PDF Publication Title:
Text from PDF Page: 041
1. INTRODUCTION The hysteresis in thermal dependence of resistivity in PrNiO3 was explained as a gradual transition from metallic to insulating phase. The transition occurs between 130 K (TMI) and around 74 K. Between 130-102 K a metallic matrix with nonmetallic inclusions is present, and between 102-74 K is more transition- ing to nonmetallic matrix with metallic phase inclusions. This behaviour was consistent to the first-order character of the transition. The Seebeck coefficient measurements indicated that in both states the majority of carriers are of electron character(35). For bulk NdNiO3 the found hysteresis was from about 130 K to MIT at 205 K(36). The Seebeck coefficient measured for high temperatures is negative and has a small absolute value of about 22 μV/K at 205 K which indicates a typical metallic state with electron-like charge carriers. The Seebeck coefficient was used to determine the Fermi energy, with using the relaxation time approximation π2k2 g(ε) S(T) = − T[ ∂ 3e n ∂ε ε=EF withg(ε)beingdensityofstates,n-chargecarrierdensity,EF -Fermienergy,and τ(ε) ∼ εα - energy-dependent relaxation time, with α corresponding to scattering mechanism. Another assumptions included parabolic band and for the case in article the α = −1. This lead to a Drude model relation of the Seebeck coefficient S(T) = −π2k2 T . (1.15) 6e EF For the metallic region, the estimated Fermi energy was found 0.41 eV for NNO, 0.4 for PNO and 0.21 for LNO. Typical metals have a higher Fermi en- ergy - for example Cu 7 eV and Au 5.5 eV (63). But the energy is also higher if the relaxation time is energy independent. Here as well, at low temperatures the Seebeck coefficient was negative suggesting that the majority of carriers is electron-like. However below 110 K its absolute value decreases that for the au- thors was an indication that dominant mechanism is not semiconductor-like or that some regime of charge compensation is present. The characteristic tempera- tures of the coefficient’s temperature dependence are a bit shifted as compared to resistivity. For Both quantities, on heating the absolute values are greater than on cooling. Additional characteristics of electronic structure were estimated as well based on the measurements. Density of states at the Fermi level g(EF ) was estimated by assuming • a parabolic band, 20 + ln(τ(ε)) ], (1.14)PDF Image | Investigation of metal-insulator transition in magnetron sputtered samarium nickelate thin films
PDF Search Title:
Investigation of metal-insulator transition in magnetron sputtered samarium nickelate thin filmsOriginal File Name Searched:
Bilewska_Investigation_of_metal_insulator_transition_in_magnetron_sputtered_samarium.pdfDIY PDF Search: Google It | Yahoo | Bing
Sulfur Deposition on Carbon Nanofibers using Supercritical CO2 Sulfur Deposition on Carbon Nanofibers using Supercritical CO2. Gamma sulfur also known as mother of pearl sulfur and nacreous sulfur... More Info
CO2 Organic Rankine Cycle Experimenter Platform The supercritical CO2 phase change system is both a heat pump and organic rankine cycle which can be used for those purposes and as a supercritical extractor for advanced subcritical and supercritical extraction technology. Uses include producing nanoparticles, precious metal CO2 extraction, lithium battery recycling, and other applications... More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)