Lasivaiheet

Lasivaiheet is a term used in materials science to describe the range of structural states that glass materials can exhibit under different thermal histories and compositions. The name combines Finnish lasi, meaning glass, with vaiheet, meaning phases, and it encompasses both the conventional amorphous glass and crystalline or partially crystalline phases that can form within a glassy matrix during heating or aging.

Overview

In typical cooling, many glass-forming systems solidify into an amorphous, disordered network. Under specific compositions and heat-treatment conditions, however, nucleation and crystal growth can occur, producing glass-ceramics where crystalline phases are embedded in a glassy matrix. The lasivaiheet concept distinguishes among a homogeneous amorphous phase, metastable or intermediate phases, and stable crystalline phases that may be present in composite materials.

Formation and control

Lasivaiheet arise from the interplay of composition, thermal history, and processing environment. Factors such as modifier oxides, network formers, impurities, and the duration and temperature of heat treatment influence nucleation rate and crystal growth. Controlling these parameters allows engineers to tailor properties such as hardness, fracture toughness, thermal stability, and optical behavior. Common study methods include differential scanning calorimetry, X-ray diffraction, and electron microscopy combined with elemental analysis.

Applications and significance

Understanding lasivaiheet helps design glass materials with specific performance targets, including improved mechanical strength, resistance to thermal shock, and tailored translucency or color. Applications span from glass-ceramics used in cookware and cookware surfaces to advanced transparent or opaque materials for optics, electronics, and structural components.

See also

Glass-ceramics; devitrification; amorphous solids.