Search

β-BaB 2 O 4 (β-BBO) powders and films were successfully synthesized by the sol-gel method using metal alkoxides. A homogeneous and stable solution was prepared by the reacton of barium metal with boron triethoxide in ethanol by addition of diethanolamine. The drip-coated precursor films began to crystallize to β-BBO on Pt substrates at 500 o C and converted to β-BBO films with preferred orientation to the c-axis at 700 o C

Highly oriented Sr 0.5 Ba 0.5 Nb 2 O 6 (SBN50) thin films have been prepared using a sol-gel method. A homogeneous and stable strontium barium niobate (Sr 1-x Ba x Nb 2 O 6 , SBN) precursor solution could be prepared via the reaction control of metal alkoxides. The SBN precursor was stabilized by the coordination of the 2-ethoxyethoxy group to metals. SBN thin films on MgO(100) crystallized to a mixture of orthorhombic and tetragonal phase at 700°C and then transformed completely to the tetragonal phase of tungsten bronze at 1000°C. Two crystal lattice planes of SBN were intergrown at an orientation of 18.5° on MgO(100). SBN50 thin films on Pt(100)/MgO(100) substrates exhibited the P-E hysteresis.

Carbazolequinone alkaloids, murrayaquinone-A (1a), and pyrayaquinone-A (2) and -B (3), as well as pyrano[3, 2-b]carbazolequinone 5, an isomer of 2 and 3, were prepared conveniently by the palladium-assisted intramolecular ring closure of the corresponding 2-arylamino-methyl-1, 4-benzoquinones 9a and 9i-k. A series of their analogues, 6-, 7-, and 8-substituted 3-methylcarbazole-1, 4-quinone derivatives 1b-g and 2-methylcarbazolequinones 6a-g corresponding to 1a-g, was also prepared in the same manner. Comparative analysis of the carbon-13 nuclear magnetic resonance spectra was found to provide useful information for the structural assignment of either 2- or 3-methylcarbazolequinones.

This paper reports on crack-free SBN (Sr{sub x}Ba{sub 1{minus}x}Nb{sub 2}O{sub 6}) thin films that have been prepared by a sol-gel method with metal alkoxides. A homogeneous and stable precursor solution was obtained from Sr and Ba metal and Nb(OEt){sub 5} in ethanol with a key additive of ethoxyethanol. SBN (where x = 0.5) powder crystallized to orthorhombic phase at 700{degrees}C, and then transformed completely to tetragonal phase at 1200{degrees}C. The formation of tetragonal SBN was observed on sapphire (R) substrates at 700{degrees}C, whereas the tetragonal phase began to appear in the powders at 1000{degrees}C. SBN films with highly preferred orientation were successfully synthesized on MgO (100) substrates at 670{degrees}C.

This paper reports on perovskite potassium tantalate niobate (KTN) powders and thin films that were synthesized from a metal alkoxide solution. Homogeneous KTN coating solutions were prepared from KOC{sub 2}H{sub 5}, Ta(OC{sub 2}H{sub 5}){sub 5}, and Nb(OC{sub 2}H{sub 5}){sub 5} in absolute ethanol. The precursor powders crystallized to pyrochlore at {approx}650{degrees}C, and then to perovskite at {approx}750{degrees}C, depending upon Ta:Nb ratio. H{sub 2}O vapor during calcination was found to play a prominent role in the direct and predominant crystallization of perovskite films with preferred orientation. Highly oriented KTN films of perovskite structure were successfully prepared on MgO (100) substrates at 675{degrees}C.

The reduction of NO with propane in the presence of excess oxygen was investigated using gallium ion-exchanged zeolite catalysts, among which ferrierite(Ga-ferrierite) and ZSM-5(Ga-ZSM-5) showed high activity in a wide range of reaction temperature.

Selective reduction of nitric oxide by ethene in the presence of excess oxygen was investigated using a gallium ion-exchanged ZSM-5 catalyst. Ga-ZSM-5 showed high activity in a wide range of reaction temperatures. In addition, Ga-ZSM-5 showed extremely high selectivity for this reaction under oxygen-rich conditions (10%). The limiting molar ratio of reacted NO to consumed ethylene was found to be 2. High catalytic activity was maintained even under high space velocity at 500°C on Ga-ZSM-5.

Selective reduction of nitric oxide with methane or ethane in the presence of excess oxygen was investigated using a gallium ion-exchanged ZSM-5 zeolite catalyst(Ga-ZSM-5). Ga-ZSM-5 was highly active and selective for NO reduction above 400 °C. The limiting molar ratios of reacted NO to consumed carbon in C2H6 and CH4 at 500 °C were found to be 1.5 and 2, respectively.

(Co,Fe)3O4 films were synthesized by the sol–gel method through metalorganic compounds. The (Co,Fe)3O4 films (Co:Fe = 2:1) showed the characteristic behavior of the spinodal decomposition by heat treatments within the miscibility gap. The coercive force of the spinodally decomposed films increased from 0.9 kOe for a solid solution to 2.0 kOe for films that underwent the spinodal decomposition. The nonmagnetic phase (rich in Co) formed by the spinodal decomposition contributes to the pinning of the movement of magnetic domain walls. On the other hand, the (Co,Fe)3O4 films (Co:Fe = 1:1) showed the typical feature of binodal decomposition during heat treatment within the miscibility gap. The binodally decomposed films showed a slight increase in the coercive force depending upon the evolution of the magnetic region.

□ Intrathecal (i.t.) injection of substance P (SP) induced reciprocal hindlimb scratching directed mainly toward the abdominal regions in mice. This behavior pattern appeared within the first minute after i.t. injection of SP. Similar behavioral effects were produced by i. t. injection of neurokinin (NK)-1 agonists, physaiaemin (Phy) and [Sar 9 , Met(02) 11 ] SP (Sar-SP). The duration of scratching varied among NK-1 agonists; of the NK-1 agonists used, Phy had the most long-lasting duration of scratching in contrast to SP that had a short duration. The rank order of scratching duration was Phy > Sar-SP > SP. SP was rapidly degraded by the solubilized enzyme extracted from the mouse spinal cord as determined by HPLC. Decay of the scratching response to these NK-1 agonists was parallel with the rate of their degradation by the solubilized enzyme. These results suggest that a relatively long-lasting scratching behavior induced by Phy is mainly attributed to the stability against peptidases in the spinal cord.

Highly oriented K(Ta,Nb)O3 (Ta:Nb = 65:35) (KTN) thin films of perovskite structure were synthesized successfully on Pt(100)/MgO(100) substrates from a metal alkoxide solution through reaction control. Homogeneous KTN coating solutions prepared from KOC2H5, Ta(OC2H5)5, and Nb(OC2H5)5 in ethanol were analyzed by 1H, 13C, and 93Nb NMR spectroscopy. The KTN precursor included a molecular-level mixture of K[M(OC2H5)6] (M = Ta, Nb) units interacting in ethanol solution. X-ray pole figure measurement showed that perovskite KTN films crystallized on Pt(100)/MgO(100) substrates had not only a (100) orientation but also a three-dimensional regularity of grains. The remanent polarization and coercive field of the KTN film (thickness, 1.0 μm) crystallized at 700°C were 1.5 μC/cm2 and 8.7 kV/cm, respectively, at 225 K.

Crack-free and highly transparent KTiOPO4 (KTP) thin films were synthesized by the sol-gel method using a homogeneous precursor solution prepared from (“BuO)2-P(O)(OH), Ti(OEt)4, and KOEt in EtOH. Precipitated powders from the solution crystallized directly to KTP above 550°C. Polycrystalline KTP thin films were obtained at 600°C on various substrates. On NdAlO3(100) substrates, KTP films with (101) and (240) preferred orientations were formed at 600°C. KTP films on glass substrates showed a refractive index of 1.75 and an absorption edge of 350 nm. KTP films exhibited the second harmonic generation of the 532 nm light on irradiaton with 1064 nm light.

Crack-free, dense, and transparent Pb0.6Ba0.4Nb2O6 (PBN60) thin films have been prepared by a sol-gel method with metal alkoxides and metal acetate. A homogeneous and stable precursor solution was obtained from Ba metal, Pb(CH3COO)2, and Nb(OEt)5 in 2-methoxyethanol. PBN60 powder crystallized to the hexagonal phase at 600°C and then completely transformed to the orthorhombic phase of the tungsten bronze structure at 1250°C. The hexagonal phase was formed on SiO2 glass, MgO(lOO), and sapphire(R) substrate at 600°C, while the orthorhombic phase was only on a sapphire(C) substrate. Orthorhombic PBN60 films with c-axis preferred orientation were successfully synthesized on sapphire(C) substrates at 600°C.

Nd: YVO4 powders and thin films were successfuly synthesized by the sol–gel method using metal alkoxides. A homogeneous and stable solution was prepared by the reaction of Y(OEt)3, VO(OiPr)3, and Nd(OEt)3 in 2-methoxyethanol. The precursor was a mixture of vanadium and yttrium double alkoxide. Precursor films were prepared by dip coating and crystallization to single-phase YVO4 at 500°C. Nd:YVO4 films were crystallized with (200) preferred orientation on glass substrates, which showed the characteristic optical absorption of neodymium.

Transparent and highly oriented Ba 2 NaNb 5 O 15 (BNN) thin films have been prepared by using metal alkoxides. A homogeneous precursor solution was prepared by the controlled reaction of NaOC 2 H 5 , Nb(OC 2 H 5 ) 5 , and barium metal. The BNN precursor included a molecular-level mixture of NaNb(OC 2 H 5 ) 6 and Ba[Nb(OC 2 H 5 ) 6 ] 2 in ethanol. The alkoxy-derived powder crystallized to a low-temperature phase, and then transformed to orthorhombic BNN (tungsten bronze) at 600°C. BNN precursor films on substrates crystallized to orthorhombic BNN at 800°C via the low-temperature phase. Highly (002) oriented BNN films of tungsten bronze structure were successfully prepared on MgO (100) substrates at 700°C by using BNN underlayer.

Crack-free and dense KTiOPO4 (KTP) fibers could be successfully synthesized through metallo-organics. A homogeneous, drawable KTP precursor solution was prepared from the reaction of (nBuO)2P(O)(OH), Ti(OEt)4, and KOEt. KTP precursor fibers crystallized to a single-phase KTP at 650°C for 0.5 h. KTP fibers were a few centimeters in length and 10–150 μm in diameter. The density of the KTP fibers was higher than 2.97 g/cm3 (>98% of theoretical density).

Robinson-type annulation, catalyzed by a combination of chiral diamine/chiral diacid,renders possible the preparation of cyclohexenone derivatives with moderate yields and high enantioselectivities.

Ba2NaNb5O15 (BNN) thin films with a tungsten bronze structure were fabricated using a precursor solution that was synthesized from barium, sodium, and niobium alkoxides. Highly (002)-oriented BNN films were prepared successfully on Pt(100)/MgO(100) substrates at 700°C, using a BNN underlayer. X-ray pole-figure measurement showed that the BNN films that crystallized on Pt(100)/MgO(100) substrates had two in-plane orientations. The remanent polarization and coercive field of the BNN film (thickness of 1.0 µm) that was crystallized at 700°C were 12.3 µC/cm2 and 101 kV/cm, respectively, at –150°C (123 K). BNN films on fused silica substrates exhibited second harmonic generation upon irradiation with 1064 nm light.

This paper reports on crack-free Pb(Zr,Ti)O[sub 3] (PZT) thin films with preferred orientation that were prepared successfully on MgO (100), SrTiO[sub 3] (100), and Pt/Ti/SiO[sub 2]/Si substrates from metal alkoxide solutions. Calcination of precursor films in a H[sub 2]O[minus] O[sub 2] gas mixture was found to be effective not only for low-temperature crystallization of perovskite PZT, but also for obtaining the preferred orientation of PZT films. Single-phase PZT films with high preferred orientation were synthesized on MgO (100) and Pt/Ti/SiO[sub 2]/Si substrates at 550[degrees] and 600[degrees] C for 2 h, respectively. The PZT film on the Pt/Ti/Si-O[sub 2]/Si substrate showed a permittivity of 520, tan [delta] of 0.03, a remanent polarization of 24 [mu]C/cm[sup 2], and a coercive field of 54 kV/cm.

This paper reports cubic BN synthesized under high-temperature and -pressure conditions from BN Powder formed by Pressure pyrolysis of borazine below 700{degrees}C and 100 MPa. The conversion of BN powder to cubic BN was strongly influenced by the residual hydrogen identified by the BH/BN ratio of IR absorption band. The activation energy for cubic BN synthesis from BN powder-20 mol% AIN was 46 kJ/mol, when the starting BN was synthesized at 250{degrees}C. A mixture of BN powder and cubic BN particles was converted to cubic BN in the 100% yield by heat treatment at 1800{degrees}C and 6.5 GPa without any catalyst. The presence of cubic BN particles does enhance the conversion to cubic BN from BN powder. The energy required for the transformation of starting BN to cubic BN in the presence of cubic BN seed was 355 kJ/mol.

Amorphous BN that contains hydrogen could be synthesized by pressure pyrolysis of borazine below 700°C at 100 MPa. The fraction of B and N bonded to H in the pyrolysis product could be controlled by changing the pressure pyrolysis condition. The pyrolysis product at 700°C and 100 MPa showed formation of B-N-B bonds of the hexagonal structure in the amorphous state with some B-H and N-H bonding remaining. Spherulitic BN could be prepared only by pyrolysis below 400°C and 100 MPa. The yield of amorphous BN from borazine was as high as about 60% by this pressure pyrolysis. Amorphous BN formed from borazine could be readily converted to cubic BN by reacting it with AIN at 1200°C and 6.5 GPa.