A shortage of "rare earth" metals, used in high-tech electronic devices, is hampering the growth of a number of technologies, U.S. experts say.

With the proliferation of technology, supplies of key elements -- particularly metals -- will be strained, they say.

Researchers at Yale University said they analyzed the usage of 62 metals or metalloids commonly found in popular technology such as smartphones. None of the 62 had alternatives that performed equally well, while 12 had no alternatives at all, researcher leader Thomas Graedel said.

Rare earth metals are expensive to mine and purify, and the processes often present serious environmental consequences, the researchers said.

Politics can be a factor, they said, citing China's decision in 2010 to restrict the export of many rare earth materials.

"As wealth and population increase worldwide in the next few decades, scientists will be increasingly challenged to maintain and improve product utility by designing new and better materials, but doing so under potential constraints in resource availability," the Yale researchers wrote in the Proceedings of the National Academy of Sciences.