Modification of Pb(Zr,Ti)O3 by Doping Mo based on High Power Ultrasonic Transducer

In view of the special requirements of transducers for power ultrasonic processing,the piezoelectric ceramic material Pb(Zr,Ti)O3 was modified by adding other effective elements.The piezoelectric ceramic piece has a good crystal phase structure,a stable piezoelectric constant,a higher dielectric constant,and a lower dielectric loss by adding a small amount of Sr^2+,Ba^2+,Ga^2+,Sn^4+,Nb^5+,etc.These properties are well suited to requirements of power ultrasonic transducer more than 1 000 W.The crystal phase structure and surface morphology of the modified piezoelectric ceramic chips were analyzed by X-ray and scanning electron microscopy (SEM) to prove that the piezoelectric ceramic chips have good crystal structure and density.The dielectric constant of the polarized piezoelectric ceramic chips was measured using an LCR meter.Finally,the piezoelectric ceramic chips were used to design the ultrasonic transducer,and the transducer was analyzed and measured by the impedance analyzer.The measurement results show that the performance of the piezoelectric ceramic chips is reasonable and feasible.

Synthesis and Characterization of Yttrium Doped Nano-zirconia by a Cationic Surfactant-assisted Route

Recently, more and more interest has been focused on zirconia for its unique characteristics. In this paper, via the preceding preparation technique, yttrium can be successfully incorporated into nano-zirconia by a cationic surfactant-assisted route. The methods of XRD, TEM, EDS, Uv-vis and N2 adsorption-desorption are adopted to characterize the synthesized samples. The results show that the yttrium has been successfully incorporated into the zirconia lattice, and the thermal stability of yttrium doped zirconia has been enhanced remarkably.

Diversiform gas sensors based on two-dimensional nanomaterials

Two-dimensional(2D)nanomaterials have been widely used in gas sensing due to their large specific surface area,high surface reactivity,and excellent gas adsorption properties.This paper reviews the typical synthesis methods of various types of 2D nanomaterials and summarizes the recent progress in gas sensors based on 2D materials,such as noble metal nanoparticles(NPs),metal oxides(MOS),conductive polymers,other new 2D materials.The methods of doping,modification,and photoexcitation can effectively improve the gas-sensing properties of 2D materials.The sensitive mechanisms of heterojunction,Schottky junction,and photoexcitation in 2D material sensors are discussed in detail.This paper discusses the application prospects of 2D materials in wearable gas sensors,food safety,and self-powered sensing,and provides ideas for further applications in environmental quality monitoring and disease diagnosis.In addition,the opportunities and challenges for gas sensors based on 2D materials are also discussed.

Effects of rare earth oxides on dielectric properties of Y_2Ti_2O_7 series ceramics

A series of Y2Ti2O7 microwave dielectric ceramics were synthesized by conventional solid-state method. The effects of rare earth oxide (La2O3, CeO2, Nd2O3, Sm2O3, Eu2O3, Gd2O3 and Dy2O3) and Nd2O3 doping content on the microstructure and dielectric properties of Y2Ti2O7 ceramics were investigated. The experimental results showed that the rare earth ions were considered to dissolve in Y-sites of the pyrochlore structure, different rare earth oxides and concentration had different influences on Y2Ti2O7 cerami...

Giant piezoresponse and promising application of environmental friendly small-ion-doped ZnO

In recent years, with the growing concerns on environmental protection and human health, new materials, such as lead-free piezoelectric materials, have received increasing attention. So far, three types of lead-free piezoelectric systems have been widely researched, i.e., perovskites, bismuth layer-structured ferroelectrics, and tungsten-bronze type ferroelectrics. This article presents a new type of environmental friendly piezoelectric material with simple structure, the transition-metal（TM）-doped ZnO. Through substituting Zn2＋ site with small size ion, we obtained a series of TM-doped ZnO with giant piezoresponse, such as Zno.975Vo.o250 of 170 pC/N, Zn0.94Cr0.06O of 120 pC/N, Zn0.913Mn0.0870 of 86 pC/N and Zn0.988Fe0.0120 of 127 pC/N. The tremendous piezoresponses are ascribed to the introduction of switchable spontaneous polarization and high permittivity in TM-doped ZnO, The microscopic origin of giant piezoresponse is also discussed. Substitution of TM ion with small ionic size for Zn2＋ results in the easier rotation of noncollinear TM-O1 bonds along the c axis under the applied field, which produces large piezoelectric displacement and corresponding piezoresponse enhancement. Furthermore, it proposes a general rule to guide the design of new wurtzite semiconductors with enhanced piezoresponses. That is, TM-dopant with ionic size smaller than Zn2＋ substitutes for Zn2＋ site will increase the piezoresponse of ZnO significantly. Finally, we discuss the improved per- formances of some TM-doped ZnO based piezoelectric devices.

Hydrothermal fabrication of selectively doped organic assisted advanced ZnO nanomaterial for solar driven photocatalysis

Hydrothermal fabrication of selectively doped（Ag＋＋ Pd3＋） advanced ZnO nanomaterial has been carried out under mild pressure temperature conditions（autogeneous; 150°C）.Gluconic acid has been used as a surface modifier to effectively control the particle size and morphology of these ZnO nanoparticles. The experimental parameters were tuned to achieve optimum conditions for the synthesis of selectively doped ZnO nanomaterials with an experimental duration of 4 hr. These selectively doped ZnO nanoparticles were characterized using powder X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FT-IR）, UV–Vis spectroscopy and scanning electron microscopy（SEM）. The solar driven photocatalytic studies have been carried out for organic dyes, i.e., Procion MX-5B dye,Cibacron Brilliant Yellow dye, Indigo Carmine dye, separately and all three mixed, by using gluconic acid modified selectively doped advanced ZnO nanomaterial. The influence of catalyst, its concentration and initial dye concentration resulted in the photocatalytic efficiency of 89% under daylight.