Stability and Proton Conductivity of AlH2P3O10 nH2O under Various Water Vapor Pressures

Abstract

íXmOöC³ºjIP AlH 2 P 3 O 10 E nH 2 O mÀè«gÓéÄï`±Á« cDÀEìcE{R åw ¶YZp¤C1538505 sÚaeîê 461Stability and proton conductivity of AlH 2 P 3 O 10 EnH 2 O (n23) were investigated in the temperature range from 75 C to 150 C under various water vapor pressures. The hydrolysis from AlH 2 P 3 O 10 EnH 2 O to Al(H 2 PO 4 ) 3 started at 100 C under a relative humidity (RH) of 60÷, and further hydrolysis to AlPO 4 took place with increasing temperature and humidity. At 75 C, the original phase was maintained under saturated water vapor pressure. Conductivity measurements at 75 C (0÷RH98÷) and 100 C (0÷RH60÷) in dicated an abrupt increase in conductivity with increasing water content n in the range of n1.0 to 2.0 at both temperatures. The proton conductivity achieved a value s5.0~10 |3 SEcm |1 at 75 C and 98÷ RH. It is assumed that the proton conductivity in the crystal became larger by formation of continuous hydrogen bonding in AlH 2 P 3 O 10 EnH 2 O.

Proton conductivity of Al(H2PO4)3–H3PO4 composites at intermediate temperature

“…Similarly, it has been reported that AlH 2 P 3 O 10 ·nH 2 O has only one semicircle (C~4.58×10 − 11 F/cm) corresponding to bulk response at 75°C in 60% RH and only a 'spike' like response in 94% RH. This was explained by the increased surface conduction at high relative humidity since the total resistance decreases more than one order of magnitude after increase relative humidity from 60% to 94%RH [33]. It is almost certain that the conduction of Al(H 2 PO 4 ) 3 -H 3 PO 4 composites is dominated by protons as protons are the only ionic species that are likely to be mobile and there is no evidence to suggest electronic conduction from impedance measurements.…”

Effects of tin phosphate nanosheet addition on proton-conducting properties of sulfonated poly(ether sulfone) membranes

“…Isothermal desorption of water was measured at various external water-vapor pressures from 95% relative humidity (RH) to dry conditions (b 2% RH) at 130°C by using a pressure-resist thermogravimetric measurement system (Nihon Bell Co., Ltd.) in which the vapor pressure of water is controlled as previously described [30]. The RH was estimated by using the expression P H2O /P s where P H2O is the vapor pressure of water in the vessel and P s is the saturated water vapor pressure at 130°C.…”

Aluminum dihydrogen tripolyphosphate: Thermodynamic characteristics

“…x 2H 2 O were studied. Authors [8] showed that in vapor water above mentioned compound transfer first of all in Al(H 2 PO 4 ) 3 and then in AlPO 4 .…”

“…For the reason the compounds are applied in different fields of technique. In papers [1,3,5,8] the series of materials with composition M III H 2 P 3 O 10 x 2H 2 O (where M III =Al, Ga, Fe, Mn, V, Cr), which have layer structure, is examined. Aluminum dihydrogen tripolyphosphate which belongs to these classes of materials is already used as a new non-toxic white anticorrosive pigment for painting.…”

“…Consideration of literature papers showed that there are no data on thermodynamics of aluminum dihydrogen tripolyphosphate. In paper [8] the conductivity and stability of AlH 2 P 3 O 10…”