Abstract: The present invention relates to nickel-manganese (Ni—Mn) binary compounds useful as an electrode material for electrochemical supercapacitors, which is one of nickel-manganese coprecipitated hydroxides having a spinel-like structure, nickel-manganese coprecipitated hydroxocarbonates having a calcite-like structure and nickel-manganese oxides having an ilmenite-like structure. The present invention also relates to a method of preparing the above nickel-manganese (Ni—Mn) binary compounds by chemical coprecipitation and freeze-drying. Since the nickel-manganese binary compounds according to the present invention show high electrochemical efficiency, good reversibility, excellent specific capacity per unit area, a low capacity fade rate and improved cycle life, they can be effectively used as an electrode material for electrochemical supercapacitors.

Abstract: There is provided a process of preparing low-temperature sintered microwave dielectric ceramics, prepared by a process comprising co-precipitating Nb and Bi or Zn in an aqueous basic solution to obtain a BiNbO4 or Zn3Nb2O8 precursor powder, thermally decomposing the powder to obtain BiNbO4 or Zn3Nb2O8 powder, adding CuO and V2O5, pulverizing and sintering the mixture, which produces ceramics having small dielectric losses (Q·f0>15,000 GHz) and high dielectric constant (k=20–45) at microwave frequencies by sintering at a low temperature of 700 to 750° C. Thus, the microwave dielectric ceramics prepared in accordance with the present invention can be advantageously used in multi-layer ceramic packaging such as filter planar antenna, microwave oscillator, etc., which comprise base metals such as silver (Ag) and copper (Cu) as an internal electrode.