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A series of Ca 0.61 Nd 0.26 Ti 1- x (Cr 0.5 Nb 0.5 ) x O 3 (CNTCN x ) (0 ≤ x ≤ 0.1) ceramics were prepared via a solid state reaction method. All CNTCN x samples were crystallized into the orthorhombic perovskite structure. The SEM micrographs indicated that the average grain sizes of samples depended on (Cr 0.5 Nb 0.5 ) 4+ concentration. And as (Cr 0.5 Nb 0.5 ) 4+ concentration increased, the average grain size of samples decreased significantly. The short range order (SRO) structure and structural distortion of oxygen octahedra proved to exist in CNTCN x crystals from Raman spectra analysis results. The microwave dielectric properties highly depended on the B-site bond strength, oxygen octahedra distortion, reduction of Ti 4+ to Ti 3+ and internal strain η. At last, the CNTCN0.06 ceramic sintered at 1400 °C for 4 h exhibited good and stable comprehensive microwave dielectric properties of ε r = 92.3, Q × f = 13,889 GHz, τ f = + 152.8 ppm/°C. [ABSTRACT FROM AUTHOR]

Abstract: c-Axis oriented AlN films were prepared on (100)-, (110)-, and (111)-oriented PZT layers by DC reactive magnetron sputtering. The evolution of c-axis preferential orientation, surface microstructure and electrical properties of the synthesized films was investigated as a function of PZT orientation. The X-ray diffraction results showed that a nearly stress free AlN film with full width at half maximum value of the rocking curve of 3.7°, can be successfully synthesized at (111)-orientated PZT layers. The change in the morphological properties with PZT orientation was investigated using the scanning electron microscopy and atomic force microscopy techniques. The morphology of the AlN films, grown on (111) PZT films, revealed good interface quality with surface roughness of 5.9nm compared to other samples. The electrical property of AlN/PZT heterostructures can be effectively improved by introducing the AlN films. Current–voltage curves of the AlN/PZT-(111) films exhibited a lowest leakage current density of approximately 10−10 Acm−2 at−5V, which showed excellent insulating characteristic. It is expected that this investigation may offer some useful guidelines to the design of MFIS capacitor and other MFIS structure devices. [Copyright &y& Elsevier]

CoFe2O4thin films were prepared on the Si (001) substrates using the sol-gel method. In this study, the effects of annealing temperature, annealing time and annealing atmosphere on the structure and magnetic properties of CoFe2O4films have been examined. X-ray diffraction analysis revealed that the films formed single spinel structures when the annealing temperature was above 450°C. The crystallization of the CFO thin films increased as the annealing temperature increased. Atomic force microscopy analysis showed that the film grain size increased with annealing temperature and that there was a single domain structure of critical size at 650°C. Vibrating sample magnetometer measurements showed that the saturation magnetization (Ms) reached a maximum and that the coercivity (Hc) varied with annealing conditions. When the CFO film was annealed at 650°C and 40 seconds, the ratio of O2:Ar was 1:1. The values for Ms and Hc had a maximum of 47.6 Am2.Kg−1and a minimum of 86.8 KA.m−1, respectively. [ABSTRACT FROM PUBLISHER]

The aluminum nitride (AlN) piezoelectric thin films doped 13% Sc atoms were deposited on (100) p-type silicon by reactive magnetron sputtering. Scandium (Sc) doping of AlN enhanced piezoelectric response drastically compared with non-doped AlN. The effects of substrate temperature of ScAlN on crystal structure and piezoelectric response were investigated. The results tested by X-ray techniques clearly show that relatively high temperature influences the growth of (002) preferentially orientation. Better lattice orientation is gained when increasing the substrate temperature (300–550 °C) , but the (002) orientation was weakened (550–650 °C) when heating continually. In addition, It is formed that the c-axis (002) orientation of ScAlN piezoelectric film has a higher piezoelectric response with a maximum value of 16.8 pC/N obtained at 550 °C under 13% Sc doped in AlN films, which is two times bigger than the results of non-doped AlN of 7.6 pC/N in contrast. [ABSTRACT FROM AUTHOR]

Abstract Er-doped AlN thin film was deposited on sapphire substrates (0001) by RF magnetron sputtering at different sputtering times. The crystalline structure, surface morphology and electrical properties of the thin films have been investigated. The XRD patterns and the SEM sectional diagram indicate that Er-doped AlN thin films present the preferred orientation of C axis. The crystalline quality of the films rises first and then decreases with the increase of sputtering time and reaches best at 90 min. Piezoelectric coefficient d 33 indicates maximum value of 9.53 pm/V. Correspondingly, the best surface morphology of thin film was obtained at 90 min and the surface roughness reached a minimum of 2.012 nm. In addition, the change of resistance is same with change of the crystalline quality and the resistivity reached a maximum of 4.36 ∗ 1012 Ω·cm at 90 min. Highlights • Er-doped AlN films were deposited by RF magnetron sputtering. • The influence of sputtering time on properties of films is discussed. • The piezoelectric coefficient of AlN films is increased by doping Er. • A maximum XRD intensity and a best grains homogeneity were reached at 90 min. [ABSTRACT FROM AUTHOR]

Er-doped AlN thin films were deposited by RF magnetron sputtering on (0001) sapphire substrates under different temperature. We systematically investigate the influence of substrate temperature on the crystalline structure and the piezoelectric properties of the films. Consequently, the XRD intensity of (0 0 2) oriented peak first increases and then decreases with increasing substrate temperature, reaching a maximum value and a highly c-axis columnar crystal structure at 200 °C. The piezoelectric constant d 33 indicates a maximum value of 9.41 pm/V at substrate temperature of 200 °C.Due to Er doping in AlN films, an improvement in their crystalline structures and piezoelectric properties is noticed. [ABSTRACT FROM AUTHOR]

Piezoelectric film based on flexible substrate, which is conductive and heat-proof, is very promising for cantilever beams to constitute vibration energy collectors. Sc-doped AlN thin films based on Hastelloy alloys flexible substrate were prepared by DC reactive magnetron sputtering under sputtering power from 110 W to 200 W. The crystal quality of ScAlN films was investigated. Results show that the sputtering power greatly influences the preparation of c -axis-oriented ScAlN thin films. The crystal quality first increases and then decreases with increase of sputtering power, reaching the best crystalline state at 170 W, presenting full width at half maximum of 2.3°. [ABSTRACT FROM AUTHOR]

The Ca 0.61 Nd 0.26 Ti 1- x (Cr 0.5 Ta 0.5 ) x O 3 (CNT-CT x ) ceramics with orthorhombic perovskite structure were prepared using the conventional solid-state method. The X-ray diffraction (XRD), Raman spectra and X-ray photoelectron spectra (XPS) were employed to investigate the correlations between crystal structure and microwave dielectric properties of CNT-CT x ceramics. The XRD results showed that all CNT-CT x samples were crystallized into the orthorhombic perovskite structure. The SEM micrographs indicated that the average grain size of samples depended on the sintering temperature. As (Cr 0.5 Ta 0.5 ) 4+ concentration increased, there was a significant decrease in the average grain size of samples. The short range order (SRO) structure and structural distortion of oxygen octahedra proved to exist in CNT-CT x crystals according to the analysis of Raman spectra results. The microwave dielectric properties highly depended on the full width at half maximum (FWHM) of Raman spectra, oxygen octahedra distortion, reduction of Ti 4+ to Ti 3+ and bond valence. At last, the CNT-CT0.05 ceramic sintered at 1420 °C for 4 h exhibited the good and stable comprehensive microwave dielectric properties: relative permittivity of 96.5, quality factor of 14,360 GHz, and temperature coefficient of resonant frequency of +153.3 ppm/°C. [ABSTRACT FROM AUTHOR]

The influences of substitution of (Al 1/2 Nb 1/2 ) 4+ on the crystal structure, Raman spectroscopy and microwave dielectric properties in Ba 3.75 Nd 9.5 Ti 18 O 54 (BNT) ceramics were investigated in this work. The sintering samples were mainly measured by SEM, XRD and Raman spectrometer. The results showed that all Ba 3.75 Nd 9.5 Ti 18- z (Al 1/2 Nb 1/2 ) z O 54 (BNT-(AN) z ) samples formed the orthorhombic tungsten-bronze type like structure. Lattice parameters of BNT-(AN) z samples were refined by Rietveld method, and unit cell volume of samples decreased as z increased. The blue shift of Raman spectral peaks was confirmed to the result of Rietveld refinement. Moreover, Raman spectra revealed that flexible oxygen octahedra networks became stressed-rigid and oxygen octahedra became more tilted, which was ascribed to Al 3+ and Nb 5+ occupational disorder when (Al 1/2 Nb 1/2 ) 4+ substituted for Ti 4+ . With increase of z value, the dielectric constant ( ε r ) and temperature coefficient of resonant frequency ( τ f ) decreased. The BNT-(AN)2 ceramic sintered at 1375 °C for 4 h exhibited excellent microwave dielectric properties: ε r = 73.9, Q × f = 13,177 GHz, and τ f = +0.3 ppm/°C. The relationship of the bond valence of the B-site to Raman shift of the A g mode, dielectric constant ( ε r ) and τ f were analyzed. [ABSTRACT FROM AUTHOR]