Freezing the Suspension of Laser Microcrystals—A New Way for Increasing the Luminescence Efficiency Response

In this work, for the first time, the property of particles to form close-packed layer in front of the freezing interface was used to increase the luminescent efficiency response for ruby and titanium-sapphire microcrystals water suspensions. An increase in the efficiency of luminescence response due to an increase in the concentration of particles at the freezing front, can be used for phase transition sensing. In addition, particles packing by freezing method can be used for tuning random laser generation or increasing the efficiency of different nonlinear optical effects in suspensions of particles.

I. Introduction

The interaction of solid particles suspended in a liquid with a moving solidification front during freezing is of great interest in engineering, especially for understanding the formation of close-packed structures. The formation of a close-packed layer of particles during the suspension freezing is of great interest due to many practical applications particularly in such fields as cryobiology [1], thermal energy storage [2], ice lens formation [3], food engineering [4], science of soft matter [5], geophysical science [6], etc. Due to this there are a lot of studies devoted to the behavior of different particles in the process of interaction with a solidification front [7]. Classical manifestation of such interaction is a process of forming a close-packed layer in front of the freezing interface during the freezing of a suspension [8], [9], [10], [11], [12]. This mechanism has been successfully used in ice-templating for obtaining porous materials [13] or obtaining composite particles, creating a shell from inorganic nanoparticles and proteins on submicron- and micron-sized porous particles [14].