Microporous Glass‐Ceramics in NASICON‐Type Copper(II) Titanium Phosphate

Abstract

A novel porous glass‐ceramic with a skeleton of a NASICON‐type copper(II) titanium phosphate was prepared via the controlled crystallization of a glass and the subsequent chemical leaching of the resulting dense glass‐ceramic. A volume‐crystallized dense glass‐ceramic comprised of CuTi2(PO4)3 and Cu3(PO4)2, whose surface was covered by a thin layer of CuO, was prepared by reheating a glass with a nominal composition of 50CuO20TiO230P2O5 (in mol%) in air. When the resulting glass‐ceramic was leached with dilute HCl, the Cu3(PO4)2 and CuO phases were dissolved out selectively, and a cuprous NASICON crystal of CuTi2(PO4)3 was converted to its cupric type, CuTi4(PO4)6, which was left as a skeleton of the porous materials. The specific surface area and the average pore radius of the porous glass‐ceramic obtained were ∼70 m2/g and ∼7 nm, respectively. The porous glass‐ceramic showed high catalytic activities for the dehydration of 2‐propanol.

Improving glass-forming ability and crystallization behavior of porous glass-ceramics in CaO–Al2O3–TiO2–P2O5 system

“…In 1990 s, Hosono et al modified the prototype glass system (CaO-TiO 2 -P 2 O 5 ) by addition of various oxides such as Li 2 O, CuO, and Na 2 O as well as introducing Ag + ions to the system through applying an ion exchange process. Hereby, they could induce electrical conductivity [4,5], catalytic activity [6,7] and antibacterial characteristic [8][9][10] in the specimens. In recent years, researchers have attempted to improve mechanical and chemical properties of the relevant porous glassceramics [11] and brought new features like self-cleaning ability to them [12].…”

Influence of Fe 2 O 3 on non-isothermal crystallization kinetics and microstructure of lithium titanium phosphate glass-ceramics

“…He has identified the restricted glass-forming regions of this system [14]. Glass-ceramics belonging to the Li 2 OTiO 2 -P 2 O 5 system exhibit superior properties such as ionic conductivity [2] and ion-exchange capacity [15] due to the formation of an alkali or alkaline-earth titanium phosphate phase which is called NASICON [4,[15][16][17]. NASICON crystals with the formula of LiTi 2 (PO 4 ) 3 , built up by corner-sharing of TiO 6 octahedron and PO 4 tetrahedron, form a class of super ionic conductors [4,[18][19][20].…”

The effect of ionic and metallic silver on the crystalline phases developed in CaO–Al2O3–TiO2–P2O5 glasses

“…During the 1990s, the aforementioned system was modified by addition of various oxides such as Li 2 O, CuO, Ag 2 O, etc. The results were new properties like ionic conductivity [2][3][4], catalytic activity [5][6][7], antibacterial effects [8][9][10] and ion exchange-ability [11][12][13].…”