elements were adjusted using a stoichiometric proportion in which weights of lead pb tellurium te and sodium na were 9 8120 g 6 1658 g and 0 0222 respectively a total weight of all particles was 16 g all raw particles were mixed inside a carbon coated quartz tube in an ar filled glove box the tube was evacuated at a pressure of 10 u2212 4 torr and then sealed the tube was soaked at temperature of about 1023 k to about 1123 k for about 1 5 hours to about 2 5 hours heated to temperature of about 1223 k to about 1323 k for about 5 5 hours to about 6 5 hours for melting and then slowly cooled to a temperature of about 923 k to about 1123 k for about 46 hours to about 50 hours as a result an obtained ingot was pulverized to a powder and then hot pressed at a temperature of 500 u00b0 celsius and at a pressure of about 90 mpa to about 110 mpa for about 0 8 hours to 1 2 hours samples were manufactured by a method including melting quenching and annealing followed by hot pressing element lead pb 3n alfa aesar element tellurium te 4n alfa aesar and element sodium na 99 95 alfa aesar were used as starting materials the weights of these elements were adjusted using a stoichiometric proportion.