This paper presents the introduction of recent progress on the studies of structure in lead tungstate crystals. The results demonstrate the polymorphous and non-stoichiometric characters and the importance of structure in researching of lead tungstate crystals.

The characteristics and development of ceramics prepared by preceramic polymer pyrolysis were reviewed. The disadvantages of such method, high porosity and large shrinkage of ceramics obtained, and the means to overcome these disadvrantages were included. Adding active fillers as one of the means was described in detail, and to select the fillers four principles were proposed. The development at home and abroad of the active fillers controlled polymer pyrolysis was also reviewed.

This paper reviewed the structures and properties of bismuth layer-structured piezoelectric
ceramics. The structures of bismuth layer-structured piezoelectric ceramics are built up by the regular intergrowth of (Bi₂O₂)²⁺
layers and perovskite (A_m-1B_mO_3m+1)^2- slabs where A is a combination of cations adequate for 12-coordinated interstices,
B is a combination of cations well suited to octahedral coordinated, and m is an integer usually lying to the range 1-5. By comparison with
barium titanate (BaTiO_3) or lead zirconate titanate (PZT) ceramics, the bismuth layer-structured piezoelectric ceramics are characterized
by: (1) lower dielectric constant; (2) higher Curie temperature; (3) stronger anisotropy in electromechanical coupling factors; (4) lower
ageing rate; (5) higher resistivity; …etc..

Previous studies showed that Curie temperature depends on atomic displacement of polarization cations, spontaneous polarization, bismuth
content in the cubooctahedral cavities, and the nature of the substituting cations such as inonic radius, electronegativities and electronic
configuration. An essentially weak point of bismuth layer-structured piezoelectric ceramics is low piezoelectric activity which can be
solved by chemical substitution or fabrication methods for orientating the grains in ceramics. It is necessary to study the relationships
between structures and properties of bismuth layer-structured piezoelectric ceramics in order to develop the materials.

This paper studied the evolution progress and feature of domain configuration while the
composition and structure changed in relaxor ferroelectric single crystals Pb(Mg_1/3Nb_2/3)O₃-PbTiO_₃. It was found that
with increasing PbTiO_3 concentration in the rhombohedral phase region of PMN-PT system, domain configuration exhibited a transition
process, i.e. microdomains-(sub-microdomains)-irregular macrodomains-regular macrodomains. And then, if PbTiO₃ increased further,
rhombohedral-tetragonal phase transition could take place, giving rise to the change from 71°(or 109°) domains to 90° ones. 90° domains demonstrated more regular or
typical configuration than 71°(or 109°) domains. In light of the showing feature of domain configuration, it was proposed
that the largest birefractive index of PMNT crystals could be taken as an optical parameter measuring their relaxor degree in ferroelectric behavior.
Moreover, the phenomena of non-uniform distribution of domain structures within a plate were observed, which arose from composition heterogeneity
and structure fluctuation. Domains with substructure were also visualized, which could be interpreted by multistage martensitic transformation. In addition, the
paper discussed the imaging features of domain configuration under the observation means including polarizing microscopes, differential
interference contrast microscopes (DIC), scanning electronic microscopes (SEM) and scanning electronic acoustic microscopes (SEAM).

Two dimensional equation describing heat conduction-radiation of Al₂O₃ single crystal was
established by light-guide model. The temperature field was calculated by finite-element method and its features were also discussed. Finally, the
theoretical result was compared with the experimental result. The convection coefficient has little effect on the temperature of crystal near the
solid-liquid interface, while it affects the temperature of crystal significantly which is far from the interface. The temperature gradient
near the solid-liquid interface increases with the growth rate increasing. The temperature curves of crystals with different length show that the
temperature changes little when the crystal is long, and the temperature field of crystal can be regarded as a quasistatic one.

To study the composition change during melting of PbO-PbBr₂-PbF₂-P₂O₅ system glass, the quantitative chemical analysis was complied to measure the
composition of the glass after melting. The results show that the loss of lead during melting is mainly ascribed to the volatilization of PbBr₂. When a sample
contains a high content of phosphorus and a low content of fluorine, the loss of bromine and phosphorus is remarkable, mainly in the form of PBr₃. On the other
hand, if a sample contains a high content of fluorine and a low content of bromine or a low content of phosphorus, bromine will not lose much while a large amount
of phosphorus and fluorine are lost during melting, mainly in the form of PF₅. The reaction between phosphorus and fluorine is much easier than that
between phosphorus and bromine. The results of thermodynamic calculation are consistent with the above results and discussions. The content of oxygen is
influenced by two factors. Volatilization of P₂O₅ decreases the content of oxygen, while the reaction between oxygen or water in air and halides in
melts increases the content of oxygen.

A series of new glasses in the PbBr₂-PbCl₂-PbF₂-PbO-P₂O₅ system were prepared and some properties of the glasses in the PbBr₂-PbCl₂-PbF₂-PbO-P₂O₅ system were studied.
Their composition dependence of glass transition temperature(T_g), thermal expansion coefficient and water durability was reported. Glasses in the
PbBr₂-PbCl₂-P₂O₅ ternary system have relative low glass transition temperature(>146℃). When PbO and/or PbF₂ are introduced into the ternary system, the glass transition temperature increases considerably. Glasses containing PbO have higher transition
temperature than those containing PbF₂. The glasses in this system have relative high thermal expansion coefficient(25×10^-6/℃). Most of the glasses exhibit good water durability,
and the dissolution rate in deionised water at 25℃ is in the order of 10^-4～10^-5mm/day. The introduction of PbO and/or PbF₂
into the glasses does not change their water durability much. With the increase of P₂O₅, the water durability of the glass becomes bad obviously.

C-nanoparticles embedded xAl₂O₃· xP₂O₅·100SiO₂ (x=0.25 or 0.5) gel-glasses were prepared by a sol-gel process. The gels synthesized through hydrolysis of PO(OC₂H5)₃, Al(NO₃)₃· 9H₂O and Si(OC₂H₅)₄, were heated at 600℃ for 10h, in which -- OC₂H₅ were carbonized to precipitate nanosized C particles. Glasses doped with C nanoparticles showed a strong roomtemperature photoluminescence with a peak at 630nm under 532nm Nd:YAG laser excitation. The photoluminescence spectra were caused by C nanoparticles embedded gel-glasses.

A fading kinetics model，T=1-B-kC₀exp(-bt), was deduced on the basis of transition probability, b, of silver colloid forming silver ion, the
solutions of the model were given by applying the measured fading kinetics parameters with a computer, and the measured fading kinetics curves and the
calculated fading kinetics curves of F-series photochromic glass containing AgX were compared. The results indicate that the fading kinetics model
preferably explains the fading process of the photochromic glass, and the transition probability, b, accurately expresses fading rate of fading kinetics. The calculated curves and measured curves of fading kinetics of F-series
photochromic glasses containing AgX are almost similar. So these results further prove that the fading kinetics model is effective to explain the
fading process, and the theory as the basis of the fading model is correct.

Adsorption behaviour of PEI on silicon carbide powder was measured by using UV spectrum. The surface charge of SiC powder was changed greatly after
the addition of PEI, its IEP changed from pH=2.0 to pH=10.5. Adsorption isotherms of dispersant on the silicon carbide surface were investigated.
Their adsorption behaviour belongs to Langmuir monolayer adsorption type. The maximum amount of PEI--H⁺(pH=3.57) adsorbed on the SiC surface is
0.0172mg/mL and that of PEI--H⁺(pH=6.61) is 0.0208mg/mL. IR spectra were obtained to verify this adsorption effect.

The densification and reaction sequence of 90wt%R-α' +10wt%12H (R=Y, Sm, Y+Sm) dual-phase ceramics hot-pressed in the temperature range of 1450~1800℃ were studied. The results show that the dual elements Y+Sm promote densification more effectively than Y-and Sin-element. In Sm-composition, Si₃N₄ disappears quickly and α-Sialon appears simultaneously with 12H--AIN--polytypoides. In Y--composition, however, Si₃N₄ dissolves slowly and 12H- AlN-polytypoid inhibits the formation of α-Sialon.

Ultrafine 3Y-TZP materials were fabricated by the rapid hot-pressing and SPS(Spark Plasma Sintering). It was found that although
the relative densities of the Y-TZP sintered by the two kinds of rapid rate sintering methods were higher than that of sintered by ordinary
hot-pressing at the similar sintering temperature, the grain sizes were larger than that obtained by pressureless sintering; On the other hand,
the structure of the samples sintered by SPS was much homogeneous than that sintered by rapid hot-pressing. The reasons of those phenomena were
also discussed. By choosing appropriate condition, ultrafine 3Y-TZP materials with a relative density of 99% could be gotten by both the two
kinds of rapid rate sintering.

A novel double perovskite-type oxide Ba(Sb ^Ⅲ, Sb^Ⅴ)O₃ was synthesized by hydrothermal crystallization methods. The phase,
morphology and particle size of the product were characterized by XRD, IR, SEM and ICP techniques. The results indicated that the
Ba(Sb ^Ⅲ,Sb^Ⅴ)O₃ oxide shows a cubic perovskite-type structure with a cell parameter a=0.415nm, and has a particle size in the range from 1 to 2μm.
The product has trivalent and pentavalent two states antimony ions. The influence of hydrothermal conditions exhibited that the optimum
alkalinity and n_{Sb( Ⅲ)}/n_Sb(Ⅴ) are 8～10 mol/L KOH medium and 0～1 respectively.

In order to realize the co-sintering with Ag/Pd electrodes in multilayer devices, PZNPZT piezoelectric ceramics were prepared by a conventional technique in the sintering temperature range from 1100℃ to 1140℃ and their piezoelectric and dielectric properties were carefully studied. The results show that soaking time is the most important factor concerning with piezoelectric and dielectric properties, d₃₃ increases from 420× 10^-12C/N to 560× 10^-12C/N and ε^T₃₃ increases from 2100 to 2900 with the increase of soaking time.

FTIR analysis combined with DSC, XRD and AFM experiments was used to study on the chemical mechanism of thermal evolution for Ba_xSr_1-xTiO₃ (BST) thin films derived by sol-gel method. Acetylacetone(HAcAc) was introduced as a chelating agent to reduce a rapid hydrolysis rate of Ti-alkoxide, to improve its crystallization path, to decrease its crystallization temperature. And then the densified and crack-free BST thin films with better crystallization were fabricated.

The effects of manganese addition on the microstructure and piezoelectric properties of PZT were studied. The valence states of manganese
were also measured by ESR. It shows that manganese coexists mainly in Mn²⁺ and Mn³⁺ in PZT ceramics. The solubility limit of MnO in PZT ceramics
is about 1.5mol%. Mn ion is preferentially incorporated in the lattice Pb site in Mn²⁺ or Mn³⁺ acted as donor when the concentration of Mn ion is
below 0.5mol%, which will improve the piezoelectric properties. In the concentration region of 0.5-1.5mol%, some Mn ion will be incorporated in the
lattice of (Ti , Zr) site in Mn³⁺ or Mn⁺² acted as acceptor, and correspondingly the Mn-doped PZT ceramics exhibit properties of both “soft” and
“hard” piezoelectrics simultaneously. When the concentration of Mn ion is larger than 1.5mol%, it will accumulate at the grain boundaries and give rise to the
decrease of piezoelectric properties of PZT ceramics. Small amount of Fe may decrease the solubility limit of Mn ion in PZT ceramics and it may also prevent
the oxidation of Mn²⁺ and Mn³⁺.

Calcium-modified lead titanate thin films deposited on si(100) substrate were prepared by sol-gel processing. The ellipsometric spectra of the PCT
ferroeclectric thin films were obtained in the spectral range of 2.3-5.0eV, and their optical constants(the refractive index n and the extinction
coefficient k) were determined. It was found that the peaks of the refractive indexes of the PCT thin films shift to the low energy region, their
absorption edges shift to lower energy with an increase in Ca doping, this suggests that the energy gap reduces after Ca ions occupied Pb ions sites.
The reasons of these shifts were also discussed.

The influence of mass flow of reactive gas on the composition and optical constants of deposited
NiCrO_x thin films was investigated. The results obtained show that NiCr target exhibits a poisoning phenomenon as O₂ flow rate
increased to a certain value during the reactive sputtering process. It is possible to deposit near transparent, dielectric thin films
as well as the non-transparent, absorbing thin films. The study of optical constants of the thin films deposited at different oxygen flow rate
may be applied to the development of solar selective surface.

Superfine spinel LiMn₂O₄ powders were synthesized with a gelation precursor by microwave-polymer network
process. The gelation precursor was obtained by mixing Li₂CO₃, Mn(NO₃) and polyacrylamide. Electrochemical tests show that the initial specific
capacity is 120mAh/g, and the degradation rate of specific capacity is only 4.7% after 50 cycles. SEM and XRD results prove that the microwave-polymer
network process can increase the purity of the phase, reduce the particle size of spinel LiMn₂O₄, and provide more active sites for Li⁺ intercalation.
The microwave-polymer network process is a new method not only for synthesizing cathode material of Li ion cells,but also for synthesizing other advanced oxide
ceramic materials.

The all-silica frameworks s lattice energy of a series of low-silica zeolites was determined by using the lattice energy minimization method. The results were compared to the lattice energy of dense polymorphs of SiO₂. All low-silica zeolites frameworks are only 43-68kJ·mol^-1 less stable thanα-quartz. This may imply that there is little energy barrier to the formation of lowsilica zeolites frameworks and explain the structural diversity observed for low-silica zeolites. The relationship of calculated lattice energies and framework structures was discussed. The results reveal that the lattice energy decreases and the relative stability of framework increases with the increase of framework densities. These XRD data of the low-silica zeolites contain very short Si-O bond length(0.1557nm), very long Si-O bond length(0.1764nm), and a large range of O-Si-O angles(93.38～133.41°), an average Si-O-Si angles close 144° and a larger range of Si-O-Si angles(127～180°).

A mathematical model of hot isostatic pressing (HIP) densification was set up upon HIP densification theory. The model was realized through computer simulation, and the computer calculation, drawing, analysis of HIP map were accomplished. The HIP map of 3Y-TZP was tested by experiments and the results of experiments cohered well with those of theoretic calculation. The optimization of HIP procedure parameters was discussed through HIP maps.

The effect of adding nanocrystalline γ-Al₂O₃ powders on the sintering behavior of alumina fibers was investigated. The nanocrystalline
powders will be stuffed into the pores formed from the packing of micron-sized alumina powders when the fiber is extruded. In the case
of 40% nanocrystalline γ-Al₂O₃ in the mixed powders, the relative green density increases from 65% to 80%. The fiber can be
sintered to near theoretical density at relatively low temperature because it is of higher density, narrower pore size distribution and
smaller mean pore size. The diametric shrinkage of the fibers extruded from the nanocrystelline γ-Al₂O₃ is higher than that made
from micron-sized powders. γ-Al₂O₃ phase is transformed to α-Al₂O₃ during sintering process.

The microstructure of in situ produced TiC/Ti₅Si₃ nanocomposite was studied. The results show
that TiC/Ti₅Si₃ nanocomposite can be fabricated by reactively hot pressing the mixed powders of SiC and Ti. Almost TiC grains are nanosized, and
there is a small amount of Ti₃SiC₂ in this nanocomposite. Some elongated Ti₃SiC₂ grains are located in Ti₅Si₃ matrix and the rest
Ti₃SiC_₂ grains in TiC grains. There is no amorphous phase on the grain boundaries of TiC and Ti₅Si₃ or TiC and Ti₃SiC₂.
Some monatomic steps can be observed at the grain boundary of TiC and Ti₅Si₃.

HA/ZrO₂ composite coatings on Ti-6Al-4V substrate were successfully deposited via plasma spraying.
The surface morphology, phase composition and bonding strength of coatings were investigated. Simulated body fluid (SBF) tests were carried out to
evaluate the bioactivity of the coatings. The results obtained indicate that the bonding strength of HA/ZrO₂ composite coatings is much higher
than that of HA coating. The bonding strength of HA/ZrO₂ 60 wt% composite coating is even high to 28.5 MPa, which is more than twice
that of HA coating. In SBF test, the coating surface was covered by carbonate-apatite, which indicates that HA/ZrO₂ composite coatings
possess good bioactivity.

The porous TiO₂ anatase nanometer thin films were prepared from alkoxide solutions containing polyethylene glycol (PEG) by sol-gel method. The effects
of PEG addition to the precursor solution on the microstructure of the resultant thin films were studied. The larger amount and the larger molecular weight of PEG,
the larger size and more pores produce in the resultant films on the decomposition of PEG during heat-treatment. However, the transmittance of the films decreases
due to the light scattering by the larger size and more pores. The film thickness was measured by SEM and weight method, and the thickness of TiO₂ films prepared
by 1 cycle (from dipping to teat-treatment at 500℃1h ) was 0.08μm or so. The chemical composition and The adsorbed hydroxyl content of the films were analyzed
with X-ray photoelectron spectroscopy(XPS) and IR spectra. Experiment results show that in the film, besides Ti and O elements, there are a certain amount of residual carbon from
the starting organometallic components and a small amount of sodium and calcium ions diffused from the glass substrates. The adsorbed hydroxyl content of such
porous thin films increases due to the larger size and more pores in the films.

Nanoscale α-Al₂O₃ powders were prepared by the polyacrylamide gel method. Because polymer-network inhibits the aggregate of Al₂O₃, nanoscale α-Al₂O₃ powders with about 10 nm size can be obtained. Its calcination temperature is 1100℃, which is 100℃ lower than general calcination temperature.

Na₂CO₃ particles were utilized to trace the thermocapillary convection of Li₂B₄O₇+ KNbO₃ melt in a loop--like crucible. The thermocapillary convection velocity field beside the crucible inner edge was experimentally measured. From thermodynamic equation this velocity field was also obtained theoretically and it confirmed with the experimental data exactly.

A new machinable glass ceramic with low melting temperature was prepared and its microstructure, machinability and mechanical properties varied significantly with the variation of crystallization temperature and time. The test results show that optimum machinability and higher bending strength can be obtained when the glass ceramic is heated at 600℃ for 6-8h or at 650℃ for 1~2h, and its bending strength can be further increased with rising crystallization temperature, but its machinability will be decreased rrapidly.

There is an increasing interest for the heat mirror films, especially, deposited on rigid or flexible black substrates used as a spectral
selective absorbing coating which differs from the common selective absorber needing a metal substrate with low emissivity. The single layer
indium tin oxides heat mirror films (HMF) were deposited onto unheated glass and rigid or flexible plastic substrates by conventional RF sputtering
technique. The relation between the thermal radiative properties and the plasma wavelength of indium tin oxides heat mirror films were obtained
based on experimental studies. The results show that it is impossible to get ITO HMF simultaneously with maximum reflectance in thermal long
wavelength region and minimum reflectance in the solar spectral region. However, the plasma wavelength can be take as a criterion to predict the
thermal radiative properties of ITO HMF, approximately.

A new process of preparing non-linear ZnO varistor ceramics was reported. The optimum processing conditions were determined as follows: Zn(NO₃)₂ and NaOH
as the raw material, the concentration of Zn²⁺ to be above 0.5mol·L^-1, pH value of 7.5, calcining temperature of 300℃, sintering temperature of 1200℃; the varistors with non-linear coefficient of 28 were obtained. The
effect of rare earth element La₂O₃ on the electrical properties of the ceramics was discussed to be: doping at low concentration is helpful to enhance
its breakdown voltage; at high concentration its voltage sensitive properties will disappear. The powder was characterized by XRD and TEM, showing the five-additive
powder to be spherical and with a diameter about 40～80 nm.

Hydrophobic SiO₂ aerogels were produced by the surface modification of alcogels prepared via sol-gel process using polyethoxydisiloxanes (E-40) as
the precursor and followed by ethanol supercritical drying. The structure of the modified silica aerogels was a silica matrix produced by hydrolysis and
condensation of polyethoxydisiloxanes. Si-CH₃ was modified on the surface of the silica matrix. The pore size decreased from 23.1nm to 18.2nm, the
specific surface area increased from 477 m²·g^-1 to 563 m²·g^-1 and the water vapor adsorption decreased from 0.04 to 0.0012(weight ratio)
after the surface modification of silica aerogels. The existence of Si-CH₃ was observed using infrared spectra.