Investigation of dielectric properties of a Li4Ti5O12 ceramic matrix for microwave temperature sensing applications

In this article, the dielectric properties of a Li4Ti5O12 (LTO) ceramic at the radio frequency (RF) and microwave (MW) regions were evaluated. X-ray diffraction showed that LTO was obtained without the presence of spurious and/or secondary phases. Complex impedance spectroscopy (CIS) analysis was conducted, whereas an activation energy (Ea) of 0.88 eV was observed. The temperature capacitance coefficient (TCC) was also calculated and demonstrated that LTO could be employed as a Class 1 ceramic capacitor. In the MW region, LTO presented ε’r = 25.4, tan δ = 5.7 × 10–4, and τf = -14.5 ppmºC−1, values that are interesting for devices that operate in the MW region. Numerical simulation demonstrated values of a realized gain of 4.78 dBi, a bandwidth of 227 MHz, and a radiation efficiency of 98%. Moreover, LTO was evaluated as a temperature sensor operating in the MW region and demonstrated a sensitivity of -0.06 MHz ºC−1. The values presented demonstrate that LTO could be employed in devices that operate in RF and MW regions.