Abstract: Lead- and barium-free crystal glass for the manual or machine production of high-grade glass objects with a refractive index higher than 1.52 and a density of at least 2.45 g/cc, wherein the crystal glass comprises the following components in weight percent. SiO2 59.0-71.0 TiO2 0.001-8.0  Al2O3 0.01-4.0  CaO  2.0-10.0 MgO 0.5-8.0 ZnO 0.01-11.0 K2O 0.08-11.0 Na2O  3.0-15.5 Sb2O3 or AS2O3 0.001-1.5  SrO 0.001-0.1  B2O3 0.01-3.0  Li2O 0.01-2.0  SO42− 0.0008-1.2   F− 0.008-0.2  as well as at least two components selected from the group consisting of Er2O3, Nd2O3, CeO2, CoO, Pr2O3, SeO, NiO and MnO and has a moisture content of 0.025 to 0.07% by weight.

Abstract: A magnetic head having layered structure for a recording medium for vertical magnetization contains a conductor body on a non-magnetic substrate for conducting the magnetic flux with two magnet legs, the end pieces of which form a thin main pole and a comparatively thicker auxiliary pole. The two magnetic poles are separated by an insulating gap layer of at least 5 .mu.m. This magnetic head and particularly its gap layer should be relatively simple to produce. Recesses are provided in the substrate to submerge at least the end piece of the auxiliary pole of one magnet leg and an adjoining part of this leg as well as at least part of the gap layer.

Abstract: A recording medium which can be magnetized vertically contains a plate-shaped carrier body of nonmagnetic material of which at least one flat side is provided with a thin nonmagnetic intermediate layer having a very smooth surface, to which at least one magnetic recording layer of a material is applied, the axis of easy magnetization of which points in a direction perpendicular to the surface of the medium. The surface of this intermediate layer should be capable of being made smooth in a relatively simple manner. The intermediate layer comprises a glass plate, preferably of fused silica or silicate glass, which is cemented to the carrier body. For the carrier body, particularly a high-strength hardened Al-alloy can be used.

Abstract: A disc-shaped nonmagnetic support body for a recording medium which can be magnetized particularly (vertically) has at least one flat side with a very smooth surface, on which at least one magnetizable storage layer can be placed. It should be possible to provide this carrier body readily with appropriate surfaces, and it should be dimensionally stable and sufficiently fracture-proof. A chemically hardened glass substrate is therefore provided which comprises, besides Na.sup.+ ions, K.sup.+ ions incorporated in zones near the surface and in addition Ag.sup.+ ions and/or Ag atoms. For hardening this glass substrate by means of an ion exchange process below the transformation temperature characteristic of the glass material, the substrate is advantageously placed for a predetermined time in a KNO.sub.3 melt, to which advantageously, maximally 10% by weight AgNO.sub.3 has been added.