Effects of high pressure on the electrical resistivity and dielectric properties of nanocrystalline SnO 2

Abstract

The electrical transport and structural properties of tin oxide nanoparticles under compression have been studied by in situ impedance measurements and synchrotron X-ray diffraction (XRD) up to 27.9 GPa. It was found that the conduction of SnO2 can be improved significantly with compression. Abnormal variations in resistivity, relaxation frequency, and relative permittivity were observed at approximately 12.3 and 25.0 GPa, which can be attributed to pressure-induced tetragonal- orthorhombic-cubic structural transitions. The dielectric properties of the SnO2 nanoparticles were found to be a function of pressure, and the dielectric response was dependent on frequency and pressure. The dielectric constant and loss tangent decreased with increasing frequency. Relaxation-type dielectric behaviour dominated at low frequencies. Whereas, modulus spectra indicated that charge carrier short-range motion dominated at high frequencies.

Raman Fingerprint of Pressure-Induced Phase Transition in SnO2 Nanoparticles: Grüneisen Parameter and Thermal Expansion

“…Each Sn atom is centered around a cage of a slightly distorted oxygen octahedron. The expected zone center optical phonon modes are A 1g + A 2g + B 1g + B 2g + E g + A 2u + 2B 1u + 3E u . Out of these, four phonons (A 2u + 3E u ) are infrared-active, the other four (A 1g + B 1g + B 2g + E g ) are Raman-active modes, and the remaining ones (A 2g + 2B 1u ) are optically silent.…”

“…Upon decrease in size of SnO 2 NPs, disorder in the outer shell of NPs increases and affects the phonon spectra . Remarkably, NPs’ phase stability is size-dependent, and its properties are argued to be strongly influenced by defects and oxygen stoichiometry. − Furthermore, as pressure is a clean parameter, Raman study of these nanomaterials under compression could provide insight into their structural and thermal behavior. Inference on thermal behavior can be obtained from the mode Gruneisen parameters that directly contribute to the thermal expansion.…”

“…Interestingly, in SnO 2 NPs (finite size), their surface modifications due to truncation of the oxygen octahedral system resulted in a reduced coordination number of the Sn cation and acted as self-defect in terms of bridging and in-plane oxygen vacancies. These defects significantly influence the phonon spectral features of SnO 2 NPs. − …”

Spray Pyrolysis Deposition and Characterisation of Dielectric SnO2 Thin Films

“…For instance the pressure -resistance relationship of a pressure transducer could be attributed to decrease in thickness and accordingly the porosity of the sensing materials when pressure is applied. (Shen et al, 2018). In addition, the conductivity in metal oxides is considered to be through thermally assisted hopping transitions between spatially separated sites/particles.…”

Influence of Ramped Compression on the Dielectric Behavior of the High-Voltage Epoxy Composites

“…It was concluded that compression increased the dielectric constant and dissipation factor of all the composites. Shen et al [ 9 ] conducted a study on dielectric properties of SnO 2 under high pressure and found that the dielectric constant and loss tangent decreased with increasing frequency. Authors of [ 10 ] studied the effects of mechanical stresses on polymeric materials and concluded that all the critical phenomena, including a decrease of dielectric strength, electrical tree growth, accumulated damage, space charge accumulation, etc., in insulating polymer materials are significantly influenced by internal (residual) and external mechanical stresses.…”