A New High-Resolution X-ray Powder Diffractometer Working in the 3-470 K Range for Phase-Transition Analyses

A high-resolution X-ray powder diffractometer is described with a source operating from 3 to 470 K. The optical design and mechanical arrangement of the diffractometer and the cryostat are optimized to provide easy (re)alignment procedures and high accuracy when the wavelength, the sample or the temperature is changed. The apparatus has been tested for peak-position accuracy, angular sensitivity and resolution (using standard materials). The tests assess the overall performance of the instrument, which is comparable to (or slightly better than) the best commercial instruments, but clearly excels over them because these performances are the same over the whole temperature range (3-470 K), allowing very accurate determination of the lattice parameters and crystal structure.