Research progress on Li₂B₄O₇ crystals grown by inodihed Bridgman techimque (Fan s process)in our lab are intruduced in detail. The features of Li₂B₄O₇ growth such as (1) the criticalrequirement of stoichiometric purity for raw material, (2) very low growth rate, (3) a convex orplane solid-liquid interface and (4) a suitable proccdure of self- anmeaimg are discussed. 3" and4" Li₂B₄O₇ boules with core-free, twin-free, no striation, no crack and no scattering particlehave been grown stably by the BR techniq. Properties of the crystal and its application in SAW devices are also reviewed.

Fluorozirconate glass is a good kind of optical material. The paper systematically researchedthe effects of PbF₄, LiF, SrF₂, HU₄, NaF and YF₃ on the refractive index, glass-forming ability andthermal expansion coeffeciency of the fluorozirconate glass. The results show that PbF₂ and LiFcan increase the refractive index of the glass, however, SrF₂ and HfF₄ can decrease the refractiveiudex. According the DTA of the glass, the optimum concentrations of these fluorides in whichthe glass has good glass-forming ability were determined.

A general procedure to predict the both unnotched and notched fatigue strength of soda-lime glass under different loading modes is given on
the basis of the cyclic fatigue behavior of the material. Because there no effective crack-shielding mechanism exists in soda-lime glass, the cyclic loading produces no
additional damage in the material. The fatigue notch factor K_f of notched specimens is approximately equal to the theoretical stress concentration factor K_t of the specimens. A
general strength-probability-time(SPT) diagram can be obtained according to the concept of equivalent stress σ_eq, in which the both effects of notch and loading-modes are
taken into account.

The spherulite growing process was observed in a glass-ceramics which consists of crystals, being in the shape of spherulites in the R₂O-RO-Al₂O₃-SiO₂ system.
It was obtained that spherulite diameter increases with the increase of crystallization time or the elevation of crystallisation temperature,
however the number of the spherulites maintains unchanged. Also it was discovered that the relationship between spherulite diameter and
nucleation temperature is a parabola type. The microstructure and its variation of inside of spherulite embryo and surrounding glass matrix were analyzed by
TEM and EDAX. The component change in the spherulite growing process was revealed clearly.

2vol% nano-ZrO₂ aqueous suspensions were obtained by different colloidal stabilization mech-anism including single-electrostatic, steric (by PEG) and electrosteric (by PMAA-NH₄). These suspensions were studied by means of Zeta potential measurements. Sedimentation experiments viscosity measurements and particle-size analysis etc. At last, we obstained that the highly dis-persed and stabilized nano-ZrO₂ aqueous suspensions in acid condition and in alkaline condition.

Al₂O₃-5vol% SiC nanoscale composite powder was prepared by the precipitation method.Al₂O₃-SiC nanocomposites were made by HP sintering. The strength of Al₂O₃-SiC nanocomposites is 467MPa, toughniess is 4. 7MPa.m^1/2. Nano SiC particles were located in Al₂O₃ grains because of the transformation of Al₂O₃ from γ phase to α phase. This intragranular microstructure is effective in improving mechanical properties. Therefore, the precipitation method is a good way to fabricate Al₂O₃-SiC nanocomposites.

Direct Coagulation Casting (DCC) is a novel near net shape process for ceramics materials. However, the green body strength by DCC is low compared with gelcasting
and injection molding. Boehmite sol was added for α-Al₂O₃-DCC in order to increase the green strength of alumina. In this paper, the characteristics of electrokinetics, rheology and coagulation process were invesigated for the system of Al₂O₃+AlOOH. In
special the effects of AlOOH addition on coagulation behaviours such as amount of enzyme and kinetics of consolidation process were discussed.

The tribological properties of TZP ceramics under solid lubrication up to 600℃ were investigated. Using either graphite or MoS₂ can reduce the friction coefficient and wear rate of
TZP/Si₃N₄ sliding couple from 25 to 600℃, however, their lubricating characteristics can be deteriorated due to the oxidation of these lubricants over excessive high temperature. Using CeO₂
and Cu can reduce the wear rate of TZP ceramics, but they don’t have apparently influence on the friction coeffcient. CeF₃ has good lubricating properties at high temperature, which is due to its completed crystallization and orientation alone (002) plane.

Yb-Y-TZP with high flexural strength and excellent fracture toughness was acquired with the complex stablizers containing Yb₂O₃ and Y₂O₃.
XRD was used to investigate the phase composition and increment of monoclinic phase content before and after fracture. The microstructure of Yb-Y-TZP was
observed and grain size was determined by SEM. The relationship between the mechanical properties, microstructure and the increment of monoclinic phase content was studied.
It was found that the fracture toughness was improved with the original flexural strength by doping 0--3 mol% Yb₂O₃ in Y-TZP. The experimental results
showed that the excellent mechanical properties were not decreased if Yb₂O₃ was added in Y-TZP to inhibit the low temperature aging and to improve the thermal shock resistance.

By a newly developed powder process, a layer of metal cobalt film was coated on the surface of fine ceramic powder of Al_2O_3 and TiC. The mixture of the two
kinds of Co-coated powder (about 70wt%Al₂O₃-Co+30wt%TiC-Co) was hot-pressed into advanced Al₂O₃-TiC-Co(ATC) ceramic. Scanning electron
microcopy (SEM) observation was employed to investigate its erosion behavior. Comparing with AT30 (70wt%Al₂O₃+30wt%TiC) ceramic, its high fracture
toughness and fracture strength with relative fine microstructure make it more resistant than At30 ceramic against particle erosion under different impact velocity and impact
angles. The SEM shows that the worn surface exhibits shallow detaching, microcrack and plastic deformation. Its proper wear resistance not only depends on its
mechanical properties, but also its microstructure.

Hydrotermal BaTiO₃ powders could be sintered at 1240℃, but the sintered exhibited high porosity and unsatisfying dielectric property due to the existance of a certain amount of surface absorbed water, lattice water and OH- etc. defects. Water and OH^- etc. defects could be removed by heating the as-prepared powders at 900℃ for 2 hours, diffractional scanning calorimetry analysis indicated that the tetragonality of the powders increased from 15% to 28%, th porosity of the sintered body was lowered,and the dielectric properties were improved.

Mullite/mullite (rodlike) and ZTM/mullite (rodlike) ceramics with the microstructure of whisker toughening ceramics were fabricated. The research and analysis demonstrated that
rodlike mullite particles had relatively high fracture strength; The growth of rodlike particles changed the fracture mode from the mainly transgranular to the mixture type of transgranular
and intergranular in monophase mullite ceramics. A lot of rodlike particles pull-out from the matrix were observed in the fracture surface of the specimens. For ZTM, compressive stresses
in the matrix would be produced by the phase transformation of ZrO₂. So the bonding forces among the rodlike particles and matrix were enhanced and the debonding of rodlike particles
became difficult. The pull-out of rodlike particles from matrix became less in the fracture surfaces and this phenomenon was even more obvious for the specimen with high m-ZrO₂
content.

The relaxor ferroelectric ceramics in Pb(Zn_1/3Nb_2/3)O₃ -BatTiO₃-PbTiO₃ system were prepared by mixed-sintering method. SRD studies revealed that the ceramics have diphasic composite structure. The dielectric properties of composite ceramics were studied, and the results showed that the temperature and frequency dependencies of capacitance as well as aging behavior can be improved with composite structure. Thus, a temperatire- stable PZN composite ceramic with excellent dielectric properties was obtained.

The pyroelectric effect in PZT and PT ceramics was measured. The structural change of the two materials with temperature was investigated by XRD method. The relationship between structure and pyroelectric effect was discussed. The experimental results exhibited that the pyroelectric effect is dependent on the change of cell parameters with temperature. The larger the change of axis c and c/a, the larger the pyroelectric coefficient.

Nitrogen-containing rare earth melilite solid solutions R₂Si_3-xAl_xO_3+xN_4-x(R=Nd,Dy, x=0, 0.3, 0.6, 1.0, R=Yb, x=0, 0.3) were prepared at the temperatures
ranged from 1500℃ to 1750℃ for 2h by pressureless sintering　technique. The reaction sequences of these compositions at the sintering temperatures
were studied. The results showed that nitrogen-containing rare earth (from Nd to Yb) melilite or its solid　solutions can be formed and their amounts in the sintered samples increase with increasing
the temperatures. However, the formation abilities of melilite solid solutions　become weak with decreasing the ionic radii of rare earth elements, i.e. light rare earth melilite solid solutions can be formed as a major phase
at the temperature as low as 1500℃, however, for midium and heavy　rare earth it needs to increase the temperature to 1700℃ and 1750℃
respectively. The other phases to occur in the sintered samples and the factors to affect the formation behaviour of melilite solid solutions were also discussed in the paper.

The fabrication technology of Na-β″-Al₂O₃ ceramic tubes by partial synthesis method was inverstigated. The β″-Al₂O₃ tubes thus prepared have more homogeneous microstructure than that of the tubes prepared by reaction sintering method. their main properties can be compared with the advanced international results.

Natural layered aluminosilicate kaolinite Al₄[Si₄O₁₀](OH)₈ was used as a starting material for perparing a new system of lithium fast ion conductors
Li_1+2x+yAl_xNd_yTi_2-x-ySi_xP_3-xO₁₂ by high temperature (800～1000℃) solid phase reaction for about 20h. A solid solution phase with R3c structure exists in a
limited composition region. The electrical measurements indicated that the maximum conductivity in the above system (referred to as Al-Nd-Lisicon) is
the initial composition with x=1.0, x=0.3, its conductivity reaches up to 3.08×10^-2S/cm at 400℃ and the activation energy is 35.2kJ/mol.

The complex oxide compounds Ln_0.67Sr_0.33MnO₃(Ln=La, Pr?, Nd, Sm) were synthesized through co-precipitation route. Compared with the
traditional ceramic sintering method, the temperature at which the compounds were formed were reduced by about 450℃. The X-ray powder diffraction patterns indicated that the structure of the compounds belongs to cubic perovskite-type phase and their crystal
unit parameters vary with the radius of rare earth ions regularly. The resistivity of samples was measured by a standard four-probe method. The results show that the radius of rare
earth ion is crucial to the ability of electric conduction of the compounds. The double exchange theory can only explain our experimental results partially. The autors deduced that the
electrons of 4f state of rare earth ions may play a role in electric conduction.

The thermal stability of synthetic diamond in air was investigated by means of DTA, heat corrosion, SEM and compressive strength test. The oxidation decomposition temperature of the synthetic diamond in air was measured. Oxidation process and oxidation mechanism of the synthetic diamond in air were discussed.

This paper discussed the effects of polymorphic form, purity and particle-size and agglomeration of TiO₂ powders on microstructure and electric properties of PTCR ceramics based onY-doped BaTiO₃. The results show that, microstructures of PTCR ceramics are influenced by polymorphic form, particle-size of the TiO₂ powders. The semiconducting process of PTCR ceramics is also influenced by polymorphic form of TiO₂. The impurity and agglomeration of raw materials will lead to degradation of PTC effect for the ceramics materials.

The solubilization behavior of metal ions and ammonia solution in AOT-isooctane-water reverse micelles was investigated by injection method, the size of reverse micelles
was then determined with dynamic light scattering technique, and the microstructure of reverse micelles containing metal ions was characterized by using freeze
fracture electron microscopic technique. With these micellar solutions, Y₂O₃ and CeO₂ stabilized ultrafine zirconia powders were prepared accordingly. Different kinds of preparative
manners were tried to examine their effects on the quality of powders thereby derived. It was found that the swollen of metal ions in reverse micelles was an essential
condition for obtaining a powder with good quality.

Ultrafine AlN powder, whose diameter was betweeen 5 and 80nm and purity was 98.4wt%, was synthesized by microwave heating in an atmosphere of nitrogen. Phenolformaldehyde resin and colloidal Al(OH)₃ were used as starting materials. The properties of the powder were determined by means of XRD, TEM, and so on. The mechanism for microwave synthesis of ultrafine AlNpowder was discussed.

Zinc ferrite was prepared by shock wave treatment of coprecipitated ferric oxide and zinc oxide misture, the product was characterized by XRD, TEM and electron diffraction. In contrast
to the zinc ferrite synthesized by high temperature calcination, the product by shock wave treatment consists of nanometer-sized zinc ferrite particles. The main reason may be that the
acting period of shock wave is very short, so the crystallites of zinc ferrite formed do not have enough time to grow to large and perfect crystallites. It is believed that the method of shock wave
treatment may be a novel method for preparing nanosized powders of composite metal oxides.

High performance SiC-AlN composites were prepared by hot-pressing with α-SiC as starting powder. The effects of composition and sintering temperature on the properties
of the materials were investigated, and SiC-5vol% AlN composites exhibited superior mechanical properties, with flexural strength, fracture toughness and Vickers
hardness of 1130MPa, 6.2MPa·m^1/2 and 28.6GPa respectively. Microstructural observations revealed that the grain size of SiC-AlN composites was obviously
inhibited and refined due to the formation of solid solutions and the development of subgrain boundaries in matrix SiC grain.

A cost-effective crystal growth method was studied to fabricate the relaxor ferroelectric single crystal of lead magnesium niobate -lead titanate (PMN-PT). The crystal of PMN-PT, 7mm in diameter was prepared, and its dielectric and piezoelectric properties measured are as follows:T_c ～170 ℃ E_c～340V/mm, ε～3500 (25℃ and 1kHz), and d₃₃ ～1040pC/N.