Abstract: There is disclosed an aluminum sintered body prepared by sintering aluminum nitride and additives, which consists essentially of(a) aluminum nitride,(b) at least one compound selected from the group consisting of an aluminum compound of a rare earth metal, an aluminum compound of an alkaline earth metal, and an aluminum compound of a rare earth metal and an alkaline earth metal, and(c) at least one element selected from the transition elements consisting of Groups IVa, Va, VIa, VIIa and VIII of the periodic table, and/or at least one compound comprising the element, and the rare earth element, alkaline earth element and transition element are supplied by the additives.

Abstract: There are disclosed an aluminum sintered body comprising(a) aluminum nitride,(b) at least one compound selected from the group consisting of an aluminum compound of a rare earth metal, an aluminum compound of an alkaline earth metal, and an aluminum compound of a rare earth metal and an alkaline earth metal, and(c) at least one element selected from the transition elements consisting of Groups IVa, Va, VIa, VIIa and VIII of the periodic table, and/or at least one compound containing said element,and a process for preparing the same comprising mixing aluminum nitride with(i) at least one of compound selected from the group consisting of a rare earth metal and/or an alkaline earth metal; and(ii) at least one of element selected from the group consisting of a transition element of Groups IVa, Va, VIa, VIIa and VIII of the periodic table, and/or at least one of a compound containing said element;and then molding and sintering the mixture.

Abstract: For higher thermal conductivity, stronger adhesion strength, excellent insulating characteristics, and multilayer interconnection, an aluminium sintered body for circuit substrates comprises a novel conductive metallized layer on the surface of the sintered body. The metallized layer comprises at least one element selected from the first group of Mo, W and Ta and at least one element selected from the second group of IIa, III, IVa group elements, lanthanide elements, and actinide elements in the periodic table, as the conductive phase element. The first group element serves to improve the heat conductivity and resistance, while the second group serves to increase the wetness and adhesion strength between the insulating body and the metallized layer. Further, the plural insulating ceramic bodies and the plural metallized conductive layers can be sintered simultaneously being stacked one above the other to permit a multilayer interconnection.

Abstract: A cladding glass for optical fiber comprises 60 to 80% by weight of silicon dioxide (SiO.sub.2), 0.5 to 10% by weight of aluminum oxide (Al.sub.2 O.sub.3), 9 to 17% by weight of an alkali metal oxide, 3 to 15% by weight of boron oxide (B.sub.2 O.sub.3) and more than 0 but not more than 3% by weight of fluorine (F). The cladding glass of this invention can simultaneously satisfy low refractive index and lowered viscosity, and is also excellent in water resistance and weathering resistance.

Abstract: Disclosed are an aluminum nitride sintered body comprising aluminum nitride, rare earth element-aluminum compounds and alkaline earth metal-aluminum compounds, and a process for producing an aluminum nitride sintered body, which comprises adding to aluminum nitride powder:(a) powder of at least one compound selected from the group consisting of rare earth element oxides, rare earth element fluorides and compounds capable of being converted into these oxides or fluorides by calcination, and(b) powder of at least one compound selected from the group consisting of alkaline earth metal oxides, alkali earth metal fluorides and compounds capable of being converted into these oxides or fluorides by calcination, in a total amount of 0.01 to 20 wt % as calculated on the weight of the oxides or the fluorides, and then molding and sintering the resultant mixture.

Abstract: An aluminum nitride sintered body prepared by a process comprising adding to a principal component of aluminum nitride an additional component of at least one of fluorides of alkaline earth metals selected from the group consisting of calcium (Ca), strontium (Sr) and barium (Ba) or at least one of fluorides of rare earth elements added in an amount of 0.01 to 20% by weight, followed by sintering.

Abstract: There is provided a multi-component system glass fiber for optical communication which comprises a multi-component system glass for core having a composition comprising SiO.sub.2, BaO, Al.sub.2 O.sub.3, B.sub.2 O.sub.3, at least one alkali metal oxide selected from Na.sub.2 O, K.sub.2 O and Li.sub.2 O, MgO and CaO in amounts as specified in the specification and claims, and a multi-component system glass for clad layer having a composition comprising SiO.sub.2, Al.sub.2 O.sub.3, B.sub.2 O.sub.3, Na.sub.2 O, K.sub.2 O, Li.sub.2 O, at least one alkaline earth metal selected from MgO and CaO in amounts as specified in the specification and claims. The core in the glass fiber for optical communication according to the present invention shows lower optical loss and the clad layer shows high weathering resistance, and the glass fiber according to the present invention suffers from no devitrification during fiber drawing and is excellent in dimensional stability.

Abstract: An optical fiber which consists of a multicomponent core glass member which is formed of SiO.sub.2, Al.sub.2 O.sub.3 and an alkali metal oxide and preferably contains CaO, MgO and B.sub.2 O.sub.3 ; and a multicomponent cladding glass member which is prepared from SiO.sub.2, Al.sub.2 O.sub.3, an alkali metal oxide and at least one component selected from the group consisting of ZnO, ZrO.sub.2 and TiO.sub.2, and preferably contains CaO, MgO and B.sub.2 O.sub.3 ; and consequently reduces transmission loss of light and exhibits prominent durability.