Pierre Curie

Pierre Curie (1859–1906) was a French physicist who was co-awarded the Nobel Prize for Physics in 1903, with his wife Marie Curie, and Henri Becquerel, for their pioneering work on radioactivity, which included the joint discovery with his wife of radium and polonium. He also discovered piezoelectricity in work performed with his brother, Jacques Curie.

Early life

Pierre Curie was born in Paris on 15 May 1859 ³. Both his father, Eugène (1827-1910), and his grandfather, Paul Étienne François Gustave (1799-1853), were physicians, the latter working for a time in London, UK ¹.

Pierre was home-schooled for his early education. He graduated with a Licence in Physics (≡ Masters) from the Sorbonne in 1878. 

Piezoelectricity

Following graduation, he was employed by the Sorbonne as a laboratory demonstrator, where he collaborated with his brother Jacques (1856-1941), during which time they co-discovered piezoelectricity, which they first reported in 1880 ^3,4. The brothers demonstrated the "converse piezoelectric effect" in 1882 ³. They invented the quartz piezoelectrometer, which is thought to have been the first practical application of the piezoelectric effect. It was used by Marie Curie to measure the tiny charges generated by radium.

Their joint scientific endeavors ended in 1883 when Jacques was appointed as a lecturer in mineralogy in the South of France at the University of Montpellier.

In 1883, Pierre left the Sorbonne, to take a position at the École Municipale de Physique et de Chimie Industrielles - or the School of Physics for short – on Rue Lhomond in Paris (now called the École Supérieure de Physique et de Chimie Industrielles (ESPCI)). It was here that Pierre received his Doctorate in Science in 1895 ¹.

Polonium and radium

Pierre first met Marie Sklodowska (1867-1934) when she asked to undertake research in his laboratory at the School of Physics. They quickly bonded over a common enthusiasm for science, and they wed on 26 July 1895 ².

In 1898, Marie chose to investigate Henri Becquerel’s 1896 discovery of radioactivity for her doctorate. At this point, Pierre also focused his efforts on working with his wife. Unfortunately, it was not possible for Marie to find space at any local laboratories to undertake her research. Eventually space was found for her in the basement of Pierre’s School of Physics.

On first sight it would have been harder to find less propitious accommodation to perform cutting edge science. It was a medium sized shoddy wooden shed at one time used as a cadaveric dissection room for medical students. It had no real floor, an old rusty stove, dilapidated tables and a chalkboard. The roof was leaky such that water constantly dripped into the shed during rainy days and lacked adequate ventilation, becoming unbearably hot in the summer ².

Nevertheless, despite this severely limited workspace, the Curies performed trailblazing research here for four years from 1898 to 1902.

In 1898, Pierre switched from researching piezoelectricity and crystallography, to join his wife in her radioactive research. By this time she had already established some basic insights into the properties of radioactivity including the fact that the quantity of rays emitted by uranium correlated well with the quantity of uranium yet did not relate to the chemical structure of the uranium compound nor any external ambient conditions. She also discovered that the only other known element at that time that was also radioactive was thorium.

Marie found however that pitchblende ore, an impure form of uranium oxide, seemed to have much more radioactivity than would be expected from its extractable uranium content alone. She therefore deduced that another unknown substance must be present and accounting for it.

Thus, the Curies used multiple chemical techniques, such as fine grinding and fractional distillation to purify out this novel element. On 18 July 1898, the Curies announced in an article that they had succeeded in isolating an extract, strong in the element bismuth, in which a new radioactive substance resided. The name polonium was coined for this putative new element, named for her land of birth.

Continuing chemical purification processes by the Curies identified a second element, which they published about in December 1898. This second element was named radium due to its intense radioactivity, a factor of two million times more than uranium ²!

Whilst the Curies were convinced that they had identified two novel elements, they knew that to achieve formal scientific recognition they would need to create pure samples of the elements rather than impure extracts and establish their atomic weights through mass spectroscopy ⁷. For this endeavor they would require staggeringly large amounts of pitchblende as radium comprised only 0.000025% of the ore! Or in other words, 1,000 kg of pitchblende would realize ~25 grams of radium, although in practice considerably less than this due to losses during multiple purification stages.

At that time, the only source of pitchblende was from Bohemia, at that time under the jurisdiction of the Austrian government, who were kind enough to donate them 1 tonne of pitchblende as long as they could arrange its transit to Paris. Although it is estimated that over the lifetime of their project, over 500 tonnes of pitchblende were used ⁷!

For the next four years, the Curies toiled on this extraction project, and decided to separate out their efforts to maximize productivity. Pierre would study the chemical properties of the new substances, whilst Marie would lead the extraction and purification efforts. Finally, in 1902, the Curies were able to announce that they had managed to extract one-tenth of a gram of radium chloride from the ore.

In further work they demonstrated that radium was responsible for the production of a gas, the element radon, although the credit for its discovery goes to Friedrich Ernst Dorn, a German physicist, who identified it in 1900 ⁶.

Radium therapy

The Curies in collaboration with Becquerel also investigated the biological effects of radium. In 1900 German scientists announced that radium’s rays could damage the skin. In order to research this, Pierre Curie deliberately placed a small amount of radium on the skin of his inner forearm for a total of ten hours ¹. His skin experienced a sunburn-like reaction with a small focus of redness without any pain. After three weeks ulceration of the skin occurred, and by six weeks, the skin encircling the wound began to heal, eventually leaving a permanent grayish scar ¹.

Following on from further extensive researches in this area, the Curies introduced radium as a disease treatment in 1903 which was termed Curie therapy.

Later life

Pierre and Marie had two children, Irene (1897-1956) and Eve ¹. Irene was herself a Nobel Prize winner for chemistry in 1935 ¹. 

In 1903, the Curies shared the Nobel Prize for Physics with Becquerel for their radioactivity discoveries. It was in 1905 that Pierre Curie re-assumed his place at the Sorbonne when he was appointed a Professor in the Faculty of Sciences and was also elected to the Academy of Science.

On 19 April 1906, at the age of only 46 years, and soon after Pierre left a meeting of the Faculties of the Sciences in Paris, he was crossing the rue Dauphine in heavy rain when he was run over by a heavy wagon which crushed his skull killing him instantaneously. It is believed his sight was obscured by his umbrella ^1-3,7.

Accolades

• Nobel Prize for physics (1903)
• election to the French Academy of Sciences (1905)

Legacy

• Curie piezoelectrometer ^1,3,4,7
• Curie point ^1,3,4,7
  • temperature at which a substance’s ferromagnetism is lost and it becomes paramagnetic
  • temperature at which a substance’s normal piezoelectric properties are lost
• co-discovery of polonium
• co-discovery of radium
• radium therapy