In this paper, we report some physical properties of AgAlP 2 O 7 compound obtained through the standard solid-state reaction technique. AgAlP 2 O 7 has been studied by X-ray diffraction, Raman spectroscopy and impedance spectroscopy. The title compound crystallized at room temperature (T = 300 K) in the monoclinic system with P2 1/c space group. The electrical properties were studied over a wide range of temperature (440-640 K) in the frequency range of 40 Hz-10 MHz. Study of frequency dependence of AC conductivity suggests that the material obeys the Jonscher's universal dynamic law. The conductivity is equal to 9.37 9 10 -5 X cm -1 at 640 K, and it is thermally activated with activation energy of 0.76 eV. The variation of DC conductivity with temperature follows the Arrhenius behavior. The calculated values of s decreased with temperature. This behavior reveals that the conduction mechanism is correlated with barrier hopping. The binding energy W m and the hopping distance R x were deduced.

Rubidium aluminium diphosphate was synthesized by a conventional solid-state technique and its conduction properties determined by impedance spectroscopy.

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The KAlP 2 O 7 compound was prepared by conventional solid-state reaction technique. The structure is confirmed by X-ray powder diffraction. The frequency-dependent electrical properties of the sample were investigated in the temperature range of 528-668 K and in the frequency range of 209 Hz-5 MHz by impedance spectroscopy. The ac conductivity has been fitted and studied using Jonscher's equation, whose exponent s varied with the temperature, showing that the non-overlapping small polaron tunneling (NSPT) is the suitable model to describe the electrical conduction mechanism. The variation of dc conductivity suggests Arrhenius type. Besides, the modulus data were analyzed using the Kohlrausch-Williams-Watts (KWW) stretched exponential function. The peak positions ω m of the above spectra shifted towards higher frequencies with the increase in temperature. Moreover, the value of activation energy for the bulk obtained from the analysis of equivalent circuit (1.11 eV) and modulus relaxation (0.91 eV) confirms that the transport is not due to a simple hopping mechanism and that the ion transport is probably due to the hopping of K + ions along [101] tunnels direction. The thermodynamic parameters were also calculated.

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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.

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