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Dielectric spectra and magnetization hysteresis loops were used to investigate the grain size effect with temperature on the electrical and magnetic response of co-precipitation derived spinel (Ni0.5Zn0.5)Fe2O4 (NZFO) ceramics. Remarkable dielectric relaxation phenomena of non-Debye type have been observed in each NZFO ceramics as confirmed by two kinds of Cole-Cole plots of the 1100 °C sintered samples, mainly due to the electron-hopping mechanism between n-type and p-type carriers and interfacial ion effect when applied an increase of temperature. The high and low response of grain and grain-boundary regions were determined by modeling the impedance experimental results on two equivalent RC circuits taking into account grain deep trap states. By employing the modified Arrhenius equation, activation energy values of different sintering temperatures were calculated and analyzed in combination with oxygen vacancy. In addition, the magnetization of various sintering temperature samples is dominated by cation distribution and surface effect in different particle ranges. [ABSTRACT FROM AUTHOR]

Room temperature tunable blue-green photoluminescence was observed in nanocrystalline (Pb1-xSrx)TiO3 thin film under UV excitation. Its emission energy increases from 2.42 (at x=0.6) to 2.76 eV (at x=0.4), while the band gap decreases from 3.6 to 3.3 eV. Thin films of (Pb1-xSrx)TiO3 were prepared on yttrium-doped zirconia substrate by a simple sol-gel technique with spinning-coating process. Atom force microscope micrographs and crystallographic studies revealed the polycrystalline perovskite-type structure of the thin films. The observed optical properties are attributed to distorted octahedral due to different cation substitutions. The work shows that this kind of wide band gap and low cost nanocrystalline thin films is a very promising material for flat panel display applications and integrated light emission devices. [ABSTRACT FROM AUTHOR]

Barium zirconate titanate Ba(Zr0.2Ti0.8)O3 (BZT) thin films on La0.7Sr0.3MnO3 (LSMO)-coated Si and Pt/Ti/SiO2/Si substrates have been prepared by pulsed laser deposition and crystallized in situ at 650 °C. Four capacitor types of LSMO/BZT/LSMO/Si, Pt/BZT/LSMO/Si, Pt/BZT/Pt/Si, and Pt/BZT/LSMO/Pt/Si were prepared to investigate the structural and dielectric properties, tunability, and figure of merits. Among them, the high (100)-oriented BZT films were grown on the (100)-textured LSMO and (111)-textured Pt electrodes. The results show that the LSMO/BZT/LSMO/Si has the highest dielectric constant of 555 and Pt/BZT/LSMO/Pt/Si has the highest tunability of 73% at 1 MHz. The high dielectric constant and tunability have been attributed to the (100) texture of the LSMO bottom layer leading to the decrease of the thickness of the interface of the dead layer. [ABSTRACT FROM AUTHOR]

The effects of Ca doping on the Curie temperature, structural, dielectric, and elastic properties of Ba0.4Sr0.6-xCaxTiO3 (0<=x<=0.3) has been studied. Powder x-ray diffraction revealed that the cubic lattice constant a decreases linearly with increasing x from 0 to 0.15, while showing an anomalous expansion between x=0.15 and x=0.18. This, together with the anomalies in the dielectric constants, Curie temperature TC, and elastic constants observed for 0.15C increases linearly with increasing x from 0 to 0.15; while deviating from linear behavior for x>0.15, TC increases persistently up to x=0.25 and thereafter shows a decrease. These variations of TC with x have been interpreted in terms of Ca-doping-induced A-site cation size variance, a substitution of a small amount of Ca ions for Ti ions, and structural phase separation. Upon cooling the longitudinal elastic constant CL shows drastic softening near TC, arising from the electrostrictive coupling between the polarization fluctuations and the elastic strains. Moreover, it was found that Ca doping induces the hardening of CL just below TC, and the magnitude of the relative hardening of CL (i.e., ΔCL/CL) increases with increasing x, implying that the tetragonal ferroelectric phase was increasingly stabilized by Ca doping. [ABSTRACT FROM AUTHOR]

(0.95-x)(Bi1/2Na1/2)TiO3-x(Bi1/2K1/2)TiO3-0.05BaTiO3 lead-free piezoelectric ceramics sabbreviated as BNT-BKT-BT100x with x varying from 0 to 20 mol %d are prepared by a solid-state reaction process. Variation of the dielectric properties and microstructure of BNT-BKT-BT100x ceramics with BKT content is studied. The results indicate that the relative permittivity εr and loss tangent tan d vary with the BKT amount. Scanning electron microscope observation also indicates that BKT in high amount affects the microstructure. X-ray diffraction analysis shows that the incorporated BKT diffuses into the BNT-BT lattice toform a solid solution during sintering. [ABSTRACT FROM AUTHOR]

A new photochromic diarylethene derivative with 2-hydrazinobenzothiazole was synthesized, and its multi-controllable switch behavior was investigated in detail when triggered by light and anions. When triggered by CN−, the absorption spectra of the diarylethene showed a new band at 474 nm with an obvious color change from colorless to bright yellow. Upon addition of I−, the diarylethene compound displayed a new absorption band at 297 nm and the original absorption at 370 nm also increased, and the fluorescence intensity exhibited obvious fluorescence quenching with fluorescence color change from a light royal blue to dark. The results indicated that the diarylethene derivative exhibited naked-eye detection of CN− and the fluorescent recognition of I−. [ABSTRACT FROM AUTHOR]

A new photochromic diarylethene derivative with 2-hydrazinobenzothiazole was synthesized, and its multi-controllable switch behavior was investigated in detail when triggered by light and anions. When triggered by CN−, the absorption spectra of the diarylethene showed a new band at 474 nm with an obvious color change from colorless to bright yellow. Upon addition of I−, the diarylethene compound displayed a new absorption band at 297 nm and the original absorption at 370 nm also increased, and the fluorescence intensity exhibited obvious fluorescence quenching with fluorescence color change from a light royal blue to dark. The results indicated that the diarylethene derivative exhibited naked-eye detection of CN− and the fluorescent recognition of I−. [ABSTRACT FROM AUTHOR]

The influence of nickel doping on the electrical properties and dielectric relaxation in ZnNiFe2O4 (ZNFO, ) ceramics has been investigated via the dielectric and complex impedance spectra measurements. According to the modified Curie-Weiss law, the diffusivity factor of the ZNFO ceramics from 1.69 to 2.02 with increasing from 0.2 to 0.5, respectively. Two relaxation peaks are observed in the nickel doped samples, by employing the modified Arrhenius equation, two activation energy values of different sintering temperatures were calculated and analyzed in combination with oxygen vacancy. The Cole-Cole plots showed that the semicircular arcs which are nonideal Debye type, and the grain boundaries resistance increases with increasing Ni concentration. [ABSTRACT FROM AUTHOR]

PbZrO3 thin films with (100) and (111) orientation were prepared by a simple sol-gel method. X-ray diffraction results revealed that post-annealing temperatures played an important role on the orientation of PbZrO3 films. The frequency dependence of dielectric properties and the ferroelectric characteristics were measured. Giant energy-storage density and energy-storage efficiency calculated from hysteresis loops achieved about 25.25 J/cm3 and 62% for PbZrO3 film with thickness of 292 nm, respectively, results indicated that PbZrO3 thin films had a potential application in energy-storage device. Optical properties of PbZrO3 thin films were analyzed by a spectroscopic ellipsometer, results revealed that (111)-orientated PbZrO3 thin films exhibited higher refractive index than that of the (100)-orientated PbZrO3 thin films. [ABSTRACT FROM AUTHOR]