A glass-ceramic comprising, in weight percent on an oxide basis, of 50 to 70% SiO.sub.2, 0 to 20% Al.sub.2O.sub.3, 12 to 23% MgO, 0 to 4% Li.sub.2O, 0 to 10% Na.sub.2O, 0 to 10% K.sub.2O, 0 to 5% ZrO.sub.2, and 2 to 12% F, wherein the predominant crystalline phase of said glass-ceramic is a trisilicic mica, a tetrasilicic mica, or a mica solid solution between trisilicic and tetrasilicic, and wherein the total of Na.sub.2O+Li.sub.2O is at least 2 wt. %; wherein the glass-ceramic can be ion-exchanged.

A method for manufacturing an optical fibre includes placing the powdery substance compactly in the fluorine doped tube to form a core section. The core section of the glass preform is defined along a longitudinal axis of the glass preform. In particular, the fluorine doped tube is sintered to solidify the powdery substance. Moreover, the glass preform is heated at high temperature to draw the optical fibre.

Disclosed in the present invention is a beam coherence eliminating element. The optical medium material of the element comprises microcrystalline glass, wherein microcrystalline particles therein have a size of 0.1-1000 nm and are distributed randomly. As the crystals in the microcrystalline glass can change the phase of light beams, the microcrystalline glass can change the phase of the light beams randomly, thereby eliminating the coherence of the beams. The crystal size of the microcrystalline glass is small, and thus does not affect the transmission efficiency of light beams. The element of the present invention has a simple structure and is convenient to use, and can be added in the process of beam transmission to easily eliminate beam coherence.

A pharmaceutical container of the present invention is a pharmaceutical container including at least a container and a coating layer, and is characterized that the coating layer is coated on at least an inner surface of the container and the coating layer contains a silicone-based resin.

An electronic-grade glass fiber composition includes the following components with corresponding amounts by weight percentages: 54.2-60% SiO.sub.2, 11-17.5% Al.sub.2O.sub.3, 0.7-4.5% B.sub.2O.sub.3, 18-23.8% CaO, 1-5.5% MgO, less than or equal to 24.8% CaO+MgO, less than 1% Na.sub.2O+K.sub.2O+Li.sub.2O, 0.05-0.8% TiO.sub.2, 0.05-0.7% Fe.sub.2O.sub.3, and 0.01-1.2% F.sub.2. The weight percentage ratio C1=SiO.sub.2/(RO+R.sub.2O) is greater than or equal to 2.20, and the total weight percentage of the above components is greater than or equal to 98.5%.

An electronic-grade glass fiber composition includes the following components with corresponding amounts by weight percentages: 54.2-60% SiO.sub.2, 11-17.5% Al.sub.2O.sub.3, 0.7-4.5% B.sub.2O.sub.3, 18-23.8% CaO, 1-5.5% MgO, less than or equal to 24.8% CaO+MgO, less than 1% Na.sub.2O+K.sub.2O+Li.sub.2O, 0.05-0.8% TiO.sub.2, 0.05-0.7% Fe.sub.2O.sub.3, and 0.01-1.2% F.sub.2. The weight percentage ratio C1=SiO.sub.2/(RO+R.sub.2O) is greater than or equal to 2.20, and the total weight percentage of the above components is greater than or equal to 98.5%.

An environment-friendly glass material, including components like SiO.sub.2, ZnO, alkali metal oxide and S, but does not contain Cd, wherein when the thickness of the environment-friendly glass material is 3 mm, the cutoff wavelength is above 550 nm, the transmittance at 800-850 nm is above 75%, the transmittance at 850-900 nm is above 80%, the transmittance at 900-1000 nm is above 83%, and the transmittance at 1000-2000 nm is above 85%. Through rational component design, the glass material of the present invention realizes environmental protection, UV and visible light cutoff, and high near-infrared transmittance at the same time.

An environment-friendly glass material, including components like SiO.sub.2, ZnO, alkali metal oxide and S, but does not contain Cd, wherein when the thickness of the environment-friendly glass material is 3 mm, the cutoff wavelength is above 550 nm, the transmittance at 800-850 nm is above 75%, the transmittance at 850-900 nm is above 80%, the transmittance at 900-1000 nm is above 83%, and the transmittance at 1000-2000 nm is above 85%. Through rational component design, the glass material of the present invention realizes environmental protection, UV and visible light cutoff, and high near-infrared transmittance at the same time.

Lithium silicate glass ceramics and precursors thereof are described, which comprise copper and are characterized by very good mechanical and optical properties and can be used in particular as restorative materials in dentistry.

Lithium silicate glass ceramics and precursors thereof are described, which contain tin and are characterized by very good mechanical and optical properties and can be used in particular as restorative materials in dentistry.