Ferroelectric-pyroelectric texture based on glass-ceramic materials containing the LaBGeO5 stillwellite-like phase

It is experimentally shown that glass-ceramic textures based on the LaBGeO5 stillwellite-like phase can be manufactured by techniques of isothermal crystallization, gradient crystallization of glass plates or small glass bars, and crystallization of glass plates under the conditions of their axial compression. The effect of the quality of glass surface and heating rate on the texture formation is studied under isothermal conditions. The dense glass-ceramic textures with degree of grain orientation up to 0.8 are obtained. Electron microscopy makes it possible to clearly observe the texture in the form of well-defined needle-shaped LaBGeO5 crystals, which grow, for the most part, normally to the glass surface. The temperature dependences of the permittivity for samples cut in parallel and perpendicular to the surface are measured. These dependences confirm the high degree of sample texturing and provide a way of revealing the ferroelectric phase transition along the polar axis at 515 degrees C, which is close to the temperature of such a transition in the LaBGeO5 single crystal. The pyroelectric coefficient for the best textures obtained is about 0.5-1.5 nC/(cm(2) K) over a wide range of temperatures. There are considerable potentials of increasing this coefficient through both the optimization of composition, glass melting, and glass-making and the texturing process.