The effect of K2O on the crystallization of niobium germanate glasses

Abstract

The effect of K2O content on the crystallization of niobium germanate glasses with 22.7- 24.27 wt% of GeO2 and 54.59-57.48 wt% of Nb2O5 was examined. The glasses crystallize by primary crystallization and the formed crystalline phases were K6Nb6Ge4O26, K3.8Nb5Ge3O20.4 and KNbO3. Increasing the K2O content caused a decrease in the GeO2 content of the primary phases. The effect of the K2O content on the kinetics of primary crystallization was analyzed. It was demonstrated that an increase of the K2O content decreased the activation energy of crystal growth at first of the crystallization peaks (Ec1). At second crystallization peaks the activation energies of crystal growth increased (Ec2)

High niobium oxide content in germanate glasses: Thermal, structural, and optical properties

“…Glasses in the binary system GeO 2 –Nb 2 O 5 are not reported since homogeneous glasses cannot be obtained under laboratory conditions, but a glass‐ceramics spontaneously formed under quenching were reported in the phases diagram by E.M. Levin . Glasses samples in the ternary system GeO 2 –Nb 2 O 5 –K 2 O with different molar ratios were reported in the literature . However, the systematic synthesis and characterization of glass sample varying the niobium concentration a well as crystallization process study of this system has not been reported yet.…”

“…16 Glasses samples in the ternary system GeO 2 -Nb 2 O 5 -K 2 O with different molar ratios were reported in the literature. [17][18][19][20][21] However, the systematic synthesis and characterization of glass sample varying the niobium concentration a well as crystallization process study of this system has not been reported yet. In fact, crystallization into the glasses by annealing is one of the most effective methods concerning preparation of transparent nanocrystallized glass-ceramics.…”

Dielectric Properties of Niobate Glass Ceramics of PbO-SrO-Na2O-Nb2O5-SiO2 System with Partial Substitution of K+ for Na+

“…It can be seen that both the crystallization peaks of PSN glass were decreased by an increase in content of potassium ions, which may be attributed to the increase crystallization activation energy of (Na,K)NbO 3 . 17 And the crystallization temperature was chosen at 900°C for 3 h in this study and the XRD spectra of the samples are shown in Fig. 2 to check the phase transformation.…”

The analysis of the nucleation process of the lithium germanium phosphate glass

“…These materials are usually obtained by the powder sintering route and the crystallization of these glasses [8,9]. This method requires the knowledge of nucleation, crystallization, and crystal growth [10][11][12]. The aim of the present study is the investigation of the nucleation of germanium phosphate glass under no isothermal and isothermal conditions.…”