Microwave-assisted hydrothermal synthesis followed by heat treatment: A new route to obtain CaZrO3

Abstract

CaZrO 3 nanoparticles were obtained by a new synthesis route: nucleation using the microwave-assisted hydrothermal method (MAH) and crystallization by heat treatment. Structural characterization by X-ray diffraction (XRD) was performed for the synthesized material and after heat treatment at 700, 800, 900, 1000 and 1200°C. At 800°C, the lakargite phase crystallization (CaZrO 3) starts and portions of the non-stoichiometric calciumzirconium oxide phase were observed by XRD and Raman spectroscopy. A residual CaCO 3 phase was present in the untreated samples. At 1200°C, the well-crystallized stoichiometric and non-stoichiometric mixed oxide phases of CaZrO 3 (crystallites of about 75 nm) were observed, along with particle agglomerates often in the micrometer range. The synthesized material was subjected to differential thermal analysis, which revealed carbonate degradation at approximately 695°C, resulting in a small loss of mass of 6%. An endothermic reaction at 85°C was observed for water loss, where there was a considerable amount of energy involved. This result showed the sensitivity to moisture absorption and adsorption processes of the CaZrO 3 sample, obtained by the MAH route. UV-Vis spectroscopy showed the characteristic gap energies for the two phases, which were 2.9 (non-stoichiometric) and 4.9 eV (stoichiometric), values smaller than those obtained by usual synthesis routes.

Investigation of thermal control in phase-changing ABO3 perovskites via first-principles predictions: general mechanism of emittance

“…9(a) shows the bandgaps of ANiO 3 (O- Pnma ) (A = Eu, Gd, Tb, Dy, Yb, La, Tm, Nd, Sm), EuBO 3 (O- Pbnm ) (B = Zr, Hf), EuTiO 3 (C- Pm 3̄ m ), DNbO 3 (O- Pnma ) (D = Ag, Ba, Ca, Sr, Eu, K, Na), SrTM 1 O 3 (C- Pm 3̄ m ) (TM 1 = Hf, Zr, Ti), KTaO 3 (C- Pm 3̄ m ), LaTM 2 O 3 (O- Pnma ) (TM 2 = Al, Sc, Fe, Cr, Ti, Ga, Co), SrTcO 3 (O- Pnma ), NaOsO 3 (O- Pbca ), MSnO 3 (R- R 3 c ) (M = Hg, Mg, Zn, Fe, Mn), NiSnO 3 (C- Pm 3̄ m ), SrNiO 3 (C- Pm 3̄ m ), BaSnO 3 (C- Pm 3̄ m ), CaSnO 3 (O- Pnma ), CoSnO 3 (O- Pnma ), TiSnO 3 (T- I 4/ mcm ), MnTiO 3 (R- R 3 c ), PbTiO 3 (T- I 4/ mcm ), CaZrO 3 (O- Pnma ), and BaFeO 3 (C- Pm 3̄ m ). As can be seen, there is good agreement in the bandgaps between our calculations and the experimental data and other reported HSE06 and G 0 W 0 data, 31–52 which demonstrates the accuracy of our method.…”

Synthesis and in situ ion irradiation of A-site deficient zirconate perovskite ceramics

“…CaZrO 3 presents at room temperature in the orthorhombic Pcmn (a À a À c + using Glazer notation 51 ), with CaZrO 3 reported to remain orthorhombic <2023 K prior to a transition to cubic symmetry. 52,53 SrZrO 3 takes the Pbnm (a À a À c + ) structure, with temperature induced phase transitions investigated by various groups. [54][55][56] Most recently Hasegawa et al 57 revisited the SrZrO 3 system and reported transitions to Ibmm (a À a À c 0 ) at 1042 K, I4/mcm (a 0 a 0 c À ) at 1119 K and to Pm 3m (a 0 a 0 a 0 ) at 1375 K. BaZrO 3 has the aristotype perovskite structure of Pm 3m (a 0 a 0 a 0 ), with no temperature related phase-transitions reported within the literature from 10 K to 1273 K. [58][59][60] Both space groups Pcmn and Pbnm are non-stand settings of Pnma (space group 62), however, within this work we refer to the most commonly used settings within the literature.…”

In Situ Capture and Conversion of CO2 to CO Using CaZrO3 Promoted Fe–CaO Dual-Functional Material

“…First, the Raman spectra of FC and CZ were studied as references under different temperatures (Figure a,b). In the CO 2 capture step, the Raman signal of the CZ sample showed a band at 711 cm –1 attributed to the vibrations of Zr–O bonds in CaZrO 3 . , Peaks for nonstoichiometric phase vibration modes, such as the peak at 141 cm –1 , were attributed to the CaZrO 3 phase . Peaks at 133, 240, and 694 cm –1 were ascribed to Fe–O vibrations in FC .…”

“…39,40 Peaks for nonstoichiometric phase vibration modes, such as the peak at 141 cm −1 , were attributed to the CaZrO 3 phase. 41 Peaks at 133, 240, and 694 cm −1 were ascribed to Fe−O vibrations in FC. 42 Moreover, the peak at 1079 cm −1 was attributed to the symmetric stretching of CO 3 2− on the CaO surface.…”