The heat capacity of LaPO4 and PrPO4 nanowhiskers

The heat capacity of monazite-type LaPO4 and PrPO4 nanocrystalline whiskers, with a diameter of 30 to 45 nm and length 1–1.5 μm, was measured by adiabatic and relaxation calorimetry. The essential difference in the heat capacity of nanowhiskers and bulk particle substances was observed only at a temperature above 100 K. The research revealed significant restrictions in the use of an adiabatic method (that uses helium as a heat-transfer gas) for measurements of nanoscale substances’ heat capacity, due to the considerable sorption of helium.