Infra-red, NMR Spectroscopy and Transport Properties of Diphosphate NaAlP2O7

Abstract

The sodium aluminum diphosphate compound has been synthesized by the classic ceramic method and characterized by X-ray diffraction technique, IR, 31 P NMR, 23 Na NMR and impedance spectroscopy. It crystallizes in monoclinic space group P2 1/c . The MAS-NMR spectra showed two and one isotropic resonances relatives to 31 P and 23 Na, respectively, revealing the existence of two phosphorus and one sodium environments in the structure. The electrical properties of this compound have been measured in the temperature range from 523 to 673 K and the frequency range from 209 Hz to 5 MHz. The Nyquist plots are fitted to an equivalent circuit modeled by a combination series of two parallel (R//C) and (R//CPE). Impedance measurements show NaAlP 2 O 7 an ionic conductor being the conductivity 1.16 9 10 -5 Xcm -1 at 613 K and E a is 0.95 eV. The conductivity provide nearly the same activation energies for electrical relaxation of mobile ions revealing that transport properties in this material appear to be due to an ionic hopping mechanism dominated by the motion of the Na ? ions along [101] tunnels direction presented in the structure of the investigated material. The peak positions x p of M 00 spectra shift toward higher frequencies with increase in temperature.

Electrical properties, conduction mechanism and modulus of diphosphate compounds

“…9,10 We have previously reported the electrical properties of MAlP 2 O 7 (M ¼ K, Ag, Na) compounds. [11][12][13] In the study reported here, we investigated MAlP 2 O 7 , including its electrical and dielectric properties, using impedance spectroscopy to determine the conduction mechanism. MAlP 2 O 7 can be distinguished by its crystal structure.…”

Investigation of structural, thermal, and electrical characteristics of zirconium-doped lithium-phosphate glasses

“…The stretched exponent has a value of one for ideal Debye relaxation. The Bergman approach, which uses a modified KWW function [ 45 ], is used to determine this parameter using the following equation (17) : …”

Vibrational characteristics of aluminum–phosphate compounds by an experimental and theoretical approach

“…The samples were sintered according to the temperatures in Table 9 . Synthesis temperatures were selected according to 4 , 11 , 28 . Due to the high hygroscopicity of P 2 O 5, it must be synthesized in tightly closed containers.…”

“…Aluminum phosphates are present in many applications, for example in chemically bonded phosphate ceramics (CBPC) with alumina, dental cement, refractory binders, composite materials, and glass–ceramics 1 – 10 . Pyrophosphates containing aluminum and monovalent cations, such as NaAlP 2 O 7 , can be used as solid electrolytes for batteries, piezoelectric and ionic conductors 11 – 13 . Furthermore, NaAlP 2 O 7 with different doped rare earth ions has potential application in white light emitting diodes (WLEDS) 14 , 15 .…”