TY - JOUR
T1 - Thermal, structural, optical, and dielectric properties of (100 -x)Li 2B 4O 7 - X(BaO-Bi 2O 3-Nb 2O 5) glasses and glass-nanocrystal composites
AU - Karthik, C.
AU - Varma, K. B.R.
PY - 2007/3
Y1 - 2007/3
N2 - Transparent glasses in the system (100 - x)Li 2B 4O 7 - x(BaO-Bi 2O 3-Nb 2O 5) (x = 10, 20, and 30) were fabricated via the conventional melt-quenching technique. The amorphous and glassy characteristics of the as-quenched samples were established by the differential thermal analyses (DTA) and X-ray powder diffraction (XRD) studies. Glass-nanocrystal composites (GNCs) i.e., the glasses embedded with BaBi 2Nb 2O 9 (BBN) nanocrystals (10-50 nm) were produced by heat-treating the as-quenched glasses at temperatures higher than 500°C Perovskite BBN phase formation through an intermediate fluorite-like phase in the glass matrix was confirmed via XRD and transmission electron microscopic (TEM) studies. The optical transmission properties of these GNCs were found to have a strong compositional (BBN content) dependence. The refractive index (n = 1.90) and optical polarizability (α o. = 15.3 × 10 -24 cm 3) of the GNC (x = 30) were larger than those of as-quenched glasses. The temperature dependent dielectric constant (Er) and loss factor (D) for the glasses and GNCs were determined in the 100-40 MHz frequency range. The Er was found to increase with increase in heat-treatment temperatures, while the loss of the glass-nanocomposites was less than that of as-quenched glasses. The sample heat-treated at 620°C/1 h (x = 30) exhibited relaxor behavior associated with a dielectric anomaly in the 150-250°C temperature range. The frequency dependence of the dielectric maximum temperature was found to obey the Vogel-Fulcher relation (E a = 0.32 eV and T f = 201 K).
AB - Transparent glasses in the system (100 - x)Li 2B 4O 7 - x(BaO-Bi 2O 3-Nb 2O 5) (x = 10, 20, and 30) were fabricated via the conventional melt-quenching technique. The amorphous and glassy characteristics of the as-quenched samples were established by the differential thermal analyses (DTA) and X-ray powder diffraction (XRD) studies. Glass-nanocrystal composites (GNCs) i.e., the glasses embedded with BaBi 2Nb 2O 9 (BBN) nanocrystals (10-50 nm) were produced by heat-treating the as-quenched glasses at temperatures higher than 500°C Perovskite BBN phase formation through an intermediate fluorite-like phase in the glass matrix was confirmed via XRD and transmission electron microscopic (TEM) studies. The optical transmission properties of these GNCs were found to have a strong compositional (BBN content) dependence. The refractive index (n = 1.90) and optical polarizability (α o. = 15.3 × 10 -24 cm 3) of the GNC (x = 30) were larger than those of as-quenched glasses. The temperature dependent dielectric constant (Er) and loss factor (D) for the glasses and GNCs were determined in the 100-40 MHz frequency range. The Er was found to increase with increase in heat-treatment temperatures, while the loss of the glass-nanocomposites was less than that of as-quenched glasses. The sample heat-treated at 620°C/1 h (x = 30) exhibited relaxor behavior associated with a dielectric anomaly in the 150-250°C temperature range. The frequency dependence of the dielectric maximum temperature was found to obey the Vogel-Fulcher relation (E a = 0.32 eV and T f = 201 K).
KW - Dielectric properties
KW - Glass-ceramics
KW - Layered perovskites
UR - http://www.scopus.com/inward/record.url?scp=34249689585&partnerID=8YFLogxK
U2 - 10.1166/jnn.2007.210
DO - 10.1166/jnn.2007.210
M3 - Article
C2 - 17450867
AN - SCOPUS:34249689585
SN - 1533-4880
VL - 7
SP - 1006
EP - 1013
JO - Journal of Nanoscience and Nanotechnology
JF - Journal of Nanoscience and Nanotechnology
IS - 3
ER -