TY - JOUR A1 - Heuser, Lina A1 - Nofz, Marianne A1 - Müller, Ralf T1 - Alkali and alkaline earth zinc and lead borate glasses: Sintering and crystallization N2 - Glasses in the systems Me2O-ZnO-B2O3 with Me = Li, Na, K, Rb (MeZB), Na2O-ZnO-CuO-B2O3 (NZCuB), CaO-ZnO-B2O3 (CaZB), and Li2O-PbO-B2O3 (LPbB) as a reference, were studied by differential thermal analysis, dilatometry, rotational viscometry, and heating microscopy. A decrease of viscosity and sintering range was found with decreasing number of fourfold coordinated boron. The viscosity of the alkali zinc borate glasses varies only slightly. LPbB and CaZB stand out by their reduced and increased viscosities, respectively. Sodium, potassium, and calcium zinc borate glasses possess a fragility above 76. All glasses were sintered to full density before crystallization. Mostly binary zinc borate phases govern crystallization. A ternary crystalline phase was detected only in the potassium containing sample. The Weinberg glass stability parameter ranges between 0.07 and 0.12. This is caused by the presence of several crystalline phases and varying melting points of even the same crystalline phase in different glass matrices. KW - Alkali zinc borate glasses KW - Lead borate glasses KW - Viscosity KW - Sintering KW - Crystallization KW - Fragility PY - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-556128 SN - 2590-1591 VL - 15 SP - 1 EP - 8 PB - Elsevier CY - Amsterdam AN - OPUS4-55612 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heuser, Lina A1 - Müller, Ralf A1 - Nofz, Marianne A1 - Deubener, J. T1 - Liquid phase sintering of alkali zinc borate glass-bearing silver pastes for applications in photovoltaics and microelectronics N2 - Liquid phase sintering of glass bearing silver pastes used in photovoltaics and microelectronics is poorly understood. In particular, the role of different network modifiers acting in the glass component and the question of the most suitable atmospheric oxygen level during sintering are still under considerable debate. To tackle these issues, low-melting and lead-free X2O-ZnO-B2O3 glasses with X = Li, Na, K and Rb (LZB, NZB, KZB and RZB) were prepared. Infrared spectroscopy showed that the glass structure was similar to each other, while an increase of tetrahedrally coordinated boron with increasing field strength of the alkali was evident. In turn, the glass transition temperature (from differential thermal analysis) increased in the order: RZB (449 °C) < KZB (460 °C) < NZB (465 °C) < LZB (472 °C). Powders of each glass were mixed with organics to receive silver-glass-pastes containing 30 vol% glass and these were subjected to heating microscopy in air. Although similar onset temperatures of sintering were recorded for Ag-NZB and Ag-LZB glass pastes, and for Ag-RZB paste and KZB-Ag-paste, respectively, differences in the crystallization behavior and final densification were observed between the former and the latter group. These were translated in terms of differences in silver dissolution and reprecipitation among the two groups. Further, running the experiments in nitrogen gas showed that sintering of all pastes was considerably hampered. The slow-down of the sinter kinetics was found to be in line with the assumed lower oxidation and dissolution of silver ions into the glass-forming liquid. T2 - 26th International Congress on Glass CY - Berlin, Germany DA - 03.07.2022 KW - Silver metallization paste KW - Sintering KW - Glass KW - Alkali zinc borate glasses KW - Viscosity KW - Structure PY - 2022 AN - OPUS4-55728 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -