Avaliação das características estruturais, morfológicas, magnéticas, termoresistivas e termoelétricas do microcompósito (NixZn1-xO)1-y (Ni50Mn37Sn10Cu3)y

Abstract

In this present study, the influence of adding the Ni50Mn37Sn10Cu3 alloy in varied proportions (y = 0, 2.5, 5, 10, 20, and 40) to a NixZn1-xO ceramic matrix (x = 0.05 and 0.1) was evaluated for the formation of a microcomposite. Zinc oxide (ZnO) arouses considerable interest due to its remarkable versatility, stemming from its unique physical and chemical properties. Doping ZnO with transition metals or incorporating it into composites are widely employed strategies to enhance its properties. However, a significant gap in academic literature is observed regarding studies involving the formation of composites with the Heusler alloy, representing an underexplored research area. The objective of this study is to evaluate the impact of including the Ni50Mn37Sn10Cu3 alloy in varied proportions (y = 0, 2.5, 5, 10, 20, and 40) in a NixZn1-xO ceramic matrix (x = 0.05 and 0.1), aiming at the formation of a microcomposite. Structural, morphological, magnetic, thermoresistive, and thermoelectric properties were investigated. The NixZn1-xO systems were synthesized through the combustion reaction method. The microcomposites (NixZn1-xO)1-y ─ (Ni50Mn37Sn10Cu3)y were successfully prepared using a uniaxial pressing of 191.1 MPa for pellet fabrication, followed by sintering at 950°C. All samples of the Ni05 and Ni10 microcomposite classes exhibited a good linear relationship between the logarithm of electrical resistivity (lnρ) and the reciprocal of the absolute temperature (1000/T) at 300K-360K. The values of the constants A, B, and C are characteristic of NTC behavior, and their curves approximate the experimental data. The resistivity ρ305, and the coefficients β, α, and NF obtained from the thermistors are approximately 0.12 MΩcm to 8.9 MΩcm, 5026 K to 9780 K, 0.017 K-1 to 0.024 K-1, and 1.03 to 1.47, respectively. Furthermore, it is observed that lower values of β and a set of higher values of α, and low activation energies are obtained for the Ni10 class, where better thermoresistive properties are observed. The magnetic properties of the samples increased as the alloy addition content increased, ranging from 51.7 to 75 for Hc, 0.018 to 1.43 for Ms, and 2∙10-4 to 0.15 for Mr. The band gap values remained in the range of semiconductor materials with values from 2.23 to 2.77 eV. The magnetic, thermoelectric, and thermoresistive characteristics can be adjusted to the desired value by altering the content of Ni50Mn37Sn10Cu3 in the NixZn1-xO matrix. The results demonstrate the potential of the studied system for NTC performance materials, with magnetic and thermoelectric properties.