Neutron and X-ray Diffraction Studies of KNO₃ Embedded into Porous Glasses

Abstract

Temperature evolution of crystal structure of KNO₃ embedded into porous glasses with average pore diameters 7 nm, 46 nm and 320 nm have been studied by neutron and X-rays diffraction. For 320 nm samples it is shown that KNO₃ phase transition temperatures and their sequence corresponds to the bulk. For 46 nm sample the temperature interval of the ferroelectric phase stability enlarges significantly and there is a temperature range where all three phases coexist. It has been demonstrated that for 7 nm samples ferroelectric phase becomes stable down to 100°K and remains stable after consequent heating-cooling cycles.

Keywords:

• Phase transitions
• ferroelectrics
• restricted geometry
• nanocomposites

Funding

This work is supported by grants of Russian Foundation of Basic Researches (11-02-00739 and 12-02-00230) and Ministry of Education and Science of Russian Federation.