![]() ![]() The two discovered radium (and later, polonium), sharing the 1903 Nobel Prize in Physics with Henri Becquerel. (Jacques became a professor of mineralogy at the University of Montpellier.) His new wife replaced his brother as his scientific partner. He became a professor of physics and chemistry at Paris in 1895. Pierre married Marie the following year, when he also finally completed his doctorate, thanks to her encouraging him to use his magnetism work as a doctoral thesis. “I think in them are questions that deal with physics.” “I must admit that those spiritual phenomena intensely interest me,” he wrote to his fiancée, Marie Sklodowska, in 1894. He even flirted with paranormal spiritualism as the 19th century drew to a close, attending séances with famed medium Eusapia Palladino, approaching them as a scientific experiment with detailed observational notes, in hopes that such study would shed light on magnetism. Another discovery was the Curie point: the critical temperature at which ferromagnetic materials cease to be ferromagnetic. Pierre moved on to investigating magnetism, uncovering an intriguing effect of temperature on paramagnetism now known as Curie’s law. Many automobiles today have ultrasonic transducers to assist drivers in measuring the distance between the rear bumper and any obstacles in its path. This set the stage for subsequent development of practical applications for such materials, beginning with sonar in 1917, when Paul Langevin developed an ultrasonic transducer for use on submarines using thin quartz crystals. More importantly, it rigorously defined the 18 possible macroscopic piezoelectric coefficients in crystal solids. ![]() In 1910, Woldemar Voigt published the definitive treatise on the subject, Lehrbuch der Kristallphysik, a massive tome describing the 20-odd classes of natural crystal with piezoelectric properties. But incremental progress was still being made. Piezoelectricity could indeed work in the other direction.Īfter the initial flurry of excitement died down, piezoelectric research faded into the background for the next 30 years or so, in part because the theory was so mathematically complex. The brothers rushed to test Lippman’s theory, and their experiments showed the mathematician was correct. The following year, mathematician Gabriel Lippman demonstrated that there should be a converse piezoelectric effect, whereby applying an electric field to a crystal should cause that material to deform in response. There was a twist to the piezoelectric saga still to come. The brothers put their discovery immediately to good use by inventing the piezoelectric quartz electrometer. ![]() The strongest piezeoelectric effects were found in quartz and Rochelle salt. As a result, the Curies found that when such materials were compressed, the mechanical strain did indeed result in an electric potential. Armed with the crudest of materials - tinfoil, glue, wire, magnets, and a simple jeweler’s saw - they tested various types of crystals, including quartz, topaz, cane sugar, Rochelle salt, and tourmaline. They expected that a piezoelectric effect would arise in materials with certain crystal asymmetries. The brothers Curie thought there would be a direct correlation between the potential generated by temperature changes and the mechanical strain that gave rise to piezoelectricity. But experimental confirmation proved elusive. This effect had been known since the mid-18th century, thanks to the work of Carl Linnaeus and Franz Aepinus, and subsequent scientists had hypothesized that there could be a relationship between the properties of mechanical stress and electrical potential. They were especially interested in the pyroelectric effect, in which a change in temperature in a crystalline material generates an electric potential. Pierre started conducting chemistry experiments at the age of 20 with Jacques, focusing on the structure of crystals. During this time, he earned a meager living as a lab instructor. He successfully earned the equivalent of a master’s degree by 18, but was forced to postpone his doctoral studies. Pierre showed an early aptitude for mathematics, and at 16 entered the Sorbonne for his university studies. It was discovered by none other than French physicist Pierre Curie, working with his older brother Jacques, who found that putting pressure on these materials created electricity (the name comes from piezein - Greek for “squeeze”).īorn in Paris in 1859 to a physician named Eugene Curie, Pierre’s early education was decidedly unorthodox: his father opted for private tutors for his son, believing it to be the best approach given the boy’s temperament and keen intellect. Microphones, quartz watches, and inkjet printers all rely on an unusual phenomenon known as the piezoelectric effect found in various crystals, ceramics, and even bone. Brothers and colleagues: Jacques (left) and Pierre (right) Curie, discoverers of the piezoelectric effect. ![]()
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