Abstract: In this present work, we adopt conventional solid state reaction techniques to obtain
CaCu3Ti4O12 (CCTO) ceramics and the dielectric properties of polycrystalline CCTO samples sintered in
the temperature range 900 − 1100°C were investigated. X-ray diffraction (XRD) patterns show no
obvious change in crystal phase with various sintering temperature. However, experimental results show
that the dielectric properties of CCTO ceramics are very sensitive to processing parameters and the
dependence of dielectric constant and loss tangent of CCTO ceramic on processing can be obtained. The
effect of sintering conditions on the surface microstructures and the electrical properties of CCTO
ceramics are also discussed in this study.
Abstract: Lithium niobate thin films have been deposited on Pt/Ti/SiO2/Si substrates by the Pechini
method from metal carboxylate gels and heat-treated at temperatures ranging from 400 to 600°C. The
thermal decomposition of the metal carboxylate precursor gels has been studied by differential thermal
analysis and thermogravimetry. The products derived from calcination of the gels at different
temperatures have been characterized by Fourier transform infrared, Roman spectrum and X-ray
diffraction. Scanning electron microscopy analysis shows the surface of the films to be smooth, dense and
crack-free. Electric properties measurement indicates that the LiNbO3 films demonstrate a ferroelectric
hysteresis loop. The remanent polarization (Pr) and coercive field (Ec) are 17.89 μC/cm2 and 35.23 kV/cm,
Abstract: Langasite (La3Ga5SiO14, LGS) and its isomorphs, were regarded as potential substrate
materials for surface acoustic wave (SAW) and bulk acoustic wave (BAW) applications. Among these
homologous compounds, the ordered structure crystals have attracted much attention for their low Ga2O3
content, high acoustic velocity and low acoustic loss. In this work, the ordered langasite structure crystals
Ca3NbGa3Si2O14 (CNGS) were grown with vertical Bridgman method for the first time. The CNGS
crystals with 25mm in diameter and 40mm in length were grown successfully from its stoichiometric melt
through LGS crystal of Ø10mm×40mm being chosen as seed. X-ray powder diffraction experiments
showed that the CNGS single crystals had a single phase and had the same structure as the LGS crystal.
The transmittance spectra with the wavelength from 200 to 800nm were recorded by means of
Spectrophotometer at room temperature.
Abstract: LSMO films with various thicknesses were prepared on single crystal Si (111) substrates
by sol-gel process. The films were dense and had a uniform microstructure. The films showed
metallic conduction characteristics at low temperature and insulator characteristics at high
temperature. The metal-insulator transition temperatures (Tmi) of the films were remarkably lower
than that of the bulk ceramics. The effect is related to the distortion of crystal lattice resulted from the
residual stress in the films.
Abstract: Highly dense Na1-xKxNbO3 (x=0.2~0.8) ceramics were successfully prepared using spark
plasma sintering (SPS) at temperature as low as 920°C. Solid solutions were formed during the
composition range investigated. The piezoelectric constant and planar mode electromechanical coupling
coefficient are significantly dependent on the Na/K ratio, with the maximum value of 148 pC/N and
38.9% at the composition Na0.5K0.5NbO3.
Abstract: XRD, SEM, bulk density and dielectric properties measurements were used to investigate the
effect of TiO2 nanopowder substitution for conventional TiO2 micro-powder on the sintering and electric
properties of PZT ceramics. Results revealed that the sintering temperature of dense Pb(Zr0.53Ti0.47)O3
ceramics was lowered about 50°C ~ 100°C when 20% and 40% of conventional TiO2 micro-powder was
substituted by TiO2 nanopowder. The electric properties were kept or even enhanced in the PZT ceramics
adopted the TiO2 nanopowder.
Abstract: (1-x)BiScO3-xPbTiO3 (BSPT) based ferroelectric ceramics were prepared by conventional
solid state process. X-ray diffraction analysis revealed that the morphotropic phase boundary (MPB)
separating the rhombohedral and tetragonal phases for the BSPT system exited near x=0.62. It was
found that the stability of perovskite structure of the BSPT system was improved with the increase of
PbTiO3 content. For the 0.36BiScO3-0.64Pb1-ySryTiO3 (BSPST) system, because of higher amount of
ionic bonding, the stability of perovskite structure for BSPT compounds containing strontium is
larger than that of non-strontium compound.
Abstract: Ultrafine (1-x)BiScO3-xPbTiO3 ferroelectric ceramics were successfully prepared by employing
nanocrystalline ceramic powder. The average ceramic grain sizes range from 0.4μm to 1.2μm with
different phases and different proceeds. The studies show the average grain sizes vary with the calcining
and sintering temperature as well as the compositions in different phases. Ceramics, sintered at 1020°C
for 3h, in morphotropic phase boundary (MPB) have the smallest grain sizes around 0.4 μm, those in
tetragonal phase and rhombohedral phase have larger grains around 0.9μm. Meanwhile, the piezoelectric
property and Curie temperature were founded size-dependent when the grain sizes are smaller than 1μm.
Abstract: The precursor powder of lead-zirconate-titanate (PZT) and NiFe2O4 (NFO) was prepared
using one step sol-gel method. The dry powders got after a series of processes were sintered via a
conventional ceramic solid-state reaction technique. All the diffraction peaks in the XRD patterns of
the composites can be readily indexed to NFO and PZT, respectively. The SEM micrograph shows
two different phases of PZT and NFO distinctly and the particle size of NFO was about 2~4 μm. The
magnetoelectric (ME) coefficient, dielectric constant, piezoelectric constant, magnetic hysteresis
loops of the samples were measured. The dc magnetic Hdc resulting in the maximum ME coefficient
varies from 0.65kOe to 1.0kOe with the increase of the NFO volume fraction. The maximum
magnetoelectric coefficient of 6.15Vcm-1Oe-1 was obtained at resonance frequency of 289.8kHz, dc
magnetic intensity of 0.8kOe and NFO volume fraction of 0.25.
Abstract: ZnO films with piezoelectric properties were deposited on polycrystalline diamond wafers for
high frequency surface acoustic wave filter applications by dc reactive magnetron sputtering. The
influences of different sputtering pressures and substrate temperatures on the properties of ZnO films
were discussed. Highly c-axis oriented, fine-grain ZnO films with excellent surface flatness (average
surface roughness of 5.3 nm) and high resistivities (6.3×107 *·cm) have been obtained. Then Al films for
interdigital-transducer were deposited on ZnO/diamond by electron evaporation, a 2.48 GHz longitudinally-
coupled double-mode surface acoustic wave filter has been fabricated using the Al/ZnO film on