A Story of Baking a Crystal
Preparing my sample before running an X-ray analysis. © private snapshot at HZB
Heating my samples in a furnace. © private snapshot at HZB
An X-ray diffractometer, a powerful tool used for the analysis of the crystal lattice. © private snapshot at HZB
Once upon a time, I was a kid who loved doing home experiments and unravel the explanation behind everyday phenomena. This passion and curiosity helped me to land up here in Berlin to work on the growth of crystalline materials at the wonderful campus of Helmholtz-Zentrum Berlin. But unlike many other stories, mine starts with an introductory question: What makes growing crystals fun and also challenging?
To understand the world, we use the scientific method to rationalise our observations and develop a theory to justify them. This is basically what scientists do every day, and for this to succeed, we need to communicate information as fast and as concisely as possible. My childhood recipe book served exactly that purpose. I used to keep track of the different ways my sister used to bake cakes. The right ingredients, the right amount of water, and the right temperature were all crucial for baking the perfect, tasty cake. If there was a certain mess-up while using the oven or if I added too much salt to the batter, it would become a disaster.
Just as baking a good cake has the right steps and a recipe book, the same goes for crystals. My project explores the synthesis of crystalline powder using the "Solid-State Synthesis" method. This is a method that produces our desired crystal compound by promoting the precursor ingredients through cycles of repeated heating and cooling. For my synthesis I needed to heat my reactants in many grinding batches again and again.
Heating cycles again and again
Baking a cake at the perfect temperature so that it is neither overcooked nor undercooked is a challenge. The same goes for crystals, but with extra steps.
The temperatures are higher, the process takes longer, and instead of an oven, we use a muffle furnace. So, for my samples, I need to heat them over and over again, also taking into consideration the molecular impurities ready to ruin my samples.
Those impurities troubled me while carrying out my synthesis. To check whether I was on the right track, I always needed to characterize my samples.
XRD to the rescue!
To check that my structural phases were right, I used the XRD machine, aka the X-ray diffractometer. Even with its daunting name, this instrument became a friend in my journey. The XRD serves a similar purpose as the intuitive perception while baking which helps to recognise when the texture of the cake is right to be called a cake. It hits the sample with strong X-rays from a tube (with an approximate voltage of 40–60 kV), and the reflected X-rays are detected, giving us signal peaks. With the guidance of my supervisor, I checked these peaks and matched them with the reported peaks. This also helped me troubleshoot impurities and other mess-ups.
A new beginning after the end
In conclusion, all this troubleshooting and playing the detective game to synthesize (bake) the right crystal lattice was surely a challenge. But the art of figuring out the right phases and the rightful matching of the experimental peaks with our theoretically calculated data makes the game of cooking interesting.
This comes to the end of my story, from helping my sister back at home bake sweet cakes to this experience. But as my favourite quote by T.S. Eliot summarizes:
“What we call the beginning is often the end. And to make an end is to make a beginning. The end is where we start from.”
- The Art of the UnknownThe first major challenge was facing my own initial lack of knowledge. Suddenly, I found myself surrounded by entirely new protocols: what can be touched with gloves, what is strictly glove-free, and how to safely move items through the space. As I did not fully know how new equipment operates, getting startled when something goes off-routine is inevitable.
- Special prize by Jugend Forscht awarded to former school internShaoxuan Wang has won a special prize in the Jugend Forscht competition for her project ‘Smart Capsules – intelligent microcapsules for glucose-dependent insulin release’. She designed the project as a “special achievement” for her A-levels. To carry out the experimental work, Shaoxuan was able to spend a further two weeks in the laboratory at the HZB Institute for Electrochemical Energy Storage, where she had completed a school internship two years earlier.
- A Maki, a Sensor and an XPS MachineIn Peru, I am part of a research project focused on developing sensors that can detect acetone. The samples were fabricated by members of our research group using different thin layers and thermal treatments. My task is to understand what happened to their surface during this process and how these changes may affect their performance as sensors.