John Desmond Bernal was born on his family's farm, Brookwatson, on the Portumna road, near Nenagh Co Tipperary in 1901 and he lived there until 1922. He was one of the important pioneers of X-ray crystallography in the 20th century. His life and achievments are vividly dewscribed in Andrew Brown's excellent biography which has been reviewed in Nature. Link to Wikipedia. Four islands in antartica are called after him in recognition of his work on the structure of ice.
Kathleen Yardley was born in Newbridge, Co. Kildare in 1903. She married Thomas Lonsdale. She was the first person to use X-Ray crystallography to determine the structure of a covalent molecule, hexamethyl benzene (1929). The structure of hexachlorobenzene was simpler to deal with (1931). If you follow the links to these papers you will get some idea of the amount of work involved at a time when modern computers were not even imagined. A building on University of Limerick Campus is called after her and NUI Maynooth award the Lonsdale Prize to the top chemistry student. There are many links which describe her life and work on the internet.
Helen Megaw was born in Dublin (44 Northumberland Road) in 1907 and went on to study science at Cambridge and to do a Ph.D. with J.D. Bernal. She in a paper with Bernal laid the foundations for what is now known as hydrogen bonding. She later solved the structure of Perovskite and it was for her work on the crystal structure of "heavy" ice that an island in the antarctic was named Megaw Island in 1962.