Modeling the Thermal Decomposition of Solids on the Basis of Lattice Energy Changes

Croix, Annemarie de La; English, Robin B.; Brown, Michael E.; Glasser, Leslie

doi:10.1006/jssc.1998.7747

Cited by 11 publications

(2 citation statements)

References 10 publications

(10 reference statements)

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“…16 We stated therein that (i) the activation energy for decomposition (E dec ) and (ii) the stability of the incipient nuclei of the metal oxide determine the ease of decomposition. 16,34 Figure 8 shows the variation of activation energy with different extent of Zn substitution, obtained from differential Friedman isoconversional analysis (see Supporting Information, Figure S5). Notably, the activation energy of solid solution with X Zn ≈ 0.17 and 0.25 shows a tremendous decrease of activation energy of parent peroxides (Table S1), apparently making the corresponding peroxy-bond cleavage easier.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Tuning the Oxygen Release Temperature of Metal Peroxides over a Wide Range by Formation of Solid Solutions

et al. 2014

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Metal peroxides, with a labile peroxy bond, constitute a distinct class of inorganic compounds that can generate singlet oxygen species and works as versatile reagents in many important industrial processes such as in polymer initiation reactions. Even after several decades after their discovery, the number of metal peroxides yet is few and their utility is severely limited by the corresponding decomposition temperatures (T dec ), which cannot be tuned to suit the most desirable condition for a particular reaction. One way of overcoming this would have been to obtain solid solutions of two peroxides with different decomposition temperatures. Surprisingly, in contrast to the vast majority of extended solids such as the oxide, hydroxide, and perovskite families, solid solutions of metal peroxides have remained so far nonexistent. Here, we explore and demonstrate that peroxides of Zn and Mg, ZnO 2 (T dec ∼ 200°C), and MgO 2 (T dec = 300°C) can form solid solutions in the entire solubility range. Importantly, the decomposition temperatures of the solid solutions lie between that for the constituent phases and changes the composition systematically. These findings provide the first genuine chemical system that can potentially be tuned to decompose at different predesigned temperatures to generate reactive oxygen species. ■ INTRODUCTIONMetal peroxides constitute an industrially important family of compounds due to their ability to produce reactive oxygen, 1 their usefulness as polymer initiator, 2−4 their prospect as active energy storage material 5−8 and at the same time, for being relatively safe as compared to organic peroxides. 9−11 To be useful in their applications, the control over the decomposition of the peroxy linkage is of utmost criticality, as this leads to the release of the reactive oxygen species. In their role as radical initiators in various polymer processing, the choice of a metal peroxide is based upon its decomposition temperature (T dec ). This is primarily because the follow-up processes for curing and the degree of polymer cross-linking is dependent upon it. 2−4 These apart, recent discoveries have shown tremendous scope for tuning of T dec of these materials in novel applications. First, for instance, Bruce and co-workers in their pioneering work have demonstrated that regulating the breaking/reforming of a peroxy linkage can radically improve the performance of high energy-density batteries. 7 Second, it has been recently shown that metal peroxide can be utilized as recyclable reagents for C−H activation reactions, which often otherwise require stringent conditions. 12 Therein too, the effectiveness of the process relies on the peroxide T dec . The dependence of their utility upon T dec , which for particular metal peroxides is fixed, 13 has severely limited the operating temperature windows for many industrial processes and the tuning of T dec for metal peroxides has remained an important research challenge for several decades. It may be recalled that borohydrides were another such rare fami...

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Section: ■ Results and Discussionmentioning

confidence: 99%

Tuning the Oxygen Release Temperature of Metal Peroxides over a Wide Range by Formation of Solid Solutions

et al. 2014

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“…However, since the ionic radius of Sr 2+ is smaller than that of Ba 2+ , Sr 2+ formed a shorter and stronger bondage with oxygen (Sr-O) than Ba 2+ (Ba-O). According to a report by de La Croix et al, 34 the lattice energy of Sr-O (À3240 kJ mol À1 ) is higher than that of Ba-O (À3021 kJ mol À1 ). In addition, due to the stronger electron attraction of Sr, the Ba-O bondage in Ba-O-Sr is slightly looser and longer when compared with that in Ba-O-Ba.…”

Section: Resultsmentioning

confidence: 94%

Preparation of single-phase three-component alkaline earth oxide of (BaSrMg)O: a high capacity and thermally stable chemisorbent for oxygen separation

et al. 2015

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This study presents a preparation method for a single-phase three-component alkaline earth oxide of (BaSrMg)O that is a high capacity and thermally stable chemisorbent for oxygen separation based on the redox reaction cycle of BaO + 1/2O 2 4 BaO 2 . First, single-phase (BaSr)CO 3 is co-precipitated based on the reaction of Ba 2+ and Sr 2+ with CO 3 2À in a solution, and then transformed to single-phase (BaSrMg) CO 3 with the addition of an Mg 2+ solution. When varying the reaction conditions, such as the reactant concentrations of Ba 2+ , Sr 2+ , Mg 2+ , and CO 3 2À and the reaction temperature, (Ba 0.52 Sr 0.06 Mg 0.42 )CO 3 crystals are identified as the most stable phase. The single-phase (BaSrMg)CO 3 is then converted into single-phase (BaSrMg)O by thermal decomposition under an H 2 atmosphere at 750 C. According to a TGA analysis, the chemisorption and desorption of oxygen in (BaSrMg)O are very fast at t 80 ¼ 3.9 min and t 80 ¼ 14 min, respectively. In addition, the chemisorption capacity of (BaSrMg)O is higher at 2.02 mmol g À1 at 700 C when compared with the chemisorption capacity of BaO/MgO at 1.75 mmol g À1 (Jin et al., Ind. Eng. Chem. Res., 2005, 44, 2942). (BaSrMg)O is also thermally stable due to the inclusion of Mg. Thus, the chemisorption capacity of (BaSrMg)O is unchanged, even over 10 redox reaction cycles. Additionally, the transient oxygen pressure required for the redox reaction of BaO-BaO 2 is shifted from 76 mmHg to 148 mmHg due to the inclusion of Sr in (BaSrMg)O. Consequently, the three component alkaline earth oxide (BaSrMg)O can be a highly effective sorbent for industrial applications to oxygen separation in terms of the process design and operation.

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