Abstract: In a thin film electroluminescent element comprising a phosphor thin film, a dielectric thin film disposed on at least one of the surfaces of the phosphor thin film and electrodes for applying a voltage across the thin films, the aforementioned dielectric thin film is formed of a dielectric material expressed by a general formula of AB.sub.2 O.sub.6 (where A represents a divalent metal element and B represents a pentavalent metal element). By employing the dielectric material, the voltage for driving a thin film electroluminescent element can be lowered without decreasing the brightness of the element. Further, by using a composite dielectric thin film in which the dielectric thin film expressed by the aforementioned general formula AB.sub.2 O.sub.6 is laminated with a dielectric thin film which is not susceptible to dielectric breakdown of self-healing type, the composite dielectric thin film is made susceptible to the dielectric breakdown of self-healing type.

Abstract: A red emission fluorescent display device employing improved SnO.sub.2 :Eu phosphor as a low-energy-electron excitation phosphor. The phosphor is manufactured by the following steps:To a starting material selected from the group consisting of at least one of metallic tin, stannous and stannic halide and stannous sulfate, europium oxide is added in the amount of 5.times.10.sup.-2 to 10 atomic % europium to tin. The mixture is heated and stirred with nitric acid until it becomes dry due to evaporation of the solvent water and unreacted nitric acid, thereby forming a mixed powder of metastannic acid and europium. Then the powder is subjected to heat treatment, causing the metastannic acid to thermally decompose and the europium to diffuse into the stannic oxide matrix.The device exhibts remarkably high luminescence intensity and it is possible to achieve the intensity of 26f.L or more under the E.sub.b of 10 V and the I.sub.b of 1.5 mA/cm.sup.2.

Abstract: A red emission fluorescent display device employing improved SnO.sub.2 :Eu phosphor as a low-energy-electron excitation phosphor. The phosphor is manufactured by the following steps:An aqueous solution of a mixture of europium and at least one material selected from stannous halides and stannous sulfate is prepared. The amount of europium ion is adjusted so that the ratio thereof to tin ions ranges between 5.times.10.sup.-2 and 10 atomic %. The solution is poured into and mixed with a hot aqueous solution including oxalic ions, while the mixed solution is being stirred, to form oxalate coprecipitates of tin and europium. After being dryed the coprecipitate is heated so as to be thermally decomposed and then is subjected to heat treatment at the temperature above that for the thermal decomposition, whereby europium ions are diffused into the stannic oxide matrix.The device exhibits remarkably high luminescence intensity which is satisfactory for practical use.

Abstract: A fluorescent display device comprising at least one phosphor screen composed of a mixture of a SnO.sub.2 :Eu phosphor with at least one of the cathodoluminescent phosphors having emission spectra and exitation properties different from SnO.sub.2 :Eu phosphor. This fluorescent display device emits light of different colors when driven at different voltages and at pulse voltages of different duty cycles. A display apparatus comprises such a fluorescent display device and a driving device with variable output voltage.

Abstract: Flake-like ceramic particles of zinc sulfide phosphor and method of preparing the same including the steps of preparing flake-like particles of basic zinc sulfate crystal doped with activator, sulfurizing in the particles carbon disulfide, and heating the sulfurized particles in hydrogen sulfide. Particularly by steeping said particles in a solution of alkaline earth metal salt prior to or after sulfurizing, grain growth in ceramic particles can be improved.

Abstract: Basic zinc compound flake-like crystalline material suited for use in crystal-oriented electronic devices and method for preparation thereof comprising the steps of preparing a solution including at least zinc ions and sulfate ions, and causing precipitation of zinc sulfate crystals by causing a reaction of components of said solution with alkali when said solution is at a temperature in the range 50.degree. to 100.degree. C. and has a pH value of in the range 4 to 6.5.

Abstract: A high temperature thermistor composition comprising a spinel-type Mg Al.sub.2 O.sub.4 and perovskite-type La CrO.sub.3 or (La, Sr) CrO.sub.3 is usable for the temperature range from 400.degree. to 600.degree. C, and a high temperature thermistor composition comprising spinel-type solid solution Mg(Al, Cr).sub.2 O.sub.4 and perovskite-type solid solution (La, Sr) CrO.sub.3 or LaCrO.sub.3 is usable for a higher temperature range up to 1000.degree. C.

Abstract: A PTC thermistor composition comprising BaTiO.sub.3, TiO.sub.2, one oxide selected from the group consisting of Nb.sub.2 O.sub.5 and Y.sub.2 O.sub.3, Al.sub.2 O.sub.3, SiO.sub.2, Li.sub.2 CO.sub.3, MnO.sub.2 and one oxide selected from the group consisting of Sb.sub.2 O.sub.3 and Bi.sub.2 O.sub.3, and process for the production thereof are provided. Said process is characterized by the addition of TiO.sub.2 and Nb.sub.2 O.sub.5 to BaTiO.sub.3 before calcination and the addition of Al.sub.2 O.sub.3, SiO.sub.2, Li.sub.2 CO.sub.3, MnO.sub.2 and Sb.sub.2 O.sub.3 after the calcination. This PTC thermistor composition has a high breakdown voltage, a large electric current at the initial moment of a voltage application which current decreases rapidly with continuing voltage application, low specific resistivity and, good stability of resistivity.

Abstract: A PTC thermistor composition containing barium oxide and titanium oxide as a base material, a semiconducting element to make the base material semiconductive and hafnium dioxide, and if necessary, an additive element. Due to the use of hafnium dioxide, the thermistor composition contributes to a large positive temperature coefficient of resistance. This invention also provides a novel method of making the thermistor composition, in which the addition of hafnium is carried out at the step of milling which comes after the step of calcining. By this method, hafnium can be very effectively used.