The Thermal Properties And Electrical Transport Properties Of Tin-silver-zinc Alloys And Intermetallic Compounds

Tin-silver-zinc alloy is a new type of Tin alloys. Because of its environmental friendly and wide applications in the electronics industry, it has attracted widespread attention. However, so far there has not been any systematic study on its physical properties. The Sn_96.5-xAg_3.5Znx (x=1, 1.5, 2) samples and its intermetallic compounds (Ag3Sn and AgZn samples) were prepared by vacuum arc melting. X-ray diffraction, differential scanning calorimetry and physical property measurement system were used to measure the structure, melting point, thermal properties and electrical transport properties of the sample.Sn₍96.50Ag_3.5 sample consists of Sn and Ag3Sn, while the Sn_96.5-xAg_3.5Znx (x=1, 1.5, 2) sample consists of Sn, Ag3Sn and AgZn, and the characteristic peaks of AgZn phase increase with increasing Zn doping. The melting point of Sn_96.5-xAg_3.5Znx (x=1, 1.5, 2) samples are 508 K, 502 K and 504 K, respectively, which is stable with increasing dopeing concentration. The phonon specific heat deviates from Debye model at low temperature range (exits Boson peak), this is because of the existence of local vibration (Einstein vibration). Resistivity in the whole temperature range can be explained by the Matthiessen law, indicating that the electron-phonon scattering plays a major role in conducting mechanisms. The temperature of 160 K is a cutoff point of the thermal conductivity, above this temperature the electronic thermal conductivity plays a dominant role, which meets the Wiedemann-Franz law, while below this temperature the phonon thermal conductivity plays a leading role. The dependences between the Seebeck coefficient and the temperature of Sn95.5Ag_3.5Zn1 and Sn94.5Ag_3.5Zn2 samples show similar regulations. Temperature coefficients of Seeback coefficient is positive at low temperature, and becomes negative at high temperature.Ag3Sn sample is single phase, and its trend of the phonon specific heat is similar with that of tin-silver-zinc samples, deviating from Debye rule in the low temperature range because of the existence of local vibrational (appears Boson peak). Its Einstein temperature is lower than that of the tin-silver-zinc samples, indicating that after adding Zn in Sn₍96.50Ag_3.5 alloy, the intensity of the Einstein vibration will be enhanced. For low temperature resistivity (below 60 K), the quantum interference term between electron impure scattering and electron-phonon scattering plays a major role in couducting mechanisms, however in the high temperature area, the quantum effects is weakened with increasing temperature, and the electron-phonon scattering becomes a dominant factor.