• Journal of the Korean Ceramic Society
• /
• v.17 no.2
• /
• pp.75-79
• /
• 1980

The effect of the additive on the dielectric property of $TiO_2$ containing 0-2.5wt %. $Sb_2O_3$ was investigated as a function of frequency from $5{\times}10^4$ to $6.3{\times}10^7$ cps and temperature from 25 to 375$^{\circ}C$. The dielectric constant increased with increasing $Sb_2O_3$ concentration from 0.25 to 0.5wt.% It is due to space charge polarization caused by increasing anion vacanices. The dielectric constant decreased for further increase in $Sb_2O_3$ concentration. It can be explained by increasing grain size effect rather than space charge polarization.

• Journal of the Korean Ceramic Society
• /
• v.44 no.4 s.299
• /
• pp.230-234
• /
• 2007

Cordierite ceramics were fabricated via a reaction sintering process using ceramics-filled polysiloxane as a precursor for cordierite ceramics. In this study, the effects of the additive composition, additive content, and sintering temperature on the sintered density and compressive strength of cordierite ceramics have been investigated The sintered densities of reaction-sintered cordierite ceramics containing $TiO_2$ as an additive were insensitive to the additive composition, additive content, and sintering temperature and ranged from $1.92g/cm^3\;to\;2.06g/cm^3$. In contrast, the cordierite ceramics containing $Y_2O_3$ showed a maximal density of $2.21g/cm^3$ at 5 wt% addition and at a sintering temperature of $1400^{\circ}C$. The compressive strength of cordierite ceramics showed the same tendency with the density. Typical compressive strength of cordierite ceramics containing 5 wt% $Y_2O_3$ as a sintering additive and sintered at $1400^{\circ}C\;was\;{\sim}480MPa$.

• Journal of the Korean Ceramic Society
• /
• v.37 no.7
• /
• pp.660-664
• /
• 2000

Effect of various kinds of additive such as AlOOH, Al(OH)3, Al2Si2O5(OH)4, Nb2O5, TiO2 and MgO on the properties and microstructures of UO2 pellet has been examined. All the tested dopants had played a role to reduce sintered density and open porosity. It was revealed that the addition of TiO2 made pellet more stable thermally. UO2 pellet doped with 0.2wt% TiO2 was swelled rather than densified after annealing for 24 hrs at 1$700^{\circ}C$. It was attributed to large pore with spherical shape. Titinia and silicon coexisted with Al element were more effective to increase grain size than other additives. It could be also revealed that the formation of liquid phase was the main cause of grain growth.

• Korean Journal of Materials Research
• /
• v.18 no.2
• /
• pp.107-111
• /
• 2008

[ $BaO{\cdot}Nd_2O_3{\cdot}5TiO_2$ ] (BNT) ceramics modified with a borate glass containing Ba, Nd and Ti as glass constituents were investigated with regard to their sintering behavior and microwave dielectric properties. An addition of iso-component glass significantly improved the sinterabilty of the BNT ceramics and lowered the sintering temperature. A maximum density of $5.29\;g/cm^3$ and an x-y shrinkage of 17% were obtained for BNT ceramics containing 10wt.% of the glass sintered at $1100^{\circ}C$. The dielectric composition without the glass additive was only slightly densified at $1100^{\circ}C$. The resulting sample exhibited two crystalline phases, $BaNd_2Ti_5O_{14}$ and $Ba_2Ti_9O_{20}$, regardless of sintering temperature and glass content. When >10wt.% glass was added, exaggerated grain growth with a less uniform microstructure was found, resulting in the subsequent reduction of the fired density and the dielectric properties. BNT ceramics containing 10wt.% of the isocomponent glass sintered at $1100^{\circ}C$ for 4 h showed promising dielectric properties of k = 71.3 and Q = 1,330.

• Journal of Sensor Science and Technology
• /
• v.13 no.2
• /
• pp.152-156
• /
• 2004

The dielectric and piezoelectric properties of 0.36Pb($Sc_{1/2}Nb_{1/2}$)$O_{3}$-0.25Pb($Ni_{1/3}Nb_{2/3}$)$O_{3}$-0.39Pb$TiO_{3}$ (hereafter PSNNT) at the morphotropic phase boundary (MPB) composition were investigated with $0{\sim}2.5$ mot% $MnO_{2}$ doping. Bulk density, dielectric loss and tetragonality of crystal structure were all improved with increasing $MnO_{2}$ additive content. With increasing $MnO_{2}$ additive content, the electromechanical coupling factor and quality factor were also increased: Electromechanical coupling $k_{p}$ and quality factor $Q_{m}$ at 2.0 mol% $MnO_{2}$ doping with were showed highest values of 55.6 % and 252, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07a
• /
• pp.375-378
• /
• 2002

We investigated the reduction of etching damage by additive O$_2$ in etching gas and recovery of etching damage by O$_2$ annealing. The PZT thin films were etched using additive Ar or O$_2$ into Cl$_2$/CF$_4$ gas mixing ratio of 8/2. In order to recover ferroelectric properties of PZT thin films after etching, the etched PZT thin films were annealed at 600 C in O$_2$ atmosphere for 10 min. The remanent polarization is decreased seriously and fatigue is accelerated in the PZT sample etched in Ar/(C1$_2$+CF$_4$) plasma, whereas these characteristics are improved in O$_2$/(Cl$_2$/CF$_4$). From x-ray photoelectron spectroscopy (XPS) analysis, the intensities of Pb-O, Zr-O and Ti-O peaks are changed and the etch byproducts such as metal chloride and metal fluoride are reduced by O$_2$ annealing. From electron probe micro analyzer (EPMA) and auger electron spectroscopy(AES), O$_2$ vacancy is observed after etching. In x-ray diffraction (XRD), the structure damage in the additive O$_2$ into C1$_2$/CF$_4$ is reduced and the improvement of ferroelectric behavioral annealed sample is consistent with the increase of the (100) and (200) PZT peaks.

• Nuclear Engineering and Technology
• /
• v.31 no.5
• /
• pp.455-464
• /
• 1999

The effect of TiO$_2$ on the sintering behavior of mixed UO$_2$-U$_3$O$_{8}$ Powder compacts has been investigated using the U$_{3}$O$_{8}$ powder made tv oxidation of defective UO$_{2}$ pellets. Without TiO$_2$, UO$_2$ pellet density is inversely proportional to U$_3$O$_{8}$ content and is below 94 %TD in the U$_3$O$_{8}$ range above 15 wt%. Using more than 0.1 wt % TiO$_2$, however, the density decreases slightly with U$_3$O$_{8}$ content and thus is higher than about 94% TD in the whole range of U$_3$O$_{8}$ content. The grain sizes of UO$_2$ pellets with more than 0.1 wt % TiO$_2$are larger than about 30${\mu}{\textrm}{m}$. Therefore, the U$_3$O$_{8}$ Powder can be reused without any restriction on its amount in UO$_2$ pellet fabrication by sintering the mixed UO$_2$-U$_3$O$_{8}$ compact with the aid of TiO$_2$. Mechanisms for densification and grain growth are proposed and discussed, based on a dilatometry study and an examination of microstructure. microstructure.

• Journal of the Korean institute of surface engineering
• /
• v.30 no.5
• /
• pp.320-332
• /
• 1997

The development of colored surface on zinc coating by the oxidation of a melten alloy of zinc with a minor amount of oxygen-avid additive such as tianium has been studied. Using a galvanizing Zinc alloy containing 0.1 to 0.3wt%Ti, gold, purple or blue color was developed clearly and stably, depending upon the extent of oxidation, by air cooling after hot dipping in a bath at temperature of $550^{\circ}C$ to $600^{\circ}C$. The source of the color is light interference with surface oxide layer. THe final color depends on the thickness of the color depends on the thickness of $TiO_2$, played So compositing, temperature and time at elevated temperature after are all controlling variables. Since oxidation film such as $TiO_2$ played role of passivation film, the corrosion resistance in a colored galvanized steel sheet. It is also thought that surface oxide layer of $TiO_2$ inhibited dissolution of the coating layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1993.05a
• /
• pp.3-5
• /
• 1993

It is very important that a spectrum of reflectance is in accord wi th a spectrum of absorbance for a effective heating. Therefore. the objective of this study was to achieve a technical composite for material plan which PTC thermistor increase a radiation property of far-infrared and keep a characteristic of R-T The Ceramic speciman studies had the composition $BaTiO_3$ with additive of 1.67 $Al_2O_3$, 3.75 $SiO_2$, 1.25 $TiO_2$, 0.15 $Sb_2O_3$ and 0.00-0.182 $MnO_2$. $MnO_2$ amounts of additives was both increase on the anomalous resistivity-temperature characteristics and high efficiency on the radiation properties bodies of far-infrared. This result shows that specimens produced high emissivity(average 0.8) of far-infrared at 4.5-15$[{\mu}m]$ by measuring a characteristic of IR and R-T.

• Fire Science and Engineering
• /
• v.9 no.2
• /
• pp.29-36
• /
• 1995

In this study, the effect of Mn $O_2$ additive on the electrical characteristics of PZN-PSS-PZT Pyroelectric materials for the fire detactor was studies. PZT ceramics used this experimental is 4 composite system $[$Pb(Z $n_{1}$3/ N $b_{2}$3/) $O_3$＋Pb(S $n_{1}$3/ S $b_{2}$3/) $O_3$＋PbTi $O_3$＋PbZr $O_3$$]$The dielectric constants and dissipation factors decreases as to Mn $O_2$ concentration increases. At the Mn $O_2$ 0.5($\omega$t%), Pyroelectric coefficient shows 8(10$^{-8C}$$\textrm{cm}^2$$^{\circ}C$) which have the highst value among other additive contents. It is found that output voltage shows maximum peck at Mn $O_2$0.7($\omega$t％) is associated with the higher pyroelectric coefficient and Lowered dielectric constant.t.