In a monolithic crystal filter which employs a combination of mass loading and acoustic coupling, a secondary mechanical wave generating resonator with short-circuited, nongrounded electrodes is employed between the input and output resonators. The input wave is applied to the intermediate resonator as well as to the input resonator, resulting in sharp peaks of attenuation which bracket the passband of the filter.

A chamber is provided which includes baffles, plates, and support members situated around a centrally located heater and crucible to define a hot zone in the lower half of the chamber where gas currents are quickly heated and thence sent to the upper half of the chamber. As a result, the motion of these currents around the hot zone is reduced, which reduction permits thermal gradients to be maintained around the crucible for controlling crystal growth therein. A resistance heater provides heat f...

Refurbishable works of art are produced on a crystalline metallic surface by forming with plastic deformation an artistic representation, annealing said crystalline surface to relieve the metallic matrix of the imposed energy of plastic deformation in the form of a locally recrystallized surface which is different in crystal grain size and frequently in geometric distribution from the original metallic matrix, and etching said metallic surface to delineate to the eye the pictorial artistic repre...

A crystal grower furnace assembly having a gastight housing, a crystal pulling rod extending into the housing coaxially with the vertical axis of the housing and the heating elements. The housing is divided into a first chamber adapted for growing a crystal by the Czochralski technique, from a melt of the crystalline material, a second chamber above the first chamber having a port for evacuation and admission of gases, and a narrow neck connecting the chambers in coaxial alignment. The rod exten...

A plurality of elongated scintillation crystals combined in a unit. The scintillation crystals may be either parallel bars or concentric tubular members. In either event separators such as aluminum foil may be used to prohibit signals from crossing between scintillation crystals. Magnesium oxide holds the individual scintillation crystals together as a unit and acts as a highly reflective material to enhance the transmission of the signals.

In the growing of crystals, the formation of carbide contaminants is prevented by eliminating direct silica-graphite contact.

A crystal for a scintillator is a single crystal of Bi.sub.4 Ge.sub.3 O.sub.12 containing up to 0.5% by weight of Bi.sub.4 Si.sub.3 O.sub.12 and/or up to 50 ppm of Gd. The light output of this crystal as a scintillator can be increased by about 20% as compared with the light output of the conventional crystal of additive-free Bi.sub.4 Ge.sub.3 O.sub.12.

In the process for growing single crystals including the steps of placing material in a crucible, heating the crucible to above the melting point of the material, and thereafter solidifying the melted material by extracting heat from a central portion of the bottom of the crucible, that improvement wherein the temperature of the side walls of the crucible is maintained at temperatures above the melting point of the material until substantially all the material within the crucible has been solidi...

A vibrator suitable for use in a timepiece is provided which includes a crystal having a torsional vibrational mode, a pair of discrete electrode tracks deposited thereon, a continuous runner defining the discrete electrode tracks and a sole conductive support member for supporting the crystal and conductively mounting the crystal, as desired. The conductive support is connected to the crystal and the material of which the conductive support is fabricated is substantially identical with the mate...

Thin strip crystals are grown by pulling the growing crystal from the melt, through a thin slit, the walls of which are not wetted by the melt. The stability of growth at the edges of the strip is achieved by maintaining the pressure of the melt adjacent the interface between crystal and melt above a critical level which is such as to cause the meniscus of the melt to be convex on all sides of the growing crystal. The critical pressure is defined as where S is the surface tension of the crystall...