Hall coefficient measurements are conducted in order to measure the carrier concentration n and Hall mobility μ. The carrier concentration is calculated from the Hall coefficient RH, designated as RH=1/ne, where e is the electronic charge. The variation in n value of Ag2Se for cycling three times with temperature is shown in Fig. 3(b). It can be seen that n for Ag2Se shows little difference between heating and cooling cycle. Below the transition temperature (425K) a typical considerable increase in carrier concentration (Figure 3(b)) is observed, with value for the carrier concentration which goes from 1.69 × 1019 cm−3 (1st cycle), 0.84× 1019 cm−3 (2nd and 3rd cycle) up to 9.88 × 1019 cm−3, which can explain the semi-conductive behavior below the structure phase. In addition, carrier concentration decreases with cycling from 1st to 3rd below phase transition temperature.