The effects of crystallite size on the powder characteristics, the resistance in air and the sensitivity to 0.5 vol % , CO-air mixture were observed. The size of SnO, powder was controlled by calcining temperature variation ( ~) of -stannic acid fabricated from . Its crystallite size. evaluated from TEM image, was in the range of 8-54nm. With the reduction of crystallite size, the adsoption peak of on FTIR curve became more clear while the lattice parameters were invariable. As the crystallite size decreased, with elements of thick film, the temperatures showing a minimum resistance in air and a maximum sensitivity to H, gas reduced. The temperature variations were assigned to the changes of activation energy of the active adsorbates, and it was suggested that the decrease of activation energy can be one of the reasons for the' sensitivity increase with the' fine powder.

Using a RF cylindrical magnetron operated with two electromagnets having a Helmholz configuration, RF magnetron plasma properties and characteristics of reactive ion ething of Si were investigated as a function of applied magnetic field strengths using 3mTorr and . Also, I-V characteristics of Schottky diodes, which were made of silicons etched under different applied magnetic field strengths and gas environments, were measured to investigate the degree of radiation damage during the reactive ion etching. As the magnetic field strent;th increased, ion densities and radical densities of the plasmas were increased linearly, however, the dc self-bias voltages induced on the powered electrode, where the specimen are located, were decreased exponentially. Maximum etch rates, which were 5 times faster than that etched without applied magnetic filed, were obtained using near lOOGauss, and, under these conditions, little or no radiation damages on the etched silicons were found.

The standard map for polyerystalline -X was construeted and indexed from pressed tape sintered bulk and compressed bulk samples were drawn by the [001-110-110] stereographie quadrant map and by the ECPs from individual grains of the speeimens. The relationship between the (001) texture development and critical current density (Jc) for various samples was discussed. An (001) orintation was preferred in the pressed tape thickness was decreased. and in the compressed bulk as the compression strain was increaesed.The (001) orientation made a signifieant in crease on Jc. We conclded that an ECP technique was very useful for the analysis of the orientation distribution in small-sized -X specimens such as superonducting tapes or thin films.

The crystal structunes of poly(ethylene terephthalate-eo-1, 4 cyciohexylene dimethylene terephthalate), P(ET CT), copolymers were studied by CPMAS solid state NMR spectroscopy. With the estimation of methylene resonance peaks, the bulkier CT component of the copolymer in the range of 0 20 mol% CT is excluded from the ET crystal lattice, whereas smaller ET component of the copolymer in the range of 66 100 mol% CT can be partially included into the CT crystal lattice. Those different crystallization behavior can be explained with the difference in chain bulkiness and crystal lattice dimension be tween two copolymer compurwnts.

A nitride layer was df'posited on the thermal oxide layer by LPCVD process. ONO(oxidenitricle oxide) capacitors with various thickness of component layer wore fabricated by wet reoxidation of the nitride with and without anrwalmg treatment and their properties were investigated. As a result of observation on the refrative index and etching behavior of the ONO fIlms, the nitride layer OF 40 A thick ness was not so dense that the bottom oxide during the reoxidation process and the capability of securing the capacitance decreased. The conduction current in the ONO multl-Iayer dielctric film was reduced as the bottom(or top) oxide layer became thicker. However, in the case of oxide with thickness more than 50A, it merely plays a factor of reduction in capacitance, and the effect of barrier for hole injection was not so much increased. Annealing of the nitride laypr bpfore reoxidation did not show a grpat effects on the refractive index and capacitance of the film, however, the annealing process increased the breakdown voltage by 2V.

Among the various test methods for stress corrusiun cracking(SCC) susceptibility evaluatiun, the slow stram rate test(SSHT) method is a rapid and effective nwthod to evaluate the SCC susceptibility of metal in relatively short time. But it is very difficult to analyze the microfracture behaviors in SCC process by using the test(SSRT) method only. Up to now, it has been well known that the acoustic emission(AE) test is the effective technique to monitor the microcrack initiation and propagation in material fracture pmcess. Therefore. in this paper, we analyzed the correlation between the see process and the characteristics of AE signal by using the SSHT and the AE test. According to the test results. the AE signals produced from the material microfracture were clearly depended on the test environment. The AE signal characteristics generated during see process in synthetic sea water were comparatively greater than those. in air. In addition, the SCC behaviors could be definitely evaluated by the amplitude parameter of AE signals.

In order to improve the oxidative resistance of carbon/carbon composites, aluminium-isopropoxide and aluminium-tri-sec-butoxide sol were coated on the surface of 2D--carbon/carbon composiles and the effects uf coating were investigated. The effects of oxidative resistance were dominant in the case of catalyst/alkoxide mole ratio, 0.07, and /alkoxide mole ratio, 100. Through the dynamic TGA analysis with the heating rate of 20%/min, oxidative initiation tempera~ ture was enhanced about . The oxidative resistance effects of alkoxide sol were improved according to the times of coating. Also the 20% weight loss time of coated samples by TGA analysis was 20% better than that of un~ coated samples. The thickness of 1^{st} coated layer was about 3m and that of and coated layers was about respectively 4~5m and the weight loss were increased with the increasing of thermal shock test times.

The silicon oxynitride bonded composite has been developed based on the selective oxidation behavier of over BN. The silicon oxynitride phase converted to the reaction between and formed on powder surface during oxidation treatment at the sintering temperature. The developed composite has excellent high-temperature strength, thermal shock resistance, precision machinability and corrosion resistance to the molten steel. The developed composite may therefore be used as, for example, break ring materials in continuous casting of steel.

The state of aggregation and optical contrast of poly(vinyl chlorich, )(PVC)!nematic liquid crystal(LC) composite film liave been studied for a wide range(30~70 wt% LC)of film composition. In addition. effects of temperature, frequency and voltage of the applied AV electric field on the film transmittance have heen measured for a film containing (6O wt % I, C, which showed maximum optical contrast. For this particular composition of film, tlw thn'shold voltage was smalkr than .40 at I kHZ, , and the rise time and decay time were smalle, r than l0Oms at 100, I kHz, and .

A newly designed torsion pendulum operating at high pressures and various temperatures has been constructed. The High Pressure Torsion Pendulum(HPTP) is capable of containing gaseous pressure to 690MPa(100, 000psi) and operating at temperatures from- to . A glass fiber braid is installed between two sample holders to accommodateliquid samples. The HPTP was fully automated and computerized using an IBM-AT personal computer to control initiation of oscillation, collect digitized data, and calculate the shear and loss moduli from damped curves, The curing process of an epoxyamine(DGEBA-DDS) system under various pressures up to 124 MPa(18, 000 psi) at has been successfully carried out and some results are presented.

In this paper, an , added during dry oxidation and annealing m Si( 111) is clarified effect ive to suppress or remove defects. Annealing effects in and ambient are estimated with dry and oxidation( added in dry oxidation) method. C;em'rated defects in dry oxidation are lengthened according to oxidation time. but any defects in oxidation are not found. Dry oxidation, after oxidation as an initial oxidation. lias the defect -removing effect at the interface of Si -. After dry or . oxidation. the annealmg 7.5% ambient brings out gettering effect of OSF. The annealing in 7.5% ambient for NI L oxidation method decreaSE,s length of OSF about 20 % compared with dry oxidation method. Tlw feature of OSF is pit type, the gettering is directed to (011) plane for (111) plane. and OSFs are etched following to 110) directIon.

Phase equilibria and reaction paths of the superconducting phases and other compatible phases at in the Bi-Sr-Ca-Cu-O system were studied. was added to by 5% up to 40 mole% Bi in the pseudo-binary system and the heat treated samples were analysed using XRD. SEM, EDS. and DT A. When Bi contents were greater than 35 mole% Bi, liquid phase was formed which was compatible with phase. The m.p. of phase decreased as the content of (Sr+Ca)decreased. phase first segregated out of liquid phase around phase during cooling of liquid phase.

In this short note, we report the result of measurement for the ferro- to paramagnetic phase transition temperature, that is Curie point of bulk gadolinium. This note is written to give the solid validity for the previous measurement of Curie point shift of gadolinium film (1. Rhee, E. Lee and S. Lee, Kor. J. of Mat. Research,3, 3, 1993). The Curie point of bulk gadolinium is determined by measuring the resistance of sample as function of temperatures. At Curie point, we can observe the resistivity anomaly which arises due to the heat capacity difference between below and above Curie point. Finally, the curie point of bulk gadolinium is found to be 19.20..