Betakristobaliitti

Betakristobaliitti is a high-temperature polymorph of silica (SiO2). It is one of the three crystalline forms of silica, along with alpha-quartz and beta-quartz, and it transforms into other silica polymorphs at different temperatures and pressures. Betakristobaliitti is stable above 1470 degrees Celsius and transforms into cristobalite, another silica polymorph, at higher temperatures.

Structurally, betakristobaliitti is characterized by a cubic crystal system. Its atoms are arranged in a framework structure where each silicon atom is tetrahedrally coordinated by four oxygen atoms, and each oxygen atom bridges two silicon atoms. This structure is similar to that of beta-quartz but with a more open arrangement of atoms. The transition from alpha-quartz to beta-quartz occurs at 573 degrees Celsius, and the transition from beta-quartz to betakristobaliitti occurs at around 870 degrees Celsius. However, the direct transition from quartz to betakristobaliitti usually occurs at temperatures above 1470 degrees Celsius, with the intermediate high-quartz phase being bypassed.

Betakristobaliitti is not commonly found in nature. It is typically formed under high-temperature conditions, such as in volcanic rocks or during industrial processes like the firing of ceramics. Due to its high-temperature stability, it can be a phase found in refractory materials and glazes. When betakristobaliitti cools below its transition temperature, it can undergo a structural change to alpha-cristobalite, which is metastable at room temperature. This phase transition can sometimes lead to cracking or stress within materials due to the volume changes involved. Understanding the behavior of betakristobaliitti is important in fields such as geology, materials science, and ceramic engineering.