser irradiation, as well as with a responsivity of 4.4×10⁴ A/W and a specific detectivity of 1.2×10¹³ Jones under the 808-nm laser irradiation. Based on the study of the photo-response mechanism for these devices, the performance improvement of the PDVT-10/CQDs based OPTs should be attributed to the favorable energy level alignment at the PDVT-10/CQDs interfaces, which enhances interfacial exciton dissociation and charge separation, meanwhile effectively suppresses the hole-electron recombination in the light-absorption layer. Furthermore, the formation of efficient carrier conduction pathway is benefited from high hole-mobility of PDVT-10 for the OPT performance enhancement. Our work offers a valuable avenue for the development of high performance light detectors.

Medical high-frequency ultrasonic transducers are widely used in fine structure imaging of human body and biological tissues. The 1-3 piezoelectric composite material has become the core material of high frequency ultrasonic transducer because of its high electromechanical coupling coefficient and low acoustic impedance. In this paper, high-performance Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ ceramic/epoxy piezoelectric composites were designed and prepared based on finite element calculation and soft template method, and the electrical properties of the materials were systematically tested. The results show that the 1-3 piezoelectric composite material has excellent acoustic comprehensive performance. The electromechanical coupling coefficient kt of the thickness expansion mode reaches 70.1%, and the acoustic impedance Za reaches 19.05 MRayl. A high-frequency ultrasonic transducer was fabricated using this material, with a-6 dB bandwidth of 85% and an insertion loss of 17.7 dB. The results show that the piezoelectric composites prepared by the soft template method have excellent comprehensive properties suitable for ultrasonic imaging, which is expected to promote the commercial application of high-frequency ultrasonic transducers.

The blend films are prepared by spin-coating the solution of a benzothiadiazole-based semiconducting polymer PffBT4T-2DT mixed with the elastomer polydimethylsiloxane (PDMS), and organic field effect transistors (OFETs) have then been constructed via a contact lamination transfer process to evaluate electrical performance of these blend films under strain. It reveals a vertically phase-separated structure in the PffBT4T-2DT/PDMS blend films, in which PffBT4T-2DT is enriched mainly in the lower layer of the film and the PDMS at the upper part. The introduction of PDMS in the blend also promotes the formation of edge-on stacking motif of the PffBT4T-2DT backbones. Notably, compared to pristine PffBT4T-2DT, the blend films exhibit significantly improved strain tolerance (stretchability), which ensures a relatively high hole mobility in OFETs even under 100% strain. The enhancement of elasticity and carrier mobility should be attributed to the PDMS matrix which effectively dissipate the energy inside the mechanically stretched film. Furthermore, the correlation between the film structure, mechanical properties and carrier transport of the blend film is clarified, based on the structural characterizations.

In this paper, cellular PP piezoelectret films with different thicknesses were prepared by microstructure control on home-made PP foams (PQ50), and their piezoelectric and acoustic properties were compared with those of commercial cellular PP piezoelectrets (HS70) developed by VTT in Finland. The results show that the Young’s modulus of cellular PQ50 films exhibits a U-shaped dependence on the film thickness, and the Young’s modulus reaches the minimum around the thickness range of 60~65μm.The polarization of the PP piezoelectret films exhibits a threshold behavior. Above the threshold voltage, the dynamic piezoelectric d₃₃ coefficient increases significantly with increasing poling voltage. For a poling voltage of 6kV, the d₃₃ of PQ50 cellular film with a thickness of 60μm reaches 355pC/N, while the d₃₃ coefficient of HS70 is 179pC/N. Within the static force range of 1~10N, the dynamic piezoelectric d₃₃ coefficient of two kinds of PP cellular piezoelectret films first decreases and then tends to be stable. Ultrasonic transducers based on optimized PQ50 and HS70 show amplitudes of 170 and 26mV and bandwidths of 320 and 180kHz, respectively. Therefore, the home-made PQ50 film with optimized micro-structure shows better piezoelectric and acoustic properties than the commercial VTT film HS70.

With the worsening of environmental pollution and energy crisis, the research and application of luminescent fiber have attracted the attention of many researchers. Luminescent fiber not only has good mechanical properties of ordinary fiber, but also has many excellent properties, such as luminescence, environmental friendliness, biocompatibility, anti-aging, and sustainable luminescence. Luminescent fiber is mainly divided into fluorescent fiber and noctilucent fiber, and noctilucent fiber can be further divided into spontaneous fiber and optical storage fiber. Luminescent fibers emit light by absorbing external energy, storing energy and emitting photons in a recurring process. The use of luminescent fiber can alleviate the problem of resource shortage and meet the demand of energy conservation and emission reduction in China. In this paper, the classification, luminescence mechanism, preparation method and application of luminescent fibers were reviewed and summarized, in order to provide theoretical support for further study of luminescent fibers.

BaTiO₃ crystals have been widely used in the field of dielectric and piezoelectric components, but BaTiO₃ has multiple phase transition temperatures, especially at room temperature, which will seriously damage the crystal quality. In order to improve the properties of BaTiO₃, doping BaTiO₃ crystals is considered. In this paper, based on first-principle calculation, the electronic structure and optical properties of BaTiO₃ doped with different Ca contents, namely Ba_1-xCa_xTiO₃ (x=0, 0.125, 0.25, 0.5), were calculated. It is found that BaTiO₃ is a direct band gap semiconductor in terms of electronic structure, and its band gap width is 1.74 eV. Doping Ca leads to an increase in the band gap of BaTiO₃. The density of states of BaTiO₃ doped with Ca is larger than that of undoped BaTiO₃, but the density of states decreases with the increase of doping content. In terms of optical properties, BaTiO₃ doping with Ca results in a significant shift in the dielectric peak. After BaTiO₃ is doped with Ca, its static dielectric constant becomes smaller. The light absorption of different wavelengths is different after BaTiO₃ is doped with different Ca contents. When Ca is 0.125, the light absorption capacity decreases greatly. The research results of Ba_1-xCa_xTiO₃ (x=0, 0.125, 0.25, 0.5) crystals in this paper show a broad application prospects in the field of optoelectronics and provide a theoretical basis for the growth and properties of this series of crystals as well.

Photocatalysis is considered to be one of the effective methods to solve the global energy crisis and environmental pollution problems. However, the low energy conversion efficiency of photocatalyst inhibits the application of photocatalysis. Vacancy is the most common crystal defect, because it can regulate the electronic structure and surface properties of photocatalyst without introducing external elements, and promote the light absorption, charge separation and migration of photocatalyst and surface reaction. Therefore, this review summarizes the latest progress of vacancy defects in photocatalysis. Firstly, some primary methods for introducing vacancy defects in photocatalyst are discussed, including common methods such as chemical reduction and high temperature treatment, and uncommon but effective methods such as hydrolysis and ultrasound. Secondly, the current characterization techniques for identifying and quantifying vacancies are mainly introduced from the aspects of microscopic characterization and spectral characterization. These techniques are helpful to understand the relationship between vacancy structure and photocatalytic properties. Subsequently, the key role of vacancy in photocatalytic process is introduced from three aspects, including absorption of light, separation and migration of charge and surface reaction. Finally, the prospects and challenges of vacancy defects in photocatalytic materials are proposed. The controllability of vacancy concentration, the synergism of composite modification and the stability of vacancy are urgent problems to be solved. This review summarizes the effective strategies of vacancy modification for photocatalysis, which can provide some theoretical reference for the relevant research.

Spontaneous polarization of ferroelectric materials can generate a built-in electric field. In this study, Ag₂O and CdS nanoparticles were supported on ferroelectric LiNbO₃ and glass substrates by physical dispersion method, and Rhodamine B (RhB) was selected as a representative organic pollutant to evaluate the photocatalytic degradation efficiency of Ag₂O and CdS on the different substrates. The results show that the photocatalytic activity of the same semiconductor nanoparticles on different substrates is LiNbO₃(+Z) > glass > LiNbO₃(-Z). On the same substrate, Ag₂O exhibits better photocatalytic activity than CdS. Based on the polarization-generated built-in electric field at the interface of semiconductor/ferroelectric and the photocatalytic degradation reaction, the mechanism of ferroelectric polarization affecting the photocatalytic degradation performance of semiconductors is proposed.

The non-coincidence of the positive and negative charge centers of perovskite ferroelectric crystals leads to spontaneous polarization inside the materials to generate a built-in electric field. The existence of built-in electric field is beneficial to the transmission and separation of photo-excited carriers. However, perovskite ferroelectric materials are mostly wide-band gap semiconductors. Photogenerated electrons and holes generated when materials are excited are easy to recombine. Therefore, adjusting their photoelectrochemical performance has become a research hotspot. In this paper, the principles and progress of controlling the photoelectrochemical performance of perovskite ferroelectric materials are introduced, such as doping and substitution of elements, deposition of precious metals on the surface, construction of semiconductor heterostructure and multi-mechanism coupling. The applications status of these materials in photocatalytic degradation of pollutants, photocatalytic hydrogen production and photoelectrochemical water splitting hydrogen production in recent years are emphatically introduced.

Photocatalytic reaction has important applications in the fields of degradation of harmful pollutants, conversion of greenhouse gases, production of hydrogen, elimination of harmful bacteria and so on. In recent years, ferroelectric materials with spontaneous polarization have been considered as a new candidate. Their spontaneous polarization can produce a built-in electric field and provide a driving force for the transmission of photogenerated carriers. This characteristic is expected to solve the thorny problem encountered in the field of photocatalysis, the recombination of electron hole pairs. Because of this characteristic, the research on the photocatalytic properties of ferroelectric materials mainly focuses on reducing the recombination of holes and electrons. But in fact, to improve the photocatalytic efficiency, we need to consider the whole catalytic process, including three key stages, photon absorption, separation and migration of photogenerated electron holes and terminal reaction. Focusing on the above three stages of photocatalytic process, this paper sorts out the typical achievements in recent years, and combs the effective means to improve the catalytic performance of ferroelectric materials in different stages of photocatalysis. It is hoped that our summary can provide a useful reference for the follow-up research work.

In recent years, bismuth sodium titanate (BNT)-based piezoelectric materials have shown large electro-strain response due to their unique field-induced phase transition, and have shown a great potential in actuator application. In our work, (Bi_0.5Na_0.5)_0.935Ba_0.065TiO₃-xSrMAlO₄ (xSrMAlO₄, M=La, Y) lead-free piezoelectric ceramics with good electrostrain performance and temperature stability are prepared by the traditional solid-phase synthesis process. The effect of SrMAlO₄ (M=La, Y) component on the phase structure and electrical properties of the ceramics is studied. The results show that the introduction of SrMAlO₄ component induces a phase transformation from rhombohedral-tetragonal coexisting phases to a single pseudo-cubic phase, and destroys the ferroelectric order of the matrix material and induces the appearance of weakly polar phase. Thus, the field-induced strain is significantly imported. When the SMA content is 0.9 mol%, the materials exhibit large strain response. Under a 70 kV/cm electric field, the unipolar strain is 0.39% (M = La) and 0.44% (M = Y), respectively, and the corresponding large signals d^*₃₃ is 557 pm/V (M = La) and 629 pm/V (M = Y), respectively. The high strain response is derived from the reversible transition from the ergodic relaxation state to the ferroelectric state driven by the electric field. In addition, it is found that 0.9 mol% SrMAlO₄ (M = Y) modified ceramic shows excellent temperature stability from room temperature to 100 ℃, which is promising for actuator applications.

Gallium droplets are grown on GaAs substrate by droplet epitaxy. The samples with different gallium deposits are characterized by AFM and the surface morphology is observed. The results show that gallium atoms in droplets under arsenic pressure can be divided into two kinds of diffusion behaviors: outward diffusion and downward etching. These diffusion behaviors are affected by substrate temperature and arsenic pressure. The results show that arsenic atoms significantly affects the surface diffusion of gallium atoms, and the inner ring depth is mainly affected by the substrate temperature. The GaAs concentric quantum rings are prepared by cooling crystallization method. The relationship between the disk radius ΔR(R_p) and the deposition amount is analyzed. The critical deposition amount of GaAs to form the diffusion disk is found to be 10 mL.

Owing to that light as an external stimulus has great advantages of non-invasive, remotely controlled and rapidly changed, photoreversible color switching materials have important applications in data storage, color display, smart windows, anti-counterfeiting and so forth. However, most of the transitional photoreversible color switching materials have problems such as poor thermal stability, low cycling performance, and slow color switching rate, which seriously restricts their developments in related fields. In recent years, the photoreversible color switching systems based on semiconductor nanomaterials/redox dyes have attracted great attentions and exhibited excellent photoreversible color switching properties because the photoreversible color switching systems integrate the outstanding photoreductive activity of semiconductor nanomaterials and the unique redox-driven color switching property of redox dyes. The photoreversible color switching systems show great potential in the applications of inkless, light-printable rewritable paper, colorimetric oxygen indicators, smart color changing textile, and high-level anti-counterfeiting. In this review, the recent progress in design principle, property and mechanism, and application of semiconductor nanomaterials/redox dyes based photoreversible color switching systems are summarized. Furthermore, the future opportunities of this field are prospected.

In this work, organic field effect transistors (OFET) have been prepared via spin-coating process, based on the blend films consisting of a novel naphthalenedicarboximide-based semiconducting polymer FN2200 and insulating polymer polystyrene (PS). A remarkable enhancement of electron mobility is found by incorporating a small amount of PS into the blend, however further increase of the PS content results in drastic lowering of carrier mobility in the blend OFETs. The vertical phase separation in the FN2200/PS blends is observed, which features the FN2200 component enriched at film surface and the PS phase located near the substrate surface, via the UV-vis absorption spectra in combination with incremental oxygen plasma etching. The grazing incidence X-ray diffraction (GIXRD) patterns reveal that the edge-on packing is facilitated in the FN2200 domains for the blend films compared to neat FN2200 films. Based on the structural investigations, a systematic explanation is presented about the significant dependence of the OFET performance on the PS content in the blend films.

Two kinds of cellulose/ZnO piezoelectric papers are prepared by crushing and dissolving methods. The papers are characterized by SEM and analyzed by a piezoelectric equipment. The differences in the structure and piezoelectric performance of the two kinds of papers are explored. The effects of ZnO addition amount, thickness of the papers, and pressure on the piezoelectric properties are discussed and compared with a PVDF film. The results show that the fibers of the piezoelectric paper prepared by the dissolving method are smooth and tightly bounded to ZnO, which makes ZnO uniformly coat on the surface of the fibers. The higher the pressure, the higher the piezoelectric properties. The thicker the piezoelectric paper, the higher the piezoelectric properties. The piezoelectric paper with 20% ZnO added by the dissolving method has high piezoelectric properties, and the maximum output current is 52.36 nA/cm². The piezoelectric properties of the piezoelectric paper are comparable to the purchased PVDF film.

Starting with reconstructed atomic-level flat GaAs(001)-β2(2×4) surface, by combining reflection high energy electron diffraction (RHEED) diffraction and different scales of scanning tunneling microscope (STM) real space scanning images, this paper has firstly obtained critical information about the morphology transformation and reconstruction of GaAs (001) surface. Besides, the relationship between surface morphologies phase transition and surface reconstructions of GaAs (001) is further investigated. The results show that the phase transition of surface morphologies are mainly drove by the variation of surface reconstruction. The surface morphologies of GaAs(001) composed of a single surface reconstruction is more easily in an ordered flat phase. The GaAs(001) surface pre-rough phase is formed by mixing two identically or two approximately reconstructed unit cells. In contrast, surface morphologies of GaAs(001) would be in a rough phase when the surface is formed by two different types of surface reconstructions. Thus, it can be concluded that the surface reconstructions are the microscopically underlying mechanism of the surface morphologies phase transition, and the surface morphologies phase transitions are the macroscopically external manifestation of surface reconstructions.

The diluted magnetic semiconductor (DMS) is a new type of semiconductor material with both semiconductor and magnetic properties, which has distinctive magnetooptical and magnetoelectric functions. Firstly, we report the research progress of diluted magnetic semiconductors and their classification. Then the advances of magnetoelectric properties for the Ⅰ-Ⅱ-Ⅴ-based DMSs in experiment and theoretical calculation are mainly reviewed, including fabrication, magnetic, origin mechanism of ferromagnetism, magneto-transport and optical properties. The origin mechanism of ferromagnetism for some DMS materials has been confirmed, and the highest Curie temperature in some new DMS materials has been comparable to that of (Ga,Mn)As. Moreover, some difficult problems of traditional DMS have been overcome. Finally, we prospect the development and application prospect of the Ⅰ-Ⅱ-Ⅴ-based new diluted magnetic semiconductors.

In recent years, due to the increasing depletion of non-renewable resources, as well as environmental crisis and other issues, the research and utilization of luminescent materials have received widespread attention. As a kind of luminescent material, luminescent fiber has its unique properties. Luminous fiber has many advantages such as non-toxic, harmless, bright color, soft material, excellent anti-aging property, and sustainable luminescence. Luminous fibers are divided into fluorescent fibers and luminous fibers, and luminous fibers are divided into self-luminous type and light-storing type. The luminescent fiber realizes the cycle function of automatically absorbing light-storing light-emitting light. It not only solves the problem of environmental protection but also conforms to the principle of sustainable development. The development of luminous fiber is the need to cope with the scarcity of resources and to realize the sustainable development of the chemical fiber industry. It is also the need to realize energy saving and emission reduction and develop a low-carbon economy. The application fields of luminous fiber materials include but are not limited to luminous printed fabrics, luminous textile applications, toys and embroidered artwork, functional clothing, anti-counterfeiting, and so on. The author sorts out and summarizes the representative results of luminescent fiber materials, mainly including the classification and application of luminescent materials, introduction and preparation methods of luminescent fibers, characteristics and applications of luminescent fibers, and the existing problems and future development of the field. The direction is forecasted.

Volatile organic amines are toxic and harmful,which pose a serious threat to the ecological environment and public safety.The rapid detection of organic amines is of great significance for environmental pollution prevention,food safety monitoring and even medical diagnosis.Based on the research progress of tin dioxide semiconductor materials in the detection of organic amine,the formation of heterojunctions between tin dioxide and metal oxides,metal sulfides,carbon materials and organic polymer reported recently,and the effects of heterojunctions on amine-gas sensing performance were summarized.The other materials possessing heterojunctions and their applications in amine-gas sensing fields were prospected.

The performance of materials based on barium strontium titanate (BST) in recent years was reviewed. The effects of different preparation conditions, different substrates and doping on the performance of BST were discussed, and the prospect of improving the performance of barium strontium titanate was presented. The electrical properties of BST were affected by physical characteristics. The density and microstructure of BST were affected by controlling the manufacturing process parameters or adding dopants, thereby improving the dielectric properties and further affecting the energy storage density of the material. Bi-doped BST ceramics exhibited typical relaxation properties. The substitution of Zr improved the frequency stability of the dielectric constant and reduced the dielectric loss obviously. The doping of Mn could effectively suppress the dielectric loss, and a proper amount of doping could improve the recoverable energy density and efficiency. Moderate cerium doping was beneficial to improve the dielectric properties. Doping of chlorophyll was expected to reduce the crystal defects and increase the intensity of the material, while improving the reflectivity of the sample.

Polyethersulfone (PES) and hollow glass microspheres (HGB) were used as fillers to modify the epoxy resin, and its effect on the mechanical and thermal properties of the epoxy polymer phase was studied. The research found that when epoxy polymer phase was prepared with 10wt% PES or HGB loadings, the shear strength increased from 39 MPa to 52 MPa, the thermal expansion coefficient decreased from 8.8 × 10^-5/K to 5.8 × 10^-5/K, and the mechanical and thermal properties of the material were significantly improved. Using PZT-4 as the piezoelectric phase, a 1-3 type piezoelectric composite material with a PES and HGB filling content of 10% by weight was prepared by a cutting and filling method. The influence of temperature on resonance frequency f_s and electromechanical coupling coefficient kt was measured by impedance analyzer. The results show that the f_s of 1-3 piezoelectric composites was 885 kHz and kt was 0.65. The change rate of f_s and kt of the material within the range of 15-50 ℃ was less than 1%, which showed good temperature stability.

In this work, graphene nano-sheets were incorporated into the matrix of semiconducting polymers P(NDI2OD-T2) and DPP-2T via solution mixing for the film preparation. The process results in a remarkable enhancement of carrier mobility on both N-type and P-type polymeric field-effect transistors (FETs). Furthermore, the aligned films of the P(NDI2OD-T2)/graphene composites have been achieved by solution drop-cast under high magnetic field. It reveals that the incorporation of small amount of graphene sheets improved the degree of chain alignment, and consequently enhanced the anisotropy of electron mobility of the OFETs compared to pristine P(NDI2OD-T2). The charge transport properties of the composite films were also improved via the film growth under a rotating magnetic field, which should originate from the enhanced face-on packing of P(NDI2OD-T2) by magnetically controlling the orientation of conjugated planes of the backbones. It suggests that the ensembles of polymer aggregated on the graphene planes facilitated magnetic alignment as well as the formation of fast conduction pathways at the polymer domain boundaries.

The quaternary ammonium salt of crosslinked chitosan prepared by chemical crosslinking method was used as the flexible substrate. After micro-stretching, PEDOT: PSS was brushed on it to prepare the flexible electrode. Further, the flexible piezoelectric sensor was obtained by assembling the flexible electrode with the self-made PVDF-TrFE/ZnO quantum dot composite piezoelectric film. The quasi-static d₃₃ tester was used to test the piezoelectric strain constant of the piezoelectric film, and the mechanical and electrical properties of the flexible electrode were tested by universal tensile testing machine and multimeter, respectively. The output performance of the piezoelectric sensor was tested by excitor test. The results show that the tensile strength of flexible electrode was 3.3 MPa and the elongation at break was 762.3%. The resistance of flexible electrode was 1.68 k Ω. The d₃₃ piezoelectric constant of PVDF-TrFE /ZnO film with two layers of spin coating was 26.1 pC/N. The output voltage of the fully flexible piezoelectric sensor was 4.46 V.

Piezoelectric and ferroelectric polymers have been widely used in sensors and actuators. Nylon ferroelectric polymer is cheap, green and stable at high temperature, so it has potential application value. Odd-odd nylon 11,11 is a new ferroelectric and piezoelectric polymer material. However, its low electroactivity limits its application. The electroactivity of PA1111 was further improved by blending with polyvinylidene fluoride (PVDF). The results shows that the piezoelectric strain coefficient, d₃₃, was increased to -6.9 pC/N and the remament polarization, Pr, was increased to 52 mC/m² for the stretched film of nylon 11,11 with 40% PVDF. The improved ferroelectric and piezoelectric properties after blending modification could be attributed to the dipolar intermolecular interactions between PA1111 and PVDF.

The geometry structures of Li_1±y (Mg_1-xFe_x)P (x=0.125; y=0, 0.125) were optimized by adopting the first-principles calculation of plane wave ultra-soft pseudo-potential technology based upon the density function theory (DFT)。Then the electronic structures, formation energies, density of states, overlapping charge distribution and electrical parameters of ions near the body central ions were calculated。The results reveal that Fe doped LiMgP was an outstanding half-metallic ferromagnet with large half-metallic energy gap of 0.500 eV and controllable electromagnetic properties, which was expected to be a good candidate of spintronic devices with great potential application。The chemical bonds of pure LiMgP were polarized covalent bonds。Fe doping led to form stronger Fe-P covalent bond than that of Mg-P。The interaction between Fe ions and Li, Mg, P ions reduced their orbital electronic number。When Li was excessive, the formation energy was the lowest and the structure was the most stable。The band gap value was decreased greatly compared with that of Fe doped alone, meanwhile, the half-metallicity was significantly weakened。Interstitial Li atoms weakened the interaction between orbits, and the overlapping charge distribution of Fe-P bonds and the net magnetic moment of the system were the smallest。When Li was insufficient, the system became metallic ferromagnetism。The orbital electronic number of the ions was the smallest, but the hybrid orbital electronic number was the largest。The distribution of electron clouds between Fe and P atoms was the densest, and the offset degree of the shared electron pairs was the smallest。The overlapping charge distribution of Fe-P bond reached the maximum of 0.78, the bond length reached the minimum, and the net magnetic moment of the system was the biggest.

Quartz optical fibers were successfully fabricated by high temperature wire drawing at different drawing rates with Yb³⁺-doped SiO₂ preform as raw material. The structure, tensile strength and attenuation characteristics of quartz optical fibers fabricated at different wire drawing rates were studied by Fourier transform infrared spectroscopy, optical fiber stress analyzer and Model 2500. The results showed that the tensile strength of quartz optical fibers increased first and then decreased with the increase of wire drawing rate. When the wire drawing rate was 1700 m/min, the tensile strength of quartz optical fibers reached the maximum of 5.2 Gpa. The higher the wire drawing speed, the easier the internal damage and the failure of optical fibers would be caused by irradiation. This was mainly because the higher the drawing speed, the shorter the time in the high temperature region, the lower the frequency of Si-O chain breakage in the optical fiber, and the higher the tensile strength of the optical fiber. However, as the wire drawing rate continued to increase, the furnace temperature gradually increased, and the frequency of Si-O chain breakage in the fiber increased. The coupling effect of the two made the fiber strength increase first and then decrease with the drawing speed. When the irradiation dose increased gradually, the irradiation loss of quartz optical fibers increased rapidly in a straight line trend, but with the increase of the irradiation dose, the increase of the irradiation loss slowed down and stabilized gradually.

In this paper, the geometry structures of Li_1±y(Zn_1-xV_x)P (x=0, 0.0625; y=0, 0.0625) were optimized by adopting the first-principles calculation of plane wave ultra-soft pseudo-potential technology based upon the density function theory. Then the electronic structures, formation energies, half metallicity, magnetism and optical properties were calculated and analyzed. The results reveal that the separation of spin and charge injection mechanisms could be achieved in LiZnP semiconductor, and the magnetic and electrical properties of diluted magnetic semiconductor would be regulated respectively by V doping and Li stoichiometry. The spin polarized impurity band introduced by single doping V showed strong half-metallicity, and sp-d orbital hybridization made the system have 2.92 μ_B magnetic moment. And the properties of the systems were also influenced by the stoichiometry of Li. In the Li-deficiency compounds, the half metallicity and magnetism became weakened, while the Curie temperature was the highest. But for the Li-excess compounds, the hybridization was enhanced, the forming energy was the lowest, and the conductivity and magnetism were the strongest because of the enhancing of sp-d hybridization.

Lead-free piezoelectric ceramics (1-x)(Na_0.5K_0.5)NbO₃-x(Ba_0.88Ca_0.12Zr_0.12Ti_0.88O₃) ((1-x)KNN-xBCZT) have been fabricated by a pressureless sintering technique. KNN and BCZT formed a homogeneous solid solution. Addition of BCZT lowered both T_C and the tetragonal-orthorhombic transformation temperature in an approximately linear relation to concentration. Lowering of the tetragonal-orthorhombic transformation temperature improved the electrical properties of the solid solution. The properties of (1-x)KNN-xBCZT reached the best when x=0.055. Use of MnO₂ as a sintering aid resulted in denser ceramics for which phase boundaries shifted to lower temperatures. 0.055BCZT-0.945KNN-0.01MnO₂ exhibited properties: d₃₃=212 pC/N, d₃₁=-75 pC/N, k_p=45%,ε=875, tanδ=0.02, T_C=340 ℃ and T_O-T=127 ℃.