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Item Specific heat measurements in pure and in (Cu, Mn, Fe, Ni)-doped single-crystals of l-arginine phosphate monohydrate(2010) Machado, Fernando Luis de Araujo; Sousa, Lázaro Luis de Lima; Cunha, R. O.; Cabral, F. A. O.; Rodrigues, Alexandre Ricalde; Carvalho, Jesiel Freitas; Santana, Ricardo Costa deThe influence of highly diluted impurities (Cu, Mn, Fe, Ni) on the temperature (T) dependence of the specific heat (cp) of l-arginine phosphate monohydrate (LAP) was investigated in the temperature range 1.8–300 K. The doped samples yielded values for cp in excess to those obtained for a pure LAP sample. The melting temperatures (Tm≈420 K) obtained by differential scanning calorimetry for pure and doped LAP samples were found not to be significantly affected by the impurities. The T-dependence of cp was fully accounted for by taking into consideration the Debye contribution, an Einstein term and a contribution due to both Frenkel and Schottky defects. The model fit all cp versus T data using a single value for both the Debye (θD=160 K) and the Einstein (TE=376.8 K) temperatures, and for the energy (εd=157.9 meV) required to create the defects.