Coexistence of nano-scale phase separation and micro-scale surface crystallization in Gd2O3–WO3–B2O3 glasses

Electronic polarizability and interaction parameter of gadolinium tungsten borate glasses with high WO3 content

“…1, the value of ΔT decreases with increasing WO 3 content, indicating that the substitution of a large amount of WO 3 for B 2 O 3 in Gd 2 O 3 -WO 3 -B 2 O 3 glasses deteriorates the thermal stability and enhances the crystallization at low temperatures. As reported by Taki et al [16], 25Gd 2 O 3 -40WO 3 -35B 2 O 3 glass shows the formation of the α-Gd 2 (WO 4 ) 3 crystalline phase in its initial crystallization. Wang et al [17] reported the formation of α-Gd 2 (WO 4 ) 3 crystals in 22.5Gd 2 O 3 -47.5WO 3 -30B 2 O 3 glass.…”

“…Araujo et al [27] proposed from Raman scattering spectra that W atoms are linked to some non-bridging oxygen atoms, e.g., W-O À or W¼O bonded species, up to about 30 mol% WO 3 in (100 À x)NaPO 3 À xWO 3 (0≦x≦70) glasses and W-O-W bond formation occurs only at WO 3 contents exceeding 30 mol%. As reported by Taki et al [16], the initial crystallization of 25Gd 2 O 3 -xWO 3 -(75 À x)B 2 O 3 glasses with high WO 3 contents such as 25Gd 2 O 3 -40WO 3 -35B 2 O 3 glass shows the formation of α-Gd 2 (WO 4 ) 3 crystals. The Raman scattering spectrum for the crystallized glass containing α-Gd 2 (WO 4 ) 3 crystals is also shown in Fig.…”

“…Optically transparent glasses were obtained in all compositions of 25Gd 2 O 3 -xWO 3 -(75 À x)B 2 O 3 with x ¼25-65, as reported in the previous paper [16]. The DTA patterns of some bulk glasses are shown in Fig.…”

“…Glasses with the nominal (batch) compositions of 25Gd 2 O 3 -xWO 3 -(75 À x)B 2 O 3 with x ¼25-65 mol% were prepared using a conventional melt quenching technique [16]. Commercial powders of reagent grade Gd 2 O 3 (purity 99.9%, Kojyundo Chemicals Laboratory (KCL) Co.), WO 3 , (purity 99.9%, KCL Co.), and B 2 O 3 (purity 99.9%, KCL Co.) were used as starting materials and were melted in a platinum crucible at 1200 1C for 30 min in an electric furnace.…”

“…In the development of WO 3 -based glasses, therefore, the design of glass system and chemical compositions are extremely important. Very recently, Taki et al [16] synthesized the glasses with the compositions of 25Gd 2 O 3 -xWO 3 -(75 À x)B 2 O 3 (mol%) with high WO 3 contents of x¼ 25-65 and found the formation of the nano-scale (2-3 nm) phase separation of tungsten-rich and boron-rich glassy phases prior to the crystallization in the glass with x¼40 mol%. Wang et al [17] also reported the glass formation in 22.5RE 2 O 3 -47.5WO 3 -30B 2 O 3 (RE: Gd and Eu) and the crystallization of α-Gd 2 (WO 4 ) 3 and α-Eu 2 (WO 4 ) 3 .…”