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A Simple Synthesis, Characterization, Kinetics and Thermodynamics of Zinc Ammonium Phosphate, ZnNH4PO4


Zinc ammonium phosphate (ZnNH4PO4) was synthesized via a simple precipitation method at room temperature. Thermal decomposition of ZnNH4PO4 occurred through five stages related to the deamination (1st and 2nd steps) and deprotonated hydrogen phosphate (3rd, 4th, 5th steps) reactions and its final decomposed product at above 600 °C was zinc pyrophosphate (to γ-Zn2P2O7). ZnNH4PO4 and γ-Zn2P2O7 samples were analyzed by XRF, XRD, FT-IR and SEM techniques, which are significant for the further treatments. Kinetic parameters (Ea, A) and thermodynamic functions (ΔH*, ΔS* and ΔG*) calculated on well-known equations have been used to support for five thermal transformation processes, reported for the first time. The kinetic results indicate that the intramolecular dehydration of the protonated hydrogen phosphate groups (3rd, 4th, 5th steps) need higher-energy pathways than the deammonium reactions (1st and 2nd steps) because of harder reactions, more difficulties and lower rates. Additionally, thermodynamic results reveal that all thermal reactions are endothermic and non-spontaneous processes. The obtained data may be useful for industrialists and academicians to apply these zinc phosphates for large roles in industrial applications.


The mineral dittmarite group is mineral and well-known formula as metal ammonium phosphate compound MNH4PO4·nH2O, where M is divalent metal such as Mg, Mn, Fe, Cu, Ni, Co, and Zn, and n = 0–12 [1,2,3,4], which was first described by Debray in the nineteenth century [1]. In the first time, this mineral group was used as slow release fertilizers that give macro- (nitrogen, phosphorus) and micro- (all divalent metal) nutrient elements [5,6,7]. Nowadays, many metal ammonium phosphate compounds have been synthetized by humans for many applications such as fertilizers, fireproof materials, pigment for paints, furnishes for protection of metals, and for extraction of divalent cations from seawater [8,9,10]. In addition, these compounds are decomposed to advanced compounds, metal pyrophosphates M2P2O7 (M: Mg, Mn, Fe, Cu, Ni, Co, and Zn) at elevated temperature (> 800 °C) [11,12,13,14,15,16]. The extensive applications of these metal pyrophosphate compounds have been reported as catalysis, ion exchange, proton conductivity, intercalation chemistry, photochemistry, and chemistry materials, cathode materials for lithium ion battery, ceramic pigments, and magnetic materials [10,11,12].

ZnNH4PO4·nH2O (n = 0–7), a crucial compound in dittmarite group has many significant potential applications and was used as the important precursor for the synthesis of Zn2P2O7 and LiZnPO4 [13]. Consequently, there were many researches on synthesis of ZnNH4PO4·nH2O (n = 0–7) such as many precipitation methods with mixing of an aqueous solution containing stoichiometric proportion of ammonium dihydrogen phosphate and zinc salts (zinc sulfate, zinc chloride, or zinc acetate) at control conditions of temperature (40–100 °C), pH (7–9) and time period (2–24 h) [2, 14]. Whereas Zn2P2O7 had been generally synthesized by solid state reaction with long-term reaction (> 6 h) at high temperature (almost 1000 °C) [15, 16]. So far, these zinc salts have not been studied sufficient as lack information such as the thermal behavior, kinetic and thermodynamic properties related the subject of thermoanalytical studies [17,18,19]. These data are interesting also from the scientific viewpoint, because the heating of a zinc ammonium phosphate is associated complex reactions to transform to zinc pyrophosphate.

The objective of this work was to study on a simpler and farter procedure of zinc ammonium phosphate and zinc pyrophosphate. The prepared samples are identified by Kjeldahl, X-ray fluorescence (XRF), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) and Scanning electron microscopic (SEM) techniques, respectively. Non-isothermal kinetics and thermodynamics of thermal transformation of zinc ammonium phosphate to zinc pyrophosphate are presented for the first time. These results obtained from such studies can be directly applied in the further work for academic scientists and industrial researchers.

Experimental Procedure


In this study, Zn(NO3)26H2O (98.0 %, Local Chemie), NH4H2PO4 (> 99.0 %, Fluka) and NH4OH (85 %) were used as starting materials. For a winsome preparation operate to give ZnNH4PO4, 21.0 mL of 1 M NH4H2PO4 was added firstly into 6.0 g of Zn(NO3)26H2O, which were magnetically stirred at room temperature for 3 min, referred to solution A. After that, 20 mL of 2 M NH4OH was admixed into the solution A, which was stirred powerfully at room temperature for 15 min and then the white precipitates were occurred. For isolation process to obtain the white powder (ZnNH4PO4), the precipitates were filtered through a suction pump, cleaned with deionized water, dried at room temperature, and finally kept in desiccators. The final decomposed product, Zn2P2O7 seemed to occur at temperature of 550 °C (Fig. 1a). So that, the prepared sample was heated in a furnace at 600 °C for 2 h to get the white powder of Zn2P2O7. The preparation reaction of ZnNH4PO4 (1) and Zn2P2O7 (2) are shown below:

Fig. 1

TG (a) and DTG (b) curves of ZnNH4PO4 at the three heating rates (10 °C·min−1, 15 °C·min−1 and 20 °C·min−1)

Adjust pH 9 by NH4OH, room temperature for 30 min, % yield 87 %

$${\text{Zn}}\left( {{\text{NO}}_{ 3} } \right)_{ 2} 6 {\text{H}}_{ 2} {\text{O}}\left( {\text{s}} \right) \, + {\text{NH}}_{ 4} {\text{H}}_{ 2} {\text{PO}}_{ 4} \to {\text{ZnNH}}_{ 4} {\text{PO}}_{ 4} \left( {\text{s}} \right) + 2 {\text{NO}}_{ 2} \left( {\text{g}} \right) + 1/ 2 {\text{O}}_{ 2} \left( {\text{g}} \right) + 7 {\text{H}}_{ 2} {\text{O}}\left( {\text{l}} \right)$$

600 °C for 2 h in open air, % yield 97 %

$${\text{ZnNH}}_{ 4} {\text{PO}}_{ 4} \left( {\text{s}} \right) \to 1/ 2 {\text{Zn}}_{ 2} {\text{P}}_{ 2} {\text{O}}_{ 7} \left( {\text{s}} \right) + {\text{NH}}_{ 3} \left( {\text{g}} \right) + 1/ 2 {\text{H}}_{ 2} {\text{O}}\left( {\text{g}} \right).$$


Thermal analysis measurements (Thermogravimetry, TG; derivative Thermogravimetry, DTG; a Perkin-Elmer TGA Pyris 1) were used to indicate the decomposed steps of the prepared ZnNH4PO4 transformed to Zn2P2O7 product. Chemical contents were analyzed by XRF (X-ray fluorescence (XRF), Bruker S4 Pioneer) and Kjeldahl methods. X-ray powder diffraction using a D8 Advanced powder diffractometer (Bruker AXS, Karlsruhe, Germany) with Cu Kα radiation (λ = 0.1546 nm) was operated to check the structure and crystallite sizes of the prepared sample and its decomposed product and the crystalline sizes were evaluated by the Scherrer method [20]. A Perkin-Elmer Spectrum GX spectrometer was run to record the room temperature FT-IR spectra in the range of 4000–400 cm−1 with eight scans and the resolution of 4 cm−1. The shapes and morphologies were examined by SEM using Hitachi S4700 after gold coating.

Kinetic Study

The kinetic study used to discuss the thermal decomposition of ZnNH4PO4 was operated by TG/DTG measuring at 3 heating rates (β; 10 °C·min−1, 15 °C·min−1, and 20 °C·min−1). Activation energies (Ea) and of five steps of thermal decomposed reactions were estimated by well-known equations: Kissinger–Akahira–Sunose (KAS) (3), Flynn–Wall–Ozawa (FWO) (4) and Kissinger (5) [21,22,23], which can be estimated by the slopes of the plots. Pre-exponential factors (A) of five steps were calculated by Kissinger Eq. (5), which can be estimated by the Y-intercepts of the plots.

KAS equation:

$${ \ln }\left( {\frac{\beta }{{{\text{T}}^{ 2} }}} \right)\,\,\, = \,{ \ln }\,\left( {\frac{{{\text{AE}}_{\upalpha} }}{{{\text{Rg(}}\alpha )}}} \right) - \left( {\frac{{{\text{E}}_{\upalpha} }}{\text{RT}}} \right).$$

FWO equation:

$${ \log }\beta \,\, = \,{ \log }\,\left( {\frac{{{\text{AE}}_{\upalpha} }}{{{\text{Rg(}}\alpha )}}} \right) - - 2.315 - 0.4567\left( {\frac{{{\text{E}}_{\upalpha} }}{\text{RT}}} \right).$$

Kissinger equation:

$${ \ln }\left( {\frac{\beta }{{{\text{T}}^{ 2} }}} \right)\,\,\, = \,{ \ln }\,\left( {\frac{{{\text{AE}}_{\upalpha} }}{\text{R}}} \right) - \left( {\frac{{{\text{E}}_{\upalpha} }}{\text{RT}}} \right)$$

where g(α), R, T and α are the integral function of conversion or determination of the mechanism reaction model [24], the gas constant, the absolute temperature (K), and the extent of conversion (\(\alpha = \frac{{m_{i} - m_{t} }}{{m_{i} - m_{f} }}\); mi, mt, and mf are the initial, current, and final sample mass, at the moment of time t), respectively.

Thermodynamic Study

Thermodynamic functions [change of entropy (ΔS*/kJ·mol−1), change of enthalpy (ΔH*/kJ·mol−1) and Gibb’s free energy (ΔG*/kJ·mol−1)] for five thermal transformation steps of ZnNH4PO4 to Zn2P4O7 were computed by well-known thermodynamic equations [25, 26] according to:

$$\Delta H* = E_{\alpha } - RT_{p}$$
$$\Delta S^{*} \, = \,R\ln \left( {\frac{Ah}{{e_{\chi } k_{B} T_{P} }}} \right)$$
$$\Delta G* = \Delta H* - T_{p} \Delta S*$$

where e = 2.7183 is the Neper number; χ is the transition factor, which is the unity for monomolecular reactions; activated energy (Eα) and pre-exponential factors are obtained by using kinetic analysis of Kissinger equation, While kB, h and Tp are the Boltzmann constant, the Planck constant and the mean peak temperature of three DTG curves [27], respectively.

Results and Discussion

Synthesis and Characterization Results

The obtained XRF and Kjeldahl data show that the chemical content of the synthesized sample and its decomposed product found to be wt% of Zntotal:Ptotal:NH4+total; 36.66:17.38:9.88 and 42.93:21.35:0.00, which correspond to the mole ratio of 1.02:1.02:1.00 and 1.00:1.05:0.00, respectively. 14.95 wt% mass loss of the synthesized sample revealed by TG data relates with the elimination of water and ammonia molecules and the retained mass is of Zn2P2O7. These results confirm that the general formula: ZnNH4PO4 and Zn2P2O7 must be the synthesized sample and its decomposed product, respectively.

The TG/DTG experiments operated in air atmosphere at three heating rates (10 °C·min−1, 15 °C·min−1 and 20 °C·min−1) over the temperature range from 50 °C to 700 °C and the O2 flow rate of 100 mL·min−1 are displayed in Fig. 1 to be obtained the data for using the calculation of kinetic and thermodynamic parameters. The thermal transformation of ZnNH4PO4 to γ-Zn2P2O7 occurs through five stages [the deamination reactions (1st and 2nd stages) and intramolecular dehydration reactions of the protonated hydrogen phosphate group (3rd to 5th stages)]. Five mass loss regions shown on TG curve are observed in 70–110 °C, 170–300 °C, 320–390 °C, 400–450 °C and 470–550 °C, which are related with the individual five DTG peaks (105 °C, 170 380 °C, 460 °C and 505 °C). The mass loss percentages of 3.00 %, 6.09 %, 3.34 %, 1.84 %, and 0.68 % correspond to the eliminations of 0.31 mol NH3, 0.69 mol NH3, %, 0.27 mol H2O, 0.17 mol H2O and 0.06 mol H2O, respectively. The thermal decomposition of ZnNH4PO4 involving the deamination of the coordinated ammonium ion (1.00 mol NH4+) and the intramolecular dehydration of the protonated phosphate groups (0.50 mol H2O) are complex mechanisms and could formally be proposed as:

$${\text{ZnNH}}_{ 4} {\text{PO}}_{ 4} \left( {\text{s}} \right) \to {\text{ZnHPO}}_{ 4} 0. 6 9 {\text{NH}}_{ 3} \left( {\text{s}} \right) + 0. 3 1 {\text{NH}}_{ 3} \left( {\text{g}} \right)$$
$${\text{ZnHPO}}_{ 4} 0. 6 9 {\text{NH}}_{ 3} \left( {\text{s}} \right) \to {\text{ZnHPO}}_{ 4} \left( {\text{s}} \right) + 0. 6 9 {\text{NH}}_{ 3} \left( {\text{g}} \right)$$
$${\text{ZnHPO}}_{ 4} \left( {\text{s}} \right) \to \raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} {\text{ Zn}}_{ 2} {\text{P}}_{ 2} {\text{O}}_{ 7} 0. 4 6 {\text{H}}_{ 2} {\text{O}}\left( {\text{s}} \right) + 0. 2 7 {\text{H}}_{ 2} {\text{O}}\left( {\text{g}} \right)$$
$$\raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} {\text{ ZnHPO}}_{ 4} 0. 4 6 {\text{H}}_{ 2} {\text{O}}\left( {\text{s}} \right) \to \raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} {\text{ Zn}}_{ 2} {\text{P}}_{ 2} {\text{O}}_{ 7} 0. 1 2 {\text{H}}_{ 2} {\text{O}}\left( {\text{s}} \right) + 0. 1 7 {\text{H}}_{ 2} {\text{O}}\left( {\text{g}} \right)$$
$$\raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} {\text{ ZnHPO}}_{ 4} 0. 1 2 {\text{H}}_{ 2} {\text{O}}\left( {\text{s}} \right) \to \raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} {\text{ Zn}}_{ 2} {\text{P}}_{ 2} {\text{O}}_{ 7} \left( {\text{s}} \right) + 0.0 6 {\text{H}}_{ 2} {\text{O}}\left( {\text{g}} \right).$$

Four intermediate compounds (ZnHPO4·0.69NH3, ZnHPO4, ZnHPO4·0.46H2O, ZnHPO4·0.12H2O) and all mixing intermediates have been occurred in thermal transformation. The final product of the thermal decomposition at T > 550 °C is zinc pyrophosphate, Zn2P2O7. The thermal transformation result reported in this work is in agreement with other metal ammonium phosphates (isostructural compounds) in literatures [4, 9, 28,29,30].

The XRD patterns of the synthesized sample and its decomposition product are shown in Fig. 2. All detectable peaks of the synthesized sample obtained are indexed as the standard data of JCPDS # 220025 for ZnNH4PO4, which indicates monoclinic phase. The strong diffraction peak at 20.196° for 2θ is attributed to the layered structure of ZnNH4PO4 [31], from which an interlayer distance of 0.8785 nm can be calculated. The average crystallite size of 67 ± 11 nm was computed from X-ray line broadening of reflections (101), (110), (002), (− 211), (103) and (020), using the Scherrer equation (i.e., D = 0.89λ/βcosθ), where λ is the wavelength of X-ray radiation, D is a constant taken as 0.89, θ is the diffraction angle and β is the full width at half maximum (FWHM) [32]. However, characteristic diffraction peaks of the crystalline, ZnNH4PO4, disappeared when heated at 600 °C for 2 h, suggesting that its structure was destroyed and a new crystal compound, Zn2P2O7 was formed. Generally, crystal structures of Zn2P2O7 are in three forms as α-Zn2P2O7, β-Zn2P2O7, and γ-Zn2P2O7, which crystallize in monoclinic (space group I2/c), monoclinic (space group C2/m), and orthorhombic (space group Pbcm), respectively. The pattern of its final product calcined at 600 °C is indexed as the standard data of JCPDS # 491240 for γ-Zn2P2O7. The decomposed product of gamma type is different from previous reports because the different condition and synthesis method and the different condition of calcination of ZnNH4PO4 precursor may are caused [15, 16]. Similarly, calculation of ZnNH4PO4, the average crystallite size of 55 ± 9 nm for the calcined sample was estimated from X-ray line broadening of reflections (120), (113), (114), (043), (142), (026) and (136). Table 1 summarizes the crystallite sizes and lattice parameters of the synthesized ZnNH4PO4 sample and its decomposed γ-Zn2P2O7 product, which indicate that the lattice parameters are close to those of the standard data.

Fig. 2

FT-IR spectra of the synthesized ZnNH4PO4 and its decomposed Zn2P2O7 product

Table 1 Average crystallite sizes and lattice parameters of ZnNH4PO4 and Zn2P2O7 calculated from XRD data

The FT-IR spectra of the ZnNH4PO4 and Zn2P2O7 samples are shown in Fig. 3. The vibrational frequencies were assigned to the relations of the fundamental vibrating units; NH4+, PO43−, P2O74− and zinc oxide (Zn–O) bond and based on the previously reported literatures [33, 34]. Form the spectrum of ZnNH4PO4 (Fig. 3a), vibrational bands of NH4+ ion observed in the regions of 3188 and 1436 cm−1 are assigned to asymmetric stretching (νasNH4) and asymmetric bending (δasNH4) vibrations, respectively. In addition, two peaks of about 2872 cm−1 and 3044 cm−1 are assigned to a second overtone band and the combination band of asymmetric bending (2δasNH4) vibrations, respectively [35]. Vibrational bands of PO43− ion related to the ν2(PO43−), ν4(PO43−), ν1(PO43−) and ν3(PO43−) vibrational modes were observed in the regions of 370–400 cm−1, 450–600 cm−1, 900–1000 cm−1 and 1000–1200 cm−1, respectively. Weak band in FT-IR spectrum is observed at below 390 cm−1 according to Zn–O bonding vibration. Form the spectrum of Zn2P2O7 (Fig. 3b), the vibrational bands for stretching modes of the PO3 unit were found at 1180 cm−1 and 1044 cm−1. The asymmetric (νasPOP), symmetric stretching (νsPOP), asymmetric bending (δasPO3) and symmetric (δsPO3) bending vibrations of this sample were observed at 906 cm−1 and 754 cm−1, 607 cm−1 and 540 cm−1, respectively. Vibrational bands in the 400–230 cm−1 region were assigned to PO3 determination, rocking mode, POP deformations, and torsional and external modes. These observed vibrational frequencies for the calcined product are characteristic modes for the pyrophosphate group. Form characterization methods (chemical analysis, TGA, XRD and FT-IR), all obtained results show that the synthesized samples as ZnNH4PO4 and Zn2P2O7, which give good consistent confirmation.

Fig. 3

XRD patterns of the synthesized ZnNH4PO4 and its decomposed Zn2P2O7 product

Figure 4 shows the changing morphologies of ZnNH4PO4 and its decomposed product Zn2P2O7. The SEM micrograph of ZnNH4PO4 (Fig. 4a) plays many small and some large non-uniform microparticles and coalescence in aggregates of nonpolyhedral shaped crystals of different sizes in the range of 2–12 μm. The SEM micrograph of Zn2P2O7 (Fig. 4b) plays retexturing and roughness surface with large and small porosities.

Fig. 4

SEM micrographs of the synthesized ZnNH4PO4 (a) and its decomposed Zn2P2O7 product (b)

Kinetic and Thermodynamic Results

The kinetics section of this paper describes the rate of reaction and mechanism through activation energy (Ea), Pre-exponential factor (A), and reaction model [g(α)], which are sometimes called the kinetic triplet. Kinetics of thermal transformation reaction is described by various equations when special features of their mechanisms are taken into account. Figure 1 shows the TG curves of ZnNH4PO4 at three heating rates that the data were collected to calculate the values of kinetics and thermodynamic parameters according to the Eqs. 16. Table 2 summarizes the parameters obtained in this calculation, including kinetic parameters (Ea, A) and thermodynamic functions (ΔH*, ΔS* and ΔG*) for five steps. The obtained results of activation energies estimated from FWO, KAS and Kissinger methods are close to each other, so the yields are reliable [36, 37]. The activation energy value for deammonium reaction in the second step is higher than that in the first step, which indicated that the second step is harder than the first step because strong intermolecular interaction and the stable products are occurred. While the activation energy value for dehydration reaction of the protonated phosphate group in the fourth step is higher than those in the third and fifth steps, which indicated that the intermediate compound (Zn2P2O7·0.46H2O) is more stable than the other intermediate compounds occurred in each other step. Additionally, the activation energy values of the deammonium reactions are lower than those of dehydration reactions of the protonated phosphate group, which confirm that ammonium ion is easy loss than the water molecule. The similar results of the pre-exponential factors estimated by Kissinger method, which are used to measure the collision frequencies, reveal that the pre-exponential factors from higher to lower are found to be the fourth, fifth, third, second and first steps, respectively. The higher pre-exponential factor value is caused from much higher collision frequency.

Table 2 Kinetic and thermodynamic values for the thermal decomposition of ZnNH4PO4

The section on thermodynamics in this paper predicts progression of the reaction by change of entropy (ΔS*/kJ·mol−1), change of enthalpy (ΔH*/kJ·mol−1) and Gibb’s free energy (ΔG*/kJ·mol−1), which are tabulated in Table 2. In the theoretical terms of activated complexes or transition theory [38,39,40], positive and negative values of ΔS* refer a malleable activated complex that leads to a large number of degrees of freedom of rotation and vibration that is indicated to a “fast” stage and a highly ordered activated complex and the degrees of freedom of rotation as well as of vibration are less than they are in the nonactivated complex, corresponded to a “slow” stage, respectively. The entropy of activation values (ΔS*) for the first and second steps related the deammonium reactions are negatives, which indicate that the transition states have a lower degree of disorder than the respective initial states (ZnNH4PO4). It means that the corresponding activated complexes in the first and second steps have a higher degree of arrangement than the initial state and indicate ‘‘slow’’ stages. Whereas the entropy of activation values (ΔS*) for the third, fourth and fifth steps related the dehydration reactions are positives, which indicate that activated complexes are a lower degree of disorder or lower degree of arrangement (higher entropy) compared with the initial state and indicate “fast” stages. Therefore, the deammonium (1st and 2nd steps) and dehydration (3rd, 4th and 5th) reactions of the thermal decomposition of ZnNH4PO4 may be interpreted as ‘‘slow’’ and “fast” stages, respectively. For the change of enthalpy (ΔH*), positive values for all decomposition steps related with the deammonium and the dehydration reactions indicate endothermic processes. The relationship of activation energy (Ea) and change of enthalpy (ΔH*) of the five decomposition steps shows that the ΔH* value of the fourth dehydration step is higher than those of the other steps, which also results in the same effect in the ΔH* value and indicated that the fourth step needs a higher-energy pathway than the other steps. Finally, positive values of the change of Gibb’s free energy (ΔG*) for all decomposition steps indicate non-spontaneous processes, which need to be connected with the external energy. The ΔG* values indicate that the dehydration reactions (3rd, 4th, 5th steps) need higher-energy pathways than the deammonium reactions (1st and 2nd steps). On the basis of thermodynamic results, we can conclude that the dehydration steps of the protonated phosphate group are harder reaction, more intermolecular interaction and lower rate than the deammonium steps. The thermal mechanism, kinetics (Ea and A) and thermodynamics (ΔH*, ΔS*and ΔG*) parameters calculated for the decomposition reactions of ZnNH4PO4 by different methods and techniques were found to be compatible.


A rapid precipitation method at room temperature and short time period (15 min) was designed to successfully obtain zinc ammonium phosphate (ZnNH4PO4). ZnNH4PO4 has been decomposed via five steps related to the deammonium and the intramolecular dehydration reactions and was heated at 600 °C to get its final decomposed product, grammar zinc pyrophosphate (γ-Zn2P2O7). The obtained results of XRF, XRD, FT-IR and SEM techniques have been used to confirm the synthesized ZnNH4PO4 and γ-Zn2P2O7 samples, which give essential data for their further appliances. The well-known methods of the kinetics and thermodynamics were used to study on thermal transformation of ZnNH4PO4 to γ-Zn2P2O7 and the calculated results of thermodynamic functions and kinetic parameters are in consistent and are used to confirm the thermal mechanisms. The simple preparation method, kinetics and thermodynamics obtained in this work demonstrate important data for industrialists and academics to produce the zinc phosphates that play large part in industrial applications.


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This work is supported by King Mongkut’s Institute of Technology Ladkrabang [KREF146002].

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Correspondence to Banjong Boonchom.

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Baitahe, R., Boonchom, B. A Simple Synthesis, Characterization, Kinetics and Thermodynamics of Zinc Ammonium Phosphate, ZnNH4PO4. Int J Thermophys 41, 33 (2020).

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  • Kinetic
  • Rapid and simple precipitation
  • Thermodynamic
  • Zinc phosphates