Narrow Results

The measurements of SbSCl_xI_1-x(x = 0.2) temperature dependent capacitance were carried out. The temperature of ferroelectric phase transition T_C ≈340 K was measured experimentally. T_C of SbSCl_xI_1-x was calculated theoretically in anharmonic and harmonic approximations. T_C was calculated in anharmonic approximation using temperature dependence of mean potential energy of Sb atoms as a function of the soft B_1u symmetry normal coordinate along c(z)-axis. Moreover, T_C was calculated in harmonic approximation using temperature dependence of vibrational thermodynamic functions (Helmholc free energy). T_C dependence from unit cell parameters a, b and from mixture composition x was carried out.

The temperature dependences of resistance, impedance and capacitance of semitransparent sensor having structure ITO/PTB7-Th:PC${}_{61}$BM/Graphene composite (semisurface type) were investigated. The transparency of the sensor was 58–60%. The dependences of the resistance, impedance and capacitance at different frequencies 100 Hz, 1 kHz, 10 kHz, 100 kHz and 200 kHz and temperature in the range of 23.8–80${}^{\circ }$C for the sensor were studied. It was observed that as the temperature increased from 23.8${}^{\circ }$C to 80${}^{\circ }$C, the resistance and impedance (at 1 kHz) of the samples decreased, on average, by a factor of 3.51 and 3.79, respectively. At same experimental conditions (1 kHz), the capacitances of the samples also decreased by a factor of 9.6. It was also noted that as frequency increased from 100 Hz to 200 kHz, the impedance of the sensor decreased by a factor of 21 and 12, at temperatures 24${}^{\circ }$C and 58${}^{\circ }$C, respectively. Under the same conditions, the capacitance decreased by a factor of 30 and 28, respectively. The temperature resistance coefficients were measured to be −1.31%/${}^{\circ }$C, −1.30%/${}^{\circ }$C, −1.27%/${}^{\circ }$C, −0.84%/${}^{\circ }$C, −0.72%/${}^{\circ }$C and −0.33%/${}^{\circ }$C for R, Z (100 Hz), Z (1 kHz), Z (10 kHz), Z (100 kHz) and Z (200 kHz), respectively. For capacitance measurement, the temperature capacitance coefficients were measured as −1.39%/${}^{\circ }$C, −1.38%/${}^{\circ }$C, −1.37%/${}^{\circ }$C, −1.36%/${}^{\circ }$C and −1.34%/${}^{\circ }$C, respectively. The semitransparent PTB7-Th- and PC${}_{61}$BM-based temperature sensor can be used for measurement of the temperature as a teaching aid in situations where visual control of illumination and light intensity is required.