Abstract: A description is given of a switching device (1) comprising a transparent substrate (3), a switching film (5) comprising a hydride of scandium and magnesium, covered with a palladium layer (7). By exchange of hydrogen, the switching film can be reversibly switched from a transparent state to a mirror-like state with zero transmission via an intermediate black absorbing state. The conversion between both states is reversible, and this phenomenon can be used, for example, in an optical switching element or sun roof.

Abstract: A description is given of a switching device (1) comprising a transparent substrate (3), a switching film (5) comprising a hydride of scandium and magnesium, covered with a palladium layer (7). By exchange of hydrogen, the switching film can be reversibly switched from a transparent state to a mirror-like state with zero transmission via an intermediate black absorbing state. The conversion between both states is reversible, and this phenomenon can be used, for example, in an optical switching element or sun roof.

Abstract: Disclosed is a hydrogen storage material comprising a magnesium-containing intermetallic compound which can form a hydride with hydrogen. The intermetallic compound comprises an alloy of magnesium and a trivalent metal selected from the group of Sc, Y, La and the rare earth elements. Preferably, the intermetallic compound comprises a scandium-magnesium alloy. In an advantageous embodiment, the hydrogen storage material also comprises a catalytically active material.

Abstract: Transflective display device having a transflector (10) which is switchable between a transparent state and a mirror-like state. Preferably, a metal hydride optical switch is used as the transflector.

Abstract: A description is given of a switching device (1) comprising a transparent substrate (3), a switching film (5) comprising a hydride of scandium and magnesium, covered with a palladium layer (7). By exchange of hydrogen, the switching film can be reversibly switched from a transparent state to a mirror-like state with zero transmission via an intermediate black absorbing state. The conversion between both states is reversible, and this phenomenon can be used, for example, in an optical switching element or sun roof.

Abstract: A description is given of a switching device (1) comprising a transparent substrate (3), a switching film (5) including hydrides of gadolinium or other trivalent metal, and magnesium, covered with a palladium layer (7). By exchange of hydrogen, the switching film can be reversibly switched from a transparent state to a mirror-like state with zero transmission via an intermediate black absorbing state. The conversion between both states is reversible, and this phenomenon can be used, for example, in an optical switching element or sun roof.

Abstract: A description is given of a switching device 1 comprising a transparent substrate 3, a switching film 5 of gadolinium having a thickness of 200 nm and a palladium layer (7) having a thickness of 10 nm. Under the influence of hydrogen gas, a transparent semiconductive layer (5) of GdH.sub.x (x>2) is formed which can be converted into a non-transparent layer of GdH.sub.x (x<2) by means of evacuation. The conversion between both compositions is reversible, and this phenomenon can for example be used in an optical switching element, a hydrogen sensor and thin displays.

Abstract: The invention provides a method of manufacturing stoichiometric potassium-lithium niobate crystals. Such crystals exhibit a high degree of double refraction and can suitably be used to double the frequency of a light wave with noncritical phase matching. By virtue of the temperature dependence of the nonlinear optical properties and the possibility of doubling the frequency at room temperature and at wavelengths from 800 to 850 nm the material according to the invention is very suitable for use in cooperation with semiconductor lasers.

Abstract: Potassium-rubidium-lithium niobate crystals having the composition(K.sub.2 O).sub.0.3-x (Rb.sub.2 O).sub.x (Li.sub.2 O).sub.0.2-y (Nb.sub.2 O.sub.5).sub.0.5+ywhere 0.05.ltoreq.x.ltoreq.0.12 and 0.ltoreq.y.ltoreq.0.025 are manufactured and used as a nonlinear optical medium in a device for doubling the frequency of a light wave, in which device a fundamental light wave is guided through the nonlinear optical medium while forming a second harmonic wave. The device brings about frequency doubling of light having wavelengths exceeding 770 nm and can be suitably used in combination with a semiconductor laser light source.

Abstract: The invention relates to a low-pressure mercury discharge lamp with a very good color rendering and with a color point (x.sub.L, y.sub.L on or adjacent the Planckian locus, provided with a gastight, radiation-transmitting envelope which contains mercury and rare gas, and provided with a luminescent layer which comprisesa first luminescent material activated by bivalent europium having an emission mainly in the blue region of the visible portion of the spectrum,a second luminescent material activated by bivalent manganese and having at least an emission band mainly in the red region of the visible spectrum anda third luminescent material having an emission mainly in the yellow region of the visible spectrum.According to the invention, the third luminescent material is defined by the formulaSr.sub.(2-x-y) M.sub.x SiO.sub.4 :Eu.sup.+2.sub.y,in which 0,0005.ltoreq.y.ltoreq.0,05, M being barium and/or calcium and 0,01.ltoreq.x.ltoreq.0,1.

Abstract: The invention provides a method of manufacturing potassium-lithium-niobate crystals having a composition which corresponds to the formula(K.sub.2 O).sub.0.3 (Li.sub.2 O).sub.0.2+a (Nb.sub.2 O.sub.5).sub.0.5+bwhere-0.01<a<0.01-0.005<b<0.005from a melt comprising potassium, lithium and niobium compounds. By adding a small quantity of vanadium, preferably in the form of V.sub.2 O.sub.5, considerably larger crystals are obtained. In addition, the homogeneity of these crystals is much better than that of the crystals obtained by the method according to the prior art.