Solid hydrogen storage materials: interstitial hydrides
Author: Lei Lei
Date: 28-03-2022
Objectives
Prepare MAPbX3 crystals for MuSR and impedance measurements using the method from Ref1.
Preparation
- Thermometer
- Sand bath
Solution preparation
- Chemical quantities
| CH3NH3PbI3 | PbI2 | CH3NH3I | GBL |
| Quantity | 6.915 g | 2.385 g | 10 mL |
| CH3NH3PbBr3 | PbBr2 | CH3NH3Br | DMF |
| Quantity | 4.5876 g | 1.3996 g | 10 mL |
The actual quantities of chemicals used are shown in Fig.1.
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| Fig.1 The setup of crystal growth apparatus using sand bath within the glovebox. |
- Temperatures
- GBL has a maximal solubility for MAPbI3 precursors at 60 °C1, and the solution is prepared and filtered under 60 °C.
- DMF has a maximal solubility for MAPbBr3 precursors at room temperature.
Filtration
The precursor solutions were filtered with a 0.22-0.25 μm PVDF syringe filter (Fig.2).
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| Fig.2 Photograph of the syringe filter used. |
Crystal growth
Apparatus
The crystal growth used the retrograde solubility of MAPbX3 precursors as reported in Ref1. The apparatus setup is shown in Fig.3 which used sand bath instead of oil bath.
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| Fig.3 The setup of crystal growth apparatus using sand bath within the glovebox. |
Clean vials
The vials were cleaned by detergent and deionised water.
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| Fig.4 The cleaned vials to be used for the growth of MAPbX3 crystals. |
MAPbBr3 growth
First trial
The temperature of the sand bath was 87.5 °C as shown in Fig.5.
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| Fig.5 The cleaned vials to be used for the growth of MAPbX3 crystals. |
A MAPBr seed was added to the filtered precursor solution before the growth. The temperature rose to 89 °C at the beginning of crystal growth (19:40).
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| Fig.6 Photograph of vials immersed in the sand bath for the growth of MAPbBr3 crystals from the precursor solution. |
The temperature was too high for growth, a lot of small crystallites form. The vials were taken out for overnight to allow the dissolve of these crystallites. A lower temperature was set for another trial.
The second go
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| Fig.7 Photograph of the crystallites formed due to the fast nuleation. |
The sand bath temperature was down to 75 °C and the vials containing the precursor solutions were placed into the bath.
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| Fig.8 Photograph of vials immersed in the sand bath (75 °C) for the growth of MAPbBr3 crystals from the precursor solution. |
The temperature decreased to ~ 72 °C the second morning.
For Further growth the temperature was increased to 82 °C.