Effect of leaching concentration and time on the morphology of pores in porous glasses

Production and properties of phase separated porous glass

“…2 Ceramics International 46 (2020) 4947-4951 associated to inter-particle spaces in between the channel walls and silica clusters (themselves as well). Instead relatively larger mesopores evolved in a broader range from 7 to 35 nm are due to the so called liquation channels [9,10]. It is important to note that all curves resemble those seen in previous studies [10,11].…”

“…However, still what is so called liquation channels are formed when alkali-borate rich phase is leached out by aqueous acidic solutions, generating interconnected, open-pore structure in the remaining silicate matrix. The silicate domains/regions of the dissolved alkali-borate phase may remain in the leaching solution as colloidal silica, coagulating to form silica clusters that cannot be dissolved in the acidic solution [6,8,9]. Accordingly, hierarchically porous artifacts with pore sizes around 7-54 nm due to liquation channels (interconnected network) [6,8], and around 2-5 nm due to spaces in between silica clusters (and the gaps that is in between those with channel walls) [6,8,9] together with intra-particle porosity (0.4-0.7 nm) [10,11] are generally observed.…”

“…The silicate domains/regions of the dissolved alkali-borate phase may remain in the leaching solution as colloidal silica, coagulating to form silica clusters that cannot be dissolved in the acidic solution [6,8,9]. Accordingly, hierarchically porous artifacts with pore sizes around 7-54 nm due to liquation channels (interconnected network) [6,8], and around 2-5 nm due to spaces in between silica clusters (and the gaps that is in between those with channel walls) [6,8,9] together with intra-particle porosity (0.4-0.7 nm) [10,11] are generally observed. The silica clusters remaining inside the channels can be removed by basic (alkaline) solutions which may further enlarge the channel diameter as well [12].…”

Room temperature direct imprinting of porous glass prepared from phase-separated glass

“…The porous layers were further treated by alkaline solutions (0.5 M NaOH). This process increased the porosity by etching the surface of the SiO 2 framework and the SiO 2 colloids (figure 1(d)) [42][43][44]. After the alkaline treatment, the samples were rinsed with hot water (60 °C) to remove residuals.…”

Femtosecond laser-induced stress-free ultra-densification inside porous glass

“…Porous glasses (PG) represent a specific promising kind of glass with multiple buried hollow channels and pores, which can be potentially filled in with different substances to provide selective absorption, lasing, and optical nonlinearity [1][2][3]. Typically, an average pore size in PG samples varies from 2 to 10 nm [4]. Local variation of PG mass density allows the fabrication of different complex embedded 3D-microstructuresaspherical micro-optical elements, matching components or soft diaphragms [5][6][7][8][9].…”