Structural, morphological, dielectric properties, impedance spectroscopy and electrical modulus of sintered Al6Si2O13–Mg2Al4Si5O18 composite for electronic applications

Abstract

In this study, the sol-gel method of low-temperature synthesis was utilized to create mullite/cordierite precursor powder. The materials (TEOS) Si(C2H5O)4, Al(NO3)3.9H2O and Mg(NO3)2 were utilized as source of SiO2, Al2O3, and MgO oxides respectively in order to create mullite/cordierite precursor gel with various concentrations and designations (MC00, MC10, MC20, MC30, MC40, and MC50). Crystalline phases were seen and described using scanning electron microscopy (SEM) and powder X-ray diffraction (XRD). After the powder was formed at 1600 °C for an hour, its sintering was looked at. For all mixes, as the cordierite concentration rises, the bulk density rises and the open porosity decreases. The existence of a vitreous phase may be the cause of the rise in bulk density and reduction in open porosity seen with rising temperatures.The dielectric characteristics of the samples have been examined at room temperature; the relative dielectric constant (εr), loss tangent (tanδ), and dielectric characteristics were assessed at frequencies of 0.1 Hz, 1, 10, 100, and 1000 kHz. At 1 kHz, the relative dielectric constant values are closest to those of mullite (εr = ∼5 to ∼ 6), and c at 1 kHz. On the other hand, the lowest dielectric losses were observed (tanδ from ∼0.06 to ∼ 0.04). The Electrical properties, electrical resistivity, AC conductivity, impedance spectroscopy, electrical modulus, and the relative quality factor (QF) of pure mullite and mullite/cordierite composite sintered at 1600 °C for 1 h (MCyy) samples were investigated as a function of cordierite content at varied frequencies (0.01 Hz, 1 kHz, 100 kHz, and 1000 kHz). The hardness (HV) and coefficient of thermal expansion (CTE) of the composite material that underwent sintering at a temperature of 1600 °C were determined by the use of a hardness tester and a dilatometer, respectively. The rise in temperature, coupled with an equal quantity of cordierite, resulted in an elevation of the apparent density and a reduction in the open porosity. In the case of the specimen subjected to sintering at a temperature of 1600 °C, the introduction of cordierite content in the range of 0–40% resulted in an observed rise in HV value from 9.15 to 12.99 GPa. However, a further increase in cordierite content to 50% led to a decrease in HV value to 10.99 GPa. Nevertheless, the CTE value throughout the temperature range of 50–1200 °C exhibited a consistent decline, ranging from 5.37 × 10−6 to 2.32 × 10−6 K−1. Notably, the composite material consisting of 50 wt% cordierite had elevated HV and the most minimal CTE value.