On the basis of previous investigation on stable criterion for glass, the authers put forwarda new stable criterion of k_D（T）=v·exp（－E／RT·D）[D＝T_c（T_p—T_c）／T₁（T₁-T_g）]，whichhas included the kinetic factor and the thermodynamic factor by means of bringing correctionfactor D into the stable criterion k(T). The low value of k_D(T) means good stability of the glass.The new criterion k_D(T) has little connection with heating rate and can be well used in differentcharacteristic temperature. When values of frequey factor v of glass are near, the criterion especially can decide the stability of the glass and shows more superiority than the criterion of k(T) of k_y(T), which cannot give a correct judgment about the stability of glass. The correctness of the new criterion of k_D(T) was verified by experiments.

More accurately calculating the heat of formation and standard entropy of phosphate, andappliying thermodynanric first approximate equation, the authors analysed the melting proeessof phosphate glass. Oxygen and water existing in the system are the mAlN reason of Pt cruciblebeing eroded, and the erosive products Pt(PO₃)₂ and Pt(PO₃)₄ can easily react with free oxides,releasing Pt particles. POCl₃ atmosphere introduced can either eliminate water and free oxides,or insulate air, so that Pt particles can be decreased.

The optical transmission, X-ray excited emission, energy spectra and decay time characteristics were measured for pure CsI crystals grown by Stockbarger process. The results show thatthe crystals has two scintillation components: a fast component peaked at 310um with <40nsdecay time and a slow component at 450um with ~2.4μs. The slow emission intensity is not stableand considerably thectcd by I- vacancy defects in the crystal. The intensity ratio of fast to slowcomponent obtAlNed is 91.8%.

The model of boundary layer in crystal growth stems from the term boundary layer in fluiddynamics. But they are not the same. As crystal growers we are actually concerned with two(coupled) aspects of the melt-to-crystal transport: (1) with the mass flux across an interface,which we will call the interfacial flux and which determines the crystal growth rate; and (2) withthe concentration profile of growth species in the melt adjacent to the crystal, which is an essentialparameter in morphological stability.

Characteristic diffusion distance is an important factor to discuss the mass flux normal to the interface. For melt growth, the theoretical values range from 0.04～0.4cm. The optical in-situ observation method has been newly developed. The method aims at observing and recording the whole process of growing and melting of oxide crystals in high temperature up to 1400℃, with very high visibility of surface kinetic processes and mass flow behaviors near the growing interface. It is measured that during KNbO₃ crystal growth rates. The formation and development of cellular interface structure are also visualized by means of this method. The result shows that the micro concentration flow near the interface is an essential parameter in morphological stability.

This paper described PWO crystals grown by Bridgman technology for the first time. Thematerials evaporated from the PbWO₄ melt were studied during tile growth of PWO crystals bymeans of both Czochralski and Bridgman mcthod. The results indicated that the evaporation rateof PbO is higher than that of WO₃. Further the X-ray luminescence properties were investigatedof different positions of PWO crystals.

Fine amorphous silicon carbide powders were prepared by vapor phase decomposition fromthe low-molecular polysilane(LPS). The pyrolysis mechanism of LPS under Ar atmosphere andthe influence of the pyrolysis conditions (temperature, duration, LPS and Ar gas flowing rate)were discussed. The silicon carbide fine powder less than 0.1μm obtAlNed after pyrolysis processis amorphous with 34%~35% carbon and 3%~4% oxygen.

B₄C-35vol% TiB₂ composite ceramics with various amounts of free carbon hot-pressed at 2070℃ were studied. The incorporation of particulate TiB₂ into B₄C raised the toughness from3.6MPa.m^1/2 to 6.5MPa.m^1/2. A further increase of composite toughness up to 7.6MPa.m^1/2 wasobtAlNed upon the addition of free carbon. SEM and TEM investigation revealed that the improvement of the composite toughness resulted from the multitoughening of both the crack deflectionassociated with the incorporation of TiB₂ particles and the produced microcrack nucleated due to the strong residual stress and weak interface caused by the presence 9of free carbon in the interface and propagated along B₄C－TiB₂ interfaces.

The effect of silane coupling agent and SiC whisker on the rheologic behavior of injectedsuspension was studied. The process parameters were optimized by the orthogonal experiment ofthe three parameter and three levels of the injection pressure, holding pressure and holding time.To delay the consolication time of the sprue, the heating and cooling apparatus in the injectionmoulded machine were developed. A suitable debindering rule was fomulated by the analysis ofPGC and TGA of organic vehicles decomposition. Finally, the stationary blades of ceramic engine were developed successfully by pressureless sintering with multi-step heat preservation.

The crystal BaTiO₃ must be poled before its photorefractive applications. A technique forinspecting inclusions efficiently in the crystals has been established before poling crystals accordingto the 90° domAlN structures with the inclusions. With considering the character of the formationof 90° domAlN and 180° domAlN, the 90° domAlN can be removed by cooling crystal BaTiO₃ slowlythrough the curie point (130.5℃), or by uniaxial pressing along a-axis. 180° domAlN can beremoved by applying electric field about 1～3×10⁵V／m on the face （001）.

9Al₂O₃.2B₂O₃ whisker was used to reinforce PZT95/5 type ferroelectric transitional ceramics.The relation between properties (including electric and mechnical properties) and whisker contentwas studied. Experiment results indicate: (1) Sintering temperature ruduces with the increase ofwhisker content. (2) Composites with proper whisker content can keep electric properties almostas good as that of base material, while their mechanical properties improved. For exemple, thecomposite with 0.3wt% whisker exhibits an increase up to 42.24% in bending strength. (3) Whisker pulling and bridging play important roles in the process of reinforcing.

The blue-emitting phosphor MGa₂S₄:Ce(M=Ca, Sr) was prepared, and its crystallinity wasanalysed by X-ray diffraction. The excitation and emission spectra of MGa₂S₄:Ce were measuredand investigated, and the effects of the cerium concentration and the composition of host materialon the PL properties for MGa₂S₄:Ce powder were studied. The results of PL measurement showedthat MGa₂S₄:Ce phosphor achieved an even more saturated blue emission, and the optimumcerium concentration for high efficiency and more saturatated blue emission was sbout 6mol% for MGa₂S₄:Ce, 3～4mol％ for SrGa₂S₄:Ce

The phase composition and morphology of Al₂O₃ powders after different heat treatments andthe influence of the characteristics of the Al₂O₃ powder on sintering performance of Na-β"-Al₂O₃were investigated. The experimental results showed that the denee β"-Al₂O₃ ceramics can beobtAlNed only from α-Al₂O₃ starting materals.

The phase diagrams of diamond synthesis in CO＋H₂ mixture gases were obtAlNed accordingto non-equilibrium thermodynamic coupling model. Thesc phase diagrams have diamond stabilityregions, which arc different from tile phase diagrams predicted by classical equilibrium thermodynamic theory. The existence of diamond stability regions is attributed to the distinctive effectsof super-equilibrium atomic hydrogen and atomic oxygen on diamond and graphite. With thepressure decreasing, the diamond stability region moves toward low CO concentration end. The diamond stability regions calculated in the present work are in agreement with the experimental results reported in literatures.

Optically transparent BaO-B₂O₃ (in mol%) system glass was successfully prepared by theconventional melting and quenching technique. After surface controlled crystallization, the grAlN-oriented transparent β-BaB₂O₃ (BBO) surface crystallized glass -ceramics were prepared. Inaddition, the polar-oriented growth kinetics of BaO-B₂O₃ glass was discussed.

The crack-growth-resistance behavior or R-curve behavior of Al₂O₃/SiC_w ceramic cuttingtool material was obtAlNed by employing the Vickers indentation/fracture stress technique. The

R- curve exhibits a steeply rising part while the crack extension is at its initial stage and thefracture toughness increases gently with tile crack propagating further. The quantitative analysisof toughening mechanisms indicates that whisker bridging is the mAlN cause of ascending fracturetoughness at the initial stage of crack extension less than λ, however, whisker pull-out operates significantly in toughening behavior with the increase of crack extension. Additionally, crack deflection also contributes to the increase of fracture toughness.

The film and bulk material of zinc sulphide were prepared by chemical vapor deposition. The nucleation and the growth of zinc sulphide crystals deposited on the graphite and quartz substrates withdifferent roughness were observed. The grAlNs of zinc sulphide deposited on the substrate surface are veryfine, with equiaoxial shape, and then grow up into columnar shape. The roughness of the substrate surfaceinfluences the nucleation density of zinc sulphide but has no effect on the growth rate of zinc sulphide increases with increasing the flow of H₂S and vapoured Zn. The growth rate exhibits maxium value at a given deposition temperature.

Using infrared transimissing, airman scattering, and X-ray diffraction spectroscopy, the authors investigated the effect of annealing temperature on the structure of amorphous hydrogenatedsilicon carbide (a-SiC:H) films prepared by the reactive sputtering method. It is found that annealing at temperature up to 800℃ results in evacuation of hydrogen atoms. Moreover, the annealingtemperature corresponding to the evacuation of H atom from CH_nbonds is higher than thatof R evacuation from SiH_n bonds. The annealing produces structural rearrangements, and the amorphous phase begins to transform into the microcrystalline phase at approximate 800℃.

Si-based nano-powders were prepared from ((CH₃)₃Si)₂NH by CVD. The powders synthesizedat 1000-1500℃ were all amorphous. When the synthesizing temperature was 1000℃, the powders were near-spherical and had a particle-size of 8~10nm. When the synthesizing temperaturewas 1400℃, the powders were spherical and well-distributed, having a particle-size of 8~10nm.After crystallization at high temperatures, the powders synthesized at low temperatures becamewhisker mAlNly contAlNing SiC with small amount of Si₃N₄, while the powders synthesized at high temperatures became to 20～40nm particles mainly containing β-SiC with small amount of α-SiC and an amorphous surface-layer of 1～2nm. When exposed to air for three months, the crystallized particles became amorphous.

SiO₂ gels were prepared by Sol-Gel processing, the influence of catalysts on the hydrolysiscondensation and structure of the gel was studied. The radius of negative ions determines thehydrolysis-condensation mechanism. Different catalysis ways and catalyst concertration, pH value,water content have great influence on the gelation time and the structure of SiO₂ gel.

The oxidation characteristics of boron carbide during sintering at 400~800℃ in air wereinvestigated. The phase structure and surface morphology of oxidized boron carbide were analyzedand observed using X-ray diffraction and scanning electron microscope, respectively. The resultsshow that the oxidation of boron carbide begins at about 600℃. After oxidized, the boron carbidepartially transformed into amorphous boron oxide. The oxidization process is a thermally activatedprocess, whose activation energy Q=17．17kJ／mol．

In this paper the resistance properties of PTCR barium titanate [Ba_0.93Sr_0.03Ca_0.04 TiO₃＋xmolY₂O₃＋1wt% AST] were measured near Curie-temperature by a complex impedance analyzer(HP4192A) from 10Hz to 10MHz. It was observed that PTCR sample exhibits an abnormal negative-temperature- coefficient in frequencies higher than 50kHz. This phenomenon can be simply explAlNed by the two dielectric-layer model, and with this model, the behavior of effectivedielectric constant and its loss in wide frequency range can be explained as well.

The structure of telluritc laser glass was analysed by X-ray diffraction, infrared spectra, raman spectraand X-ray photoelectron spectra. The glass structure mAlNly consisted of TeO₃₊₁ structure units or TeO₃structure units, and distorted TeO₄ units also existed.

The carbothermal reduction nitridation of alumina powder contAlNing MgAl₂O₄ spinel was investigated. Its results show that a great dcal of aluminum oxynitride spinel could be manufacturedat the temperatures lower than 1600℃ and the content of aluminum oxynitride phase and its compositions in the product strongly depend on the firing temperatures and adding MgAl₂O₄ spinel.Aluminum oxynitrides resulted from different adding content of MgAl₂O₄ at varied temperaturespossess different lattice parameters.

Ultrafine SiO₂ powders are prepared from water-glass and HCl through the process of addingsurfactant. The specific surface area of the powders was more than 1000m²/g, and their particlesize was about 0.1μm. The effects of the amount of surfactant and the concentration of reactantson the properties of products were studied. BET, XRD, TEM and some other experiment methodswere used to investigate the structure and other physical propertics of the sample.

F_RL-F_RH phase transitional composite ceramics were prepared. The pyroelectric effect of theceramics was investigated. The output of pyroelectric current during the F_RL-F_RH phase transitionwas simulated by a computer. The results indicated that ion diffussion exists on the interfacebetween neighbour compositions. The influence of ion diffussion to the macroscopic pyroelectriceffect depends on the phase transitional property of relative compositions. The computer simulationmethod for pyroelectric current of multicomposition ceramics is an effective way to analyse the situation of ion diffussiom, and it is also helpful to design and study new functional materials.

The influence of the initial concentration of titanium sulfate and reaction temperature onthe preparation of mica pearl pigments was studied by chedrical analysis method. The resultsindicated that both the initial concentration and the reaction temperature are sensitive faCtors inhydrolysis. The hydrolysis product self catalyzes the hydrolysis process. Also the action energyobtAlNed from the relation of temperature and the degree of hydrolysis of Ti4+ in the preparationof pigments(91.8kJ/mol) was lower than that in the titanium sulfate solution(140.4kJ/mol).

The temperature dependence of the normalized resistance of Nb₃Te₄ single crystal was measured finder different magnetic fields and different electric fields around T₁=100K. It was found that magnetic fieldssuppress the kystercsis of the phase transition temperature, and electric fields broaden tile hysteresis. Thetemperature dependence of the magnetic susceptibility of Nb₃Te₄ single crystal showed that antimagnetiesignal occurs below T₂=50K.

Three-phase composite ceramic electrolyte was prepared and studied. The XRD pattern ofthis material shows a composited phase structurd of LiNaSO₄ and γ-Al₂O₃. High conductivety(10^-2 to 10^-1 S/cm) can be achieved at 500℃. A phase transition appears at about 499℃. It maybe caused by an existence of bbc phase. Al₂O₃ makes a good LiNaSO₄-Al₂O₃ skeleton at hightemperature, and the conductivity enhanced. The proton transport number for high temperaturephase is 0.9~1.0.

The effects of various specially made admixtures on properties of CFRC were studied. Theresults reveal that by using MKC, together with proper manufacturing technologyt the electricalconductivity, dispersion of fibre in cement and compression sensibility of CFRC are much improved,compared to the corresponding plAlN CFRC values. In addition, CKH can improve the electricalconductance of CFRC evidently.

Friction and wear of alumina ceramics were conducted in dry sliding from room temperatureto 1200℃. Both friction and wear decreased obviously over 600℃. The friction coefficient at1200℃ was only 60% as that at room temperature. The specific wear rate at 1200℃ decreasedtwo orders of magnitude than that at 600℃, down to 5×10^-16m³/(N.m). There are three modelsof wear mechanism in the temperature range. Before 600℃, abrasive wear and development ofmicrocracks are the dominating mechanism. Between 600℃ and 1000℃, a amooth surface layer with very fine grains, similar to the structure of nano-ceramics, was formed. Plastic deformation and recrystallization controls the friction and wear. At 1200℃, a glassy film occurred on the surface by the severe plastic deformation, which makes the friction be in hydro-dynamic lubrication.

Morphologies of ALN whiskers grown by vapor-liquid-solid mechanism (VLS) were investigated. Several types of whisker structures such as growth hill, stack structure were found. Orientations of AlN whiskers were studied, besides preferential crystallographic planes, {101n}(n=1,2,3)were found to be growth layers. Axial screw dislocation growth mechanism was confirmed, alsooblique growth mechanism was proposed.

The visible cathodolumincscence (CL) spectrum of the visible light emitting porous silicon(peaked at 680nm) was obtAlNed and proved to be similar to the photoluminescence one. The sourceof CL was detected by the scanning electron microscopy (SEM). The SEM microphotographes ofthe surface of the sample shows that the CL only emits from the surface layer and there is no CLfrom the porous layer where the surface layer dropped off. The SEM microphotogrophes on thecross section of the sample shows the same result. The above experiments suggest again that the visible luminescence from the porous silicon is from the fluorescent material in the surface layer of the porous silicon.

High pure ultrafinc Si3N4 powders were obtAlNed by Plasma Cold-discharge Chemical VaporDeposition Method. After storage for various time and baking with infrared lamp, IR spectra ofthe powders were measured. IR spectra revealed that oxidation occurred as soon as the powderexposed to the air. With the continuation of the storage, the oxidation on the surface developedand the adsorption peak of Si-O bond obviously increased while the adsorption peaks of So-N-Siand Si-H bonds decreased. The characteristic adsorptions of PCVD synthesized amorphous films were wide and strong, similar to those of the fresh synthesized powder. Howere they did not change with time.

Liquid phase regions of 1700℃ with nitrogen concentration higher than 40eq% in the systemsof Sm and Nd-Si-Al-O-N were determined. Both systems possess extensive liquid phase regionsat 40eq% N. With incrcasing nitrogen content, the liquid phasc regions contract towards Si-richcompositions. The maximum solubility of nitrogen in the Sm(Nd)-sialon liquids is slightly above30eq%, wihch is much higher than that in Y-sialon liquid, of which the highest nitrogen concentration of slightly above 30eq% was determined.

The TiO₂ nano-powder was prepared by the precipitation of Ti(OC₄H₉)₄ in aqueous solution.By using FT-IR, as well as potential techniques, it was found that the preparing process and thepost-process affect the suffice status of TiO₂ nancy powder. The factor to affect the agglomerationwas analyzied theoretically, so that the best process to control the agglomeration of nano powderswas found.