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A one-pot oxidation from cyclohexane to adipic acid has been developed, catalyzed by Fe-porphyrin in the presence of molecular oxygen without any additives. When the reaction temperature is 140 °C, oxygen pressure is 2.5 MPa, concentration of catalyst is 1.33 × 10 -5 mol %, and reaction time is 8 h, the yield of adipic acid reaches 21.4%. A turnover number of about 24582 is thus far the highest one among those reported for the direct oxidation from cyclohexane to adipic acid.

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In the current work, the bulk (1-x) Bi 0.5 Na 0.5 TiO 3 -xCaTiO 3 [BNCT100x] system was synthesized via solidstate route. CaTiO 3 in solid solution with Bi 0.5 Na 0.5 TiO 3 was observed to decrease the dielectric constant at higher temperature and raise the dielectric constant at lower temperature. Polarization hysteresis measurements indicated that the ferroelectricity of Bi 0.5 Na 0.5 TiO 3 was weakened with an increase of CaTiO 3 , resulted in the shift of the depolarization temperature (T d ) toward lower temperatures. X-ray diffraction analysis revealed that TiO 2 was produced as a secondary phase due to the losses of Bi and Na during milling and sintering processes. Moreover, the addition of Ca promoted the segregation of Ti out of BNT grains. Dielectric properties of BNCT12 ceramics with different dopant levels of Mn were characterized as a function of temperature for potential use of high-temperature capacitors. Modification of BNCT12 materials with Mn improved the temperature characteristic of capacitance (−55°C to 250°C, △C/C 25°C ≤ ±15%). Finally, by doping 1.5 wt% Mn, the dielectric constant at room temperature could reach over 900, with a low dielectric loss below 1% and a high insulation resistivity about 10 12 Ω•cm. Furthermore, a small amount of Mn influenced the microstructure in the way to inhibit the long grains and grain growth of BNCT solution ceramics. However, excess Mn caused abnormal grain growth, and therefore, rectangle grains appeared again.

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BaTiO 3 (BT) based X9R ceramics with high permittivity about 1700 were prepared by doping and presintering technique. Pure Bi 0.5 Na 0.5 TiO 3 (BNT) dopant was synthesized by the conventional solid state reaction first. Using this new approach, high performance BTBNT (BT doped with BNT) materials, owning high Curie temperature (139°C), flat ferroelectric transition region and large permittivity at room temperature, were obtained. The effects of several dopants on dielectric properties of BTBNT ceramics were measured by the LCR meter. The suppression effect for the peaks in the dielectric constant at Curie temperature of these dopants have been ranked as follows: BiNbO 4 >CaZrO 3 >Nb 2 O 5 >BNT.More and more multilayer ceramic capacitors (MLCs) have been used in harsh circumstances, such as engine electronic control unit (ECU), crank angle sensor (CAS) and antilock brake system (ABS) module which are mounted in an engine room of an automobile [1,2]. In order to use fewer long power cables, the next generation of these electronic devices must be located very close to the electric actuator, for example directly on the engine, into the transmission, and near the brake disk [3,4], which require components with the ability to work at temperature of 175°C [5]. It is clearly recognized that electronic equipments which can work at ambient temperature higher than 150°C without external cooling are beneficial for a variety of important applications, especially in the automotive, oil & gas, aerospace and energy production industries [4,[6][7][8]. High temperature chip capacitor has been applied in drilling devices and engines at high temperature. However, to our knowledge, BaTiO 3 based X9R (−55 to 175°C, △C/C 25°C =±15%) ceramics with high permittivity have not been reported.Tetragonal barium titanate (BaTiO 3 , BT) is a kind of ferroelectric perovskite which exhibits high permittivity at room temperature, making it a desirable material for MLCs applications. However, BaTiO 3 displays three dielectric anomalies associating with phase transitions at −90°C, 0°C and 125°C. These anomalies cause large changes in dielectric constant near the transition temperature, particularly near Curie temperature (Tc). The dielectric constant drops down strongly above Curie temperature and consequently one major work is to raise Curie temperature up to 175°C for researching and developing high temperature capacitors. The doping effect on Curie temperature of BaTiO 3 has been extensively researched. It is well known that the Curie point can be raised rapidly to a higher temperature by doping Pb ion which replaces Ba ion. However, the use of lead-based ceramics has been limited as the toxicity of lead oxide and its high vapor pressure during sintering caused serious environmental problems. Recently, Qi et al. [9] found one feasible method to increase the Tc from 128°C to 130°C by boron oxide vapor doping, but the raise of Tc was not obvious and it was not convenient for practical application. In this case, it is necessary to develop a high ef...

High-temperature capacitor materials sintered at 1120°C were prepared in a BaTiO 3 (BT)-Na 0.5 Bi 0.5 TiO 3 (NBT)-Nb 2 O 5 -ZnO-CaZrO 3 system. The Curie temperature of BaTiO 3 was increased by NBT doping, and a secondary phase occurred when adding ‡5 mol% NBT. The effects of Nb 2 O 5 , ZnO, and CaZrO 3 on the dielectric properties and the microstructure of BT ceramics doped with 1 mol% NBT were analyzed. The overall dielectric constant decreased when the Nb 2 O 5 content increased, and increased when the ZnO content increased. The dielectric constant peak at the Curie temperature was effectively depressed, and a broad secondary dielectric constant peak appeared at 60°C when the ZnO concentration was ‡4.5 mol%. Significant grain growth was observed by scanning electron microscope (SEM) analysis as the amount of ZnO increased. The high-temperature capacitor specification (À55°C to +175°C, DC/C 25°C less than ±15%) is met when 7 mol% to 8 mol% CaZrO 3 is added.