Influence of Gd2O3 on thermal stability of oxyfluoride glasses

Abstract

The aim of the research was to determine the influence of Gd 2 O 3 addition on the thermal stability of glasses from BaF 2 -NaF-Na 2 O-Gd 2 O 3 -Al 2 O 3 -SiO 2 system. Thermal analysis was carried out using DSC method. An impact of Gd 2 O 3 on thermal parameters such as transformation temperature (T g ), onset temperature of crystallization (T x ), peak crystallization temperature (T p ), change of specific heat (DC p ) and enthalpy of crystallization (DH) was determined. On the basis of thermal analysis, controlled crystallization was conducted. The glass-ceramic materials were identified by XRD. Crystallization kinetics of the glasses was made on the basis of two models: Kissinger and Ozawa. Changes of the glass structure were evaluated in FTIR study. It was determined that the addition of Gd 2 O 3 to the aluminosilicate glass increases the transformation temperature, simultaneously with reducing the Dc p and thermal stability DT values. It results in the decrease of DH. As shown, Gd significantly increases the crystallization activation energy of NaAlSi 3 O 8 . Complete substitution of Al 2 O 3 with Gd 2 O 3 leads to forming of Gd 9.33 (SiO 4 ) 6 O 2 . Forming of Na-silicates is not observed. Because of the participation of Gd in forming of fluoride phases (BaGdF 5 , GdF 3 ), crystallization of Gd 9.33 (SiO 4 ) 6 O 2 is impeded.

Investigation of Crystallization Kinetics of Na2ZnP2O7 Glass Using XRD and DTA Analysis

“…The crystallization mechanism parameters differ from glass to another one as noticed earlier. [ 50–52 ]…”

“…The crystallization mechanism parameters differ from glass to another one as noticed earlier. [50][51][52] In order to evaluate the relationship between the activation energy and the crystallized fraction X, analytical method of Kissinger-Akahira-Sunose (KAS) has been used as follows: [30,34] ln…”

Structural evolution, crystallization behaviour and mid-infrared emission properties in Yb/Ho codoped oxyfluoride germanosilicate glass ceramics with varied Si/Ge ratio

“…The lower Si-O bond strength and higher Ge-O bond strength can also result in similar change between Si-O-Si(Al) bending vibration at around 710 cm -1 and Ge-O-Ge(Al) bending vibration at around 600 cm -1 . The band at around 453 cm -1 related to O-Si-O bending vibration gradually disappear with decreasing the Si content 25,26 . As shown in Fig.…”

“…The lower Si-O bond strength and higher Ge-O bond strength can also result in similar change between Si-O-Si(Al) bending vibration at around 710 cm -1 and Ge-O-Ge(Al) bending vibration at around 600 cm -1 . The band at around 453 cm -1 related to O-Si-O bending vibration gradually disappear with decreasing the Si content25,26 . As shown in Fig.4(b), there are no obvious changes in the FTIR spectra of G1 and GC1 sample, indicating that crystallization process has little impact on Si-O network in G1 sample because crystallization only occur in fluoride phase.…”

Metal salts as dopants for ZnO ceramics-thermogravimetry coupled with mass spectrometry studies

“…The important information from measurements by this technique is the temperature at which decomposition of additives (inorganic or organic) ends and what type of gases are released to the atmosphere during decomposition. Thermal analysis also allows to determine thermal stability of organic and inorganic materials [22,23]. Thermogravimetry was also applied to investigate thermal behaviour of different metal salts, including copper nitrates and acetates [24][25][26].…”