The [001]-oriented Pb(Mg1/3Nb2/3)O3-0.25PbTiO3(PMN-0.25PT) single crystal has been poled by alternating current polarization (ACP). The piezoelectric, dielectric, and electromechanical properties of PMN-0.25PT crystals were investigated with the variations of the electric field, polarization frequency, and cycles. For the piezoelectric performance of the PMN-0.25PT crystal, the optimum ACP condition was obtained under the electric field of 12–18 kV/cm in the frequency range of 20–40 Hz and after 20 cycles. It gives the crystals an increase by 40% from 1220 pC/N to 1730 pC/N in the piezoelectric coefficient compared with traditional direct current polarization. The patterns of the periodic stripe nanodomains under different polarization conditions were revealed by piezoresponse force microscopy. The enhancement of the piezoelectric performance is attributed to the high density of these domain walls. This work indicates that ACP is an effective way to modify the piezoelectric performance of PMN-0.25PT crystals and make it a promising candidate for sensors and transducers.

No abstract

No abstract

The pyroelectric properties and thermal stability of a [001]-oriented tetragonal 1 mol. % Mn-doped 0.29Pb(In1/2Nb1/2)O3-0.29Pb(Mg1/3Nb2/3)O3-0.42PbTiO3 [Mn-PIN-PMN-PT(29/29/42)] ternary single crystal were investigated. The single crystal exhibited a high pyroelectric coefficient of p = 6.0 × 10−4 C m−2 K−1 and figures of merit (FOMs) at 1 kHz for a current responsivity of Fi = 2.4 × 10−10 mV−1, a voltage responsivity of Fv = 0.08 m2 C−1, and a detectivity of Fd = 19.8 × 10−5 Pa−1/2 which were weakly dependent on frequency. These all increased linearly upon increasing temperature to 120 °C. Furthermore, the values of p for the ternary single crystal were weakly dependent on thermal annealing temperatures (Ta), maintaining over 75% of the original value at Ta < 160 °C, which was 70 °C higher than that of the [111]-oriented rhombohedral 1 mol. % Mn-doped 0.73Pb(Mg1/3Nb2/3)O3–0.27PbTiO3 [Mn-PMN-PT(73/27)] binary single crystal. These excellent pyroelectric properties, together with good thermal stability and wide operational temperature, make the [001]-oriented tetragonal Mn-PIN-PMN-PT(29/29/42) single crystal a promising candidate for pyroelectric detection and thermal imaging applications.

The rheological behavior of polypropylene/ novolac blends was investigated with special reference to the effects of the blend ratio, compatibilization, and dynamic cure. The polypropylene and all the polypropylene/novolac blends presented evidence of shear-thinning behavior. The novolac, compatibilizer, and dynamic cure had dramatic effects on the rheological behavior of the polypropylene. Various rheological plots, including plots of the viscosity, storage modulus, loss modulus, and loss angle, Han plots, and Cole-Cole plots, were used to ana-lyze the polypropylene/novolac blends. The results showed that the compatibilization together with the dynamic cure could increase the viscosity and modulus because of the formation of a grafting polymer between the maleic anhydride grafted polypropylene and the curing novolac resin.

Western Jilin province has the most serious area of soda salinization in Northeast China, which affects and restricts the sustainable development of agriculture. The effects of physico-chemical properties of rhizosphere and non-rhizosphere soil on soil microbial diversity and enzyme activities (polyphenol oxidase, catalase, invertase, amylase) were evaluated in typical soda saline-alkali paddy field. Community-level physiological profile (CLPP) based on Biolog-ECO plates was used to assess the functional diversity of soil microorganisms. Exchangeable sodium percentage (ESP) and pH were negative correlated with the microbial activity (AWCD), soil enzyme activities (amylase, sucrose, and catalase, except for polyphenol oxidase) in rice rhizosphere and non-rhizosphere soil (P < 0.05). The indexes of microbial diversity in rice rhizosphere soil were significantly higher than that of non-rhizosphere soil. The utilization of amino acids by rice rhizosphere microorganisms was relatively high, while non-rhizosphere soil had relatively high utilization of carboxylic acid, phenolic acid, and amine. Among the selected physico-chemical properties, soil organic carbon (SOC) and soil water content (SWC) had the greatest influence on the variation of microbial diversity indexes and enzyme activities in rhizosphere soil. ESP and pH showed a significant positive correlation with carbon source utilization, especially for amine (AM) and phenolic acid (PA) carbon source utilization (P < 0.05) by means of RDA, and the utilization rate of AM and PA carbon sources by rice rhizosphere and non-root soil microorganisms was P1 < P2 < P3.

No abstract

No abstract